.gitignore

@@ -1,3 +1,20 @@
-/bin
+# Build output.
-.clangd
+/bin/
+build/
+
+# Editor/IDE, whatever people use.
+.vscode/
+.idea/
+*.suo
+*.user
+*.clangd/
+compile_commands.json
+
+# For those messy OS'es that like to put files everywhere.
+.DS_Store
+
+# Misc.
 assets/design_doc.org
+.clangd
+*.swp
+*.db

CMakeLists.txt

@@ -1,30 +1,55 @@
 cmake_minimum_required(VERSION 3.16)
+project(bettola CXX C)
 
-project(bettola VERSION 0.1)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-# Let's use C++17?
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-# include directories..
+# === Sol2 ===
-include_directories(libbettola/include)
+include(FetchContent)
-include_directories(src)
+FetchContent_Declare(
+  sol2
+  GIT_REPOSITORY https://github.com/ThePhD/sol2.git
+  GIT_TAG v3.3.1
+)
+FetchContent_MakeAvailable(sol2)
 
-# Deps.
+# === Asio ===
-find_package(SDL3   REQUIRED)
+FetchContent_Declare(
-find_package(GLEW   REQUIRED)
+  asio
-find_package(OpenGL REQUIRED)
+  GIT_REPOSITORY https://github.com/chriskohlhoff/asio
+  git_TAG asio-1-36-0
+)
+FetchContent_MakeAvailable(asio)
 
-# Build our shared lib.
+# === SQLite ===
-add_subdirectory(libbettola)
+# Supress the developer warning for using Populate with declared content.
+# We need it because sqlite zip isn't a CMAKE project.
+cmake_policy(SET CMP0169 OLD)
+FetchContent_Declare(
+  sqlite_source
+  URL https://sqlite.org/2025/sqlite-amalgamation-3500400.zip
+  URL_HASH SHA256=1d3049dd0f830a025a53105fc79fd2ab9431aea99e137809d064d8ee8356b032
+  DOWNLOAD_EXTRACT_TIMESTAMP true
+)
+FetchContent_GetProperties(sqlite_source)
+if(NOT sqlite_source_POPULATED)
+  FetchContent_Populate(sqlite_source)
+  add_library(sqlite STATIC "${sqlite_source_SOURCE_DIR}/sqlite3.c")
+  target_include_directories(sqlite PUBLIC "${sqlite_source_SOURCE_DIR}")
+endif()
+# Revert policy to default.
+cmake_policy(SET CMP0169 NEW)
 
-# Will need to clean build each time you add a new file though -.-
+# === sqlite_modern_cpp (SQLite wrapper) ===
-file(GLOB_RECURSE SOURCES "src/*.cpp")
+FetchContent_Declare(
-add_executable(bettola ${SOURCES})
+  sqlite_modern_cpp
+  GIT_REPOSITORY https://github.com/SqliteModernCpp/sqlite_modern_cpp.git
+  GIT_TAG v3.2
+)
+FetchContent_MakeAvailable(sqlite_modern_cpp)
 
-target_link_libraries(bettola PRIVATE bettola_lib SDL3::SDL3 GLEW::glew OpenGL::GL)
+add_subdirectory(common)
-
+add_subdirectory(client)
-# Server executable.
+add_subdirectory(server)
-file(GLOB_RECURSE SERVER_SOURCES "srv/*.cpp")
-add_executable(bettola_server ${SERVER_SOURCES})
-target_link_libraries(bettola_server PRIVATE bettola_lib)

Makefile

@@ -1,46 +1,38 @@
-SHELL:=/bin/bash
+# Wrapper Makefile.
-BUILD_DIR:=bin
-PROJECT_NAME:=bettola
-EXECUTABLE:=$(BUILD_DIR)/$(PROJECT_NAME)
 
-CXX_COMPILER:=clang++
+# Build artifacts.
-CMAKE_MAKEFILE:=$(BUILD_DIR)/Makefile
+BUILD_DIR := bin
 
-.PHONY: all build config run clean help
+# Client path.
+CLIENT_EXE := $(BUILD_DIR)/client/bettolac
+# Server path.
+SERVER_EXE := $(BUILD_DIR)/server/bettolas
 
-# Default.
+.PHONY: all build config runc sp runs clean
+
+# Default target when running 'make'.
 all: build
 
-# Build project, if not configured, then do that first.
+build: config
-build: $(CMAKE_MAKEFILE)
+	@echo "=== Building Bettola. ==="
-	@echo "==== Building Bettola ===="
+	@$(MAKE) -C $(BUILD_DIR)
-	@cmake --build $(BUILD_DIR)
-
-# run 'config' target if the build directory or CMake cache is missing.
-$(CMAKE_MAKEFILE):
-	$(MAKE) config
 
 config:
-	@echo "==== Configuring Bettola with CMake ===="
+	@echo "=== Configuring Project. ==="
-	@mkdir -p $(BUILD_DIR)
+	@cmake -B $(BUILD_DIR) -S . -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-	@cmake -S . -B$(BUILD_DIR) -DCMAKE_CXX_COMPILER=$(CXX_COMPILER) -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
 
-# Build and run.
+runc: build
-run: all
+	@echo "=== Running Bettola Client. ==="
-	@echo "==== Running Bettola ===="
+	@$(CLIENT_EXE)
-	$(EXECUTABLE)
+
+sp: build
+	@echo "=== Running Bettola Client (Single Player). ==="
+	@$(CLIENT_EXE) -sp
+
+runs: build
+	@echo "=== Running Bettola Server. ==="
+	@$(SERVER_EXE)
 
-# Remove build dir.
 clean:
-	@echo "==== Cleaning Bettola ===="
+	@echo "=== Cleaning Build Directory. ==="
 	@rm -rf $(BUILD_DIR)
-	@echo "==== Project Cleaned ===="
-
-help:
-	@echo "Available commands:"
-	@echo "	make        - Build the project (default)."
-	@echo "	make build  - Build the project."
-	@echo "	make run    - Build and run the project."
-	@echo "	make config - Force CMake to re-configure the project."
-	@echo "	make clean  - Remove all build files"
-

README.org

@@ -1,35 +1,44 @@
-#+TITLE: Bettola Game
+#+TITLE: Working Title: Bettola
 
-A 2D RPG game and engine created with C++, SDL3, and OpenGL.
+A multiplayer hacking simulator with a graphical OS, built in C++ and OpenGL.
 
 * Dependencies
-The following dependencies are requird:
+The following dependencies are required:
  - A C++ compiler (e.g., clang, g++)
  - CMake (3.16 or newer)
  - SDL3 development libraries
+ - Asio networking library (managed by CMake)
  - GLEW development libraries
+ - FreeType development libraries
+ - Lua 5.4 development libraries
+ - sol2 (header-only, managed by CMake)
 
 ** Installation (Debian)
-You can install all required dependencies with the following command:
+You can install most required dependencies with the following command:
 #+BEGIN_SRC bash
 sudo apt update
-sudo apt install build-essential clang cmake libsdl3-dev libglew-dev
+sudo apt install build-essential clang cmake libsdl3-dev libglew-dev libfreetype-dev liblua5.4-dev
 #+END_SRC
 
 * Build Instructions
-This project uses a top-level Makefile to simplify the CMake workflow. All build artifacts will be placed in the =bin/= directory.
+This project uses a top-level Makefile to simplify the CMake workflow. Build
+artifacts will be placed in the =bin/= directory.
 
-Run the following from the root of the project directory.
+Simply run the following commands from the root of the project directory:
 
  - *Build the project:*
-   The executable will be located in =bin/bettola=.
    #+BEGIN_SRC bash
    make
    #+END_SRC
 
- - *Build and run the project:*
+ - *Build and run the client:*
    #+BEGIN_SRC bash
-   make run
+   make runc
+   #+END_SRC
+
+ - *Build and run the server:*
+   #+BEGIN_SRC bash
+   make runs
    #+END_SRC
 
  - *Clean the project:*
@@ -37,3 +46,53 @@ Run the following from the root of the project directory.
    #+BEGIN_SRC bash
    make clean
    #+END_SRC
+
+* Project Structure
+  The codebase is organised into three main components:
+  - =common/=: A shared library (=libbettola=) containing code used by both the
+    client and server.
+  - =client/=: The game client (=bettolac=), handles rendering, UI, and user input.
+  - =server/=: The game server (=bettolas=) manages game state and the world
+    simulation.
+
+* Planned Features
+  /Note: [X] indicates a feature that is currently in progress or complete.
+
+** Core Gameplay & Hacking
+   - [X] Custom-built graphical OS desktop environment.
+   - [X] Interactive terminal with command history and scrolling.
+   - [X] Draggable and focusable UI windows.
+   - [X] Local and remote virtual file systems (VFS).
+   - [X] Core filesystem commands (=ls=, =cd=).
+   - [X] Remote system connections via ingame =ssh= tool.
+   - [X] Network scanning tools to discover hosts, open ports, and running
+     services.
+   - [ ] A deep exploit system based on service versions (e.g., SSH, FTP, HTTP).
+   - [ ] Ability to find, modify, and write new exploits.
+   - [ ] Functionality to upload/download files to and from remote systems.
+   - [ ] Log cleaning utilities and other tools for covering your tracks.
+   - [ ] Social engineering through in-game email and websites.
+
+** The World
+   - [ ] Narrative-driven main storyline (serves as tutorial before the sandbox
+     world).
+   - [ ] Emergent gameplay arising from the interaction of world systems.
+   - [ ] A persistent, shared "core" universe of high-level NPC networks.
+   - [ ] A unique, procedurally generated "local neighbourhood" for each new
+     player.
+   - [ ] NPC factions and corporations with simulated goals and stock markets.
+   - [ ] Dynamic missions generated organically from the state of the world.
+   - [ ] Active NPC system administrators who patch vulnerabilities and hunt for
+     intruders.
+
+** Player Systems & Progression
+   - [X] Embedded Lua scripting engine for creating custom tools.
+   - [X] In-game code editor with syntax highlighting etc.
+   - [ ] Secure, sandboxed execution of player scripts with CPU/RAM as a
+     resource.
+   - [ ] An in-game internet with a web browser, email, and online banking.
+   - [ ] Online stores for purchasing virtual hardware, software, and exploits.
+   - [ ] The ability to purchase and upgrade dedicated servers.
+   - [ ] Hosting of player-owned services (web, FTP, etc.).
+   - [ ] Creation of custom websites using HTML and basic JS.
+   - [ ] Player-to-player secure messaging and file transfers.

assets/boot_messages.txt

@@ -0,0 +1,24 @@
+[  0.000000] Bettola version 6.1.0-bettola (dev@bettola)
+[  0.000000] Command line: BOOT_IMAGE=/vmbettola-6.1.0 ro quiet
+[  0.134589] ACPI: PM-Timer IO Port: 0x808
+[  0.345821] pci 0000:00:02.0: vgaarb: setting as boot VGA device
+[  0.345911] pci 0000:00:03.0: enp0s3: identified as [B77A:1337]
+[  0.582190] systemd[1]: Starting systemd-journald.service...
+[  0.621337] systemd-journald[218]: Journal started.
+[  1.123456] EXT4-fs (sda1): mounted filesystem with ordered data mode.
+[  1.567890] systemd[1]: Reached target Local File Systems.
+[  1.890123] systemd[1]: Starting systemd-logind.service...
+[  2.101122] systemd[1]: Starting NetworkManager.service...
+[  2.334455] NetworkManager[310]: <info>  [1678886400.123] NetworkManager (version 1.40.0) is
+starting...
+[  2.800100] enp0s3: Link is up at 1000 Mbps, full duplex.
+[  3.123456] systemd[1]: Reached target Network.
+[  3.500000] systemd[1]: Starting Bettola Daemon...
+[  3.600000] bettolad[420]: Initializing VFS...
+[  3.700000] bettolad[420]: Generating world...
+[  4.100000] bettolad[420]: World generation complete. Seed: 0xDEADBEEF
+[  4.200000] bettolad[420]: Listening on 0.0.0.0:1337
+[  4.500000] systemd[1]: Started Bettola Daemon.
+[  4.800000] systemd[1]: Reached target Multi-User System.
+[  5.000000] systemd[1]: Starting Graphical Interface.
+[  5.500000] bettolac-greeter: Starting display manager...

assets/menu_background_snippets.txt

@@ -0,0 +1,34 @@
+map -sV 10.0.2.15
+ls -la /etc/
+ps aux | grep 'sshd'
+gcc exploit.c -o exploit
+SELECT * FROM users;
+import requests
+while(true){};
+});
+sudo rm -rf /
+netstat -anp
+arp -a
+ssh root@192.168.1.1
+git commit -m 'Initial commit'
+hydra -l user -P wordlist.txt ftp://...
+Hello, world.
+All your base are belong to us
+// TODO: fix this later
+42
+1337
+zerocool
+acidburn
+cereal_killer
+ping -c 4 google.com
+traceroute 8.8.8.8
+</div>
+<a>
+password123
+GOD
+Have you tried turning it off and on again?
+Connection established.
+SYN/ACK
+Firewall breach detected.
+Decrypting /etc/shadow...
+root::0:0:root:/root:/bin/bash

assets/scripts/bin/build.lua

@@ -0,0 +1,27 @@
+-- /bin/build - "Compiles" a .lua file into an executable.
+local source_filename = arg[1]
+
+if not source_filename then
+  return "build: missing file operand"
+end
+
+-- Check for .lua extension.
+if not source_filename:match("%.lua$") then
+  return "build: input file must be a .lua file"
+end
+
+local current_dir = bettola.get_current_dir(context)
+local source_node = current_dir.children[source_filename]
+
+if not source_node then
+  return "build: cannot open '" .. source_filename .."': No such file"
+end
+
+if source_node.type ~= 0 then
+  return "build: '" .. source_filename .. "' is not a regular file"
+end
+
+local executable_filename = source_filename:gsub("%.lua$", "")
+local source_content = source_node.content
+
+return bettola.create_executable(context, executable_filename, source_content)

assets/scripts/bin/cat.lua

@@ -0,0 +1,19 @@
+-- /bin/cat - Concatenate files and print on stdout.
+local filename = arg[1]
+if not filename then
+  return "" -- No arguments, return nothing.
+end
+
+local current_dir = bettola.get_current_dir(context)
+local target_node = current_dir.children[filename]
+
+if not target_node then
+  return "cat: " .. filename .. ": No such file or directory."
+end
+
+if target_node.type == 1 then
+  return "cat: " .. filename .. ": Is a directory"
+end
+
+-- It's a file, return it's contents. :)
+return target_node.content

assets/scripts/bin/cd.lua

@@ -0,0 +1,7 @@
+-- /bin/cd - Change Directory.
+local target = arg[1]
+if not target then
+  return "" -- No argument, just return to prompt.
+end
+
+return bettola.cd(context, target)

assets/scripts/bin/echo.lua

@@ -0,0 +1,25 @@
+-- /bin/echo - Display contents of a text file.
+local content_parts = {}
+local filename = nil
+local found_redirect = false
+
+for i, v in ipairs(arg) do
+  if v == ">" then
+    found_redirect = true
+    filename = arg[i+1]
+    break
+  else
+    table.insert(content_parts, v)
+  end
+end
+
+if found_redirect then
+  if not filename then
+    return "echo: syntax error: expected filename after '>'"
+  end
+  local content = table.concat(content_parts, " ")
+  return bettola.write_file(context, filename, content)
+else
+  return table.concat(arg, " ")
+end
+

assets/scripts/bin/exit.lua

@@ -0,0 +1,6 @@
+-- /bin/exit - Disconnects from a remote session or cloes terminal window.
+if is_remote_session then
+  return bettola.disconnect(context)
+else
+  return bettola.close_terminal(context)
+end

assets/scripts/bin/ls.lua

@@ -0,0 +1,62 @@
+-- /bin/ls - Lists files in a directory.
+--
+-- Iterate over the 'children' map exposed via C++.
+
+local function format_permissions(perms)
+  local rwx = { "-", "-", "-", "-", "-", "-", "-", "-", "-" }
+  if(perms & 0x100) ~= 0 then rwx[1] = "r" end -- Owner read.
+  if(perms & 0x080) ~= 0 then rwx[2] = "w" end -- Owner write.
+  if(perms & 0x040) ~= 0 then rwx[3] = "x" end -- Owner execute.
+  if(perms & 0x020) ~= 0 then rwx[4] = "r" end -- Group read.
+  if(perms & 0x010) ~= 0 then rwx[5] = "w" end -- Group write.
+  if(perms & 0x008) ~= 0 then rwx[6] = "x" end -- Group execute.
+  if(perms & 0x004) ~= 0 then rwx[7] = "r" end -- Other read.
+  if(perms & 0x002) ~= 0 then rwx[8] = "w" end -- Other write.
+  if(perms & 0x001) ~= 0 then rwx[9] = "x" end -- Other execute.
+  return table.concat(rwx)
+end
+
+local function get_file_size(node)
+  if node.type == 0 then -- FILE_NODE.
+    return #node.content
+  else
+    return 0 -- Dirs don't have content size in this context.
+  end
+end
+
+local function ls_long_format(dir)
+  local output = {}
+  for name, node in pairs(dir.children) do
+    local line_type = (node.type == 1) and "d" or "-"
+    local perms = format_permissions(node.permissions)
+    local owner = node.owner_id
+    local group = node.group_id
+    local size  = get_file_size(node)
+    table.insert(output, string.format("%s%s %d %d %5d %s", line_type, perms, owner, group, size, name))
+  end
+  table.sort(output)
+  return table.concat(output, "\n")
+end
+
+local function ls_short_format(dir)
+  local output = {}
+  for name, node in pairs(dir.children) do
+    local display_name = name
+    if node.type == 1 then -- DIR_NODE
+      display_name = display_name .. "/"
+    elseif node.type == 2 then --EXEC_NODE
+      display_name = display_name .. "*"
+    end
+    table.insert(output, display_name)
+  end
+  table.sort(output)
+  return table.concat(output, "\t") -- Tab separated short format.
+end
+
+local current_dir = bettola.get_current_dir(context);
+
+if arg[1] == "-l" then
+  return ls_long_format(current_dir)
+else
+  return ls_short_format(current_dir)
+end

assets/scripts/bin/nmap.lua

@@ -0,0 +1,9 @@
+-- /bin/nmap - Network exploration tool and security/port scanner.
+local target_ip = arg[1]
+
+if not target_ip then
+  return "nmap: requires a target host to be specified"
+end
+
+-- TODO: Add args such as -sV for version detection etc.
+return bettola.nmap(context, target_ip)

assets/scripts/bin/rm.lua

@@ -0,0 +1,3 @@
+local file_to_remove = arg[1]
+if not file_to_remove then return "rm: missing operand" end
+return bettola.rm(context, file_to_remove)

assets/scripts/bin/scp.lua

@@ -0,0 +1,8 @@
+local source = arg[1]
+local destination = arg[2]
+
+if not source or not destination then
+  return "usage: scp source destination"
+end
+
+return bettola.scp(context, source, destination)

assets/scripts/bin/ssh.lua

@@ -0,0 +1,4 @@
+-- /bin/ssh - Connects to a remote host.
+local target = arg[1]
+if not target then return "ssh: missing operand" end
+return bettola.ssh(context, target)

assets/shaders/cloud.frag

@@ -1,85 +0,0 @@
-#version 330 core
-out vec4 FragColor;
-
-in vec3 TexCoords;
-
-uniform sampler2D u_CloudTexture;
-uniform vec3 u_SunPos;
-
-const float PI = 3.14159265359;
-
-/* Atmosphere parameters. */
-const float ATMOSPHERE_RADIUS     = 6520275.0;
-const float PLANET_RADIUS         = 6371000.0;
-const float RAYLEIGH_SCALE_HEIGHT = 8000.0;
-const float MIE_SCALE_HEIGHT      = 1200.0;
-
-/* Scattering coefficients. */
-const vec3 RAYLEIGH_SCATTERING_COEFF  = vec3(0.0000058, 0.0000135, 0.0000331);
-const vec3 MIE_SCATTERING_COEFF       = vec3(0.00002);
-
-/* Mie scattering parameters. */
-const float MIE_G = 0.76;
-
-/* Number of samples for ray marching. */
-const int SAMPLES = 16;
-const int LIGHT_SAMPLES = 8;
-
-float ray_sphere_intersect(vec3 origin, vec3 dir, float radius) {
-  float a = dot(dir, dir);
-  float b = 2.0 * dot(origin, dir);
-  float c = dot(origin, origin) - radius * radius;
-  float d = b * b - 4.0 * a * c;
-  if (d < 0.0) {
-    return -1.0;
-  }
-  return (-b + sqrt(d)) / (2.0 * a);
-}
-
-vec3 get_sky_color(vec3 dir) {
-  vec3 eye = vec3(0.0, PLANET_RADIUS + 1.0, 0.0);
-  float dist = ray_sphere_intersect(eye, dir, ATMOSPHERE_RADIUS);
-  vec3 totalRayleigh = vec3(0.0);
-  vec3 totalMie = vec3(0.0);
-  float stepSize = dist / float(SAMPLES);
-  for (int i = 0; i < SAMPLES; i++) {
-    vec3 p = eye + dir * (float(i) + 0.5) * stepSize;
-    float h = length(p) - PLANET_RADIUS;
-    float rayleighDensity = exp(-h / RAYLEIGH_SCALE_HEIGHT);
-    float mieDensity = exp(-h / MIE_SCALE_HEIGHT);
-    float lightDist = ray_sphere_intersect(p, normalize(u_SunPos), ATMOSPHERE_RADIUS);
-    float lightStepSize = lightDist / float(LIGHT_SAMPLES);
-    float opticalDepthLight = 0.0;
-    for (int j = 0; j < LIGHT_SAMPLES; j++) {
-      vec3 lp = p + normalize(u_SunPos) * (float(j) + 0.5) * lightStepSize;
-      float lh = length(lp) - PLANET_RADIUS;
-      opticalDepthLight += exp(-lh / RAYLEIGH_SCALE_HEIGHT) * lightStepSize;
-    }
-    vec3 transmittance = exp(-(opticalDepthLight * RAYLEIGH_SCATTERING_COEFF
-          + opticalDepthLight * MIE_SCATTERING_COEFF));
-    totalRayleigh += rayleighDensity * stepSize * transmittance;
-    totalMie += mieDensity * stepSize * transmittance;
-  }
-
-  float mu = dot(dir, normalize(u_SunPos));
-  float rayleighPhase = 3.0 / (16.0 * PI) * (1.0 + mu * mu);
-  float miePhase = 3.0 / (8.0 * PI) * ((1.0 - MIE_G * MIE_G)
-      * (1.0 + mu * mu)) / ((2.0 + MIE_G * MIE_G) * pow(1.0 + MIE_G
-      * MIE_G - 2.0 * MIE_G * mu, 1.5));
-  return 20.0 * (totalRayleigh * RAYLEIGH_SCATTERING_COEFF * rayleighPhase
-      + totalMie * MIE_SCATTERING_COEFF * miePhase);
-}
-
-void main() {
-  float u = atan(TexCoords.z, TexCoords.x) / (2.0 * PI) + 0.5;
-  float v = asin(TexCoords.y) / PI + 0.5;
-  float cloudAlpha = texture(u_CloudTexture, vec2(u,v)).r;
-
-  vec3 skyColor = get_sky_color(normalize(TexCoords));
-  vec3 cloudColor = mix(skyColor, vec3(1.0), smoothstep(0.5, 0.8, cloudAlpha));
-
-  float poleFade = 1.0 - abs(TexCoords.y);
-  float finalAlpha = smoothstep(0.0, 0.2, poleFade) * smoothstep(0.5, 0.8, cloudAlpha);
-
-  FragColor = vec4(pow(cloudColor, vec3(1.0/2.2)), finalAlpha);
-}

assets/shaders/cloud.vert

@@ -1,21 +0,0 @@
-#version 330 core
-layout (location = 0) in vec3 aPos;
-
-out vec3 TexCoords;
-
-uniform float u_Time;
-uniform float u_ScrollSpeed;
-uniform mat4 model;
-uniform mat4 view;
-uniform mat4 projection;
-
-void main() {
-  TexCoords = aPos;
-
-  /* Rotate texture coords around Y axis for scrolling. */
-  float angle = u_Time * u_ScrollSpeed;
-  mat3 rot = mat3(cos(angle), 0, sin(angle), 0, 1, 0, -sin(angle), 0, cos(angle));
-  TexCoords = rot * TexCoords;
-
-  gl_Position = projection * view * model * vec4(aPos, 1.0);
-}

assets/shaders/shape.frag

@@ -0,0 +1,8 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec3 ourColor;
+
+void main() {
+  FragColor = vec4(ourColor, 1.0);
+}

assets/shaders/shape.vert

@@ -0,0 +1,12 @@
+#version 330 core
+layout (location = 0) in vec2 aPos;
+layout (location = 1) in vec3 aColor;
+
+uniform mat4 projection;
+
+out vec3 ourColor;
+
+void main() {
+  gl_Position = projection * vec4(aPos.x, aPos.y, 0.0, 1.0);
+  ourColor = aColor;
+}

assets/shaders/simple.frag

@@ -1,50 +0,0 @@
-#version 330 core
-out vec4 FragColor;
-
-in vec3 FragPos;
-in vec3 Normal;
-in vec3 WorldPos;
-in float Detail;
-
-uniform vec3 objectColor;
-uniform vec3 lightColor;
-uniform vec3 lightDir; /* Normalised direction vector for the light source. */
-uniform bool u_IsTerrain;
-
-void main() {
-  vec3 finalColor;
-  vec3 norm = normalize(Normal);
-
-  /* Define colours for different terrain types. */
-  if(u_IsTerrain) {
-    vec3 grassColor1 = vec3(0.4, 0.6, 0.2);
-    vec3 grassColor2 = vec3(0.3, 0.5, 0.15);
-    vec3 rockColor = vec3(0.5, 0.5, 0.4);
-    vec3 steepColor = vec3(0.35, 0.3, 0.25);
-
-    /* Create patchy grass colur using the detail noise. */
-    float detailFactor = smoothstep(-0.2, 0.2, Detail);
-    vec3 finalGrassColor = mix(grassColor1, grassColor2, detailFactor);
-
-    /* Blend from grass to rock between height of 2.0 and 4.0. */
-    float heightFactor = smoothstep(2.0, 4.0, WorldPos.y);
-    finalColor = mix(finalGrassColor, rockColor, heightFactor);
-
-    /* Flat surface has a normal.y of 1.0. A steep slope is closer to 0. */
-    float slopeFactor = 1.0 - smoothstep(0.6, 0.8, norm.y);
-    finalColor = mix(finalColor, steepColor, slopeFactor);
-
-  } else {
-    finalColor = objectColor;
-  }
-
-  /* Standard lighting calculations. */
-  float ambientStrength = 0.4;
-  vec3 ambient = ambientStrength * lightColor;
-
-  float diff = max(dot(norm, normalize(-lightDir)), 0.0);
-  vec3 diffuse = diff * lightColor;
-
-  vec3 result = (ambient + diffuse) * finalColor;
-  FragColor = vec4(result, 1.0);
-}

assets/shaders/simple.vert

@@ -1,23 +0,0 @@
-#version 330 core
-layout (location = 0) in vec3 aPos;
-layout (location = 1) in vec3 aNormal;
-layout (location = 2) in float aDetail;
-
-out vec3 FragPos;
-out vec3 Normal;
-out vec3 WorldPos;
-out float Detail;
-
-uniform mat4 model;
-uniform mat4 view;
-uniform mat4 projection;
-
-void main() {
-  /* Pass position and normal vectors to the fragment shader in world space. */
-  FragPos = vec3(model * vec4(aPos, 1.0));
-  WorldPos = FragPos;
-  Normal  = mat3(transpose(inverse(model))) * aNormal;
-  Detail = aDetail;
-
-  gl_Position = projection * view * vec4(FragPos, 1.0);
-}

assets/shaders/sky.frag

@@ -1,80 +0,0 @@
-#version 330 core
-out vec4 FragColor;
-
-in vec3 v_WorldPos;
-
-uniform vec3 u_SunPos;
-
-const float PI = 3.14159265359;
-
-/* Atmosphere parameters. */
-const float ATMOSPHERE_RADIUS     = 6520275.0;
-const float PLANET_RADIUS         = 6371000.0;
-const float RAYLEIGH_SCALE_HEIGHT = 8000.0;
-const float MIE_SCALE_HEIGHT      = 1200.0;
-
-/* Scattering coefficients. */
-const vec3 RAYLEIGH_SCATTERING_COEFF = vec3(0.0000058, 0.0000135, 0.0000331);
-const vec3 MIE_SCATTERING_COEFF      = vec3(0.00002);
-
-/* Mie scattering parameters. */
-const float MIE_G = 0.76;
-
-/* Number of samples for ray marching. */
-const int SAMPLES       = 16;
-const int LIGHT_SAMPLES = 8;
-
-float ray_sphere_intersect(vec3 origin, vec3 dir, float radius) {
-  float a = dot(dir, dir);
-  float b = 2.0 * dot(origin, dir);
-  float c = dot(origin, origin) - radius * radius;
-  float d = b * b - 4.0 * a * c;
-  if (d < 0.0) {
-    return -1.0;
-  }
-  return (-b + sqrt(d)) / (2.0 * a);
-}
-
-void main() {
-  vec3 dir = normalize(v_WorldPos);
-  vec3 eye = vec3(0.0, PLANET_RADIUS + 1.0, 0.0);
-
-  float dist = ray_sphere_intersect(eye, dir, ATMOSPHERE_RADIUS);
-
-  vec3 totalRayleigh = vec3(0.0);
-  vec3 totalMie = vec3(0.0);
-
-  float stepSize = dist / float(SAMPLES);
-  for(int i = 0; i < SAMPLES; i++) {
-    vec3 p = eye + dir * (float(i) + 0.5) * stepSize;
-    float h = length(p) - PLANET_RADIUS;
-
-    float rayleighDensity = exp(-h / RAYLEIGH_SCALE_HEIGHT);
-    float mieDensity = exp(-h / MIE_SCALE_HEIGHT);
-
-    float lightDist = ray_sphere_intersect(p, normalize(u_SunPos), ATMOSPHERE_RADIUS);
-    float lightStepSize = lightDist / float(LIGHT_SAMPLES);
-    float opticalDepthLight = 0.0;
-    for(int j = 0; j < LIGHT_SAMPLES; j++) {
-      vec3 lp = p + normalize(u_SunPos) * (float(j) + 0.5) * lightStepSize;
-      float lh = length(lp) - PLANET_RADIUS;
-      opticalDepthLight += exp(-lh / RAYLEIGH_SCALE_HEIGHT) * lightStepSize;
-    }
-
-    vec3 transmittance = exp(-(opticalDepthLight * RAYLEIGH_SCATTERING_COEFF
-          + opticalDepthLight * MIE_SCATTERING_COEFF));
-      totalRayleigh += rayleighDensity * stepSize * transmittance;
-      totalMie += mieDensity * stepSize * transmittance;
-    }
-
-    float mu = dot(dir, normalize(u_SunPos));
-    float rayleighPhase = 3.0 / (16.0 * PI) * (1.0 + mu * mu);
-    float miePhase = 3.0 / (8.0 * PI) * ((1.0 - MIE_G * MIE_G)
-        * (1.0 + mu * mu)) / ((2.0 + MIE_G * MIE_G)
-        * pow(1.0 + MIE_G * MIE_G - 2.0 * MIE_G * mu, 1.5));
-
-    vec3 finalColor = 20.0 * (totalRayleigh * RAYLEIGH_SCATTERING_COEFF
-        * rayleighPhase + totalMie * MIE_SCATTERING_COEFF * miePhase);
-
-    FragColor = vec4(pow(finalColor, vec3(1.0/2.2)), 1.0);
-}

assets/shaders/sky.vert

@@ -1,13 +0,0 @@
-#version 330 core
-layout (location = 0) in vec3 aPos;
-
-uniform mat4 view;
-uniform mat4 projection;
-
-out vec3 v_WorldPos;
-
-void main() {
-  v_WorldPos = aPos;
-  vec4 pos = projection * view * vec4(aPos, 1.0);
-  gl_Position = pos.xyww;
-}

assets/shaders/text.frag

@@ -0,0 +1,11 @@
+#version 330 core
+in  vec2 TexCoords;
+in  vec3 ourColor;
+out vec4 color;
+
+uniform sampler2D text;
+
+void main() {
+  vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TexCoords).r);
+  color = vec4(ourColor, 1.0) * sampled;
+}

assets/shaders/text.vert

@@ -0,0 +1,15 @@
+#version 330 core
+layout (location = 0) in vec2 aPos;
+layout (location = 1) in vec2 aTexCoords;
+layout (location = 2) in vec3 aColor;
+
+out vec2 TexCoords;
+out vec3 ourColor;
+
+uniform mat4 projection;
+
+void main() {
+  gl_Position = projection * vec4(aPos, 0.0, 1.0);
+  TexCoords   = aTexCoords;
+  ourColor    = aColor;
+}

client/CMakeLists.txt

@@ -0,0 +1,25 @@
+file(GLOB_RECURSE CLIENT_SOURCES "src/*.cpp")
+# Explicitly list server sources needed for single-player to avoid main() conflict.
+set(SERVER_SOURCES
+  "../server/src/network_manager.cpp"
+  "../server/src/player.cpp"
+)
+
+add_executable(bettolac
+  ${CLIENT_SOURCES}
+  ${SERVER_SOURCES}
+)
+
+find_package(SDL3 REQUIRED)
+find_package(GLEW REQUIRED)
+find_package(OpenGL REQUIRED)
+find_package(Freetype REQUIRED)
+find_package(Threads REQUIRED)
+
+target_link_libraries(bettolac PRIVATE bettola SDL3::SDL3 ${GLEW_LIBRARIES}
+  ${OPENGL_LIBRARIES} ${FREETYPE_LIBRARIES} Threads::Threads)
+
+target_include_directories(bettolac PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src
+  # Add server include dir for single player mode.
+  ${CMAKE_SOURCE_DIR}/server/src
+  ${GLEW_INCLUDE_DIRS} ${OPENGL_INCLUDE_DIR} ${FREETYPE_INCLUDE_DIRS})

client/src/client_network.cpp

@@ -0,0 +1,101 @@
+#include <cstdio>
+#include <functional>
+#include <string>
+#include "net/tcp_connection.h"
+
+#include "client_network.h"
+
+ClientNetwork::ClientNetwork(void) : _io_context() {}
+
+ClientNetwork::~ClientNetwork(void) {
+  disconnect();
+}
+
+bool ClientNetwork::connect(const std::string& host, uint16_t port) {
+  try {
+    /* Resolve hostname into list of endpoints. */
+    asio::ip::tcp::resolver resolver(_io_context);
+    asio::ip::tcp::resolver::results_type endpoints =
+        resolver.resolve(host, std::to_string(port));
+
+    /* Create connection object. It will own a socket. */
+    _connection = std::make_shared<net::TcpConnection>(_io_context,
+                                                       asio::ip::tcp::socket(_io_context));
+
+    /* Connect to server. */
+    asio::connect(_connection->socket(), endpoints);
+
+    if(!_connection->socket().is_open()) {
+      return false;
+    }
+
+    /* Define callbacks for the connection. */
+    _connection->start(
+      [this](const std::string& msg) {
+        /* Push new messages to the thread safe queue. */
+        this->_incoming_messages.push_back(msg);
+      },
+      [this]() {
+        /* Reset our connection on server disconnect. */
+        fprintf(stderr, "[BettolaClient] Server disconnected.\n");
+        this->_connection.reset();
+      });
+
+    /* Start io_context in background thread. */
+    _context_thread = std::thread([this]() { _io_context.run(); });
+
+  } catch(const std::exception& e) {
+    fprintf(stderr, "[BettolaClient] Connection exception: %s\n", e.what());
+    return false;
+  }
+  return true;
+}
+
+void ClientNetwork::disconnect(void) {
+  /* Stop the context, should cause the io_context.run() call in the
+   * background thread to return.
+   */
+  _io_context.stop();
+
+  /* Wait for the background thread to finish. */
+  if(_context_thread.joinable()) {
+    _context_thread.join();
+  }
+
+  /* Should be safe to close the socket now that thread is stoped <questionmark> */
+  if(is_connected()) {
+    /* Close the socket. Causes outstanding async operations
+     * in TcpConnection to compete with an error, which in return
+     * triggers the on_disconnect callback.
+     */
+    _connection->socket().close();
+  }
+
+  /* Kill background thread. */
+  _io_context.stop();
+  if(_context_thread.joinable()) {
+    _context_thread.join();
+  }
+
+  /* Release connection object. */
+  _connection.reset();
+}
+
+bool ClientNetwork::is_connected(void) {
+  return _connection && _connection->socket().is_open();
+}
+
+void ClientNetwork::send(const std::string& message) {
+  if(is_connected()) {
+    _connection->send(message);
+  }
+}
+
+bool ClientNetwork::poll_message(std::string& message) {
+  if(_incoming_messages.empty()) {
+    return false;
+  }
+  message = _incoming_messages.pop_front();
+  return true;
+}
+

client/src/client_network.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <asio.hpp>
+#include <memory.h>
+#include <string>
+#include <thread>
+
+#include "asio/io_context.hpp"
+#include "net/tcp_connection.h"
+#include "net/ts_queue.h"
+
+class ClientNetwork {
+public:
+  ClientNetwork(void);
+  ~ClientNetwork(void);
+
+  bool connect(const std::string& host, uint16_t port);
+  void disconnect(void);
+  bool is_connected(void);
+
+  void send(const std::string& message);
+
+  bool poll_message(std::string& message);
+
+private:
+  asio::io_context _io_context;
+  std::thread _context_thread;
+  std::shared_ptr<net::TcpConnection> _connection;
+  TsQueue<std::string> _incoming_messages;
+};

client/src/debug/debug_overlay.cpp

@@ -0,0 +1,52 @@
+#include <cstdio>
+
+#include "debug_overlay.h"
+#include "ui/ui_renderer.h"
+#include "gfx/types.h"
+
+DebugOverlay::DebugOverlay(void) :
+    _fps(0.0f),
+    _frame_time(0.0f),
+    _draw_calls(0),
+    _shape_vertices(0),
+    _text_vertices(0),
+    _update_timer(0.0f) {}
+
+void DebugOverlay::update(float dt, int draw_calls, int shape_verts, int txt_verts) {
+  _update_timer += dt;
+  /* Only update a few times per sec to keep them readable. */
+  if(_update_timer > 0.2f) {
+    _update_timer     = 0.0f;
+    _frame_time       = dt * 1000.0f;
+    _fps              = 1.0f / dt;
+    _draw_calls       = draw_calls;
+    _shape_vertices   = shape_verts;
+    _text_vertices    = txt_verts;
+  }
+}
+
+void DebugOverlay::render(UIRenderer* ui_renderer) {
+  const Color text_color  = { 0.0f, 1.0f, 0.0f }; /* Bright green. */
+  const float line_height = 18.0f;
+  const float padding     = 5.0f;
+
+  char buffer[256];
+
+  /* Manages its own rendering batch. */
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  snprintf(buffer, sizeof(buffer), "FPS: %.0f (%.2f ms)", _fps, _frame_time);
+  ui_renderer->render_text(buffer, padding, padding+line_height*1, text_color);
+
+  snprintf(buffer, sizeof(buffer), "Draw Calls: %d", _draw_calls);
+  ui_renderer->render_text(buffer, padding, padding+line_height*2, text_color);
+
+  snprintf(buffer, sizeof(buffer), "Vertices: %d (Shape %d, Text: %d)",
+           _shape_vertices + _text_vertices, _shape_vertices, _text_vertices);
+  ui_renderer->render_text(buffer, padding, padding+line_height*3, text_color);
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}
+

client/src/debug/debug_overlay.h

@@ -0,0 +1,24 @@
+#pragma once
+
+class UIRenderer;
+
+/**
+ * Renders real-time performance metrics on screen.
+ */
+class DebugOverlay {
+public:
+  DebugOverlay(void);
+
+  void update(float dt, int draw_calls, int shape_verts, int txt_verts);
+  void render(UIRenderer* ui_renderer);
+
+private:
+  float _fps;
+  float _frame_time;
+  int _draw_calls;
+  int _shape_vertices;
+  int _text_vertices;
+
+  /* Oh? You want to be able to read the stats?! */
+  float _update_timer;
+};

client/src/debug/debug_stats.cpp

@@ -0,0 +1,5 @@
+#include "debug_stats.h"
+
+int DebugStats::draw_calls      = 0;
+int DebugStats::shape_vertices  = 0;
+int DebugStats::text_vertices   = 0;

client/src/debug/debug_stats.h

@@ -0,0 +1,14 @@
+#pragma once
+
+struct DebugStats {
+  static int draw_calls;
+  static int shape_vertices;
+  static int text_vertices;
+
+  static void reset(void) {
+    draw_calls      = 0;
+    shape_vertices  = 0;
+    text_vertices   = 0;
+  }
+};
+

client/src/game_state.cpp

@@ -0,0 +1,371 @@
+#include <cstdio>
+#include <memory>
+#include <sstream>
+#include <string>
+#include <thread>
+#include <chrono>
+
+#include "gfx/types.h"
+#include "net/constants.h"
+#include "net/message_protocol.h"
+#include "client_network.h"
+#include "network_manager.h"
+#include "game_state.h"
+#include "terminal.h"
+#include "ui/desktop.h"
+#include "ui/ui_window.h"
+#include "ui/editor.h"
+#include "ui/login_screen.h"
+#include <SDL3/SDL_events.h>
+#include <ui/main_menu.h>
+#include <ui/boot_sequence.h>
+#include "debug/debug_overlay.h"
+
+void GameState::_init_desktop(void) {
+  _desktop = std::make_unique<Desktop>(_screen_width, _screen_height, this, _initial_session_id);
+
+  auto term = std::make_unique<Terminal>(this);
+  term->set_session_id(_initial_session_id);
+
+  auto term_window = std::make_unique<UIWindow>("Terminal", 100, 100, 800, 500);
+  term_window->set_session_id(_initial_session_id);
+  UIWindow* window_ptr = term_window.get();
+  term_window->set_content(std::move(term));
+  _desktop->add_window(std::move(term_window));
+  _desktop->register_session(_initial_session_id, window_ptr);
+}
+
+void GameState::_run_server(void) {
+  try {
+    NetworkManager server("bettola_sp.db");
+    server.start(SINGLE_PLAYER_PORT);
+    /*
+     * Server's start() method is non-blocking, but NetworkManager
+     * object must be kept alive. We'll just loop forever and let the OS
+     * clean up the thread when main exits ;)
+     */
+    while(true) {
+      std::this_thread::sleep_for(std::chrono::seconds(5));
+    }
+  } catch(const std::exception& e) {
+    fprintf(stderr, "Single-player server thread exception: %s\n", e.what());
+  }
+}
+
+GameState::GameState(void) :
+    _current_screen(Screen::MAIN_MENU),
+    _screen_width(0),
+    _screen_height(0),
+    _is_single_player(false),
+    _show_debug_overlay(false),
+    _initial_session_id(0) {_debug_overlay = std::make_unique<DebugOverlay>();}
+
+GameState::~GameState(void) = default;
+
+void GameState::init(int screen_width, int screen_height) {
+  _screen_width   = screen_width;
+  _screen_height  = screen_height;
+  /* Create and connect the network client. */
+  _network = std::make_unique<ClientNetwork>();
+
+  _main_menu = std::make_unique<MainMenu>(screen_width, screen_height);
+}
+
+void GameState::start_single_player_now(int screen_width, int screen_height) {
+  _is_single_player = true;
+  _screen_width     = screen_width;
+  _screen_height    = screen_height;
+  fprintf(stdout, "Starting in single-player mode...\n");
+  std::thread server_thread(&GameState::_run_server, this);
+  server_thread.detach();
+  std::this_thread::sleep_for(std::chrono::milliseconds(200));
+
+  _network = std::make_unique<ClientNetwork>();
+  if(!_network->connect("127.0.0.1", SINGLE_PLAYER_PORT)) {
+    /* TODO: Handle connection failure. */
+  }
+  _current_screen = Screen::DESKTOP;
+  _init_desktop();
+}
+
+void GameState::handle_event(SDL_Event* event, int screen_width, int screen_height) {
+  if(event->type == SDL_EVENT_KEY_DOWN && event->key.key == SDLK_D &&
+      (event->key.mod & SDL_KMOD_CTRL)) {
+    _show_debug_overlay = !_show_debug_overlay;
+    return; /* Consume the event. */
+  }
+  switch(_current_screen) {
+  case Screen::MAIN_MENU:
+    if(_main_menu) {
+      _main_menu->handle_event(event);
+    }
+    break;
+  case Screen::LOGIN:
+    if(_login_screen) {
+      _login_screen->handle_event(event);
+    }
+    break;
+  case Screen::BOOTING:
+    /* TODO: */
+    break;
+  case Screen::DESKTOP:
+    if(_desktop) {
+      _desktop->handle_event(event, screen_width, screen_height);
+    }
+    break;
+  }
+}
+
+void GameState::update(float dt, int draw_calls, int shape_verts, int text_verts) {
+  _debug_overlay->update(dt, draw_calls, shape_verts, text_verts);
+  switch(_current_screen) {
+  case Screen::MAIN_MENU: {
+    if(!_main_menu) break;
+    Screen next_screen = _main_menu->update(dt);
+    if(next_screen != Screen::MAIN_MENU) {
+      const MenuButton* clicked_button = _main_menu->get_clicked_button();
+      if(clicked_button) {
+        _is_single_player = clicked_button->is_single_player;
+      }
+      _current_screen = next_screen;
+      _main_menu.reset(); /* Free mem. */
+
+      if(_current_screen == Screen::LOGIN) {
+        /* Connect to server. */
+        if(_is_single_player) {
+          fprintf(stdout, "Starting in single-player mode...\n");
+          std::thread server_thread(&GameState::_run_server, this);
+          server_thread.detach();
+          std::this_thread::sleep_for(std::chrono::milliseconds(200));
+          if(!_network->connect("127.0.0.1", SINGLE_PLAYER_PORT)) {
+            /* TODO: Handle connection failure. */
+          }
+        } else {
+          if(!_network->connect("127.0.0.1", MULTIPLAYER_PORT)) {
+            /* TODO: Handle connection failure. */
+          }
+        }
+        _login_screen = std::make_unique<LoginScreen>(_screen_width, _screen_height);
+      }
+    }
+    break;
+  }
+  case Screen::LOGIN: {
+    if(_login_screen && _login_screen->is_login_attempted()) {
+      std::string username = _login_screen->get_username();
+      std::string password = _login_screen->get_password();
+
+      if(_login_screen->is_new_account_mode()) {
+        std::string hostname = _login_screen->get_hostname();
+        _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_CREATE_ACCOUNT,
+                                                   {username, password, hostname}));
+      } else {
+        _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_LOGIN,
+                                                   {username, password}));
+      }
+      _login_screen->clear_login_attempt(); /* Try to spam my server now b.tch! */
+    }
+
+    /* Check for server response to our login attempt. */
+    std::string server_msg;
+    while(_network->poll_message(server_msg)) {
+      net_protocol::Opcode opcode;
+      std::vector<std::string> args;
+      net_protocol::parse_message(server_msg, opcode, args);
+
+      switch(opcode) {
+        case net_protocol::Opcode::S2C_LOGIN_SUCCESS:
+        case net_protocol::Opcode::S2C_CREATE_ACCOUNT_SUCCESS:
+          /* Don't switch screen yet, wait for the session ID. */
+          break;
+        case net_protocol::Opcode::S2C_SESSION_CREATED:
+          if(!args.empty()) {
+            _initial_session_id = std::stoul(args[0]);
+          }
+          _current_screen = Screen::BOOTING;
+          _login_screen.reset(); /* Free mem. */
+          _boot_sequence = std::make_unique<BootSequence>();
+          break;
+        case net_protocol::Opcode::S2C_LOGIN_FAIL:
+          _login_screen->set_error_message(args.empty() ? "Login failed." : args[0]);
+          break;
+        case net_protocol::Opcode::S2C_CREATE_ACCOUNT_FAIL:
+          _login_screen->set_error_message(args.empty() ? "Account creation failed." :
+                                            args[0]);
+          break;
+        default:
+          fprintf(stderr, "Recieved unexpected opcode %d during login.\n",
+                  static_cast<int>(opcode));
+          break;
+      }
+      /* If we successfully changed screen, stop processing messages for this frame. */
+      if(_current_screen == Screen::BOOTING) {
+        break;
+      }
+    }
+    break;
+  }
+  case Screen::BOOTING: {
+    if(!_boot_sequence) break; /* Shouldn't happen. */
+    if(_boot_sequence->is_finished()) {
+      _current_screen = Screen::DESKTOP;
+      _init_desktop();
+      _boot_sequence.reset(); /* Free mem. */
+    }
+    break;
+  }
+  case Screen::DESKTOP: {
+    std::string server_msg;
+    while(_network->poll_message(server_msg)) {
+      net_protocol::Opcode opcode;
+      std::vector<std::string> args;
+      net_protocol::parse_message(server_msg, opcode, args);
+
+      switch(opcode) {
+        case net_protocol::Opcode::S2C_SESSION_CREATED:
+          if(!args.empty()) {
+            uint32_t session_id = std::stoul(args[0]);
+            UIWindow* new_term = _desktop->get_window_awaiting_session_id();
+            if(new_term) {
+              Terminal* term = dynamic_cast<Terminal*>(new_term->get_content());
+              if(term) {
+                new_term->set_session_id(session_id);
+                term->set_session_id(session_id);
+                _desktop->register_session(session_id, new_term);
+              }
+            }
+          }
+          break;
+        case net_protocol::Opcode::S2C_FILE_DATA:
+          if(args.size() == 3) {
+            uint32_t session_id = std::stoul(args[0]);
+            auto editor = std::make_unique<Editor>(args[1]);
+            editor->set_buffer_content(args[2]);
+            auto editor_window = std::make_unique<UIWindow>(args[1].c_str(),
+                                                            200, 200, 600, 400);
+            editor_window->set_session_id(session_id);
+            editor_window->set_content(std::move(editor));
+            _desktop->add_window(std::move(editor_window));
+          }
+          break;
+        case net_protocol::Opcode::S2C_DISCONNECT: {
+          if(!args.empty()) {
+            uint32_t session_id = std::stoul(args[0]);
+            UIWindow* window = _desktop->get_window_by_session_id(session_id);
+            if(window) {
+              Terminal* terminal = dynamic_cast<Terminal*>(window->get_content());
+              if(terminal) {
+                terminal->add_history("Connection closed.");
+              }
+            }
+          }
+        }
+        break;
+        case net_protocol::Opcode::S2C_CLOSE_WINDOW: {
+          if(!args.empty()) {
+            uint32_t session_id = std::stoul(args[0]);
+            UIWindow* window = _desktop->get_window_by_session_id(session_id);
+            if(window) {
+              window->close();
+            }
+          }
+        }
+        break;
+        case net_protocol::Opcode::S2C_COMMAND_RESPONSE: {
+          if(args.size() == 2) {
+            uint32_t session_id = std::stoul(args[0]);
+            UIWindow* window = _desktop->get_window_by_session_id(session_id);
+            if(window) {
+              Terminal* terminal = dynamic_cast<Terminal*>(window->get_content());
+              if(terminal) {
+                /* Server sends "output\nprompt", split them. */
+                size_t last_newline = args[1].find_last_of('\n');
+                if(last_newline != std::string::npos) {
+                  std::string prompt = args[1].substr(last_newline+1);
+                  terminal->set_prompt(prompt);
+
+                  std::string output = args[1].substr(0, last_newline);
+                  if(!output.empty()) {
+                    /* Split multiline output and push each line to history. */
+                    std::stringstream ss(output);
+                    std::string line;
+                    while(std::getline(ss, line, '\n')) {
+                      terminal->add_history(line);
+                    }
+                  }
+                } else {
+                  terminal->add_history(args[1]);
+                }
+              }
+            }
+          }
+        }
+        break;
+      }
+    }
+    if(_desktop) {
+      _desktop->update(dt, _screen_width, _screen_height);
+    }
+    break;
+    }
+  }
+}
+
+void GameState::render(const RenderContext& context) {
+  switch(_current_screen) {
+  case Screen::MAIN_MENU:
+    if(_main_menu) {
+      _main_menu->render(context.ui_renderer);
+    }
+    break;
+  case Screen::LOGIN:
+    if(_login_screen) {
+      _login_screen->render(context);
+    }
+    break;
+  case Screen::BOOTING:
+    if(_boot_sequence) {
+      _boot_sequence->render(context.ui_renderer);
+    }
+    break;
+  case Screen::DESKTOP:
+    if(_desktop) {
+      _desktop->render(context);
+    }
+    break;
+  }
+
+  if(_show_debug_overlay) {
+    _debug_overlay->render(context.ui_renderer);
+  }
+}
+
+void GameState::send_network_command(uint32_t session_id, const std::string& command) {
+  if(_network && _network->is_connected()) {
+    _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_COMMAND,
+                                               {std::to_string(session_id), command}));
+  }
+}
+
+void GameState::send_file_write_request(uint32_t session_id, const std::string& path,
+                                        const std::string& content) {
+  _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_WRITE_FILE,
+                                             {std::to_string(session_id), path, content}));
+}
+
+void GameState::send_file_read_request(uint32_t session_id, const std::string& path) {
+  _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_READ_FILE,
+                                             {std::to_string(session_id), path}));
+}
+
+void GameState::send_build_file_request(uint32_t session_id, const std::string& path,
+                                        const std::string& content) {
+  _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_BUILD_FILE,
+                                             {std::to_string(session_id), path, content}));
+}
+
+void GameState::send_create_session_request(void) {
+  if(_network && _network->is_connected()) {
+    _network->send(net_protocol::build_message(net_protocol::Opcode::C2S_CREATE_SESSION));
+  }
+}

client/src/game_state.h

@@ -0,0 +1,58 @@
+#pragma once
+
+#include <memory>
+
+#include "gfx/types.h"
+
+class DebugOverlay;
+class ClientNetwork;
+class Desktop;
+class LoginScreen;
+class BootSequence;
+class MainMenu;
+class ShapeRenderer;
+class TextRenderer;
+union SDL_Event;
+
+enum class Screen {
+  LOGIN,
+  MAIN_MENU,
+  BOOTING,
+  DESKTOP
+};
+
+class GameState {
+public:
+  GameState(void);
+  ~GameState(void);
+
+  void init(int screen_width, int screen_height);
+  void start_single_player_now(int screen_width, int screen_height);
+  void handle_event(SDL_Event* event, int screen_width, int screen_height);
+  void update(float dt, int draw_calls, int shape_verts, int text_verts);
+  void render(const RenderContext& context);
+
+  /* Public network interface for UI components. */
+  void send_network_command(uint32_t session_id, const std::string& command);
+  void send_file_write_request(uint32_t session_id, const std::string& path, const std::string& content);
+  void send_build_file_request(uint32_t session_id, const std::string& path, const std::string& content);
+  void send_file_read_request(uint32_t session_id, const std::string& path);
+  void send_create_session_request(void);
+
+private:
+  std::unique_ptr<ClientNetwork>  _network;
+  std::unique_ptr<Desktop>        _desktop;
+  std::unique_ptr<BootSequence>   _boot_sequence;
+  std::unique_ptr<LoginScreen>    _login_screen;
+  std::unique_ptr<MainMenu>       _main_menu;
+  std::unique_ptr<DebugOverlay>   _debug_overlay;
+  bool                            _show_debug_overlay;
+  Screen                          _current_screen;
+  int                             _screen_width;
+  int                             _screen_height;
+  bool                            _is_single_player;
+  uint32_t                        _initial_session_id;
+
+  void _init_desktop(void);
+  void _run_server(void);
+};

client/src/gfx/shader.cpp

@@ -0,0 +1,86 @@
+#include <cstdio>
+#include <cstring>
+#include <fstream>
+#include <sstream>
+#include <string>
+
+#include <GL/glew.h>
+#include "shader.h"
+
+std::string read_file(const char* path) {
+  std::ifstream file(path);
+  if(!file.is_open()) {
+    printf("Failed to open file: %s\n", path);
+    return "";
+  }
+
+  std::stringstream buffer;
+  buffer << file.rdbuf();
+  return buffer.str();
+}
+
+Shader::Shader(const char* vert_path, const char* frag_path) {
+  std::string vert_string = read_file(vert_path);
+  std::string frag_string = read_file(frag_path);
+  if(vert_string.empty() || frag_string.empty()) {
+    return;
+  }
+
+  const char* vert_source = vert_string.c_str();
+  const char* frag_source = frag_string.c_str();
+
+  unsigned int vert, frag;
+  vert = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vert, 1, &vert_source, NULL);
+  glCompileShader(vert);
+  _check_compile_errors(vert, "VERTEX");
+
+  frag = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(frag, 1, &frag_source, NULL);
+  glCompileShader(frag);
+  _check_compile_errors(frag, "FRAGMENT");
+
+  id = glCreateProgram();
+  glAttachShader(id, vert);
+  glAttachShader(id, frag);
+  glLinkProgram(id);
+  _check_compile_errors(id, "PROGRAM");
+
+  glDeleteShader(vert);
+  glDeleteShader(frag);
+}
+
+void Shader::use(void) {
+  glUseProgram(id);
+}
+
+void Shader::set_mat4(const char* name, const float* value) {
+  glUniformMatrix4fv(glGetUniformLocation(id, name), 1, GL_FALSE, value);
+}
+
+void Shader::set_vec3(const char* name, float v1, float v2, float v3) {
+  glUniform3f(glGetUniformLocation(id, name), v1, v2, v3);
+}
+
+void Shader::set_int(const char* name, int value) {
+  glUniform1i(glGetUniformLocation(id, name), value);
+}
+
+void Shader::_check_compile_errors(unsigned int shader_id, const char* type) {
+  int success;
+  char info_log[1024];
+  if(strcmp(type, "PROGRAM") != 0) {
+    glGetShaderiv(shader_id, GL_COMPILE_STATUS, &success);
+    if(!success) {
+      glGetShaderInfoLog(shader_id, 1024, NULL, info_log);
+      printf("Shader compilation error (%s):\n%s\n", type, info_log);
+    }
+  } else {
+    glGetProgramiv(shader_id, GL_LINK_STATUS, &success);
+    if(!success) {
+      glGetProgramInfoLog(shader_id, 1024, NULL, info_log);
+      printf("Shader linking error (%s):\n%s\n", type, info_log);
+    }
+  }
+}
+

client/src/gfx/shader.h

@@ -0,0 +1,16 @@
+#pragma once
+
+class Shader {
+public:
+  unsigned int id;
+
+  Shader(const char* vertex_path, const char* fragment_path);
+
+  void use(void);
+  void set_mat4(const char* name, const float* value);
+  void set_vec3(const char* name, float v1, float v2, float v3);
+  void set_int(const char* name, int value);
+
+private:
+  void _check_compile_errors(unsigned int shader, const char* type);
+};

client/src/gfx/shape_renderer.cpp

@@ -0,0 +1,82 @@
+#include <GL/glew.h>
+
+#include "shape_renderer.h"
+#include "debug/debug_stats.h"
+#include "math/math.h"
+
+ShapeRenderer::ShapeRenderer(unsigned int screen_width, unsigned int screen_height) {
+  math::ortho_proj(_projection, 0.0f, (float)screen_width, 0.0f, (float)screen_height, -1.0f, 1.0f);
+
+  /* Load shader. */
+  _shape_shader = new Shader("assets/shaders/shape.vert",
+                             "assets/shaders/shape.frag");
+  _shape_shader->use();
+  _shape_shader->set_mat4("projection", _projection);
+
+  /* Configure VAO/VBO for batch rendering. */
+  glGenVertexArrays(1, &_vao);
+  glGenBuffers(1, &_vbo);
+  glBindVertexArray(_vao);
+  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(ShapeVertex) * MAX_SHAPE_VERTICES, nullptr, GL_DYNAMIC_DRAW);
+
+  /* Position attribute. */
+  glEnableVertexAttribArray(0);
+  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(ShapeVertex), (void*)0);
+  /* Colour attribute. */
+  glEnableVertexAttribArray(1);
+  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(ShapeVertex), (void*)offsetof(ShapeVertex, r));
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+
+  _vertices.reserve(MAX_SHAPE_VERTICES);
+}
+
+ShapeRenderer::~ShapeRenderer(void) {
+  delete _shape_shader;
+}
+
+void ShapeRenderer::begin(void) {
+  _vertices.clear();
+}
+
+void ShapeRenderer::flush(void) {
+  if(_vertices.empty()) return;
+
+  _shape_shader->use();
+  glBindVertexArray(_vao);
+
+  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+  glBufferSubData(GL_ARRAY_BUFFER, 0, _vertices.size() * sizeof(ShapeVertex), _vertices.data());
+
+  DebugStats::draw_calls++;
+  DebugStats::shape_vertices += _vertices.size();
+
+  glDrawArrays(GL_TRIANGLES, 0, _vertices.size());
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+}
+
+void ShapeRenderer::draw_rect(int x, int y, int width, int height, const Color& color) {
+  float x_f = (float)x;
+  float y_f = (float)y;
+  float w_f = (float)width;
+  float h_f = (float)height;
+
+  _vertices.push_back({x_f,       y_f+h_f,    color.r, color.g, color.b});
+  _vertices.push_back({x_f,       y_f,        color.r, color.g, color.b});
+  _vertices.push_back({x_f+w_f,   y_f,        color.r, color.g, color.b});
+
+  _vertices.push_back({x_f,       y_f+h_f,    color.r, color.g, color.b});
+  _vertices.push_back({x_f+w_f,   y_f,        color.r, color.g, color.b});
+  _vertices.push_back({x_f+w_f,   y_f+h_f,    color.r, color.g, color.b});
+}
+
+void ShapeRenderer::draw_triangle(int x1, int y1, int x2, int y2, int x3,
+                                  int y3, const Color& color) {
+  _vertices.push_back({(float)x1, (float)y1, color.r, color.g, color.b});
+  _vertices.push_back({(float)x2, (float)y2, color.r, color.g, color.b});
+  _vertices.push_back({(float)x3, (float)y3, color.r, color.g, color.b});
+}

client/src/gfx/shape_renderer.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <vector>
+
+#include "shader.h"
+#include "types.h"
+
+struct ShapeVertex {
+  float x, y, r, g, b;
+};
+
+const int MAX_SHAPES_PER_BATCH = 10000;
+const int VERTICES_PER_RECT = 6;
+const int MAX_SHAPE_VERTICES = MAX_SHAPES_PER_BATCH * VERTICES_PER_RECT;
+
+class ShapeRenderer {
+public:
+  ShapeRenderer(unsigned int screen_width, unsigned int screen_height);
+  ~ShapeRenderer(void);
+
+  void begin(void);
+  void flush(void);
+
+  void draw_rect(int x, int y, int width, int height, const Color& color);
+  void draw_triangle(int x1, int y1, int x2, int y2, int x3, int y3,
+                     const Color& color);
+
+private:
+  Shader* _shape_shader;
+  unsigned int _vao, _vbo;
+  std::vector<ShapeVertex> _vertices;
+  float _projection[16];
+};

client/src/gfx/txt_renderer.cpp

@@ -0,0 +1,186 @@
+#include <cstdio>
+#include "gfx/types.h"
+#include <GL/glew.h>
+#include <SDL3/SDL_render.h>
+#include <freetype/freetype.h>
+
+#include "txt_renderer.h"
+#include "debug/debug_stats.h"
+#include "math/math.h"
+
+TextRenderer::TextRenderer(unsigned int screen_width, unsigned int screen_height) {
+  /* Create projection matrix. */
+  math::ortho_proj(_projecton, 0.0f, (float)screen_width, 0.0f, (float)screen_height, -1.0f, 1.0f);
+
+  /* Load shader. */
+  _txt_shader = new Shader("assets/shaders/text.vert",
+                           "assets/shaders/text.frag");
+  _txt_shader->use();
+  _txt_shader->set_mat4("projection", _projecton);
+
+  /* Configure VAO/VBO for batch rendering. */
+  glGenVertexArrays(1, &_vao);
+  glGenBuffers(1, &_vbo);
+  glBindVertexArray(_vao);
+  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+  /* Pre-allocate buffer memory. */
+  glBufferData(GL_ARRAY_BUFFER, sizeof(TextVertex) * MAX_VERTICES, nullptr, GL_DYNAMIC_DRAW);
+
+  /* Position attribute. */
+  glEnableVertexAttribArray(0);
+  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(TextVertex), (void*)0);
+  /* Texture coord attribute. */
+  glEnableVertexAttribArray(1);
+  glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(TextVertex), (void*)offsetof(TextVertex, s));
+  /* Colour attribute. */
+  glEnableVertexAttribArray(2);
+  glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(TextVertex), (void*)offsetof(TextVertex, r));
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+
+  /* Pre-allocate vector capacity. */
+  _vertices.reserve(MAX_VERTICES);
+}
+
+TextRenderer::~TextRenderer(void) {
+  delete _txt_shader;
+  glDeleteTextures(1, &_atlas_texture_id);
+}
+
+void TextRenderer::load_font(const char* font_path, unsigned int font_size) {
+  FT_Library ft;
+  if(FT_Init_FreeType(&ft)) {
+    printf("Could not init FreeType Library\n");
+    return;
+  }
+
+  FT_Face face;
+  if(FT_New_Face(ft, font_path, 0, &face)) {
+    printf("Failed to load font: %s\n", font_path);
+    return;
+  }
+
+  FT_Set_Pixel_Sizes(face, 0, font_size);
+  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+  /* Calculate atlas dimensions. */
+  unsigned int atlas_width  = 0;
+  unsigned int atlas_height = 0;
+  unsigned int max_height   = 0;
+
+  for(unsigned char c = 0; c < 128; c++) {
+    if(FT_Load_Char(face, c, FT_LOAD_RENDER)) {
+      printf("Failed to load Glyph for char %c\n", c);
+      continue;
+    }
+
+    atlas_width += face->glyph->bitmap.width;
+    max_height = std::max(max_height, face->glyph->bitmap.rows);
+  }
+
+  atlas_height = max_height;
+
+  /* Create the atlas texture. */
+  glGenTextures(1, &_atlas_texture_id);
+  glBindTexture(GL_TEXTURE_2D, _atlas_texture_id);
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, atlas_width, atlas_height, 0, GL_RED,
+               GL_UNSIGNED_BYTE, 0);
+
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  /* Fill the atlas texture with data. */
+  int x_offset = 0;
+  for(unsigned char c = 0; c < 128; c++) {
+    if(FT_Load_Char(face, c, FT_LOAD_RENDER)) {
+      continue;
+    }
+
+    /* Copy glyph bitmap to atlas. */
+    glTexSubImage2D(
+      GL_TEXTURE_2D, 0, x_offset, 0,
+      face->glyph->bitmap.width, face->glyph->bitmap.rows,
+      GL_RED, GL_UNSIGNED_BYTE, face->glyph->bitmap.buffer
+    );
+
+    /* Store character metrics and texture coords. */
+    _chars[c] = {
+      {(int)face->glyph->bitmap.width, (int)face->glyph->bitmap.rows },
+      {face->glyph->bitmap_left, face->glyph->bitmap_top},
+      (unsigned int)face->glyph->advance.x,
+      (float)x_offset / atlas_width,
+      0.0f,
+      (float)face->glyph->bitmap.width / atlas_width,
+      (float)face->glyph->bitmap.rows / atlas_height
+    };
+    x_offset += face->glyph->bitmap.width;
+  }
+
+  glBindTexture(GL_TEXTURE_2D, 0);
+
+  FT_Done_Face(face);
+  FT_Done_FreeType(ft);
+}
+
+void TextRenderer::begin(void) {
+  _vertices.clear();
+}
+
+void TextRenderer::flush(void) {
+  if(_vertices.empty()) {
+    return;
+  }
+
+  _txt_shader->use();
+  glActiveTexture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_2D, _atlas_texture_id);
+  glBindVertexArray(_vao);
+
+  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+  glBufferSubData(GL_ARRAY_BUFFER, 0, _vertices.size() * sizeof(TextVertex), _vertices.data());
+
+  DebugStats::draw_calls++;
+  DebugStats::text_vertices += _vertices.size();
+
+  glDrawArrays(GL_TRIANGLES, 0, _vertices.size());
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+  glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+void TextRenderer::render_text(const char* text, float x, float y, const Color& color) {
+  for(const char* p = text; *p; p++) {
+    unsigned char c = *p;
+    character ch = _chars[c];
+
+    float xpos = x + ch.bearing[0];
+    float ypos = y - (ch.size[1] - ch.bearing[1]);
+    float w = ch.size[0];
+    float h = ch.size[1];
+
+    _vertices.push_back({xpos,      ypos+h,   ch.tx,          ch.ty,        color.r, color.g, color.b});
+    _vertices.push_back({xpos,      ypos,     ch.tx,          ch.ty+ch.th,  color.r, color.g, color.b});
+    _vertices.push_back({xpos+w,    ypos,     ch.tx+ch.tw,    ch.ty+ch.th,  color.r, color.g, color.b});
+
+    _vertices.push_back({xpos,      ypos+h,   ch.tx,          ch.ty,        color.r, color.g, color.b});
+    _vertices.push_back({xpos+w,    ypos,     ch.tx+ch.tw,    ch.ty+ch.th,  color.r, color.g, color.b});
+    _vertices.push_back({xpos+w,    ypos+h,   ch.tx+ch.tw,    ch.ty,        color.r, color.g, color.b});
+
+    x += (ch.advance >> 6);
+  }
+}
+
+float TextRenderer::get_text_width(const char* text, float scale) {
+  float width = 0.0f;
+  for(const char* p = text; *p; p++) {
+    unsigned char c = *p;
+    if(c < 128) {
+      width += (_chars[c].advance >> 6) * scale;
+    }
+  }
+  return width;
+}

client/src/gfx/txt_renderer.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <ft2build.h>
+#include <vector>
+#include FT_FREETYPE_H
+
+#include "shader.h"
+#include "types.h"
+
+struct TextVertex {
+  float x, y, s, t, r, g, b;
+};
+
+/* State of a single charactrer glyph. */
+struct character {
+  int size[2];
+  int bearing[2];
+  unsigned int advance;
+  float tx, ty; /* x and y offset of glyph in texture atlas. */
+  float tw, th; /* width and height of glyph in texture atlas. */
+};
+
+const int MAX_GLYPHS_PER_BATCH = 10000;
+const int VERTICES_PER_GLYPH = 6;
+const int MAX_VERTICES = MAX_GLYPHS_PER_BATCH * VERTICES_PER_GLYPH;
+
+class TextRenderer {
+public:
+  TextRenderer(unsigned int screen_width, unsigned int screen_height);
+  ~TextRenderer(void);
+
+  void load_font(const char* font_path, unsigned int font_size);
+  void render_text(const char* text, float x, float y, const Color& color);
+  float get_text_width(const char* text, float scale);
+
+  void begin(void);
+  void flush(void);
+
+
+private:
+  Shader* _txt_shader;
+  unsigned int _vao, _vbo;
+  unsigned int _atlas_texture_id;
+  character _chars[128];
+  std::vector<TextVertex> _vertices;
+  float _projecton[16];
+};

client/src/gfx/types.h

@@ -0,0 +1,17 @@
+#pragma once
+
+class UIRenderer;
+
+struct Color {
+  float r, g, b;
+};
+
+struct Rect {
+  int x, y, w, h;
+};
+
+struct RenderContext {
+  UIRenderer* ui_renderer;
+  int screen_height;
+  bool show_cursor;
+};

client/src/main.cpp

@@ -0,0 +1,164 @@
+#include <memory>
+#include <cstdio>
+#include <string>
+#include <GL/glew.h>
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_keyboard.h>
+#include <SDL3/SDL_timer.h>
+
+#include "db/db.h"
+
+#include "gfx/shape_renderer.h"
+#include "gfx/txt_renderer.h"
+#include "game_state.h"
+#include "ui/ui_renderer.h"
+#include "gfx/types.h"
+#include "ui/cursor_manager.h"
+#include "debug/debug_stats.h"
+
+const int SCREEN_WIDTH  = 1280;
+const int SCREEN_HEIGHT = 720;
+int main(int argc, char** argv) {
+  /* Init SDL. */
+  if(!SDL_Init(SDL_INIT_VIDEO)) {
+    printf("SDL could not initialise! SDL_ERROR: %s\n", SDL_GetError());
+    return 1;
+  }
+
+  /* Set OpenGL attributes. */
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
+  /* Create a window. */
+  SDL_Window* window = SDL_CreateWindow(
+    "Bettola Client",
+    SCREEN_WIDTH,
+    SCREEN_HEIGHT,
+    SDL_WINDOW_OPENGL
+  );
+
+  if(window == NULL) {
+    printf("Unable to create window! SDL_ERROR: %s\n", SDL_GetError());
+    return 1;
+  }
+
+  /* Create OpenGL context. */
+  SDL_GLContext context = SDL_GL_CreateContext(window);
+  if(context == NULL) {
+    printf("OpenGL context could not be created! SDL_ERROR: %s\n", SDL_GetError());
+    return 1;
+  }
+
+  /* Initialise GLEW. */
+  glewExperimental = GL_TRUE;
+  GLenum glewError = glewInit();
+  if (glewError != GLEW_OK) {
+    /* NOTE:
+     * Dear future self, or other intrepid developer:
+     * In some environments (like the Fedora VM I tested),
+     * glewInit() returns an error here even when the context is valid.
+     * This is a known quirk. We print the error but continue anyway,
+     * because it's not fatal. Don't "fix" this by making it exit. Thank you.
+     * It's GLEW, not you.
+     */
+    fprintf(stderr, "Warning: glewInit failed with error code %u: %s. Attempting to continue anyway.\n",
+            glewError, glewGetErrorString(glewError));
+  }
+
+  /* Configure OpenGL. */
+  glEnable(GL_BLEND);
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+  /* Listen for text input. */
+  SDL_StartTextInput(window);
+
+  /* Init cursor manager. */
+  CursorManager::init();
+
+  /* Init text renderer. */
+  TextRenderer* txt_render_instance = new TextRenderer(SCREEN_WIDTH, SCREEN_HEIGHT);
+  txt_render_instance->load_font("assets/fonts/hack/Hack-Regular.ttf", 14);
+
+  /* Init shape renderer. */
+  ShapeRenderer* shape_renderer_instance = new ShapeRenderer(SCREEN_WIDTH, SCREEN_HEIGHT);
+
+  /* Init UI renderer. */
+  UIRenderer* ui_renderer_instance = new UIRenderer(shape_renderer_instance,
+                                                    txt_render_instance, SCREEN_HEIGHT);
+
+  auto game_state = std::make_unique<GameState>();
+  if(argc > 1 && std::string(argv[1]) == "-sp") {
+    game_state->start_single_player_now(SCREEN_WIDTH, SCREEN_HEIGHT);
+  } else {
+    game_state->init(SCREEN_WIDTH, SCREEN_HEIGHT);
+  }
+
+  /* timer for cursor blink. */
+  Uint32 last_blink_time = 0;
+  bool show_cursor = true;
+
+  /* Timestep. */
+  Uint64 last_frame_time = SDL_GetPerformanceCounter();
+  float dt = 0.0f;
+
+  bool running = true;
+  while(running) {
+    /* Reset per-frame stats. */
+    DebugStats::reset();
+
+    /* Event handling. */
+    SDL_Event event;
+    while(SDL_PollEvent(&event)) {
+      if(event.type == SDL_EVENT_QUIT) { running = false; }
+      game_state->handle_event(&event, SCREEN_WIDTH, SCREEN_HEIGHT);
+    }
+
+    /* Calculate delta time. */
+    Uint64 current_frame_time = SDL_GetPerformanceCounter();
+    dt = (current_frame_time - last_frame_time) / (float)SDL_GetPerformanceFrequency();
+    last_frame_time = current_frame_time;
+
+    /* Clamp dt to avoid large jumps. */
+    if(dt > 0.1f) dt = 0.1f;
+
+    Uint32 current_time = SDL_GetTicks();
+    if(current_time - last_blink_time > 500) { /* Every 500ms. */
+      show_cursor = !show_cursor;
+      last_blink_time = current_time;
+    }
+
+    /* Clear screen. */
+    glClearColor(0.04f, 0.05f, 0.06, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    RenderContext context = {
+      ui_renderer_instance,
+      SCREEN_HEIGHT,
+      show_cursor
+    };
+    game_state->render(context);
+
+    /* Update game state after rendering so stats are for the frame just rendered.
+     * I know this is unusual, but given the text based nature of the game
+     * we won't see a negative impact, and this is better than a large refactor ;)
+     */
+    game_state->update(dt, DebugStats::draw_calls, DebugStats::shape_vertices,
+                       DebugStats::text_vertices);
+
+    /* It's really odd to call it SwapWindow now, rather than SwapBuffer. */
+    SDL_GL_SwapWindow(window);
+  }
+
+  /* Cleanup. */
+  game_state.reset();
+  delete ui_renderer_instance;
+  delete shape_renderer_instance;
+  delete txt_render_instance;
+  SDL_GL_DestroyContext(context);
+  CursorManager::quit();
+  SDL_DestroyWindow(window);
+  SDL_Quit();
+
+  return 0;
+}

client/src/terminal.cpp

@@ -0,0 +1,218 @@
+#include <cstdio>
+#include <memory>
+#include <sstream>
+#include <SDL3/SDL.h>
+#include <GL/glew.h>
+#include <SDL3/SDL_events.h>
+
+#include "terminal.h"
+#include "game_state.h"
+#include "gfx/types.h"
+#include "ui/editor.h"
+#include "ui/window_action.h"
+
+Terminal::Terminal(GameState* game_state)
+    : _game_state(game_state), _should_close(false), _command_history_index(0),
+      _scroll_offset(0), _prompt(""), _pending_action({ActionType::NONE}),
+      _session_id(0) {
+  _input_view = std::make_unique<TextView>(&_input_buffer, false, false, false);
+}
+
+Terminal::~Terminal(void) {}
+
+void Terminal::update(int content_width, int content_height) {
+
+}
+
+void Terminal::add_history(const std::string& line) {
+  std::string line_with_spaces;
+  for(char ch : line) {
+    if(ch == '\t') {
+      line_with_spaces += "   ";
+    } else {
+      line_with_spaces += ch;
+    }
+  }
+  _history.push_back(line_with_spaces);
+
+  if(line == "__CLOSE_CONNECTION__") {
+    _should_close = true;
+  }
+}
+
+void Terminal::set_prompt(const std::string& prompt) {
+  _prompt = prompt;
+}
+
+bool Terminal::should_close(void) {
+  return _should_close;
+}
+
+WindowAction Terminal::get_pending_action(void) {
+  WindowAction action = _pending_action;
+  _pending_action.type = ActionType::NONE;
+  return action;
+}
+
+void Terminal::set_session_id(uint32_t id) {
+  _session_id = id;
+}
+
+uint32_t Terminal::get_session_id(void) const {
+  return _session_id;
+}
+
+void Terminal::_on_ret_press(int content_height) {
+  std::string command = _input_buffer.get_line(0);
+  if(!command.empty()) {
+    _command_history.push_back(command);
+  }
+  _command_history_index = _command_history.size();
+
+  _input_buffer.clear();
+
+  if(command == "clear") {
+    _history.push_back(_prompt + "> " + command);
+    _history.clear();
+    return;
+  }
+
+  /* Client-side command handling. */
+  std::stringstream ss(command);
+  std::string cmd_name;
+  ss >> cmd_name;
+  if(cmd_name == "edit") {
+    _history.push_back(_prompt + "> " + command);
+    ss >> _pending_action.payload1; /* filename. */
+    _pending_action.type = ActionType::READ_FILE;
+    return;
+  }
+
+  _history.push_back(_prompt + "> " + command);
+  _game_state->send_network_command(_session_id, command);
+
+  /* After processing a command, always snap to the bottom. */
+  float line_height = 20.0f;
+  int visible_lines = content_height / line_height;
+  int max_scroll = (_history.size()+1) - visible_lines;
+  if(max_scroll < 0) max_scroll = 0;
+  _scroll_offset = max_scroll;
+}
+
+void Terminal::handle_input(SDL_Event* event, int window_x, int window_y, int window_gl_y,
+                            int content_width, int content_height) {
+  /* Pass input to TextView; if true, RET was pressed. */
+  if(event->type == SDL_EVENT_KEY_DOWN) {
+    switch(event->key.key) {
+      case SDLK_UP:
+        if(!_command_history.empty()) {
+          _command_history_index = std::max(0, _command_history_index-1);
+          _input_buffer.set_text(_command_history[_command_history_index]);
+        }
+        break;
+      case SDLK_DOWN:
+        if(!_command_history.empty()) {
+          _command_history_index =
+            std::min((int)_command_history.size(), _command_history_index+1);
+          if(_command_history_index < (int)_command_history.size()) {
+            _input_buffer.set_text(_command_history[_command_history_index]);
+          } else {
+            _input_buffer.clear();
+          }
+        }
+        break;
+      default:
+      float line_height = 20.0f;
+      int visible_lines = content_height / line_height;
+      int max_scroll = (_history.size()+1) - visible_lines;
+      if(max_scroll < 0) max_scroll = 0;
+
+      if(_input_view->handle_event(event, content_height)) { _on_ret_press(content_height); }
+      else {
+        _scroll_offset = max_scroll; /* Always snap to bottom on key press. */
+      }
+    }
+  } else if(event->type == SDL_EVENT_TEXT_INPUT) {
+    if(_input_view->handle_event(event, content_height)) { _on_ret_press(content_height); }
+    else {
+      float line_height = 20.0f;
+      int visible_lines = content_height / line_height;
+      int max_scroll = (_history.size()+1) - visible_lines;
+      if(max_scroll < 0) max_scroll = 0;
+      _scroll_offset = max_scroll; /* Always snap to bottom on text input. */
+    }
+  }
+}
+
+void Terminal::scroll(int amount, int win_content_height) {
+  /* amount > 0 = scroll up. amount < 0 = scroll down. */
+  _scroll_offset += amount;
+
+  /* Lower bound: Don't scroll below the top of the history. */
+  if(_scroll_offset < 0) {
+    _scroll_offset = 0;
+  }
+  /* Upper bound: Don't scroll past the last command. */
+  float line_height = 20.0f;
+  int visible_lines = win_content_height / line_height;
+  int max_scroll = (_history.size()+1) - visible_lines;
+  if(max_scroll < 0) max_scroll = 0;
+  if(_scroll_offset > max_scroll) {
+    _scroll_offset = max_scroll;
+  }
+}
+
+void Terminal::render(const RenderContext& context, int x, int y_screen, int y_gl,
+                      int width, int height) {
+  const Color white = { 1.0f, 1.0f, 1.0f };
+  const Color green = { 0.2f, 1.0f, 0.2f };
+  float line_height = 20.0f;
+  float padding     = 5.0f;
+
+  /*
+   * Auto-scroll to bottom if the user has not manually scrolled up.
+   * Ensures input line is always visible after submitting a command.
+   */
+  int visible_lines = (height-padding) / line_height;
+  int max_scroll_offset = (_history.size() + 1) - visible_lines;
+  if(max_scroll_offset < 0) max_scroll_offset = 0;
+  if(_scroll_offset >= max_scroll_offset - 1) _scroll_offset = max_scroll_offset;
+
+  context.ui_renderer->begin_text();
+
+  /* Enable scissor test to clip rendering to the window content area. */
+  glEnable(GL_SCISSOR_TEST);
+  glScissor(x, y_gl, width, height);
+
+  /* Draw History. */
+  for(size_t i = _scroll_offset; i < _history.size(); ++i) {
+    float line_y_pos = y_screen + padding + ((i - _scroll_offset) * line_height);
+    /* Culling: If line is already below the view, stop. */
+    if(line_y_pos > y_screen + height) { break; }
+    context.ui_renderer->render_text(_history[i].c_str(), x+padding, line_y_pos+18, white);
+  }
+
+  /* Draw current input line. */
+  float prompt_line_y = (y_screen + padding) + ((_history.size() - _scroll_offset) * line_height);
+  float prompt_baseline_y = prompt_line_y + 18;
+
+  /* Render prompt string. */
+  std::string prompt_str = _prompt + "> ";
+  context.ui_renderer->render_text(prompt_str.c_str(), x+padding, prompt_baseline_y, green);
+
+  /* Render text view for the input right after prompt. */
+  float input_x_pos = x + padding + (prompt_str.length() * 8.5f); /* Estimate width */
+  float input_width = width - (input_x_pos-x);
+  SyntaxTheme theme; /* Terminal doesn't need highlighting, just a default theme. */
+  _input_view->render_text_content(context.ui_renderer, theme, input_x_pos, prompt_line_y, input_width, line_height);
+
+  context.ui_renderer->flush_text();
+
+  if(context.show_cursor) {
+    context.ui_renderer->begin_shapes();
+    _input_view->render_cursor(context.ui_renderer, theme, input_x_pos, prompt_line_y, input_width, line_height);
+    context.ui_renderer->flush_shapes();
+  }
+  /* Disable scissor test. */
+  glDisable(GL_SCISSOR_TEST);
+}

client/src/terminal.h

@@ -0,0 +1,47 @@
+#pragma once
+#include <string>
+#include <vector>
+#include <memory>
+#include <SDL3/SDL.h>
+
+#include "gfx/types.h"
+#include "ui/text_buffer.h"
+#include "ui/text_view.h"
+#include "ui/i_window_content.h"
+#include "ui/window_action.h"
+
+class GameState;
+
+class Terminal : public IWindowContent {
+public:
+  Terminal(GameState* game_state);
+  ~Terminal(void);
+
+  void update(int content_width, int content_height) override;
+  void handle_input(SDL_Event* event, int window_x, int window_y, int window_gl_y,
+                    int content_width, int content_height) override;
+  void render(const RenderContext& context, int x, int y_screen, int y_gl,
+              int width, int height) override;
+  void scroll(int amount, int content_height) override;
+  void add_history(const std::string& line);
+  void set_prompt(const std::string& prompt);
+  bool should_close(void) override;
+  WindowAction get_pending_action(void) override;
+  void set_session_id(uint32_t id);
+  uint32_t get_session_id(void) const;
+
+private:
+  void _on_ret_press(int content_height);
+
+  bool _should_close;
+  std::vector<std::string> _command_history;
+  int _command_history_index;
+  std::vector<std::string> _history;
+  int _scroll_offset;
+  std::string _prompt;
+  GameState* _game_state;
+  TextBuffer _input_buffer;
+  WindowAction _pending_action;
+  uint32_t _session_id;
+  std::unique_ptr<TextView> _input_view;
+};

client/src/ui/boot_sequence.cpp

@@ -0,0 +1,58 @@
+#include <fstream>
+#include <string>
+#include <vector>
+#include <cstdio>
+#include "ui/ui_renderer.h"
+
+#include "boot_sequence.h"
+#include <SDL3/SDL_timer.h>
+
+BootSequence::BootSequence(void) {
+  /* Load boot messages. */
+  std::ifstream boot_file("assets/boot_messages.txt");
+  if(!boot_file.is_open()) {
+    printf("ERROR: Failed to open assets/boot_messages.txt\n");
+    _messages.push_back("ERROR: boot_messages.txt not found.");
+  } else {
+    std::string line;
+    while(std::getline(boot_file, line)) {
+      if(!line.empty()) {
+        _messages.push_back(line);
+      }
+    }
+  }
+
+  /* Init timings. */
+  _start_time = SDL_GetTicks();
+  _line_interval_ms = 150; /* 150ms between each line. */
+  /* Total duration is time for all lines plus a 2-second pause at the end. */
+  _total_duration_ms = (_messages.size() * _line_interval_ms) + 2000;
+}
+
+BootSequence::~BootSequence(void) {}
+
+bool BootSequence::is_finished(void) {
+  return (SDL_GetTicks() - _start_time) >= _total_duration_ms;
+}
+
+void BootSequence::render(UIRenderer* ui_renderer) {
+  ui_renderer->begin_text();
+
+  const Color text_color  = { 0.9f, 0.9f, 0.9f }; /* grey/white */
+  const float line_height = 18.0f;
+  const float padding     = 15.0f;
+
+  Uint32 elapsed_time = SDL_GetTicks() - _start_time;
+  int lines_to_show = elapsed_time / _line_interval_ms;
+
+  if(lines_to_show > _messages.size()) {
+    lines_to_show = _messages.size();
+  }
+
+  for(int i = 0; i < lines_to_show; ++i) {
+    float y_pos = padding + (i*line_height);
+    ui_renderer->render_text(_messages[i].c_str(), padding, y_pos, text_color);
+  }
+
+  ui_renderer->flush_text();
+}

client/src/ui/boot_sequence.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <vector>
+#include <string>
+#include <SDL3/SDL.h>
+
+#include "ui/ui_renderer.h"
+
+class BootSequence {
+public:
+  BootSequence(void);
+  ~BootSequence(void);
+
+  bool is_finished(void);
+  void render(UIRenderer* ui_renderer);
+private:
+  std::vector<std::string> _messages;
+  Uint32 _start_time;
+  Uint32 _line_interval_ms;   /* Time for each line to appear. */
+  Uint32 _total_duration_ms;  /* Total time for the whole sequence. */
+};

client/src/ui/cursor_manager.cpp

@@ -0,0 +1,39 @@
+#include <cstdio>
+
+#include "cursor_manager.h"
+#include <SDL3/SDL_error.h>
+#include <SDL3/SDL_mouse.h>
+
+SDL_Cursor* CursorManager::_arrow_cursor  = nullptr;
+SDL_Cursor* CursorManager::_resize_cursor = nullptr;
+
+void CursorManager::init(void) {
+  _arrow_cursor   = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_DEFAULT);
+  _resize_cursor  = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_NWSE_RESIZE);
+
+  if(!_arrow_cursor || !_resize_cursor) {
+    printf("Failed to create system cursors! SDL_Error: %s\n", SDL_GetError());
+  }
+}
+
+void CursorManager::set_cursor(CursorType type) {
+  SDL_Cursor* cursor_to_set = _arrow_cursor;
+  switch(type) {
+  case CursorType::ARROW:
+    cursor_to_set = _arrow_cursor;
+    break;
+  case CursorType::RESIZE_NWSE:
+    cursor_to_set = _resize_cursor;
+    break;
+  }
+
+  if(SDL_GetCursor() != cursor_to_set) {
+    SDL_SetCursor(cursor_to_set);
+  }
+}
+
+void CursorManager::quit(void) {
+  SDL_DestroyCursor(_arrow_cursor);
+  SDL_DestroyCursor(_resize_cursor);
+}
+

client/src/ui/cursor_manager.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <SDL3/SDL_mouse.h>
+
+enum class CursorType {
+  ARROW,
+  RESIZE_NWSE /* Diagonal resize arrow. */
+};
+
+class CursorManager {
+public:
+  static void init(void);
+  static void set_cursor(CursorType type);
+  static void quit(void);
+
+private:
+  static SDL_Cursor* _arrow_cursor;
+  static SDL_Cursor* _resize_cursor;
+};

client/src/ui/desktop.cpp

@@ -0,0 +1,324 @@
+#include <algorithm>
+#include <ctime>
+#include <fstream>
+#include <cmath>
+#include <memory>
+#include <ui/cursor_manager.h>
+#include <SDL3/SDL_events.h>
+#include <SDL3/SDL_video.h>
+
+#include "gfx/types.h"
+#include "game_state.h"
+#include "desktop.h"
+#include "terminal.h"
+#include "ui/i_window_content.h"
+#include "ui/launcher.h"
+#include "ui/taskbar.h"
+#include "ui/ui_window.h"
+#include "ui/editor.h"
+#include "ui/window_action.h"
+
+static const std::string& get_random_snippet(const std::vector<std::string>& snippets) {
+  if(snippets.empty()) {
+    static const std::string err = "ERR";
+    return err;
+  }
+  return snippets[rand() % snippets.size()];
+}
+
+Desktop::Desktop(int screen_width, int screen_height, GameState* game_state,
+                 uint32_t initial_session_id) {
+  _taskbar = std::make_unique<Taskbar>(screen_width, screen_height);
+  _initial_session_id = initial_session_id;
+  _game_state= game_state;
+  _focused_window = nullptr;
+  _window_awaiting_session_id = nullptr;
+  _launcher_is_open = false;
+  _launcher = std::make_unique<Launcher>(5, 0, 200); /* Tmp y-coord. */
+  int launcher_y = screen_height - _taskbar->get_height() - _launcher->get_height();
+  _launcher->set_y(launcher_y);
+
+  /* Load snippets for temp wallpaper. */
+  std::ifstream snippet_file("assets/menu_background_snippets.txt");
+  if(snippet_file.is_open()) {
+    std::string line;
+    while(std::getline(snippet_file, line)) {
+      if(!line.empty()) { _snippets.push_back(line); }
+    }
+  }
+
+  /* Init animated background. */
+  for(int i = 0; i < 100; ++i) {
+    float y_pos = (float)(rand() % screen_height);
+    _background_text.push_back(
+      {get_random_snippet(_snippets), (float)(rand() % screen_width),
+        y_pos,
+        (float)(rand() % 30 + 10) / 100.0f,
+        (int)y_pos
+      });
+  }
+}
+
+/* Desktop owns UIWindow, make sure we delete them. */
+Desktop::~Desktop(void) {}
+
+void Desktop::add_window(std::unique_ptr<UIWindow> window) {
+  UIWindow* window_ptr = window.get();
+  _windows.push_back(std::move(window));
+  _taskbar->add_window(window_ptr);
+  _set_focused_window(window_ptr);
+}
+
+void Desktop::_set_focused_window(UIWindow* window) {
+  if(window == _focused_window) {
+    return;
+  }
+
+  /* Unfocus old window. */
+  if(_focused_window) {
+    _focused_window->set_focused(false);
+  }
+
+  /* Set new focused window. */
+  _focused_window = window;
+  if(_focused_window) {
+    _focused_window->set_focused(true);
+
+    /* Move newly focused window to end of vector so it's rendered on top. */
+    auto it = std::find_if(_windows.begin(), _windows.end(),
+                           [window](const std::unique_ptr<UIWindow>& p) {
+                             return p.get() == window;
+                           });
+    if(it != _windows.end()) {
+      std::rotate(it, it+1, _windows.end());
+    }
+  }
+}
+
+void Desktop::handle_event(SDL_Event* event, int screen_width, int screen_height) {
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+
+    /* If click is on taskbar, ignore it on the down-event. Let the up-event handle it. */
+    if(_taskbar->is_point_inside(mouse_x, mouse_y)) {
+      return;
+    }
+
+    /* When launcher open, check for outside click to close it. */
+    if(_launcher_is_open && !_launcher->is_point_inside(mouse_x, mouse_y, screen_height)) {
+      _launcher_is_open = false;
+      return;
+    }
+
+    /* If click not on focused window, find which window should receive focus. */
+    bool click_on_window = false;
+    for(int i = _windows.size()-1; i >= 0; --i) {
+      if(_windows[i].get()->is_point_inside(mouse_x, mouse_y)) {
+        /* Top most window. Focus it. */
+        UIWindow* target = _windows[i].get();
+        if(!target->is_minimized()) {
+          _set_focused_window(target);
+          /* Pass event down to newly focused window to handle dragging, etc. */
+          target->handle_event(event, screen_width, screen_height, _taskbar->get_height());
+        }
+        click_on_window = true;
+        break;
+      }
+    }
+    /* Click wasn't on a window. Unfocus. */
+    if(!click_on_window) {
+      _set_focused_window(nullptr);
+    }
+  } else if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
+    if(_taskbar->is_start_button_clicked(event, screen_height)) {
+      _launcher_is_open = !_launcher_is_open;
+    } else if(_launcher_is_open) {
+      std::string app_to_launch = _launcher->handle_event(event, screen_height);
+      if(app_to_launch == "Terminal") {
+        auto term = std::make_unique<Terminal>(_game_state);
+        auto term_window = std::make_unique<UIWindow>("Terminal", 150, 150, 800, 500);
+        _window_awaiting_session_id = term_window.get();
+        term_window->set_content(std::move(term));
+        add_window(std::move(term_window));
+        _launcher_is_open = false;
+        _game_state->send_create_session_request();
+      } else if(app_to_launch == "Editor") {
+        auto editor = std::make_unique<Editor>();
+        auto editor_window = std::make_unique<UIWindow>("Editor", 200, 200, 600, 400);
+        editor_window->set_session_id(_initial_session_id);
+        editor_window->set_content(std::move(editor));
+        add_window(std::move(editor_window));
+        _launcher_is_open = false;
+      }
+    } else {
+      UIWindow* clicked_window = _taskbar->handle_event(event, screen_height);
+      if(clicked_window) {
+        if(clicked_window == _focused_window && !clicked_window->is_minimized()) {
+          clicked_window->minimize();
+          _set_focused_window(nullptr);
+        } else {
+          clicked_window->restore();
+          _set_focused_window(clicked_window);
+        }
+      }
+    }
+  } else if(event->type == SDL_EVENT_MOUSE_MOTION) {
+    /* Update cursor if hovering over any resize handle. */
+    for(int i = _windows.size() - 1; i >= 0; --i) {
+      if(_windows[i]->is_mouse_over_resize_handle(event->motion.x, 
+                                                  event->motion.y)) {
+        return CursorManager::set_cursor(CursorType::RESIZE_NWSE);
+      }
+    }
+    CursorManager::set_cursor(CursorType::ARROW);
+  }
+
+  /* Pass all other non-down-click events to focused window. */
+  if(_focused_window && event->type != SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    _focused_window->handle_event(event, screen_width, screen_height, _taskbar->get_height());
+  }
+}
+
+void Desktop::update(float dt, int screen_width, int screen_height) {
+  /* Remove closed windows. */
+  if(_focused_window) {
+    IWindowContent* content = _focused_window->get_content();
+    if(content) {
+      WindowAction action = content->get_pending_action();
+      uint32_t session_id = _focused_window->get_session_id();
+      switch(action.type) {
+        case ActionType::WRITE_FILE: {
+          if(session_id != 0) {
+            _game_state->send_file_write_request(session_id, action.payload1, action.payload2);
+          }
+          break;
+        }
+        case ActionType::READ_FILE: {
+          if(session_id != 0) {
+            _game_state->send_file_read_request(session_id, action.payload1);
+          }
+          break;
+        }
+        case ActionType::BUILD_FILE: {
+          if(session_id != 0) {
+            _game_state->send_build_file_request(session_id, action.payload1, action.payload2);
+          }
+          break;
+        }
+        default:
+          break;
+      }
+    }
+  }
+  for(auto& window : _windows) {
+    if(window) {
+      window->update();
+    }
+  }
+  _update_wallpaper(dt, screen_width, screen_height);
+  _windows.erase(std::remove_if(_windows.begin(), _windows.end(),
+                                [this](const std::unique_ptr<UIWindow>& w) {
+                                  if (w->should_close()) {
+                                    /* Also remove from session map. */
+                                    uint32_t session_to_remove = 0;
+                                    for(auto const& [sid, win] : _session_windows) {
+                                      if(win == w.get()) {
+                                        session_to_remove = sid;
+                                        break;
+                                      }
+                                    }
+                                    if(session_to_remove != 0)
+                                      _session_windows.erase(session_to_remove);
+                                    _taskbar->remove_window(w.get());
+                                    if (w.get() == _focused_window) {
+                                      _focused_window = nullptr;
+                                    }
+                                    return true;
+                                  }
+                                  return false;
+                                }),
+                 _windows.end());
+}
+
+void Desktop::register_session(uint32_t session_id, UIWindow* window) {
+  _session_windows[session_id] = window;
+  if(_window_awaiting_session_id == window) {
+    _window_awaiting_session_id = nullptr;
+  }
+}
+
+UIWindow* Desktop::get_window_by_session_id(uint32_t session_id) {
+  if(_session_windows.count(session_id)) {
+    return _session_windows.at(session_id);
+  }
+  return nullptr;
+}
+
+UIWindow* Desktop::get_focused_window(void) {
+  return _focused_window;
+}
+
+UIWindow* Desktop::get_window_awaiting_session_id(void) {
+  return _window_awaiting_session_id;
+}
+
+void Desktop::render(const RenderContext& context) {
+  /* Pass 1: Background. */
+  context.ui_renderer->begin_text();
+  _render_wallpaper(context.ui_renderer);
+  context.ui_renderer->flush_text();
+
+  /* Pass 2: Windows Render in order, last window is top-most. */
+  for(size_t i = 0; i < _windows.size(); ++i) {
+    auto& win_i = _windows[i];
+    if(win_i->is_minimized()) continue;
+
+    bool is_occluded = false;
+    Rect rect_i = win_i->get_rect();
+
+    /* Check against all windows on top of this one. */
+    for(size_t j = i+1; j < _windows.size(); ++j) {
+      auto& win_j = _windows[j];
+      if(win_j->is_minimized()) continue;
+
+      Rect rect_j = win_j->get_rect();
+      if(rect_i.x >= rect_j.x && (rect_i.x + rect_i.w) <= (rect_j.x + rect_j.w) &&
+          rect_i.y >= rect_j.y && (rect_i.y + rect_i.h) <= (rect_j.y + rect_j.h)) {
+        is_occluded = true;
+        break;
+      }
+    }
+    if(!is_occluded) {
+      win_i->render(context);
+    }
+  }
+
+  /* Pass 3: Top-level static UI (taskbar, Launcher, etc.). */
+  context.ui_renderer->begin_text();
+  if(_launcher_is_open) {
+    _launcher->render(context.ui_renderer);
+  }
+  _taskbar->render(context.ui_renderer, _focused_window);
+  context.ui_renderer->flush_text();
+}
+
+void Desktop::_render_wallpaper(UIRenderer* ui_renderer) {
+  const Color wallpaper_color = { 0.0f, 0.15f, 0.08f };
+  for(auto& line : _background_text) {
+    ui_renderer->render_text(line.text.c_str(), std::round(line.x),
+                              line.render_y, wallpaper_color);
+  }
+}
+
+void Desktop::_update_wallpaper(float dt, int screen_width, int screen_height) {
+  for(auto& line : _background_text) {
+    line.y_precise -= line.speed * dt * 100.0f;
+    line.render_y = static_cast<int>(std::round(line.y_precise));
+    if(line.render_y < 0) {
+      line.y_precise = screen_height;
+      line.x = (float)(rand() % screen_width);
+      line.text = get_random_snippet(_snippets);
+    }
+  }
+}

client/src/ui/desktop.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include <map>
+#include <SDL3/SDL.h>
+
+#include "gfx/types.h"
+#include "ui/ui_window.h"
+#include "ui/taskbar.h"
+#include "ui/launcher.h"
+#include "ui/ui_renderer.h"
+
+class GameState;
+
+/* Animated background stuff. */
+struct ScrollingText {
+  std::string text;
+  float x;
+  float y_precise; /* sub-pixel animation. */
+  float speed;
+  int render_y;    /* For pixel-perfect rendering. */
+};
+
+class Desktop {
+public:
+  Desktop(int screen_width, int screen_height, GameState* game_state,
+          uint32_t initial_session_id);
+  ~Desktop(void);
+
+  void add_window(std::unique_ptr<UIWindow> window);
+  void handle_event(SDL_Event* event, int screen_width, int screen_height);
+  void update(float dt, int screen_width, int screen_height);
+  void render(const RenderContext& context);
+
+  void register_session(uint32_t session_id, UIWindow* window);
+  UIWindow* get_window_by_session_id(uint32_t session_id);
+  UIWindow* get_focused_window(void);
+  UIWindow* get_window_awaiting_session_id(void);
+
+private:
+  void _set_focused_window(UIWindow* window);
+  void _render_wallpaper(UIRenderer* ui_renderer);
+  void _update_wallpaper(float dt, int screen_width, int screen_height);
+
+  std::vector<std::unique_ptr<UIWindow>> _windows;
+  std::unique_ptr<Taskbar>      _taskbar;
+  std::unique_ptr<Launcher>     _launcher;
+  UIWindow*                     _focused_window;
+  UIWindow*                     _window_awaiting_session_id;
+  std::map<uint32_t, UIWindow*> _session_windows;
+  GameState*                    _game_state;
+  std::vector<ScrollingText>    _background_text;
+  std::vector<std::string>      _snippets;
+  bool                          _launcher_is_open;
+  uint32_t                      _initial_session_id;
+};

client/src/ui/editor.cpp

@@ -0,0 +1,114 @@
+#include "editor.h"
+#include <memory>
+
+#include "text_view.h"
+#include "gfx/types.h"
+#include "ui/window_action.h"
+
+Editor::Editor(void)
+    : _should_close(false), _pending_action({ActionType::NONE}),
+      _filename("untitled.txt") {
+  _view = std::make_unique<TextView>(&_buffer, true, true, true);
+  _menu_bar = std::make_unique<MenuBar>(25);
+  _menu_bar->add_menu("File");
+  _menu_bar->add_menu_item("File", "Save", [this]() {
+    _pending_action = {ActionType::WRITE_FILE, _filename, _buffer.get_text()};
+  });
+  _menu_bar->add_menu("Build");
+  _menu_bar->add_menu_item("Build", "Run Build", [this]() {
+    _pending_action = {ActionType::BUILD_FILE, _filename, _buffer.get_text()};
+  });
+}
+
+Editor::Editor(const std::string& filename)
+    : _should_close(false), _pending_action({ActionType::NONE}),
+      _filename(filename) {
+  _view = std::make_unique<TextView>(&_buffer, true, true, true);
+  _menu_bar = std::make_unique<MenuBar>(25);
+  _menu_bar->add_menu("File");
+  _menu_bar->add_menu_item("File", "Save", [this]() {
+    _pending_action = {ActionType::WRITE_FILE, _filename, _buffer.get_text()};
+  });
+  _menu_bar->add_menu("Build");
+  _menu_bar->add_menu_item("Build", "Run Build", [this]() {
+    _pending_action = {ActionType::BUILD_FILE, _filename, _buffer.get_text()};
+  });
+}
+
+Editor::~Editor(void) {}
+
+void Editor::update(int content_width, int content_height) {
+  /* Nothing to do yet. */
+}
+
+void Editor::handle_input(SDL_Event* event, int window_x, int window_y, int window_gl_y,
+                          int content_width, int content_height) {
+  if(!event) return;
+
+  _menu_bar->handle_event(event, window_x, window_y);
+
+  /* We don't care about the return val here. RET is just newline. */
+  if(event->type == SDL_EVENT_KEY_DOWN && event->key.key == SDLK_S &&
+      (event->key.mod & SDL_KMOD_CTRL)) {
+    /* C-S pressed, create a save action. */
+    _pending_action = { ActionType::WRITE_FILE, _filename, _buffer.get_text() };
+  } else {
+    _view->handle_event(event, content_height);
+  }
+}
+
+void Editor::render(const RenderContext& context, int x, int y_screen, int y_gl,
+                    int width, int height) {
+  int menu_bar_height = _menu_bar->get_height();
+  int content_y = y_screen + menu_bar_height;
+  int content_height = height - menu_bar_height;
+
+  /* Pass 1: Main Bar Background.*/
+  context.ui_renderer->begin_shapes();
+  _menu_bar->render_bar_bg(context.ui_renderer, x, y_screen, width);
+  context.ui_renderer->flush_shapes();
+
+  context.ui_renderer->enable_scissor(x, y_gl, width, content_height);
+
+  /* Pass 2: Main text view. */
+  context.ui_renderer->begin_text();
+  _view->render_text_content(context.ui_renderer, _theme, x, content_y, width, content_height);
+  context.ui_renderer->flush_text();
+
+  /* Pass 3: Editor cursor. */
+  if(context.show_cursor) {
+    context.ui_renderer->begin_shapes();
+    _view->render_cursor(context.ui_renderer, _theme, x, content_y, width, content_height);
+    context.ui_renderer->flush_shapes();
+  }
+
+  context.ui_renderer->disable_scissor();
+
+  /* Pass 4: Menu bar text and dropdown. */
+  context.ui_renderer->begin_text();
+  _menu_bar->render_bar_text(context.ui_renderer, x, y_screen, width);
+  _menu_bar->render_dropdown(context.ui_renderer, x, y_screen, width);
+  context.ui_renderer->flush_text();
+}
+
+void Editor::scroll(int amount, int content_height) {
+  _view->scroll(amount, content_height);
+}
+
+bool Editor::should_close(void) {
+  return _should_close;
+}
+
+void Editor::set_buffer_content(const std::string& content) {
+  _buffer.set_text(content);
+}
+
+WindowAction Editor::get_pending_action(void) {
+  WindowAction action = _pending_action;
+  _pending_action.type = ActionType::NONE; /* Clear action. */
+  return action;
+}
+
+const std::string& Editor::get_filename(void) const {
+  return _filename;
+}

client/src/ui/editor.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <memory>
+
+#include "gfx/types.h"
+#include "i_window_content.h"
+#include "ui/text_buffer.h"
+#include "ui/window_action.h"
+#include "ui/menu_bar.h"
+
+class TextView;
+
+struct SyntaxTheme {
+  Color normal    = { 1.0f, 1.0f, 1.0f };
+  Color keyword   = { 0.8f, 0.6f, 1.0f };
+  Color string    = { 1.0f, 0.8f, 0.6f };
+  Color number    = { 0.6f, 1.0f, 0.8f };
+  Color comment   = { 0.6f, 0.6f, 0.6f };
+  Color line_num  = { 0.5f, 0.6f, 0.7f };
+};
+
+class Editor : public IWindowContent {
+public:
+  Editor(void);
+  Editor(const std::string& filename);
+  ~Editor(void) override;
+
+  void update(int content_width, int content_height) override;
+  void handle_input(SDL_Event* event, int window_x, int window_y, int window_gl_y,
+                    int content_widht, int content_heigth) override;
+  void render(const RenderContext& context, int x, int y_screen, int y_gl,
+              int width, int height) override;
+  void scroll(int amount, int content_height) override;
+  bool should_close(void) override;
+  void set_buffer_content(const std::string& content);
+  WindowAction get_pending_action(void) override;
+  const std::string& get_filename(void) const;
+
+private:
+  TextBuffer _buffer;
+  std::unique_ptr<TextView> _view;
+  std::unique_ptr<MenuBar> _menu_bar;
+  bool _should_close;
+  WindowAction _pending_action;
+  SyntaxTheme _theme;
+  std::string _filename;
+};

client/src/ui/i_window_content.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <SDL3/SDL_events.h>
+
+#include "window_action.h"
+#include "gfx/types.h"
+
+class IWindowContent {
+public:
+  virtual ~IWindowContent(void) = default;
+  virtual void update(int content_width, int content_height) = 0;
+  virtual void handle_input(SDL_Event* event, int window_x, int window_y, int window_gl_y,
+                            int content_width, int content_height) = 0;
+  virtual void render(const RenderContext& context, int x, int y_screen, int y_gl,
+                      int width, int height) = 0;
+  virtual void scroll(int amount, int content_height) = 0;
+  virtual bool should_close(void) = 0;
+  virtual WindowAction get_pending_action() = 0;
+};

client/src/ui/launcher.cpp

@@ -0,0 +1,76 @@
+#include "launcher.h"
+#include <SDL3/SDL_mouse.h>
+#include "ui/ui_renderer.h"
+
+Launcher::Launcher(int x, int y, int width) : _x(x), _y(y), _width(width) {
+  /* TODO: Hardcode the launcher apps for now. */
+  _apps.push_back("Terminal");
+  _apps.push_back("Editor");
+
+  int item_height = 30;
+  _height = _apps.size() * item_height;
+}
+
+Launcher::~Launcher(void) {}
+
+bool Launcher::is_point_inside(int x, int y, int screen_height) const {
+  return (x >= _x && x <= _x + _width && y>= _y && y <= _y + _height);
+}
+
+void Launcher::render(UIRenderer* ui_renderer) {
+  const Color bg_color    = { 0.15f, 0.17f, 0.19f };
+  const Color text_color  = { 0.9f,  0.9f,  0.9f  };
+  const Color hover_color = { 0.3f,  0.32f, 0.34f };
+
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  /* Note: y-coord is TOP of launcher menu. */
+  ui_renderer->draw_rect(_x, _y, _width, _height, bg_color);
+
+  int item_height = 30;
+  int item_y = _y;
+
+  float mouse_x, mouse_y;
+  SDL_GetMouseState(&mouse_x, &mouse_y);
+
+  for(const auto& app_name : _apps) {
+    /* Check for hover. */
+    if(mouse_x >= _x && mouse_x <= _x + _width &&
+       mouse_y >= item_y && mouse_y <= item_y + item_height) {
+      ui_renderer->draw_rect(_x, item_y, _width, item_height, hover_color);
+    }
+
+    ui_renderer->render_text(app_name.c_str(), _x+10, item_y+20, text_color);
+    item_y += item_height;
+  }
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}
+
+std::string Launcher::handle_event(SDL_Event* event, int screen_height) {
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+
+    int item_height = 30;
+    int item_y = _y;
+    for(const auto& app_name : _apps) {
+      if(mouse_x >= _x && mouse_x <= _x + _width &&
+         mouse_y >= item_y && mouse_y <= item_y + item_height) {
+        return app_name; /* Return name of clicked app. */
+      }
+      item_y += item_height;
+    }
+  }
+  return ""; /* Nothing clicked. */
+}
+
+void Launcher::set_y(int y) {
+  _y = y;
+}
+
+int Launcher::get_height(void) const {
+  return _height;
+}

client/src/ui/launcher.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <SDL3/SDL_events.h>
+
+class UIRenderer;
+
+class Launcher {
+public:
+  Launcher(int x, int y, int width);
+  ~Launcher(void);
+
+  void render(UIRenderer* ui_renderer);
+  std::string handle_event(SDL_Event* event, int screen_height);
+  bool is_point_inside(int x, int y, int screen_height) const;
+  void set_y(int y);
+  int get_height(void) const;
+
+private:
+  int _x, _y, _width, _height;
+  std::vector<std::string> _apps;
+};

client/src/ui/login_screen.cpp

@@ -0,0 +1,195 @@
+#include <string>
+#include <vector>
+
+#include "gfx/types.h"
+#include "ui/ui_renderer.h"
+#include "ui/login_screen.h"
+
+LoginScreen::LoginScreen(int screen_width, int screen_height) :
+    _screen_width(screen_width),
+    _screen_height(screen_height) {
+
+  _is_new_account = false; /* Default to login. */
+
+  /* Position tabs relative to the form. */
+  const int form_center_x   = _screen_width  / 2 - 25;
+  const int tabs_y          = (_screen_height / 2 - 100) + 200;
+  _login_tab_rect           = { form_center_x-90, tabs_y, 80,  30 };
+  _create_account_tab_rect  = { form_center_x+10, tabs_y, 150, 30 };
+}
+
+LoginScreen::~LoginScreen(void) {}
+
+void LoginScreen::update(float dt) {
+  /* TODO: */
+}
+
+void LoginScreen::render(const RenderContext& context) const {
+  UIRenderer* ui_renderer = context.ui_renderer;
+
+  /* Colours. */
+  const Color bg_color            = { 0.06f,  0.07f,  0.09f };
+  const Color text_color          = { 0.8f,   0.8f,   0.8f  };
+  const Color inactive_box_color  = { 0.1f,   0.1f,   0.15f };
+  const Color active_box_color    = { 0.15f,  0.15f,  0.2f  };
+  const Color warning_color       = { 0.7f,   0.3f,   0.3f  };
+  const Color active_tab_color    = { 0.9f,   0.9f,   0.9f  };
+  const Color inactive_tab_color  = { 0.4f,   0.5f,   0.6f  };
+
+  /* Layout. */
+  const int box_width   = 300;
+  const int box_height  = 30;
+  const int center_x    = (_screen_width - box_width) / 2;
+  const int start_y     = _screen_height / 2 - 100;
+
+  const Rect username_rect = { center_x, start_y+40,  box_width, box_height };
+  const Rect password_rect = { center_x, start_y+100, box_width, box_height };
+  const Rect hostname_rect = { center_x, start_y+160, box_width, box_height };
+
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  /* Draw background. */
+  ui_renderer->draw_rect(0, 0, _screen_width, _screen_height, bg_color);
+
+  /* Draw mode-switch tabs. */
+  ui_renderer->render_text("[Login]", _login_tab_rect.x, _login_tab_rect.y + 20,
+                           _is_new_account ? inactive_tab_color : active_tab_color);
+  ui_renderer->render_text("[Create Account]", _create_account_tab_rect.x,
+                           _create_account_tab_rect.y + 20,
+                           _is_new_account ? active_tab_color : inactive_tab_color);
+
+  /* Draw title. */
+  const char* title = _is_new_account ? "Create Account" : "Login";
+  float title_width = ui_renderer->get_text_renderer()->get_text_width(title, 1.0f);
+  ui_renderer->render_text(title, (_screen_width-title_width)/2, start_y, text_color);
+
+  /* Draw error message if it exists. */
+  if(!_error_message.empty()) {
+    float error_width = ui_renderer->get_text_renderer()->get_text_width(_error_message.c_str(), 1.0f);
+    ui_renderer->render_text(_error_message.c_str(), (_screen_width-error_width)/2,
+                             start_y+20, warning_color);
+  }
+
+  /* Draw input boxes and labels. */
+  /* Username */
+  ui_renderer->render_text("Username", username_rect.x, username_rect.y-5, text_color);
+  ui_renderer->draw_rect(username_rect.x, username_rect.y, username_rect.w, username_rect.h,
+                         _active_field == 0 ? active_box_color : inactive_box_color);
+  ui_renderer->render_text(_username_input.c_str(), username_rect.x+10, username_rect.y+20, text_color);
+  if(_active_field == 0 && context.show_cursor) {
+    float cursor_x = username_rect.x + 10 +
+      ui_renderer->get_text_renderer()->get_text_width(_username_input.c_str(), 1.0f);
+    ui_renderer->draw_rect((int)cursor_x, username_rect.y+5, 2, 20, text_color);
+  }
+
+  /* Password. */
+  ui_renderer->render_text("Password", password_rect.x, password_rect.y-5, text_color);
+  ui_renderer->draw_rect(password_rect.x, password_rect.y, password_rect.w, password_rect.h,
+                         _active_field == 1 ? active_box_color : inactive_box_color);
+  ui_renderer->render_text(_password_input.c_str(), password_rect.x+10, password_rect.y+20, text_color);
+  if(_active_field == 1 && context.show_cursor) {
+    float cursor_x = password_rect.x + 10 +
+      ui_renderer->get_text_renderer()->get_text_width(_password_input.c_str(), 1.0f);
+    ui_renderer->draw_rect((int)cursor_x, password_rect.y+5, 2, 20, text_color);
+  }
+
+  /* Hostname (only for new account). */
+  if(_is_new_account) {
+    ui_renderer->render_text("Hostname", hostname_rect.x, hostname_rect.y-5, text_color);
+    ui_renderer->draw_rect(hostname_rect.x, hostname_rect.y, hostname_rect.w, hostname_rect.h,
+                           _active_field == 2 ? active_box_color : inactive_box_color);
+    ui_renderer->render_text(_hostname_input.c_str(), hostname_rect.x+10, hostname_rect.y+20, text_color);
+    if(_active_field == 2 && context.show_cursor) {
+      float cursor_x = hostname_rect.x + 10 +
+        ui_renderer->get_text_renderer()->get_text_width(_hostname_input.c_str(), 1.0f);
+      ui_renderer->draw_rect((int)cursor_x, hostname_rect.y+5, 2, 20, text_color);
+    }
+  }
+
+  /* Draw the security warning. */
+  const char* warning_title = "Security Warning";
+  float warning_title_width = ui_renderer->get_text_renderer()->get_text_width(warning_title, 1.0f);
+  ui_renderer->render_text(warning_title, (_screen_width-warning_title_width)/2,
+                           _screen_height-120, warning_color);
+  const std::vector<std::string> warning_lines = {
+    "Passwords in Bettola are stored in plain text by design.",
+    "Players, can, and will attempt to obtain your password.",
+    "DO NOT use a password you have used for any other game or service.",
+    "Use a unique, throwaway password for this game only!"
+  };
+  for(size_t i = 0; i < warning_lines.size(); ++i) {
+    const std::string& line = warning_lines[i];
+    float line_width = ui_renderer->get_text_renderer()->get_text_width(line.c_str(), 1.0f);
+    ui_renderer->render_text(line.c_str(), (_screen_width-line_width)/2, 
+                             _screen_height-100+(i*20), warning_color);
+  }
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}
+
+void LoginScreen::set_error_message(const std::string& msg) {
+  _error_message = msg;
+}
+
+void LoginScreen::handle_event(const SDL_Event* event) {
+  if(event->type == SDL_EVENT_TEXT_INPUT) {
+    /* Append character to active input string. */
+    switch(_active_field) {
+      case 0: _username_input += event->text.text; break;
+      case 1: _password_input += event->text.text; break;
+      case 2: if(_is_new_account) { _hostname_input += event->text.text; } break;
+    }
+  } else if(event->type == SDL_EVENT_KEY_DOWN) {
+    if(event->key.key == SDLK_BACKSPACE) {
+      /* Handle backspace. */
+      switch(_active_field) {
+        case 0: if(!_username_input.empty()) { _username_input.pop_back(); } break;
+        case 1: if(!_password_input.empty()) { _password_input.pop_back(); } break;
+        case 2: if(_is_new_account && !_hostname_input.empty()) {
+          _hostname_input.pop_back();
+        }
+        break;
+      }
+    } else if(event->key.key == SDLK_TAB) {
+      /* Tab to switch fields. */
+      int num_fields = _is_new_account ? 3 : 2;
+      _active_field = (_active_field+1) % num_fields;
+    } else if(event->key.key == SDLK_RETURN) {
+      _login_attempted = true;
+    }
+  } else if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    /* Handle mouse clicks. */
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+
+    /* Recalculate rects to check for clicks. */
+    const int box_width = 300;
+    const int start_y = _screen_height / 2 - 100;
+    const int center_x = (_screen_width - box_width) / 2;
+
+    const Rect username_rect = { center_x, start_y+40,  box_width, 30 };
+    const Rect password_rect = { center_x, start_y+100, box_width, 30 };
+    const Rect hostname_rect = { center_x, start_y+160, box_width, 30 };
+
+    auto is_inside = [&](const Rect& rect) {
+      return mouse_x >= rect.x && mouse_x <= rect.x + rect.w &&
+             mouse_y >= rect.y && mouse_y <= rect.y + rect.h;
+    };
+
+    if(is_inside(_login_tab_rect)) {
+      _is_new_account = false;
+      _username_input.clear(); _password_input.clear(); _hostname_input.clear();
+    } else if(is_inside(_create_account_tab_rect)) {
+      _is_new_account = true;
+      _username_input.clear(); _password_input.clear(); _hostname_input.clear();
+    } else if(is_inside(username_rect)) {
+      _active_field = 0;
+    } else if(is_inside(password_rect)) {
+      _active_field = 1;
+    } else if(_is_new_account && is_inside(hostname_rect)) {
+      _active_field = 2;
+    }
+  }
+}

client/src/ui/login_screen.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+#include <string>
+
+#include "gfx/types.h"
+
+class LoginScreen {
+public:
+  LoginScreen(int screen_width, int screen_height);
+  ~LoginScreen(void);
+
+  void update(float dt);
+  void render(const RenderContext& context) const;
+  void handle_event(const SDL_Event* event);
+
+  bool is_login_attempted(void)  const { return _login_attempted; }
+  std::string get_username(void) const { return _username_input;  }
+  std::string get_password(void) const { return _password_input;  }
+  std::string get_hostname(void) const { return _hostname_input;  }
+  bool is_new_account_mode(void) const { return _is_new_account;  }
+  void clear_login_attempt(void)       { _login_attempted = false;}
+  void set_error_message(const std::string& msg);
+
+private:
+  /* UI State. */
+  std::string _username_input;
+  std::string _password_input;
+  std::string _hostname_input;
+  std::string _error_message;
+
+  bool _login_attempted   = false;
+  bool _is_new_account    = true;
+  int _active_field       = 0; /* 0: username, 1: password, 2: hostname. */
+
+  /* Screen dimensions. */
+  int _screen_width;
+  int _screen_height;
+
+  /* Clickable tabs for mode switching. */
+  Rect _create_account_tab_rect;
+  Rect _login_tab_rect;
+};

client/src/ui/main_menu.cpp

@@ -0,0 +1,148 @@
+#include <SDL3/SDL_events.h>
+#include <fstream>
+#include <vector>
+#include "ui/ui_renderer.h"
+
+#include "main_menu.h"
+
+/* Get a random snippet form loaded word list. */
+static const std::string& get_random_snippet(const std::vector<std::string>& snippets) {
+  /* If empty, return a default to avoid a crash? */
+  if(snippets.empty()) {
+    static const std::string empty_str = "ERROR: snippets file not found";
+    return empty_str;
+  }
+  int index = rand() % snippets.size();
+  return snippets[index];
+}
+
+MainMenu::MainMenu(int screen_width, int screen_height) :
+    _screen_width(screen_width), _screen_height(screen_height),
+    _next_screen(Screen::MAIN_MENU) {
+
+  /* Load snippets form file. */
+  std::ifstream snippet_file("assets/menu_background_snippets.txt");
+  if(!snippet_file.is_open()) {
+    printf("ERROR: Failed to open assets/menu_background_snippets.txt\n");
+  } else {
+    std::string line;
+    while(std::getline(snippet_file, line)) {
+      if(!line.empty()) {
+        _snippets.push_back(line);
+      }
+    }
+  }
+
+  /* Initialise buttons. */
+  const int button_width  = 200;
+  const int button_height = 50;
+  const int center_x = (screen_width/2) - (button_width/2);
+  const int center_y = (screen_height/2);
+
+  _buttons.push_back({
+    "Single-Player",
+    { center_x, center_y + 30, button_width, button_height },
+    Screen::LOGIN, /* This will trigger the login screen. */
+    true,
+    false
+  });
+  _buttons.push_back({
+    "Online",
+    { center_x, center_y - 30, button_width, button_height },
+    Screen::LOGIN,
+    false,
+    false
+  });
+
+  /* Initialise animated background. */
+  srand(time(NULL));
+  for(int i = 0; i < 100; ++i) {
+    _background_text.push_back({
+      get_random_snippet(_snippets),
+      (float)(rand() % screen_width),
+      (float)(rand() % screen_height),
+      (float)(rand() % 50 + 20) / 100.0f /* Random speed. */
+    });
+  }
+}
+
+MainMenu::~MainMenu(void) {}
+
+void MainMenu::handle_event(SDL_Event* event) {
+  if(event->type == SDL_EVENT_MOUSE_MOTION) {
+    int mouse_x = event->motion.x;
+    int mouse_y = event->motion.y;
+    for(auto& button : _buttons) {
+      button.is_hovered = (mouse_x >= button.rect.x
+        && mouse_x <= button.rect.x + button.rect.w
+        && mouse_y >= button.rect.y
+        && mouse_y <= button.rect.y + button.rect.h);
+    }
+  } else if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    for(const auto& button : _buttons) {
+      if(button.is_hovered) {
+        _next_screen = button.action;
+        _clicked_button = &button;
+        break; /* Once clicked button found, exit. */
+      }
+    }
+  }
+}
+
+Screen MainMenu::update(float dt) {
+  _update_background(dt);
+  return _next_screen;
+}
+
+void MainMenu::render(UIRenderer* ui_renderer) {
+  /* Pass 1: Background text. */
+  ui_renderer->begin_text();
+  _render_background(ui_renderer);
+  ui_renderer->flush_text();
+
+  /* Pass 2: Buttons. */
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  /* Button colours. */
+  const Color button_color        = { 0.1f, 0.15f, 0.2f };
+  const Color button_hover_color  = { 0.2f, 0.25f, 0.3f };
+  const Color text_color          = { 0.8f, 0.8f,  0.8f };
+
+  for(const auto& button : _buttons) {
+    /* Draw button background. */
+    if(button.is_hovered) {
+      ui_renderer->draw_rect(button.rect.x, button.rect.y, button.rect.w,
+                                button.rect.h, button_hover_color);
+    } else {
+      ui_renderer->draw_rect(button.rect.x, button.rect.y, button.rect.w,
+                                button.rect.h, button_color);
+    }
+
+    /* Draw button text centered. */
+    float text_width = ui_renderer->get_text_renderer()->get_text_width(button.label.c_str(), 1.0f);
+    float text_x = button.rect.x + (button.rect.w - text_width) / 2.0f;
+    ui_renderer->render_text(button.label.c_str(), text_x, button.rect.y + 32, text_color);
+  }
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}
+
+void MainMenu::_update_background(float dt) {
+  for(auto& line : _background_text) {
+    line.y -= line.speed * dt * 100.0f;
+    if(line.y < 0) {
+      line.y = _screen_height;
+      line.x = (float)(rand() % _screen_width);
+      line.text = get_random_snippet(_snippets);
+    }
+  }
+}
+
+void MainMenu::_render_background(UIRenderer* ui_renderer) {
+  const Color background_text_color = { 0.0f, 0.35f, 0.15f }; /* Dark green. */
+  for(const auto& line : _background_text) {
+    ui_renderer->render_text(line.text.c_str(), line.x, line.y, background_text_color);
+  }
+}

client/src/ui/main_menu.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <vector>
+#include <string>
+
+#include "gfx/types.h"
+#include "ui/ui_renderer.h"
+#include "game_state.h"
+
+union SDL_Event;
+
+struct MenuButton {
+  std::string label;
+  Rect rect;
+  Screen action; /* Change state. */
+  bool is_single_player;
+  bool is_hovered = false;
+};
+
+class MainMenu {
+public:
+  MainMenu(int screen_width, int screen_height);
+  ~MainMenu(void);
+
+  void handle_event(SDL_Event* event);
+  Screen update(float dt);
+  void render(UIRenderer* ui_renderer);
+
+  const MenuButton* get_clicked_button(void) const { return _clicked_button; }
+
+private:
+  void _update_background(float dt);
+  void _render_background(UIRenderer* ui_renderer);
+
+  /* For animated background. */
+  struct ScrollingText {
+    std::string text;
+    float x;
+    float y;
+    float speed;
+  };
+
+  std::vector<ScrollingText> _background_text;
+  int _screen_height;
+  int _screen_width;
+
+  /* Buttons. */
+  std::vector<MenuButton>  _buttons;
+  std::vector<std::string> _snippets;
+  Screen                   _next_screen;
+  const MenuButton*        _clicked_button = nullptr;
+};

client/src/ui/menu_bar.cpp

@@ -0,0 +1,112 @@
+#include "menu_bar.h"
+#include "gfx/shape_renderer.h"
+#include "gfx/txt_renderer.h"
+#include "gfx/types.h"
+
+MenuBar::MenuBar(int height)
+    : _height(height) {}
+
+MenuBar::~MenuBar(void) {}
+
+void MenuBar::add_menu(const std::string& label) {
+  _menus.push_back({label, {}, false});
+}
+
+void MenuBar::add_menu_item(const std::string& menu_label, const std::string& item_label,
+                       std::function<void()> action) {
+  for(auto& menu : _menus) {
+    if(menu.label == menu_label) {
+      menu.items.push_back({item_label, action});
+      return;
+    }
+  }
+}
+
+int MenuBar::get_height(void) const {
+  return _height;
+}
+
+void MenuBar::handle_event(SDL_Event* event, int window_x, int window_y) {
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+    const int title_bar_height = 30;
+
+    int menu_bar_screen_y = window_y + title_bar_height;
+    int current_menu_x = window_x;
+    bool click_on_bar = false;
+
+    if(mouse_y >= menu_bar_screen_y && mouse_y <= menu_bar_screen_y + _height) {
+      for(size_t i = 0; i < _menus.size(); ++i) {
+        int menu_width = 60;
+        if(mouse_x >= current_menu_x && mouse_x <= current_menu_x + menu_width) {
+          _open_menu_index = (_open_menu_index == (int)i) ? -1: i;
+          click_on_bar = true;
+          break;
+        }
+        current_menu_x += menu_width;
+      }
+    }
+
+    if(click_on_bar) return;
+
+    if(_open_menu_index != -1) {
+      Menu& open_menu = _menus[_open_menu_index];
+      int dropdown_x = window_x + (_open_menu_index * 60);
+      int dropdown_y = menu_bar_screen_y + _height;
+      int item_height = 30;
+      int dropdown_width = 150;
+
+      for(const auto& item: open_menu.items) {
+        if(mouse_x >= dropdown_x && mouse_x <= dropdown_x + dropdown_width &&
+           mouse_y >= dropdown_y && mouse_y <= dropdown_y + item_height) {
+          item.action();
+          _open_menu_index = -1; /* Close menu. */
+          return;
+        }
+        dropdown_y += item_height;
+      }
+    }
+    /* Close any open menu when clicked outside. */
+    _open_menu_index = -1;
+  }
+}
+
+void MenuBar::render_bar_bg(UIRenderer* ui_renderer, int x, int y, int width) {
+  const Color bg_color    = { 0.15f, 0.17f, 0.19f };
+  ui_renderer->draw_rect(x, y, width, _height, bg_color);
+}
+
+void MenuBar::render_bar_text(UIRenderer *ui_renderer, int x, int y, int width) {
+  const Color text_color  = { 0.9f,  0.9f,  0.9f  };
+
+  int menu_x = x;
+  for(size_t i = 0; i < _menus.size(); ++i) {
+    int menu_width = 60;
+    ui_renderer->render_text(_menus[i].label.c_str(), menu_x+10, y+20, text_color);
+    menu_x += menu_width;
+  }
+}
+
+void MenuBar::render_dropdown(UIRenderer* ui_renderer, int x, int y, int width ) {
+  if(_open_menu_index == -1) return;
+
+  const Color bg_color    = { 0.15f, 0.17f, 0.19f };
+  const Color text_color  = { 0.9f,  0.9f,  0.9f  };
+
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  int menu_x = x + (_open_menu_index*60);
+  int item_y = y + _height;
+  int item_height = 30;
+  int dropdown_width = 150;
+  for(const auto& item : _menus[_open_menu_index].items) {
+    ui_renderer->draw_rect(menu_x, item_y, dropdown_width, item_height, bg_color);
+    ui_renderer->render_text(item.label.c_str(), menu_x+10, item_y+20, text_color);
+    item_y += item_height;
+  }
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}

client/src/ui/menu_bar.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <functional>
+#include <SDL3/SDL_events.h>
+
+#include "ui/ui_renderer.h"
+
+struct MenuItem {
+  std::string label;
+  std::function<void()> action;
+};
+
+struct Menu {
+  std::string label;
+  std::vector<MenuItem> items;
+  bool is_open = false;
+};
+
+class MenuBar {
+public:
+  MenuBar(int height);
+  ~MenuBar(void);
+
+  void add_menu(const std::string& label);
+  void add_menu_item(const std::string& menu_label, const std::string& item_label,
+                     std::function<void()> action);
+
+  void handle_event(SDL_Event* event, int window_x, int window_y);
+  void render_bar_bg(UIRenderer* ui_renderer, int x, int y, int width);
+  void render_bar_text(UIRenderer* ui_renderer, int x, int y, int width);
+  void render_dropdown(UIRenderer* ui_renderer, int x, int y, int width);
+
+  int get_height(void) const;
+private:
+  int _height;
+  std::vector<Menu> _menus;
+  int _open_menu_index = -1;
+};

client/src/ui/taskbar.cpp

@@ -0,0 +1,114 @@
+#include <algorithm>
+#include <memory>
+#include <chrono>
+#include <ctime>
+#include <iomanip>
+#include <sstream>
+
+#include "taskbar.h"
+#include "ui/ui_renderer.h"
+#include "ui/ui_window.h"
+
+Taskbar::Taskbar(int screen_width, int screen_height) {
+  _width  = screen_width;
+  _height = 32;
+  _y_pos  = screen_height - _height; /* Taskbar at bottom because boring? */
+  _start_button_width = 60;
+}
+
+Taskbar::~Taskbar(void) {}
+
+void Taskbar::add_window(UIWindow* window) {
+  _buttons.push_back({window, window->get_title()});
+}
+
+void Taskbar::remove_window(UIWindow* window) {
+  _buttons.erase(
+    std::remove_if(_buttons.begin(), _buttons.end(),
+                   [window](const TaskbarButton& btn) {
+                     return btn.window == window;
+                   }),
+    _buttons.end());
+}
+
+void Taskbar::render(UIRenderer* ui_renderer, UIWindow* focused_window) {
+  const Color taskbar_color         = { 0.1f, 0.12f, 0.14f };
+  const Color button_color          = { 0.2f, 0.22f, 0.24f };
+  const Color button_focused_color  = { 0.3f, 0.32f, 0.34f };
+  const Color button_text_color     = { 0.9f, 0.9f,  0.9f  };
+
+  ui_renderer->begin_shapes();
+  ui_renderer->begin_text();
+
+  ui_renderer->draw_rect(0, _y_pos, _width, _height, taskbar_color);
+
+  /* Draw start button. */
+  ui_renderer->draw_rect(5, _y_pos + 5, _start_button_width - 10,
+                            _height - 10, button_color);
+  ui_renderer->render_text("[B]", 20, _y_pos + 20, button_text_color);
+
+  /* Draw app buttons. */
+  int button_width  = 150;
+  int padding       = 5;
+  int x_offset      = _start_button_width + padding;
+
+  for(const auto& button: _buttons) {
+    bool is_focused = (button.window == focused_window);
+    ui_renderer->draw_rect(x_offset, _y_pos + padding, button_width,
+                              _height - (padding * 2),
+                              is_focused ? button_focused_color : button_color);
+
+    /* TODO: Truncate text when too long. */
+    ui_renderer->render_text(button.title.c_str(), x_offset + 10,
+                              _y_pos + 20, button_text_color);
+    x_offset += button_width + padding;
+  }
+  /* Draw clock. */
+  auto now = std::chrono::system_clock::now();
+  auto in_time_t = std::chrono::system_clock::to_time_t(now);
+  std::stringstream ss;
+  ss << std::put_time(std::localtime(&in_time_t), "%H:%M");
+  std::string time_str = ss.str();
+
+  ui_renderer->render_text(time_str.c_str(), _width-50, _y_pos+20, button_text_color);
+
+  ui_renderer->flush_shapes();
+  ui_renderer->flush_text();
+}
+
+UIWindow* Taskbar::handle_event(SDL_Event* event, int screen_height) {
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+
+    int button_width  = 150;
+    int padding       = 5;
+    int x_offset      = _start_button_width + padding;
+    for(const auto& button : _buttons) {
+      if(mouse_x >= x_offset && mouse_x <= x_offset + button_width &&
+         mouse_y >= _y_pos && mouse_y <= _y_pos + _height) {
+        return button.window; /* Return clicked window. */
+      }
+      x_offset += button_width + padding;
+    }
+  }
+  return nullptr; /* No window button was clicked. */
+}
+
+bool Taskbar::is_start_button_clicked(SDL_Event* event, int screen_height) {
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+    return (mouse_x >= 0 && mouse_x <= _start_button_width && mouse_y >= _y_pos &&
+            mouse_y <= _y_pos + _height);
+  }
+  return false;
+}
+
+int Taskbar::get_height(void) const {
+  return _height;
+}
+
+bool Taskbar::is_point_inside(int x, int y) const {
+  return (y >= _y_pos && y<= _y_pos + _height);
+}

client/src/ui/taskbar.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <SDL3/SDL_events.h>
+#include <string>
+#include <vector>
+
+class UIWindow;
+class UIRenderer;
+
+struct TaskbarButton {
+  UIWindow* window;
+  std::string title;
+};
+
+class Taskbar {
+public:
+  Taskbar(int screen_width, int screen_height);
+  ~Taskbar(void);
+
+  void add_window(UIWindow* window);
+  void remove_window(UIWindow* window);
+
+  void render(UIRenderer* ui_renderer, UIWindow* focused_window);
+  UIWindow* handle_event(SDL_Event* event, int screen_height);
+  bool is_start_button_clicked(SDL_Event* event, int screen_height);
+  bool is_point_inside(int x, int y) const;
+
+  int get_height(void) const;
+private:
+  std::vector<TaskbarButton> _buttons;
+  int _width;
+  int _height;
+  int _y_pos;
+  int _start_button_width;
+};

client/src/ui/text_view.cpp

@@ -0,0 +1,250 @@
+#include <SDL3/SDL_events.h>
+#include <string>
+
+#include "text_view.h"
+#include "gfx/types.h"
+#include "ui/editor.h"
+#include "ui/text_buffer.h"
+#include "ui/ui_renderer.h"
+
+TextView::TextView(TextBuffer* buffer, bool handle_ret, bool show_line_numbers,
+                   bool syntax_highlighting) :
+      _buffer(buffer),
+      _scroll_offset(0),
+      _handle_ret(handle_ret),
+      _show_line_numbers(show_line_numbers),
+      _syntax_highlighting(syntax_highlighting) {
+
+  _lua_keywords = {
+    "and", "break", "do", "else", "elseif", "end", "false", "for",
+    "function", "if", "in", "local", "nil", "not", "or", "repeat",
+    "return", "then", "true", "until", "while"
+  };
+}
+
+TextView::~TextView(void) = default;
+
+bool TextView::handle_event(SDL_Event* event, int content_height) {
+  if(!_buffer) return false;
+
+  if(event->type == SDL_EVENT_TEXT_INPUT) {
+    _buffer->insert_char(event->text.text[0]);
+    _ensure_cursor_visible(content_height);
+  } else if(event->type == SDL_EVENT_KEY_DOWN) {
+    switch(event->key.key) {
+      case SDLK_BACKSPACE:
+        _buffer->backspace();
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_RETURN:
+        /*
+         * For editor, we want a real newline.
+         * For terminal, we just want to submit. No newline.
+         * We'll return true and let the parent component do the do'ing.
+         */
+        if(_handle_ret) {
+          _buffer->newline();
+        }
+        _ensure_cursor_visible(content_height);
+        return true;
+        break;
+      case SDLK_LEFT:
+        _buffer->move_cursor(-1,0);
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_RIGHT:
+        _buffer->move_cursor(1,0);
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_UP:
+        _buffer->move_cursor(0,-1);
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_DOWN:
+        _buffer->move_cursor(0,1);
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_HOME:
+        _buffer->move_cursor_home();
+        _ensure_cursor_visible(content_height);
+        break;
+      case SDLK_END:
+        _buffer->move_cursor_end();
+        break;
+      default:
+        break;
+    }
+  }
+  return false;
+}
+
+void TextView::scroll(int amount, int content_height) {
+  _scroll_offset += amount;
+
+  if(_scroll_offset < 0) {
+    _scroll_offset = 0;
+  }
+  float line_height = 20.0f;
+  int visible_lines = static_cast<int>(content_height / line_height)-1;
+  int max_scroll = _buffer->get_line_count() - visible_lines;
+  /* Allow one extra scroll step if content is larger than visible area. */
+  if(_buffer->get_line_count() > visible_lines) max_scroll += 1;
+  if(max_scroll < 0) {
+    max_scroll = 0;
+  }
+  if(max_scroll < 0) max_scroll = 0;
+  if(_scroll_offset > max_scroll) {
+    _scroll_offset = max_scroll;
+  }
+}
+
+std::vector<Token> TextView::_tokenize_line(const std::string& line) {
+  std::vector<Token> tokens;
+  std::string current_token_text;
+  TokenType current_token_type = TokenType::NORMAL;
+
+  for(size_t i = 0; i < line.length(); ++i) {
+    char c = line[i];
+
+    /* Check for comments. */
+    if(i + 1 < line.length() && c == '-' && line[i+1] == '-') {
+      if(!current_token_text.empty()) {
+        tokens.push_back({current_token_type, current_token_text});
+      }
+      tokens.push_back({TokenType::COMMENT, line.substr(i)});
+      return tokens;
+    }
+
+    /* Check for strings. */
+    if(c == '"') {
+      if(!current_token_text.empty()) {
+        tokens.push_back({current_token_type, current_token_text});
+      }
+      size_t end_quote = line.find('"', i+1);
+      if(end_quote == std::string::npos) {
+        tokens.push_back({TokenType::STRING, line.substr(i)});
+        return tokens;
+      }
+      tokens.push_back({TokenType::STRING, line.substr(i, end_quote - i+1)});
+      i = end_quote;
+      current_token_text = "";
+      continue;
+    }
+
+    /* Check for numbers. */
+    if(isdigit(c) && (current_token_text.empty() || current_token_type == TokenType::NUMBER)) {
+      current_token_type = TokenType::NUMBER;
+      current_token_text += c;
+    } else if(isalnum(c) || c == '_') { /* Keywords and identifiers. */
+      if(current_token_type != TokenType::NORMAL) {
+        tokens.push_back({current_token_type, current_token_text});
+        current_token_text = "";
+      }
+      current_token_type = TokenType::NORMAL;
+      current_token_text += c;
+    } else { /* Delimiters. */
+      if(!current_token_text.empty()) {
+        if(_lua_keywords.count(current_token_text)) {
+          tokens.push_back({TokenType::KEYWORD, current_token_text});
+        } else {
+          tokens.push_back({current_token_type, current_token_text});
+        }
+        current_token_text = "";
+      }
+      tokens.push_back({TokenType::NORMAL, std::string(1, c)});
+      current_token_type = TokenType::NORMAL;
+    }
+  }
+
+  if(!current_token_text.empty()) {
+    if(_lua_keywords.count(current_token_text)) {
+      tokens.push_back({TokenType::KEYWORD, current_token_text});
+    } else {
+      tokens.push_back({current_token_type, current_token_text});
+    }
+  }
+  return tokens;
+}
+
+void TextView::render_text_content(UIRenderer* ui_renderer, const SyntaxTheme& theme,
+                                   int x, int y, int width, int height) {
+  if(!_buffer) return;
+
+  const float line_height   = 20.0f; /* TODO: Get font metrics? */
+  const float padding       = 5.0f;
+  const float gutter_width  = _show_line_numbers ? 40.0f : 0.0f;
+
+  float current_y = y;
+
+  for(size_t i = _scroll_offset; i < _buffer->get_line_count(); ++i) {
+    /*
+     * Culling: If the top of the current line is already below the bottom of the
+     * view, we can stop rendering completely.
+     */
+    if(current_y >= y + height) {
+      break;
+    }
+
+    if(_show_line_numbers) {
+      /* Render line number. */
+      std::string line_num_str = std::to_string(i+1);
+      float line_num_text_width =
+        ui_renderer->get_text_renderer()->get_text_width(line_num_str.c_str(), 1.0f);
+      ui_renderer->render_text(line_num_str.c_str(), x+padding+(gutter_width-line_num_text_width-10),
+                              current_y+18, theme.line_num);
+    }
+
+    float current_x = x+padding + gutter_width;
+    if(_syntax_highlighting) {
+      std::vector<Token> tokens = _tokenize_line(_buffer->get_line(i));
+      for(const auto& token : tokens) {
+        Color color = theme.normal;
+        switch(token.type) {
+          case TokenType::KEYWORD:  color = theme.keyword;  break;
+          case TokenType::STRING:   color = theme.string;   break;
+          case TokenType::NUMBER:   color = theme.number;   break;
+          case TokenType::COMMENT:  color = theme.comment;  break;
+          default: break;
+        }
+        ui_renderer->render_text(token.text.c_str(), current_x, current_y+18, color);
+        current_x += ui_renderer->get_text_renderer()->get_text_width(token.text.c_str(), 1.0f);
+      } 
+    } else {
+      ui_renderer->render_text(_buffer->get_line(i).c_str(), current_x, current_y+18, theme.normal);
+    }
+    current_y += line_height;
+  }
+}
+
+void TextView::render_cursor(UIRenderer* ui_renderer, const SyntaxTheme& theme,
+                             int x, int y, int width, int height) {
+  const float line_height   = 20.0f; /* TODO: Get font metrics? */
+  const float padding       = 5.0f;
+  const float gutter_width  = _show_line_numbers ? 40.0f : 0.0f;
+  Point cursor_pos = _buffer->get_cursor_pos();
+  std::string line_before_cursor = _buffer->get_line(cursor_pos.row).substr(0, cursor_pos.col);
+  float text_width =
+  ui_renderer->get_text_renderer()->get_text_width(line_before_cursor.c_str(), 1.0f);
+  float cursor_x = x + padding + gutter_width + text_width;
+  float cursor_y = y + (cursor_pos.row - _scroll_offset) * line_height;
+  if(cursor_y >= y && cursor_y < y + height) {
+    ui_renderer->draw_rect(cursor_x, cursor_y, 2, line_height, theme.normal);
+  }
+}
+
+void TextView::_ensure_cursor_visible(int content_height) {
+  Point cursor_pos = _buffer->get_cursor_pos();
+  float line_height = 20.0f;
+  int visible_lines = static_cast<int>(content_height / line_height)-1;
+
+  /* If cursor above current scroll view, scroll up. */
+  if(cursor_pos.row < _scroll_offset) {
+    _scroll_offset = cursor_pos.row;
+  } else if(cursor_pos.row >= _scroll_offset + visible_lines) {
+    /* Below, scroll down. */
+    _scroll_offset = cursor_pos.row - visible_lines+1;
+  }
+
+  /* Re-clamp scroll offset to ensure it's within valid bounds. */
+  scroll(0, content_height);
+}

client/src/ui/text_view.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <SDL3/SDL_events.h>
+#include <string>
+#include <vector>
+#include <unordered_set>
+
+#include "ui/text_buffer.h"
+#include "ui/ui_renderer.h"
+#include "ui/editor.h" /* For SyntaxTheme */
+
+class TextRenderer;
+
+enum class TokenType {
+  NORMAL,
+  KEYWORD,
+  STRING,
+  NUMBER,
+  COMMENT
+};
+
+struct Token {
+  TokenType type;
+  std::string text;
+};
+
+class TextView {
+public:
+  TextView(TextBuffer* buffer, bool handle_ret, bool show_line_numbers, bool syntax_highlighting);
+  ~TextView(void);
+
+  bool handle_event(SDL_Event* event, int content_height);
+  void scroll(int amount, int content_height);
+  void render_text_content(UIRenderer* ui_renderer, const SyntaxTheme& theme,
+                           int x, int y, int width, int height);
+  void render_cursor(UIRenderer* ui_renderer, const SyntaxTheme& theme,
+                     int x, int y, int width, int height);
+
+private:
+  void _ensure_cursor_visible(int content_height);
+  std::vector<Token> _tokenize_line(const std::string& line);
+
+  TextBuffer* _buffer;
+  int _scroll_offset;
+  bool _handle_ret;
+  bool _show_line_numbers;
+  bool _syntax_highlighting;
+  std::unordered_set<std::string> _lua_keywords;
+};

client/src/ui/ui_renderer.cpp

@@ -0,0 +1,64 @@
+#include <GL/glew.h>
+
+#include "ui_renderer.h"
+#include "gfx/shape_renderer.h"
+#include "gfx/txt_renderer.h"
+
+UIRenderer::UIRenderer(ShapeRenderer* shape_renderer, TextRenderer* txt_renderer, int screen_height)
+    : _shape_renderer(shape_renderer), _txt_renderer(txt_renderer), _screen_height(screen_height) {}
+
+void UIRenderer::draw_rect(int x, int y, int width, int height, const Color& color) {
+  if(!_shape_renderer) return;
+  /* Convert top-left screen coord to bottom-left GL coord. */
+  int y_gl = _screen_height - y - height;
+  _shape_renderer->draw_rect(x, y_gl, width, height, color);
+}
+
+void UIRenderer::draw_triangle(int x1, int y1, int x2, int y2, int x3, int y3, const Color& color) {
+  if(!_shape_renderer) return;
+  /* Convert top-left screen coord to bottom-left GL coord. */
+  int y1_gl = _screen_height - y1;
+  int y2_gl = _screen_height - y2;
+  int y3_gl = _screen_height - y3;
+  _shape_renderer->draw_triangle(x1, y1_gl, x2, y2_gl, x3, y3_gl, color);
+}
+
+void UIRenderer::render_text(const char* text, int x, int y, const Color& color) {
+  if(!_txt_renderer) return;
+  /* Convert the screen-space baseline y-coord to GL-space baseline y-coord. */
+  int y_gl = _screen_height - y;
+  _txt_renderer->render_text(text, x, y_gl, color);
+}
+
+void UIRenderer::begin_text(void) {
+  if(!_txt_renderer) return;
+  _txt_renderer->begin();
+}
+
+void UIRenderer::flush_text(void) {
+  if(!_txt_renderer) return;
+  _txt_renderer->flush();
+}
+
+void UIRenderer::begin_shapes(void) {
+  if(!_shape_renderer) return;
+  _shape_renderer->begin();
+}
+
+void UIRenderer::flush_shapes(void) {
+  if(!_shape_renderer) return;
+  _shape_renderer->flush();
+}
+
+TextRenderer* UIRenderer::get_text_renderer(void) {
+  return _txt_renderer;
+}
+
+void UIRenderer::enable_scissor(int x, int y, int width, int height) {
+  glEnable(GL_SCISSOR_TEST);
+  glScissor(x, y, width, height);
+}
+
+void UIRenderer::disable_scissor(void) {
+  glDisable(GL_SCISSOR_TEST);
+}

client/src/ui/ui_renderer.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include "gfx/shape_renderer.h"
+#include "gfx/txt_renderer.h"
+#include "gfx/types.h"
+
+/*
+ * I'm so damn sick of working between two rendering systems!
+ * Here! Have a wrapper around the low-level renderers to provide a f.cking
+ * consistant top-left origin for all UI components.
+ */
+class UIRenderer {
+public:
+  UIRenderer(ShapeRenderer* shape_renderer, TextRenderer* txt_renderer, int screen_height);
+
+  void draw_rect(int x, int y, int width, int height, const Color& color);
+  void draw_triangle(int x1, int y1, int x2, int y2, int x3, int y3, const Color& color);
+  void render_text(const char* text, int x, int y, const Color& color);
+
+  void begin_text(void);
+  void flush_text(void);
+
+  void begin_shapes(void);
+  void flush_shapes(void);
+
+  /* Expose underlying text renderer for things like width calculation. */
+  TextRenderer* get_text_renderer(void);
+
+  void enable_scissor(int x, int y, int width, int height);
+  void disable_scissor(void);
+
+private:
+  ShapeRenderer*  _shape_renderer;
+  TextRenderer*   _txt_renderer;
+  int             _screen_height;
+};

client/src/ui/ui_window.cpp

@@ -0,0 +1,224 @@
+#include "ui_window.h"
+#include <SDL3/SDL_events.h>
+#include <SDL3/SDL_hidapi.h>
+#include <memory>
+#include "ui/i_window_content.h"
+#include "ui_renderer.h"
+
+UIWindow::UIWindow(const char* title, int x, int y, int width, int height) :
+    _title(title),
+    _x(x),
+    _y(y),
+    _width(width),
+    _height(height),
+    _content(nullptr),
+    _is_dragging(false),
+    _is_hovered(false),
+    _is_focused(false),
+    _should_close(false),
+    _state(WindowState::NORMAL),
+    _is_resizing(false),
+    _resize_margin(10) {
+  /* Init title bar buttons. */
+  _title_bar_buttons.push_back({WindowButtonAction::CLOSE,    {0.8f, 0.2f, 0.2f}});
+  _title_bar_buttons.push_back({WindowButtonAction::MAXIMIZE, {0.2f, 0.8f, 0.2f}});
+  _title_bar_buttons.push_back({WindowButtonAction::MINIMIZE, {0.8f, 0.8f, 0.2f}});
+}
+
+UIWindow::~UIWindow(void) {}
+
+void UIWindow::minimize(void) {
+  _state = WindowState::MINIMIZED;
+}
+
+void UIWindow::restore(void) {
+  _state = WindowState::NORMAL;
+}
+
+bool UIWindow::is_minimized(void) const {
+  return _state == WindowState::MINIMIZED;
+}
+
+const std::string& UIWindow::get_title(void) const {
+  return _title;
+}
+
+Rect UIWindow::get_rect(void) const {
+  return { _x, _y, _width, _height };
+}
+
+bool UIWindow::is_mouse_over_resize_handle(int mouse_x, int mouse_y) const {
+  return (mouse_x >= _x + _width  - _resize_margin && mouse_x <= _x + _width &&
+          mouse_y >= _y + _height - _resize_margin &&
+          mouse_y <= _y + _height);
+}
+
+bool UIWindow::should_close(void) const {
+  return _should_close;
+}
+
+void UIWindow::update(void) {
+  if(_content) {
+    if(_content->should_close()) { _should_close = true; }
+  }
+}
+
+void UIWindow::set_content(std::unique_ptr<IWindowContent> content) {
+  _content = std::move(content);
+}
+
+void UIWindow::set_focused(bool focused) {
+  _is_focused = focused;
+}
+
+IWindowContent* UIWindow::get_content(void) {
+  return _content.get();
+}
+
+bool UIWindow::is_point_inside(int x, int y) {
+  return (x >= _x && x <= _x + _width &&
+          y >= _y && y <= _y + _height);
+}
+
+void UIWindow::render(const RenderContext& context) {
+  int title_bar_height = 30;
+
+  context.ui_renderer->begin_shapes();
+  context.ui_renderer->begin_text();
+
+  /* Define colours. */
+  const Color frame_color             = { 0.2f,  0.2f,  0.25f };
+  const Color title_bar_color         = { 0.15f, 0.15f, 0.2f  };
+  const Color focused_title_bar_color = { 0.3f,  0.3f,  0.4f  };
+  const Color title_text_color        = { 0.9f,  0.9f,  0.9f  };
+  const Color resize_handle_color     = { 0.9f,  0.9f,  0.9f  };
+
+  /* Draw main window frame/background. */
+  context.ui_renderer->draw_rect(_x, _y, _width, _height, frame_color);
+
+  /* Draw title bar. */
+  if(_is_focused) {
+    context.ui_renderer->draw_rect(_x, _y, _width, title_bar_height, focused_title_bar_color);
+  } else {
+    context.ui_renderer->draw_rect(_x, _y, _width, title_bar_height, title_bar_color);
+  }
+
+  /* Draw title text. */
+  context.ui_renderer->render_text(_title.c_str(), _x+5, _y+20, title_text_color);
+
+  /* Draw title bar buttons. */
+  int button_size = 20;
+  int button_margin = 5;
+  int x_offset = _x + _width - button_size - button_margin;
+  for(const auto& button : _title_bar_buttons) {
+    context.ui_renderer->draw_rect(x_offset, _y+button_margin, button_size,
+                                   button_size, button.color);
+    x_offset -= (button_size + button_margin);
+  }
+
+  /* Draw Resize handle. */
+  int corner_x = _x + _width;
+  int corner_y = _y + _height;
+  context.ui_renderer->draw_triangle(corner_x, corner_y - 10, corner_x - 10,
+                                corner_y, corner_x, corner_y, resize_handle_color);
+
+  /* Flush the shapes and text for the window frame and title bar. */
+  context.ui_renderer->flush_shapes();
+  context.ui_renderer->flush_text();
+
+  if(_content) {
+    int content_screen_y = _y + title_bar_height;
+    int content_height = _height - title_bar_height;
+    int content_width = _width;
+    /* Got to pass GL y-coord for scissor box to work correctly. */
+    int content_gl_y = context.screen_height - content_screen_y - content_height;
+    _content->render(context, _x, content_screen_y, content_gl_y, content_width, content_height);
+  }
+}
+
+void UIWindow::handle_event(SDL_Event* event, int screen_width,
+                            int screen_height, int taskbar_height) {
+  int title_bar_height = 30;
+
+  if(event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
+    int mouse_x = event->button.x;
+    int mouse_y = event->button.y;
+
+    /* Check for title bar button clicks. */
+    int button_size = 20;
+    int button_margin = 5;
+    int x_offset = _x + _width - button_size - button_margin;
+    for(const auto& button : _title_bar_buttons) {
+      if(mouse_x >= x_offset && mouse_x <= x_offset + button_size &&
+         mouse_y >= _y + button_margin && mouse_y <= _y + button_margin + button_size) {
+        switch(button.action) {
+        case WindowButtonAction::CLOSE:
+          _should_close = true;
+          break;
+        case WindowButtonAction::MAXIMIZE:
+          if(_state == WindowState::MAXIMIZED) {
+            _x          = _pre_maximize_rect.x;
+            _y          = _pre_maximize_rect.y;
+            _width      = _pre_maximize_rect.w;
+            _height     = _pre_maximize_rect.h;
+            _state      = WindowState::NORMAL;
+          } else {
+            _pre_maximize_rect = { _x, _y, _width, _height };
+            _x = 0; _y = 0;
+            _width = screen_width; _height = screen_height - taskbar_height;
+            _state = WindowState::MAXIMIZED;
+          }
+          break;
+        case WindowButtonAction::MINIMIZE:
+          minimize();
+          break;
+        }
+        return; /* Button clicked, no need to process further. */
+      }
+      x_offset -= (button_size + button_margin);
+    }
+
+    /* Check for resize handle click (bottom-right corner). */
+    if(is_mouse_over_resize_handle(mouse_x, mouse_y) &&
+       _state != WindowState::MAXIMIZED) {
+      _is_resizing = true;
+    } else if(mouse_x >= _x && mouse_x <= _x + _width &&
+       mouse_y >= _y && mouse_y <= _y + title_bar_height &&
+       _state != WindowState::MAXIMIZED) {
+      /* Is click within title bar? */
+      _is_dragging = true;
+      _drag_offset_x = mouse_x - _x;
+      _drag_offset_y = mouse_y - _y;
+    }
+  } else if(event->type == SDL_EVENT_MOUSE_BUTTON_UP) {
+    _is_dragging = false;
+    _is_resizing = false;
+  } else if(event->type == SDL_EVENT_MOUSE_MOTION) {
+    if(_is_dragging) {
+      _x = event->motion.x - _drag_offset_x;
+      _y = event->motion.y - _drag_offset_y;
+    } else if(_is_resizing) {
+      int new_width   = event->motion.x - _x;
+      int new_height  = event->motion.y - _y;
+      _width  = (new_width  > 100) ? new_width  : 100; /* Min width.  */
+      _height = (new_height >  80) ? new_height :  80; /* Min height. */
+    }
+
+    /* Check if mouse hovered over window. */
+    _is_hovered = is_point_inside(event->motion.x, event->motion.y);
+  } else if(event->type == SDL_EVENT_MOUSE_WHEEL) {
+    /* Only scroll window if mouse is hovering. */
+    if(_is_hovered && _content) {
+      /* SDL's wheel motion is negative scroll up on the y. */
+      int content_height_gl = _height - title_bar_height;
+      _content->scroll(-event->wheel.y, content_height_gl);
+    }
+  }
+  if(_content) {
+    int y_gl = screen_height - _y - _height;
+    int content_height = _height - title_bar_height;
+    int content_width = _width;
+    _content->handle_input(event, _x, _y, y_gl, content_width, content_height);
+  }
+}
+

client/src/ui/ui_window.h

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "gfx/types.h"
+#include "i_window_content.h"
+
+enum class WindowState {
+  NORMAL,
+  MINIMIZED,
+  MAXIMIZED
+};
+
+enum class WindowButtonAction {
+  CLOSE,
+  MAXIMIZE,
+  MINIMIZE
+};
+
+struct TitleBarButton {
+  WindowButtonAction action;
+  Color color;
+};
+
+class UIWindow {
+public:
+  UIWindow(const char* title, int x, int y, int width, int height);
+  ~UIWindow(void);
+
+  void update(void);
+  void render(const RenderContext& context);
+  void handle_event(SDL_Event* event, int screen_width, int screen_height,
+                    int taskbar_height);
+  void minimize(void);
+  void restore(void);
+  void close(void) { _should_close = true; }
+  bool is_minimized(void) const;
+  bool should_close(void) const;
+  void set_focused(bool focused);
+  bool is_point_inside(int x, int y);
+  void set_content(std::unique_ptr<IWindowContent> content);
+  IWindowContent* get_content(void);
+  bool is_mouse_over_resize_handle(int mouse_x, int mouse_y) const;
+  const std::string& get_title(void) const;
+  Rect get_rect(void) const;
+  void set_session_id(uint32_t id) { _session_id = id; }
+  uint32_t get_session_id(void) const { return _session_id; }
+
+private:
+  friend class Taskbar; /* Allow taskbar to access private members. */
+  int _x, _y, _width, _height;
+  Rect _pre_maximize_rect;
+  std::string _title;
+  std::unique_ptr<IWindowContent> _content;
+  bool _is_focused; /* Managed by desktop. */
+  bool _is_hovered; /* Send scroll events even if not focused. */
+  bool _should_close;
+
+  std::vector<TitleBarButton> _title_bar_buttons;
+  WindowState _state;
+
+  bool _is_dragging;
+  int _drag_offset_x, _drag_offset_y;
+
+  bool _is_resizing;
+  int _resize_margin;
+
+  uint32_t _session_id;
+};

client/src/ui/window_action.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+
+enum class ActionType {
+  NONE,
+  WRITE_FILE,
+  READ_FILE,
+  BUILD_FILE,
+  CLOSE_WINDOW
+};
+
+struct WindowAction {
+  ActionType type = ActionType::NONE;
+  std::string payload1; /* i.e., filename. */
+  std::string payload2; /* i.e., content. */
+};

common/CMakeLists.txt

@@ -0,0 +1,16 @@
+find_package(Lua 5.4 REQUIRED)
+
+file(GLOB_RECURSE BETTOLA_SOURCES "src/*.cpp")
+
+add_library(bettola
+  ${BETTOLA_SOURCES}
+)
+
+target_link_libraries(bettola PUBLIC ${LUA_LIBRARIES} sol2 sqlite)
+
+target_include_directories(bettola PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src
+  ${LUA_INCLUDE_DIR}
+  ${asio_SOURCE_DIR}/asio/include
+  ${sqlite_modern_cpp_SOURCE_DIR}/hdr
+)
+

common/src/bettola.cpp

@@ -0,0 +1,6 @@
+#include <cstdio>
+#include "bettola.h"
+
+void bettola_function(void) {
+  printf("Hello from libbettola!\n");
+}

common/src/bettola.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void bettola_function(void);

common/src/db/database_manager.cpp

@@ -0,0 +1,97 @@
+#include "database_manager.h"
+#include <memory>
+#include "vfs.h"
+
+DatabaseManager::DatabaseManager(const std::string& db_path) :
+    _db(db_path) {
+  _player_repository  = std::make_unique<PlayerRepository>(_db);
+  _machine_repository = std::make_unique<MachineRepository>(_db);
+  _service_repository = std::make_unique<ServiceRepository>(_db);
+  _vfs_repository     = std::make_unique<VFSRepository>(_db);
+
+  _db <<  "CREATE TABLE IF NOT EXISTS players("
+          "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+          "username TEXT NOT NULL UNIQUE,"
+          "password TEXT NOT NULL,"
+          "hostname TEXT NOT NULL,"
+          "home_machine_id INTEGER"
+          ");";
+
+  _db <<  "CREATE TABLE IF NOT EXISTS machines ("
+          "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+          "owner_id INTEGER,"
+          "hostname TEXT NOT NULL,"
+          "ip_address TEXT NOT NULL UNIQUE"
+          ");";
+
+  _db <<  "CREATE TABLE IF NOT EXISTS vfs_nodes ("
+          "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+          "machine_id INTEGER NOT NULL,"
+          "parent_id INTEGER,"
+          "name TEXT NOT NULL,"
+          "type INTEGER NOT NULL,"
+          "content TEXT,"
+          "owner_id INTEGER NOT NULL,"
+          "group_id INTEGER NOT NULL,"
+          "permissions INTEGER NOT NULL"
+          ");";
+  _db <<  "CREATE TABLE IF NOT EXISTS services ("
+          "id INTEGER PRIMARY KEY AUTOINCREMENT,"
+          "machine_id INTEGER NOT NULL,"
+          "port INTEGER NOT NULL,"
+          "name TEXT NOT NULL"
+          ");";
+}
+
+DatabaseManager::~DatabaseManager(void) {
+  /* db is auto closed when _db goes out of scope. */
+}
+
+bool DatabaseManager::create_player(const std::string& username, const std::string& password,
+                                    const std::string& hostname, vfs_node* vfs_template) {
+  long long player_id   = 0;
+  long long machine_id  = 0;
+
+  try {
+    _db << "BEGIN;";
+
+    player_id = _player_repository->create(username, password, hostname);
+
+    /* Create the home machine. */
+    /* TODO: Implement real IP allication. */
+    std::string ip_address = "192.168.1." + std::to_string(player_id);
+    machine_id = _machine_repository->create(player_id, hostname, ip_address);
+
+    _player_repository->set_home_machine_id(player_id, machine_id);
+
+    /* Create the root dir for the new machine's VFS. */
+    long long root_id = _vfs_repository->create_node(machine_id, nullptr, "/", DIR_NODE,
+                                                     "", player_id, player_id, 0755);
+
+    /* Create default subdirs. */
+    _vfs_repository->create_node(machine_id, &root_id, "home", DIR_NODE,
+                                 "", player_id, player_id, 0755);
+    _vfs_repository->create_node(machine_id, &root_id, "etc", DIR_NODE,
+                                 "", player_id, player_id, 0755);
+
+    /* Create /bin and get it's ID */
+    long long bin_id = _vfs_repository->create_node(machine_id, &root_id, "bin", DIR_NODE,
+                                                    "", player_id, player_id, 0755);
+
+    /* Copy scripts from template into new machine's /bin */
+    vfs_node* template_bin = vfs_template->children["bin"];
+    for(auto const& [name, node] : template_bin->children) {
+      _vfs_repository->create_node(machine_id, &bin_id, name, node->type, node->content,
+                                   player_id, player_id, 0755);
+    }
+
+    /* Add default SSH service. */
+    _service_repository->create(machine_id, 22, "SSH");
+
+    _db << "COMMIT";
+  } catch(const std::exception& e) {
+    _db << "ROLLBACK;"; /* Ensure atomicity. */
+    return false;
+  }
+  return true;
+}

common/src/db/database_manager.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <string>
+#include <memory>
+
+#include "service_repository.h"
+#include "player_repository.h"
+#include "machine_repository.h"
+#include "vfs_repository.h"
+#include "sqlite_modern_cpp.h"
+#include "vfs.h"
+
+class DatabaseManager {
+public:
+  DatabaseManager(const std::string& db_path);
+  ~DatabaseManager(void);
+
+  /* Return true on success, false if user already exists. */
+  bool create_player(const std::string& username, const std::string& password,
+                     const std::string& hostname, vfs_node* vfs_template);
+
+  PlayerRepository& players(void)   { return *_player_repository;  }
+  MachineRepository& machines(void) { return *_machine_repository; }
+  ServiceRepository& services(void) { return *_service_repository; }
+  VFSRepository& vfs(void)          { return *_vfs_repository;     }
+
+  sqlite::database _db;
+
+private:
+  std::unique_ptr<PlayerRepository> _player_repository;
+  std::unique_ptr<MachineRepository> _machine_repository;
+  std::unique_ptr<ServiceRepository> _service_repository;
+  std::unique_ptr<VFSRepository> _vfs_repository;
+};

common/src/db/db.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#include <sqlite_modern_cpp.h>

common/src/db/machine_repository.cpp

@@ -0,0 +1,49 @@
+#include "machine_repository.h"
+#include "sqlite_modern_cpp.h"
+
+MachineRepository::MachineRepository(sqlite::database& db) : _db(db) {}
+
+long long MachineRepository::create(std::optional<long long> owner_id,
+                                    const std::string& hostname,
+                                    const std::string& ip_address) {
+  if(owner_id.has_value()) {
+    _db << "INSERT INTO machines (owner_id, hostname, ip_address) VALUES(?, ?, ?);"
+        << owner_id.value() << hostname << ip_address;
+  } else {
+    _db << "INSERT INTO machines (owner_id, hostname, ip_address) VALUES (NULL, ?, ?);"
+        << hostname << ip_address;
+  }
+  return _db.last_insert_rowid();
+}
+
+int MachineRepository::get_npc_count(void) {
+  int count = 0;
+  _db << "SELECT count(*) FROM machines WHERE owner_id IS NULL;" >> count;
+  return count;
+}
+
+std::vector<MachineData> MachineRepository::get_all_npcs(void) {
+  std::vector<MachineData> machines;
+  _db << "SELECT id, ip_address FROM machines WHERE owner_id IS NULL;"
+      >> [&](long long id, std::string ip_address) {
+        machines.push_back({id, ip_address});
+    };
+  return machines;
+}
+
+std::vector<MachineData> MachineRepository::get_all(void) {
+  std::vector<MachineData> machines;
+  _db << "SELECT id, ip_address FROM machines;"
+      >> [&](long long id, std::string ip_address) {
+      machines.push_back({id, ip_address});
+    };
+  return machines;
+}
+
+std::string MachineRepository::get_hostname(long long machine_id) {
+  std::string hostname;
+  _db << "SELECT hostname FROM machines WHERE id = ?;"
+      << machine_id
+      >> hostname;
+  return hostname;
+}

common/src/db/machine_repository.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <optional>
+#include "sqlite_modern_cpp.h"
+
+/* Struct to hold machine data. */
+struct MachineData {
+  long long id;
+  std::string ip_address;
+};
+
+class MachineRepository {
+public:
+  MachineRepository(sqlite::database& db);
+
+  long long create(std::optional<long long> owner_id, const std::string& hostname,
+                   const std::string& ip_address);
+  int get_npc_count(void);
+  std::vector<MachineData> get_all_npcs(void);
+  std::vector<MachineData> get_all(void);
+  std::string get_hostname(long long machine_id);
+
+private:
+  sqlite::database& _db;
+};
+

common/src/db/player_repository.cpp

@@ -0,0 +1,34 @@
+#include "player_repository.h"
+
+PlayerRepository::PlayerRepository(sqlite::database& db) : _db(db) {}
+
+long long PlayerRepository::create(const std::string& username, const std::string& password,
+                         const std::string& hostname) {
+  _db << "INSERT INTO players (username, password, hostname) VALUES (?, ?, ?);"
+      << username
+      << password
+      << hostname;
+  return _db.last_insert_rowid();
+}
+
+bool PlayerRepository::authenticate(const std::string& username, const std::string& password) {
+  bool authed = false;
+  _db << "SELECT id FROM players WHERE username = ? AND password = ?;"
+      << username
+      << password
+      >> [&](long long id) {authed = true;};
+  return authed;
+}
+
+long long PlayerRepository::get_home_machine_id(const std::string& username) {
+  long long machine_id = -1;
+  _db << "SELECT home_machine_id FROM players WHERE username = ?;"
+      << username
+      >> machine_id;
+  return machine_id;
+}
+
+void PlayerRepository::set_home_machine_id(long long player_id, long long machine_id) {
+  _db << "UPDATE players SET home_machine_id = ? WHERE id = ?;"
+      << machine_id << player_id;
+}

common/src/db/player_repository.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <string>
+
+#include "sqlite_modern_cpp.h"
+
+class PlayerRepository {
+public:
+  PlayerRepository(sqlite::database& db);
+
+  long long create(const std::string& username, const std::string& password,
+                   const std::string& hostname);
+  bool authenticate(const std::string& username, const std::string& password);
+  long long get_home_machine_id(const std::string& username);
+  void set_home_machine_id(long long player_id, long long machine_id);
+
+private:
+  sqlite::database& _db;
+};

common/src/db/service_repository.cpp

@@ -0,0 +1,19 @@
+#include "service_repository.h"
+#include "sqlite_modern_cpp.h"
+
+ServiceRepository::ServiceRepository(sqlite::database& db) : _db(db) {}
+
+void ServiceRepository::create(long long machine_id, int port, const std::string& name) {
+  _db << "INSERT INTO services (machine_id, port, name) VALUES (?, ?, ?);"
+      << machine_id << port << name;
+}
+
+std::map<int, std::string> ServiceRepository::get_for_machine(long long machine_id) {
+  std::map<int, std::string> services;
+  _db << "SELECT port, name FROM services WHERE machine_id = ?;"
+      << machine_id
+      >> [&](int port, std::string name) {
+        services[port] = name;
+    };
+  return services;
+}

common/src/db/service_repository.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+#include <map>
+
+#include "sqlite_modern_cpp.h"
+
+class ServiceRepository {
+public:
+  ServiceRepository(sqlite::database& db);
+
+  void create(long long machine_id, int port, const std::string& name);
+  std::map<int, std::string> get_for_machine(long long machine_id);
+
+private:
+  sqlite::database& _db;
+};

common/src/db/vfs_repository.cpp

@@ -0,0 +1,46 @@
+#include "vfs_repository.h"
+
+VFSRepository::VFSRepository(sqlite::database& db) : _db(db) {}
+
+long long VFSRepository::create_node(long long machine_id, long long* parent_id,
+                                     const std::string& name, vfs_node_type type,
+                                     const std::string& content,
+                                     uint32_t owner_id, uint32_t group_id,
+                                     uint16_t permissions) {
+  if(parent_id) {
+    _db << "INSERT INTO vfs_nodes (machine_id, parent_id, name, type, content, "
+           "owner_id, group_id, permissions) "
+           "VALUES (?, ?, ?, ?, ?, ?, ?, ?);"
+        << machine_id << *parent_id << name << type << content << owner_id
+        << group_id << permissions;
+  } else {
+    _db << "INSERT INTO vfs_nodes (machine_id, parent_id, name, type, content, "
+           "owner_id, group_id, permissions) "
+           "VALUES (?, NULL, ?, ?, ?, ?, ?, ?);"
+        << machine_id << name << type << content
+        << owner_id << group_id << permissions;
+  }
+  return _db.last_insert_rowid();
+}
+
+std::vector<vfs_node*> VFSRepository::get_nodes_for_machine(long long machine_id) {
+  std::vector<vfs_node*> nodes;
+  _db << "SELECT id, parent_id, name, type, content, owner_id, group_id, permissions "
+         "FROM vfs_nodes WHERE machine_id = ?;"
+      << machine_id
+      >> [&](long long id, long long parent_id, std::string name, int type,
+             std::string content, uint32_t owner_id, uint32_t group_id, uint16_t permissions) {
+        vfs_node* node    = new vfs_node();
+        node->id          = id;
+        node->parent_id   = parent_id;
+        node->name        = name;
+        node->type        = (vfs_node_type) type;
+        node->content     = content;
+        node->owner_id    = owner_id;
+        node->group_id    = group_id;
+        node->permissions = permissions;
+
+        nodes.push_back(node);
+    };
+  return nodes;
+}

common/src/db/vfs_repository.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "vfs.h"
+#include "sqlite_modern_cpp.h"
+
+class VFSRepository {
+public:
+  VFSRepository(sqlite::database& db);
+
+  long long create_node(long long machine_id, long long* parent_id,
+                        const std::string& name, vfs_node_type type,
+                        const std::string& content = "",
+                        uint32_t owner_id = 0, uint32_t group_id = 0,
+                        uint16_t permissions = 0755);
+
+  std::vector<vfs_node*> get_nodes_for_machine(long long machine_id);
+
+private:
+  sqlite::database& _db;
+};

common/src/i_network_bridge.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <string>
+
+class Machine;
+
+class INetworkBridge {
+public:
+  virtual Machine* get_machine_by_ip(const std::string& ip) = 0;
+  virtual void release_machine(long long machine_id) = 0;
+};

common/src/lua_api.cpp

@@ -0,0 +1,306 @@
+#include <sol/call.hpp>
+#include <sol/types.hpp>
+#include <sstream>
+
+#include "i_network_bridge.h"
+#include "lua_api.h"
+#include "session.h"
+#include "machine.h"
+#include "vfs.h"
+#include "util.h"
+
+namespace api {
+
+vfs_node* get_current_dir(Session& context) {
+  return context.get_current_dir();
+}
+
+std::string rm(Session& context, const std::string& filename) {
+  vfs_node* current_dir = context.get_current_dir();
+  auto it = current_dir->children.find(filename);
+
+  if(it == current_dir->children.end()) {
+    return "rm: cannot remove '" + filename + "': No such file or directory.";
+  }
+  if(it->second->type == DIR_NODE) {
+    return "rm: cannot remove '" + filename + "': Is a directory.";
+  }
+
+  delete it->second; /* Free the memory for the node. */
+  current_dir->children.erase(it); /* Remove from map. */
+  return "";
+}
+
+std::string write_file(Session& context, const std::string& path,
+                       const std::string& content) {
+  vfs_node* parent_dir = nullptr;
+  std::string filename;
+
+  if(path[0] == '/') {
+    Machine* session_machine = context.get_session_machine();
+    vfs_node* root = session_machine->vfs_root;
+
+    size_t last_slash = path.find_last_of('/');
+    if(last_slash == 0) {
+      /* File in root. */
+      parent_dir = root;
+      filename = path.substr(1);
+    } else {
+      std::string parent_path = path.substr(0, last_slash);
+      parent_dir = find_node_by_path(root, parent_path);
+      filename = path.substr(last_slash+1);
+    }
+  } else {
+    /* Relative path. */
+    parent_dir = context.get_current_dir();
+    filename = path;
+  }
+
+  if(!parent_dir) {
+    return "write: cannot create file '" + path + "': No such file or directory";
+  }
+
+  if(parent_dir->type != DIR_NODE) {
+    return "write: cannot create file in '" + get_full_path(parent_dir) + "': Not a directory";
+  }
+
+  auto it = parent_dir->children.find(filename);
+  if(it != parent_dir->children.end()) {
+    if(it->second->type == DIR_NODE) {
+      return "write: " + path + ": Is a directory";
+    }
+    it->second->content = content;
+  } else {
+    /* File does not exist, create it. */
+    vfs_node* new_file = new_node(filename, FILE_NODE, parent_dir);
+    new_file->content = content;
+    parent_dir->children[filename] = new_file;
+  }
+  return "";
+}
+
+std::string create_executable(Session& context, const std::string& path,
+                              const std::string& content) {
+  vfs_node* parent_dir = nullptr;
+  std::string filename;
+
+  if(path[0] == '/') {
+    Machine* session_machine = context.get_session_machine();
+    vfs_node* root = session_machine->vfs_root;
+
+    size_t last_slash = path.find_last_of('/');
+    if(last_slash == 0) {
+      parent_dir = root;
+      filename = path.substr(1);
+    } else {
+      std::string parent_path = path.substr(0, last_slash);
+      parent_dir = find_node_by_path(root, parent_path);
+      filename = path.substr(last_slash+1);
+    }
+  } else {
+    parent_dir = context.get_current_dir();
+    filename = path;
+  }
+
+  if(!parent_dir) {
+    return "create_executable: cannot create file '" + path + "': No such file or directory";
+  }
+
+  if(parent_dir->type != DIR_NODE) {
+    return "create_executable: cannot create file in '" + get_full_path(parent_dir)
+        + "': Not a directory";
+  }
+
+  /* Overwrite if exists. */
+  auto it = parent_dir->children.find(filename);
+  if(it != parent_dir->children.end()) {
+    delete it->second;
+    parent_dir->children.erase(it);
+  }
+  vfs_node* new_exec = new_node(filename, EXEC_NODE, parent_dir);
+  new_exec->content = util::xor_string(content);
+  parent_dir->children[filename] = new_exec;
+  return "";
+}
+
+std::string cd(Session& context, const std::string& path) {
+  vfs_node* current_dir = context.get_current_dir();
+
+  if(path == "..") {
+    if(current_dir->parent) {
+      context.set_current_dir(current_dir->parent);
+    }
+  } else {
+    auto it = current_dir->children.find(path);
+    if(it != current_dir->children.end() && it->second->type == DIR_NODE) {
+      context.set_current_dir(it->second);
+    } else {
+      return "cd: no such file or directory: " + path;
+    }
+  }
+  return "";
+}
+
+std::string ls(Session& context) {
+  vfs_node* dir = context.get_current_dir();
+  if(dir->type != DIR_NODE) {
+    return "ls: not a directory";
+  }
+
+  std::stringstream ss;
+  for(auto const& [name, node] : dir->children) {
+    ss << name;
+    if(node->type == DIR_NODE) {
+      ss << "/";
+    }
+    ss << "   ";
+  }
+  return ss.str();
+}
+
+std::string ssh(Session& context, const std::string& ip) {
+  INetworkBridge* bridge = context.get_network_bridge();
+  Machine* target_machine = bridge->get_machine_by_ip(ip);
+
+  if(target_machine) {
+    context.set_session_machine(target_machine);
+    return "Connected to " + ip;
+  } else {
+    return "ssh: Could not resolve hostname " + ip + ": Name or service not found";
+  }
+}
+
+std::string nmap(Session& context, const std::string& ip) {
+  INetworkBridge* bridge = context.get_network_bridge();
+  Machine* target_machine = bridge->get_machine_by_ip(ip);
+
+  if(!target_machine) {
+    return "nmap: Could not resolve host: " + ip;
+  }
+
+  /* Read services from the cached machine object, not the DB. */
+  auto services = target_machine->services;
+
+  /* Release the machine from the cache if it's a remote machine. */
+  if(target_machine != context.get_session_machine()) {
+    bridge->release_machine(target_machine->id);
+  }
+
+  if(services.empty()) {
+    return "No open ports for " + ip;
+  }
+
+  std::stringstream ss;
+  ss << "Host: " << ip << "\n";
+  ss << "PORT\tSTATE\tSERVICE\n";
+  for(auto const& [port, service_name] : services) {
+    ss << port << "/tcp\t" << "open\t" << service_name << "\n";
+  }
+  return ss.str();
+}
+
+std::string disconnect(Session& context) {
+  Machine* current_machine = context.get_session_machine();
+  if(current_machine != context.get_home_machine()) {
+    INetworkBridge* bridge = context.get_network_bridge();
+    bridge->release_machine(current_machine->id);
+  }
+  context.set_session_machine(context.get_home_machine());
+  return "Connection closed.";
+}
+
+std::string close_terminal(Session& context) {
+  return "__CLOSE_CONNECTION__";
+}
+
+struct ScpPath {
+  std::string host;
+  std::string path;
+};
+
+ScpPath parse_scp_path(const std::string& arg) {
+  size_t colon_pos = arg.find(':');
+  if(colon_pos != std::string::npos) {
+    return {arg.substr(0, colon_pos), arg.substr(colon_pos+1)};
+  } else {
+    return {"", arg};
+  }
+}
+
+std::string scp(Session& context, const std::string& source_arg,
+                const std::string& dest_arg) {
+  ScpPath source_path = parse_scp_path(source_arg);
+  ScpPath dest_path = parse_scp_path(dest_arg);
+  Machine* session_machine = context.get_session_machine();
+  INetworkBridge* bridge = context.get_network_bridge();
+
+  Machine* source_machine = source_path.host.empty()
+    ? session_machine : bridge->get_machine_by_ip(source_path.host);
+
+  Machine* dest_machine = dest_path.host.empty()
+    ? session_machine : bridge->get_machine_by_ip(dest_path.host);
+
+  if(!source_machine) {
+    return "scp: " + source_path.host + ": Name or service not known";
+  }
+  if(!dest_machine) {
+    if(source_machine != session_machine) bridge->release_machine(source_machine->id);
+    return "scp: " + dest_path.host + ": Name or service not known";
+  }
+
+  /* Simplified to use only absolute paths for now. */
+  vfs_node* source_node = find_node_by_path(source_machine->vfs_root, source_path.path);
+
+  if(!source_node || source_node->type != FILE_NODE) {
+    if(source_machine != session_machine) bridge->release_machine(source_machine->id);
+    if(dest_machine != session_machine) bridge->release_machine(dest_machine->id);
+    return "scp: " + source_path.path + ": No such file or directory";
+  }
+
+  vfs_node* dest_node = find_node_by_path(dest_machine->vfs_root, dest_path.path);
+  vfs_node* dest_dir = nullptr;
+  std::string dest_filename;
+
+  if(dest_node && dest_node->type == DIR_NODE) {
+    dest_dir = dest_node;
+    dest_filename = source_node->name;
+  } else {
+    size_t last_slash = dest_path.path.find_last_of('/');
+    if(last_slash != std::string::npos) {
+      std::string parent_path = dest_path.path.substr(0, last_slash);
+      if(parent_path.empty()) parent_path = "/";
+      dest_dir = find_node_by_path(dest_machine->vfs_root, parent_path);
+      dest_filename = dest_path.path.substr(last_slash+1);
+    } else {
+      dest_dir = dest_machine->vfs_root;
+      dest_filename = dest_path.path;
+    }
+  }
+
+  if(!dest_dir) {
+    if(source_machine != session_machine) bridge->release_machine(source_machine->id);
+    if(dest_machine != session_machine) bridge->release_machine(dest_machine->id);
+    return "scp: " + dest_path.path + ": No such file or directory";
+  }
+
+  if(dest_dir->children.count(dest_filename)) {
+    vfs_node* existing_node = dest_dir->children[dest_filename];
+    if(existing_node->type == DIR_NODE) {
+      if(source_machine != session_machine) bridge->release_machine(source_machine->id);
+      if(dest_machine != session_machine) bridge->release_machine(dest_machine->id);
+      return "scp: " + dest_path.path + ": Is a directory";
+    }
+    existing_node->content = source_node->content;
+  } else {
+    vfs_node* new_file = new_node(dest_filename, FILE_NODE, dest_dir);
+    new_file->content = source_node->content;
+    dest_dir->children[dest_filename] = new_file;
+  }
+
+  if(source_machine != session_machine) bridge->release_machine(source_machine->id);
+  if(dest_machine != session_machine) bridge->release_machine(dest_machine->id);
+
+  return "";
+}
+
+} /* namespace api */

common/src/lua_api.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <string>
+#include "vfs.h"
+
+class Session;
+class NetworkManager;
+
+namespace api {
+
+/* FILESYSTEM ACTIONS. */
+vfs_node* get_current_dir(Session& context);
+std::string rm(Session& context, const std::string& filename);
+std::string write_file(Session& context, const std::string& path,
+                       const std::string& content);
+std::string create_executable(Session& context, const std::string& path,
+                              const std::string& content);
+std::string ls(Session& context);
+std::string cd(Session& context, const std::string& path);
+std::string scp(Session& context, const std::string& source,
+                const std::string& destination);
+
+/* NETWORK ACTIONS. */
+std::string ssh(Session& context, const std::string& ip);
+std::string nmap(Session& context, const std::string& ip);
+std::string disconnect(Session& context);
+
+/* SYSTEM ACTIONS. */
+std::string close_terminal(Session& context);
+
+} /* namespace api */

common/src/lua_processor.cpp

@@ -0,0 +1,84 @@
+#include <sol/forward.hpp>
+#include <sol/object.hpp>
+#include <sol/protected_function_result.hpp>
+#include <sol/raii.hpp>
+
+#include "lua_processor.h"
+#include "lua_api.h"
+#include "session.h"
+#include "vfs.h"
+
+LuaProcessor::LuaProcessor(Session& context) {
+  _lua.open_libraries(sol::lib::base, sol::lib::string, sol::lib::table);
+
+  /* Remove some dangerous functions from the base lib. */
+  _lua["dofile"]          = sol::nil;
+  _lua["loadfile"]        = sol::nil;
+  _lua["load"]            = sol::nil;
+  _lua["pcall"]           = sol::nil;
+  _lua["xpcall"]           = sol::nil;
+  _lua["collectgarbage"]  = sol::nil;
+  _lua["getmetatable"]    = sol::nil;
+  _lua["setmetatable"]    = sol::nil;
+  _lua["rawequal"]        = sol::nil;
+  _lua["rawget"]          = sol::nil;
+  _lua["rawset"]          = sol::nil;
+  _lua["rawlen"]          = sol::nil;
+
+  /* Expose vfs_node struct members to Lua. */
+  _lua.new_usertype<vfs_node>("vfs_node",
+                              "name",         &vfs_node::name,
+                              "type",         &vfs_node::type,
+                              "children",     &vfs_node::children,
+                              "content",      &vfs_node::content,
+                              "owner_id",     &vfs_node::owner_id,
+                              "group_id",     &vfs_node::group_id,
+                              "permissions",  &vfs_node::permissions);
+
+  /* Expose CommandProcessor to Lua. DON'T ALLOW SCRIPTS TO CREATE IT THOUGH! */
+  _lua.new_usertype<Session>("Session", sol::no_constructor);
+
+  /* Create the 'bettola' API table. */
+  sol::table bettola_api = _lua.create_named_table("bettola");
+  bettola_api.set_function("rm",                &api::rm);
+  bettola_api.set_function("ls",                &api::ls);
+  bettola_api.set_function("write_file",        &api::write_file);
+  bettola_api.set_function("create_executable", &api::create_executable);
+  bettola_api.set_function("get_current_dir",   &api::get_current_dir);
+  bettola_api.set_function("cd",                &api::cd);
+  bettola_api.set_function("scp",               &api::scp);
+  bettola_api.set_function("close_terminal",    &api::close_terminal);
+  bettola_api.set_function("ssh",               &api::ssh);
+  bettola_api.set_function("nmap",              &api::nmap);
+  bettola_api.set_function("disconnect",        &api::disconnect);
+}
+
+LuaProcessor::~LuaProcessor(void) {}
+
+sol::object LuaProcessor::execute(const std::string& script, Session& context,
+                                  const std::vector<std::string>& args, bool is_remote) {
+  try {
+    /* Pass C++ objects/points into the Lua env. */
+    _lua["is_remote_session"] = is_remote;
+    _lua["context"] = &context;
+
+    /* Create and populate the 'arg' table for the script. */
+    sol::table arg_table = _lua.create_table();
+    for(size_t i = 0; i < args.size(); ++i) {
+      arg_table[i+1] = args[i]; /* Lua arrays 1-indexed. */
+    }
+    _lua["arg"] = arg_table;
+
+    sol::protected_function_result result = _lua.safe_script(script);
+    if(result.valid()) {
+      return result;
+    } else {
+      sol::error err = result;
+      return sol::make_object(_lua, err.what());
+    }
+
+  } catch(const sol::error& e) {
+    /* Return the error message as a string in a sol::object. */
+    return sol::make_object(_lua, e.what());
+  }
+}

common/src/lua_processor.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <sol/sol.hpp>
+#include <vector>
+#include <vfs.h>
+#include <string>
+
+class Session;
+
+class LuaProcessor {
+public:
+  LuaProcessor(Session& context);
+  ~LuaProcessor(void);
+
+  /* Executes a string of lua code and returns result as a string. */
+  sol::object execute(const std::string& script, Session& context,
+                      const std::vector<std::string>& args, bool is_remote);
+private:
+  sol::state _lua;
+};

common/src/machine.cpp

@@ -0,0 +1,6 @@
+#include "machine.h"
+#include "vfs.h"
+
+Machine::~Machine(void) {
+  delete_vfs_tree(vfs_root);
+}

common/src/machine.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <string>
+#include <map>
+#include <cstdint>
+
+#include "vfs.h"
+
+
+class Machine {
+public:
+  Machine(uint32_t id, std::string hostname) :
+      id(id),
+      hostname(std::move(hostname)),
+      vfs_root(nullptr),
+      is_vfs_a_copy(false) {}
+
+  ~Machine(void); /* Clean up VFS tree. */
+
+  uint32_t id;
+  std::string hostname;
+  vfs_node* vfs_root;
+  std::map<int, std::string> services;
+  bool is_vfs_a_copy; /* Flag for CoW mechanism. */
+
+  /* TODO: We'll add hardware and sh.t here. */
+};

common/src/machine_manager.cpp

@@ -0,0 +1,148 @@
+#include <filesystem>
+#include <fstream>
+#include <sstream>
+#include <map>
+
+#include "db/database_manager.h"
+#include "machine_manager.h"
+#include "machine.h"
+#include "vfs.h"
+#include "util.h"
+
+vfs_node* copy_vfs_node(vfs_node* original, vfs_node* new_parent) {
+  if(!original) {
+    return nullptr;
+  }
+
+  /* Create the new node and copy its properties. */
+  vfs_node* new_copy = new_node(original->name, original->type, new_parent,
+                                original->owner_id, original->group_id,
+                                original->permissions);
+
+  new_copy->content = original->content;
+
+  /* Recursively copy all children. */
+  for(auto const& [key, child_node] : original->children) {
+    new_copy->children[key] = copy_vfs_node(child_node, new_copy);
+  }
+
+  return new_copy;
+}
+
+MachineManager::MachineManager(DatabaseManager* db_manager) :
+    _db_manager(db_manager) {
+  /* Create template VFS that holds shared, read-only directories. */
+  _vfs_template_root = new_node("/", DIR_NODE, nullptr);
+  vfs_node* bin = new_node("bin", DIR_NODE, _vfs_template_root, 0, 0, 0755); /* System owned. */
+  _vfs_template_root->children["bin"] = bin;
+
+  /* Load all scripts from assets/scripts/bin into the VFS. */
+  const std::string path = "assets/scripts/bin";
+  for(const auto & entry : std::filesystem::directory_iterator(path)) {
+    if(entry.is_regular_file() && entry.path().extension() == ".lua") {
+      std::ifstream t(entry.path());
+      std::stringstream buffer;
+      buffer << t.rdbuf();
+      std::string filename_with_ext = entry.path().filename().string();
+      std::string filename = filename_with_ext.substr(0, filename_with_ext.find_last_of('.'));
+      vfs_node* script_node = new_node(filename, EXEC_NODE, bin, 0, 0, 0755); /* System owned. */
+      script_node->content = util::xor_string(buffer.str());
+      bin->children[filename] = script_node;
+      fprintf(stderr, "Loaded executable: /bin/%s\n", filename.c_str());
+    }
+  }
+}
+
+MachineManager::~MachineManager(void) {
+  delete_vfs_tree(_vfs_template_root);
+}
+
+Machine* MachineManager::create_machine(uint32_t id, const std::string& hostname,
+                                         const std::string& system_type) {
+  auto* new_machine = new Machine(id, hostname);
+
+  vfs_node* root = new_node("/", DIR_NODE, nullptr, 0, 0, 0755); /* Root owned by system (0). */
+
+  /* Create directories for this specific VFS. */
+  vfs_node* home = new_node("home", DIR_NODE, root, id, id, 0755); /* Owned by player. */
+  vfs_node* user = new_node("user", DIR_NODE, home);
+  home->children["user"] = user;
+  vfs_node* readme = new_node("readme.txt", FILE_NODE, user, id, id, 0644); /* Owned by player. */
+  readme->content = "Welcome to your new virtual machine.";
+  user->children["readme.txt"] = readme;
+
+  /* Link to the shared directories from the template. */
+  root->children["bin"] = copy_vfs_node(_vfs_template_root->children["bin"], root);
+  /* Ensure copied bin directory has the correct owner/group/permissions. */
+  root->children["bin"]->owner_id = 0; /* System owned. */
+  root->children["bin"]->group_id = 0;
+  root->children["bin"]->permissions = 0755;
+
+  /* Assign the VFS to the new machine. */
+  new_machine->vfs_root = root;
+
+  if(system_type == "npc") {
+    vfs_node* npc_file = new_node("npc_system.txt", FILE_NODE, root, 0, 0, 0644);
+    npc_file->content = "This guy sucks nuts!";
+    root->children["npc_system.txt"] = npc_file;
+
+  }
+
+  return new_machine;
+}
+
+/* Recursively build the VFS tree from database nodes. */
+void build_tree(vfs_node* parent, const std::map<long long, vfs_node*>& nodes) {
+  for(auto const& [id, node] : nodes) {
+    /* Inefficient but safe. Would be better to group nodes by parent_id. */
+    if(node->parent_id == parent->id) {
+      parent->children[node->name] = node;
+      node->parent = parent;
+      if(node->type == DIR_NODE) {
+        build_tree(node, nodes);
+      }
+    }
+  }
+}
+
+Machine* MachineManager::load_machine(long long machine_id) {
+  printf("DEBUG: load_machine called for machine_id: %lld\n", machine_id);
+
+  std::string hostname = _db_manager->machines().get_hostname(machine_id);
+
+  Machine* machine = new Machine(machine_id, hostname);
+
+  /* Load all VFS nodes for this machine from the database. */
+  std::map<long long, vfs_node*> node_map;
+  vfs_node* root = nullptr;
+
+  auto nodes = _db_manager->vfs().get_nodes_for_machine(machine_id);
+  for(vfs_node* node : nodes) {
+    node_map[node->id] = node;
+    if(node->name == "/") {
+      root = node;
+    }
+  }
+
+  machine->services = _db_manager->services().get_for_machine(machine_id);
+
+  if(root) {
+    build_tree(root, node_map);
+    machine->vfs_root = root;
+  }
+  return machine;
+}
+
+long long MachineManager::get_machine_id_by_ip(const std::string& ip) {
+  if(_ip_to_id_map.count(ip)) {
+    return _ip_to_id_map[ip];
+  }
+  return 0;
+}
+
+void MachineManager::init(void) {
+  auto all_machines = _db_manager->machines().get_all();
+  for(const auto& machine_data : all_machines) {
+    _ip_to_id_map[machine_data.ip_address] = machine_data.id;
+  }
+}

common/src/machine_manager.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <map>
+#include <string>
+
+#include "db/database_manager.h"
+#include "machine.h"
+#include "vfs.h"
+
+/* Recursive copy function for our Copy-on-Write behaviour. */
+vfs_node* copy_vfs_node(vfs_node* original, vfs_node* new_parent);
+
+class MachineManager {
+public:
+  MachineManager(DatabaseManager* db_manager);
+  ~MachineManager(void); /* TODO: Implement recursive VFS deletion. */
+
+  Machine* create_machine(uint32_t id, const std::string& hostname,
+                          const std::string& system_type);
+  Machine* load_machine(long long machine_id);
+  void init(void);
+
+  vfs_node* get_vfs_template(void) { return _vfs_template_root; }
+
+  /* Machine lookup. */
+  long long get_machine_id_by_ip(const std::string& ip);
+
+private:
+  DatabaseManager* _db_manager;
+  vfs_node* _vfs_template_root;
+
+  /* In memory cache of all machines, loaded or not. */
+  std::map<std::string, long long> _ip_to_id_map;
+  std::map<long long, Machine*> _world_machines;
+};
+

common/src/math/math.h

@@ -0,0 +1,29 @@
+#pragma once
+
+namespace math {
+
+inline void ortho_proj(float* mat, float left, float right, float bottom, float top,
+           float near, float far) {
+
+  mat[0]  = 2.0f / (right - left);
+  mat[4]  = 0.0f;
+  mat[8]  = 0.0f;
+  mat[12] = -(right + left) / (right - left);
+
+  mat[1]  = 0.0f;
+  mat[5]  = 2.0f / (top - bottom);
+  mat[9]  = 0.0f;
+  mat[13] = -(top + bottom) / (top - bottom);
+
+  mat[2]  = 0.0f;
+  mat[6]  = 0.0f;
+  mat[10] = -2.0f / (far - near);
+  mat[14] = -(far + near) / (far - near);
+
+  mat[3]  = 0.0f;
+  mat[7]  = 0.0f;
+  mat[11] = 0.0f;
+  mat[15] = 1.0f;
+}
+
+} /* namespace math */

common/src/net/constants.h

@@ -0,0 +1,5 @@
+#pragma once
+#include <cstdint>
+
+const uint16_t MULTIPLAYER_PORT   = 1337;
+const uint16_t SINGLE_PLAYER_PORT = 1338;