/**
 * @file spfx.c
 *
 * @brief Handle the specific effects.
 */

#include <SDL.h>

#include "lephisto.h"
#include "log.h"
#include "pilot.h"
#include "physics.h"
#include "opengl.h"
#include "pause.h"
#include "rng.h"
#include "spfx.h"

#define SPFX_GFX          "../gfx/spfx/"  /**< Graphics location. */
#define SPFX_CHUNK        32              /**< Chunk to allocate when needed. */
#define SHAKE_VEL_MOD     0.0012          /**< Shake modifier. */
#define SHAKE_MOD_FACTOR  0.2             /**< Shake modifier factor. */

/* Special hardcoded effects.. */

/* Shake, AKA RUMBLE! */
static double shake_rad = 0.;             /**< Current shake radius (0 = no shake). */
Vec2 shake_pos = { .x = 0., .y = 0. };    /**< Current shake pos. Used in nebulae.c */
static Vec2 shake_vel = { .x = 0., .y = 0. }; /**< Current shake vel. */
static int shake_off = 1;                 /**< 1 if shake is not active. */

/**
 * @struct SPFX_Base
 *
 * @brief Generic special effect.
 */
typedef struct SPFX_Base_ {
  char* name;     /**< Name of the special effect. */

  double ttl;     /**< Time to live. */
  double anim;    /**< Total duration in ms. */

  glTexture* gfx; /**< Will use each sprite as a frame. */
} SPFX_Base;

static SPFX_Base* spfx_effects = NULL;  /**< Total special effects. */
static int spfx_neffects = 0;           /**< Total number of special effects. */

/**
 * @struct SPFX
 *
 * @brief An actual in-game active special effect.
 */
typedef struct SPFX_ {
  Vec2 pos;       /**< Current position. */
  Vec2 vel;       /**< Current velocity. */

  int lastframe;  /**< Need when pausing. */
  int effect;     /**< Actual effect. */
  double timer;   /**M Time left. */
} SPFX;

/* Front stack is for effects on player. */
/* Back is for everything else. */
static SPFX*  spfx_stack_front   = NULL;  /**< Frontal special effect layer. */
static int   spfx_nstack_front  = 0;      /**< Number of special effects in front. */
static int   spfx_mstack_front  = 0;      /**< Memory allocated for frontal special effects. */
static SPFX* spfx_stack_back   = NULL;    /**< Back special effect layer. */
static int   spfx_nstack_back  = 0;       /**< Number of special effects in the back. */
static int   spfx_mstack_back  = 0;       /**< Memory allocated for special effects in back. */

static int spfx_base_load(char* name, int ttl, int anim, char* gfx, int sx, int sy);
static void spfx_base_free(SPFX_Base* effect);
static void spfx_destroy(SPFX* layer, int* nlayer, int spfx);
static void spfx_update_layer(SPFX* layer, int* nlayer, const double dt);

/**
 * @fn static int spfx_base_load(char* name, int ttl, int anim, char* gfx, int sx, int sy)
 *
 * @brief Load an SPFX_Base into the stack based on some params.
 *    @param name Name of the spfx.
 *    @param ttl Time to live of the spfx.
 *    @param gfx Name of the graphic effect to use.
 *    @param sx Number of x sprites in the graphic.
 *    @param sy Number of y sprites in the graphic.
 *    @return 0 on success.
 */
static int spfx_base_load(char* name, int ttl, int anim, char* gfx, int sx, int sy) {
  SPFX_Base* cur;
  char buf[PATH_MAX];

  /* Create new effect. */
  spfx_effects = realloc(spfx_effects, ++spfx_neffects*sizeof(SPFX_Base));
  cur = &spfx_effects[spfx_neffects-1];

  /* Fill it with the data. */
  cur->name = strdup(name);
  cur->anim = (double)anim / 1000.;
  cur->ttl  = (double)ttl / 1000.;
  sprintf(buf, SPFX_GFX"%s", gfx);
  cur->gfx = gl_newSprite(buf, sx, sy);

  return 0;
}

/**
 * @fn static void spfx_base_free(SPFX_Base* effect)
 *
 * @brief Free an SPFX_Base.
 *    @param effect SPFX_Base to free.
 */
static void spfx_base_free(SPFX_Base* effect) {
  if(effect->name != NULL)  free(effect->name);
  if(effect->gfx != NULL)   gl_freeTexture(effect->gfx);
}

/**
 * @fn int spfx_get(char* name)
 *
 * @brief Get the id of an spfx based on name.
 *    @param name Name to match.
 *    @return ID of the special effect or -1 on error.
 */
int spfx_get(char* name) {
  int i;
  for(i = 0; i < spfx_neffects; i++)
    if(strcmp(spfx_effects[i].name, name)==0)
      return i;
  WARN("SPFX '%s' not found!", name);
  return -1;
}

/**
 * @fn int spfx_load(void)
 *
 * @brief Load the spfx stack.
 *    @return 0 on success.
 * 
 * @todo Make spfx not hardcoded.
 */
int spfx_load(void) {
  /* Standard explosion effects. */
  spfx_base_load("ExpS", 400, 400, "exps.png", 6, 5);
  spfx_base_load("ExpM", 450, 450, "expm.png", 6, 5);
  spfx_base_load("ExpL", 500, 500, "expl.png", 6, 5);
  spfx_base_load("cargo", 15000, 5000, "cargo.png", 6, 6);
  return 0;
}

/**
 * @fn void spfx_free(void)
 *
 * @brief Free the spfx stack.
 */
void spfx_free(void) {
  int i;

  /* Get rid of all the particles and free the stacks. */
  spfx_clear();
  if(spfx_stack_front) free(spfx_stack_front);
  spfx_stack_front = NULL;
  spfx_mstack_front = 0;
  if(spfx_stack_back) free(spfx_stack_back);
  spfx_stack_back = NULL;
  spfx_mstack_back = 0;

  for(i = 0; i < spfx_neffects; i++)
    spfx_base_free(&spfx_effects[i]);
  free(spfx_effects);
  spfx_effects = NULL;
  spfx_neffects = 0;
}

/**
 * @fn void spfx_add(int effect,
 *             const double px, const double py,
 *             const double vx, const double vy,
 *             const int layer) {
 *
 * @brief Create a new special effect.
 *    @param effect Base effect identifier to use.
 *    @param px X position of the effect.
 *    @param py Y position of the effect.
 *    @param vx X velocity of the effect.
 *    @param vy Y velocity of the effect.
 *    @param layer Layer to put the effect on.
 */
void spfx_add(int effect,
              const double px, const double py,
              const double vx, const double vy,
              const int layer) {

  SPFX* cur_spfx;
  double ttl, anim;

  if((effect < 0) || (effect > spfx_neffects)) {
    WARN("Trying to add spfx with invalid effect!");
    return;
  }

  /* Select the layer. */
  if(layer == SPFX_LAYER_FRONT) {
    /* Front layer. */
    if(spfx_mstack_front < spfx_nstack_front+1) {
      /* We need more memory. */
      spfx_mstack_front += SPFX_CHUNK;
      spfx_stack_front = realloc(spfx_stack_front, spfx_mstack_front*sizeof(SPFX));
    }
    cur_spfx = &spfx_stack_front[spfx_nstack_front];
    spfx_nstack_front++;
  }
  else if(layer == SPFX_LAYER_BACK) {
    /* Back layer. */
    if(spfx_mstack_back < spfx_nstack_back+1) {
      /* Need more memory. */
      spfx_mstack_back += SPFX_CHUNK;
      spfx_stack_back = realloc(spfx_stack_back, spfx_mstack_back*sizeof(SPFX));
    }
    cur_spfx = &spfx_stack_back[spfx_nstack_back];
    spfx_nstack_back++;
  }

  /* The actualy adding of the spfx. */
  cur_spfx->effect = effect;
  vect_csetmin(&cur_spfx->pos, px, py);
  vect_csetmin(&cur_spfx->vel, vx, vy);
  /* timer magic if ttl != anim. */
  ttl = spfx_effects[effect].ttl;
  anim = spfx_effects[effect].anim;
  if(ttl != anim)
    cur_spfx->timer = ttl + RNGF()*anim;
  else
    cur_spfx->timer = ttl;
}

/**
 * @fn void spfx_clear(void)
 *
 * @brief Clear all the currently running effects.
 */
void spfx_clear(void) {
  int i;

  /* Clear front layer. */
  for(i = spfx_nstack_front-1; i >= 0; i--)
    spfx_destroy(spfx_stack_front, &spfx_nstack_front, i);

  /* Clear back layer. */
  for(i = spfx_nstack_back-1; i >= 0; i--)
    spfx_destroy(spfx_stack_back, &spfx_nstack_back, i);

  /* Clear rumble. */
  shake_rad = 0.;
  shake_pos.x = shake_pos.y = 0.;
  shake_vel.x = shake_vel.y = 0.;
}

/**
 * @fn static void spfx_destroy(SPFX* layer, int* nlayer, int spfx)
 *
 * @brief Destroys an active spfx.
 *    @param layer Layer the spfx is on.
 *    @param nlayer Pointer to the number of elements in the layer.
 *    @param spfx Position of the spfx in the stack.
 */
static void spfx_destroy(SPFX* layer, int* nlayer, int spfx) {
  (*nlayer)--;
  memmove(&layer[spfx], &layer[spfx+1], (*nlayer-spfx)*sizeof(SPFX));
}

/**
 * @fn void spfx_update(const double dt)
 *
 * @brief Update all the spfx.
 *    @param dt Current delta tick.
 */
void spfx_update(const double dt) {
  spfx_update_layer(spfx_stack_front, &spfx_nstack_front, dt);
  spfx_update_layer(spfx_stack_back,  &spfx_nstack_back, dt);
}

/**
 * @fn static void spfx_update_layer(SPFX* layer, int* nlayer, const double dt)
 *
 * @brief Update an individual spfx.
 *    @param layer Layer the spfx is on.
 *    @param nlayer Pointer to the assosiated nlayer.
 *    @param dt Current delta tick.
 */
static void spfx_update_layer(SPFX* layer, int* nlayer, const double dt) {
  int i;

  for(i = 0; i < *nlayer; i++) {
    layer[i].timer -= dt; /* Less time to live. */

    /* Time to die!!! */
    if(layer[i].timer < 0.) {
      spfx_destroy(layer, nlayer, i);
      i--;
      continue;
    }
    /* Mkay. Update it now. */
    vect_cadd(&layer[i].pos, dt*VX(layer[i].vel), dt*VY(layer[i].vel));
  }
}

/**
 * @fn void spfx_start(double dt)
 *
 * @brief Prepare the rendering for the special effects.
 *
 * Should be called at the beginning of the rendering loop.
 *    @param dt Current delta tick.
 */
void spfx_start(const double dt) {
  GLdouble bx, by, x, y;
  double inc;

  if(shake_off == 1) return; /* Save the cycles. */
  bx = SCREEN_W / 2;
  by = SCREEN_H / 2;

  if(!paused) {
    inc = dt*100000.;

    /* Calculate new position. */
    if(shake_rad > 0.01) {
      vect_cadd(&shake_pos, shake_vel.x * inc, shake_vel.y * inc);
      
      if(VMOD(shake_pos) > shake_rad) {
        /* Change direction. */
        vect_pset(&shake_pos, shake_rad, VANGLE(shake_pos));
        vect_pset(&shake_vel, SHAKE_VEL_MOD*shake_rad,
            -VANGLE(shake_pos) + (RNGF()-0.5) * M_PI);
      }
      /* The shake decays over time. */
      shake_rad -= SHAKE_DECAY * dt * SHAKE_MOD_FACTOR;
      if(shake_rad < 0.) shake_rad = 0.;

      x = shake_pos.x;
      y = shake_pos.y;
    } else {
      shake_rad = 0.;
      shake_off = 1;
      x = 0.;
      y = 0.;
    }
  }
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-bx+x, bx+x,  -by+y, by+y, -1., 1.);
}

/**
 * @fn void spfx_shake(double mod)
 *
 * @brief Increases the current rumble level.
 *
 * Rumble will decay over time.
 *    @param mod Modifier to increase levely by.
 */
void spfx_shake(double mod) {
  shake_rad += mod*SHAKE_MOD_FACTOR;
  if(shake_rad > SHAKE_MAX) shake_rad = SHAKE_MAX;
  shake_off = 0;

  vect_pset(&shake_vel, SHAKE_VEL_MOD*shake_rad, RNGF() * 2. * M_PI);
}

/**
 * @fn void spfx_cinematic(void)
 *
 * @brief Set the cinematic mode.
 *
 * Should be run at the end of the render loop if needed.
 */
void spfx_cinematic(void) {
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix(); /* Translation matrix. */
  glTranslated(-(double)SCREEN_W/2., -(double)SCREEN_H/2., 0);
  
  COLOUR(cBlack);
  glBegin(GL_QUADS);
    glVertex2d(0.,         0.);
    glVertex2d(0.,         SCREEN_H*0.2);
    glVertex2d(SCREEN_W,   SCREEN_H*0.2);
    glVertex2d(SCREEN_W,   0.);
    glVertex2d(0.,         SCREEN_H);
    glVertex2d(SCREEN_W,   SCREEN_H);
    glVertex2d(SCREEN_W,   SCREEN_H*0.8);
    glVertex2d(0.,         SCREEN_H*0.8);
  glEnd();

  glPopMatrix(); /* Translation matrix. */
}

/**
 * @fn void spfx_render(const int layer)
 * 
 * @brief Render the entire spfx layer.
 *    @param layer Layer to render.
 */
void spfx_render(const int layer) {
  SPFX* spfx_stack;
  int i, spfx_nstack;
  SPFX_Base* effect;
  int sx, sy;
  double time;

  /* Get the appropriate layer. */
  switch(layer) {
  case SPFX_LAYER_FRONT:
    spfx_stack = spfx_stack_front;
    spfx_nstack = spfx_nstack_front;
    break;
  case SPFX_LAYER_BACK:
    spfx_stack = spfx_stack_back;
    spfx_nstack = spfx_nstack_back;
    break;
  }

  /* Now render the layer. */
  for(i = spfx_nstack-1; i >= 0; i--) {
    effect = &spfx_effects[spfx_stack[i].effect];

    /* Simplifies. */
    sx = (int)effect->gfx->sx;
    sy = (int)effect->gfx->sy;

    if(!paused) { /* Don't calculate frame if paused. */
      time = fmod(spfx_stack[i].timer, effect->anim) / effect->anim;
      spfx_stack[i].lastframe = sx * sy * MIN(time, 1.);
    }

    /* Render. */
    gl_blitSprite(effect->gfx,
                  VX(spfx_stack[i].pos), VY(spfx_stack[i].pos),
                  spfx_stack[i].lastframe % sx,
                  spfx_stack[i].lastframe / sx,
                  NULL);
  }
}