/*
  Example program for small3dlib, showing a Quake-like level.

  author: Miloslav Ciz
  license: CC0 1.0
*/

#define TEXTURES 1 // whether to use textures for the level
#define FOG 1

#include <SDL2/SDL.h>
#include <stdio.h>
#include <time.h>

#define S3L_NEAR_CROSS_STRATEGY 3

#if TEXTURES
  #define S3L_PERSPECTIVE_CORRECTION 2
#else
  #define S3L_PERSPECTIVE_CORRECTION 0
#endif

#define S3L_NEAR (S3L_FRACTIONS_PER_UNIT / 5)

#define S3L_FLAT 0
#define S3L_SORT 0
#define S3L_Z_BUFFER 1
#define S3L_MAX_TRIANGES_DRAWN 512

#define S3L_PIXEL_FUNCTION drawPixel

#define S3L_MAX_PIXELS (1024 * 1024)

#include "../small3dlib.h"

#include "levelModel.h"
#include "levelTextures.h"

S3L_Scene scene;

S3L_Vec4 teleportPoint;

uint32_t pixels[S3L_MAX_PIXELS];

uint32_t frame = 0;
uint8_t *texture = 0;
uint32_t previousTriangle = 1000;
S3L_Vec4 uv0, uv1, uv2;

void clearScreen()
{
  memset(pixels,255,S3L_MAX_PIXELS * sizeof(uint32_t));
}

static inline void setPixel(int x, int y, uint8_t red, uint8_t green, uint8_t blue)
{
  uint8_t *p = ((uint8_t *) pixels) + (y * S3L_resolutionX + x) * 4 + 1;

  *p = blue;
  ++p;
  *p = green;
  ++p;
  *p = red;
}

void sampleTexture(S3L_Unit u, S3L_Unit v, uint8_t *r, uint8_t *g, uint8_t *b)
{
  u = (u * LEVEL_TEXTURE_WIDTH) / S3L_FRACTIONS_PER_UNIT;
  v = (v * LEVEL_TEXTURE_HEIGHT) / S3L_FRACTIONS_PER_UNIT;

  u = S3L_wrap(u,LEVEL_TEXTURE_WIDTH);
  v = S3L_wrap(v,LEVEL_TEXTURE_HEIGHT);

  const uint8_t *t = texture + (v * LEVEL_TEXTURE_WIDTH + u) * 3;

  *r = *t;
  t++;
  *g = *t;
  t++;
  *b = *t;
}

void drawTeleport(int16_t x, int16_t y, S3L_ScreenCoord size)
{
  int16_t halfSize = size / 2;

  S3L_ScreenCoord x0 = S3L_max(0,x - halfSize);
  S3L_ScreenCoord x1 = S3L_min(S3L_resolutionX,x + halfSize);
  S3L_ScreenCoord y0 = S3L_max(0,y - halfSize);
  S3L_ScreenCoord y1 = S3L_min(S3L_resolutionY,y + halfSize);

  S3L_ScreenCoord row = y0 - (y - halfSize);

  for (S3L_ScreenCoord j = y0; j < y1; ++j)
  {
    S3L_ScreenCoord i0, i1;

    if (row <= halfSize)
    {
      i0 = S3L_max(x0,x - row); 
      i1 = S3L_min(x1,x + row); 
    }
    else
    {
      i0 = S3L_max(x0,x - size + row); 
      i1 = S3L_min(x1,x + size - row); 
    }

    for (S3L_ScreenCoord i = i0; i < i1; ++i)
      if (rand() % 8 == 0)
        setPixel(i,j,255,0,0);

    row++;
  }
}

void drawPixel(S3L_PixelInfo *p)
{
  uint8_t r, g, b;

#if TEXTURES
  if (p->triangleID != previousTriangle)
  {
    uint8_t material = levelMaterials[p->triangleIndex];

    switch (material)
    {
      case 0:
        texture = level1Texture;
        break;

      case 1:
        texture = level2Texture;
        break;

      case 2:
      default:
        texture = level3Texture;
        break;
    }

    S3L_getIndexedTriangleValues(p->triangleIndex,levelUVIndices,levelUVs,2,&uv0,&uv1,&uv2);
    previousTriangle = p->triangleID;
  }

  S3L_Unit uv[2];

  uv[0] = S3L_interpolateBarycentric(uv0.x,uv1.x,uv2.x,p->barycentric);
  uv[1] = S3L_interpolateBarycentric(uv0.y,uv1.y,uv2.y,p->barycentric);

  sampleTexture(uv[0],uv[1],&r,&g,&b);
#else
  switch (p->modelIndex)
  {
    case 0: r = 255; g = 0; b = 0; break;
    case 1: r = 0; g = 255; b = 0; break;
    case 2:
    default: r = 0; g = 0; b = 255; break;
  }
#endif

#if FOG
  S3L_Unit fog = (p->depth * 
#if TEXTURES
    8
#else
    16
#endif
  ) / S3L_FRACTIONS_PER_UNIT;

  r = S3L_clamp(((S3L_Unit) r) - fog,0,255);
  g = S3L_clamp(((S3L_Unit) g) - fog,0,255);
  b = S3L_clamp(((S3L_Unit) b) - fog,0,255);
#endif

  setPixel(p->x,p->y,r,g,b); 
}

S3L_Transform3D modelTransform;
S3L_DrawConfig conf;

clock_t nextT;

int fps = 0;

void draw()
{
  S3L_newFrame();

  clearScreen();

  S3L_drawScene(scene);

  S3L_Vec4 screenPoint;

  project3DPointToScreen(teleportPoint,scene.camera,&screenPoint);

  if (screenPoint.w > 0 && 
      screenPoint.x >= 0 && screenPoint.x < S3L_resolutionX &&
      screenPoint.y >= 0 && screenPoint.y < S3L_resolutionY &&
      screenPoint.z < S3L_zBufferRead(screenPoint.x,screenPoint.y)) 
    drawTeleport(screenPoint.x,screenPoint.y,screenPoint.w);

  clock_t nowT = clock();

  double timeDiff = ((double) (nowT - nextT)) / CLOCKS_PER_SEC;

  fps++;

  if (timeDiff >= 1.0)
  {
    nextT = nowT;
    printf("FPS: %d\n",fps);

    printf("camera: ");
    S3L_logTransform3D(scene.camera.transform);
    fps = 0;
  }
}

int main()
{
  S3L_resolutionX = 640;
  S3L_resolutionY = 480;

  SDL_Window *window = SDL_CreateWindow("level demo", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, S3L_resolutionX, S3L_resolutionY, SDL_WINDOW_SHOWN); 
  SDL_Renderer *renderer = SDL_CreateRenderer(window,-1,0);
  SDL_Texture *texture = SDL_CreateTexture(renderer,SDL_PIXELFORMAT_RGBX8888, SDL_TEXTUREACCESS_STATIC, S3L_resolutionX, S3L_resolutionY);
  SDL_Surface *screenSurface = SDL_GetWindowSurface(window);
  SDL_Event event;

  teleportPoint.x = 6 * S3L_FRACTIONS_PER_UNIT;
  teleportPoint.y = -3 * S3L_FRACTIONS_PER_UNIT;
  teleportPoint.z = 3 * S3L_FRACTIONS_PER_UNIT / 2;
  teleportPoint.w = S3L_FRACTIONS_PER_UNIT;

  nextT = clock();

  levelModelInit();

  S3L_sceneInit(&levelModel,1,&scene);

  int running = 1;

  while (running) // main loop
  {
    int newWidth = -1, newHeight = -1;

    draw();
    SDL_UpdateTexture(texture,NULL,pixels,S3L_resolutionX * sizeof(uint32_t));

    while (SDL_PollEvent(&event))
      if (event.type == SDL_QUIT)
        running = 0;

    S3L_Vec4 camF, camR;
 
    S3L_rotationToDirections(scene.camera.transform.rotation,20,&camF,&camR,0);

    const uint8_t *state = SDL_GetKeyboardState(NULL);

    if (state[SDL_SCANCODE_A])
      scene.camera.transform.rotation.y += 1;
    else if (state[SDL_SCANCODE_D])
      scene.camera.transform.rotation.y -= 1;
    else if (state[SDL_SCANCODE_W])
      scene.camera.transform.rotation.x += 1;
    else if (state[SDL_SCANCODE_S])
      scene.camera.transform.rotation.x -= 1;

    if (state[SDL_SCANCODE_UP])
      S3L_vec3Add(&scene.camera.transform.translation,camF);
    else if (state[SDL_SCANCODE_DOWN])
      S3L_vec3Sub(&scene.camera.transform.translation,camF);
    else if (state[SDL_SCANCODE_LEFT])
      S3L_vec3Sub(&scene.camera.transform.translation,camR);
    else if (state[SDL_SCANCODE_RIGHT])
      S3L_vec3Add(&scene.camera.transform.translation,camR);

    if (state[SDL_SCANCODE_K])
      newHeight = S3L_resolutionY + 4;
    else if (state[SDL_SCANCODE_I])
      newHeight = S3L_resolutionY - 4;
    else if (state[SDL_SCANCODE_J])
      newWidth = S3L_resolutionX - 4;
    else if (state[SDL_SCANCODE_L])
      newWidth = S3L_resolutionX + 4;

    if (
         (
           (newWidth != -1 && newWidth > 0) ||
           (newHeight != -1 && newHeight > 0)
         ) &&
        (newWidth * S3L_resolutionY <= S3L_MAX_PIXELS) &&
        (newHeight * S3L_resolutionX <= S3L_MAX_PIXELS))
    {
      if (newWidth != -1)
        S3L_resolutionX = newWidth;

      if (newHeight != -1)
        S3L_resolutionY = newHeight;

      SDL_DestroyTexture(texture);
      texture = SDL_CreateTexture(renderer,SDL_PIXELFORMAT_RGBX8888, SDL_TEXTUREACCESS_STATIC, S3L_resolutionX, S3L_resolutionY);
      SDL_SetWindowSize(window,S3L_resolutionX,S3L_resolutionY);
    }

    SDL_RenderClear(renderer);
    SDL_RenderCopy(renderer,texture,NULL,NULL);
    SDL_RenderPresent(renderer);

    frame++;
  }

  return 0;
}