#include <chrono>
#include <cmath>

#include "world.h"
#include "bettola/game/chunk.h"
#include "bettola/noise/fast_noise_lite.h"

World::World(void) {
  _noise.SetSeed(std::chrono::high_resolution_clock::now().time_since_epoch().count());
  _noise.SetNoiseType(FastNoiseLite::NoiseType_Perlin);
  _noise.SetFrequency(0.02f);

  _noise.SetFractalType(FastNoiseLite::FractalType_FBm);
  _noise.SetFractalOctaves(5);
  _noise.SetFractalLacunarity(2.0f);
  _noise.SetFractalGain(0.5);
}

BettolaLib::Game::Chunk& World::get_chunk(int x, int z) {
  ChunkPos pos = {x, z};
  auto it = _chunks.find(pos);
  if(it != _chunks.end()) {
    return it->second;
  }

  /* If chunk doesn't exist, generate it. */
  BettolaLib::Game::Chunk& new_chunk = _chunks[pos];
  _generate_chunk(new_chunk, x, z);
  return new_chunk;
}

void World::_generate_chunk(BettolaLib::Game::Chunk& chunk, int chunk_x, int chunk_z) {
  for(int z = 0; z < BettolaLib::Game::CHUNK_DATA_HEIGHT; ++z) {
    for(int x = 0; x < BettolaLib::Game::CHUNK_DATA_WIDTH; ++x) {
      /* Calculate world coordinates. */
      float world_x = (float)(chunk_x * (BettolaLib::Game::CHUNK_WIDTH  - 1)
        + (x - BettolaLib::Game::CHUNK_BORDER_SIZE));
      float world_z = (float)(chunk_z * (BettolaLib::Game::CHUNK_HEIGHT - 1)
        + (z - BettolaLib::Game::CHUNK_BORDER_SIZE));

      /* generate noise value. */
      chunk.heightmap[z * BettolaLib::Game::CHUNK_DATA_WIDTH + x] = fabsf(_noise.GetNoise(world_x, world_z));
    }
  }
}