/******
  SDL opengl renderer
******/
#include <SDL/SDL_opengl.h>
#include "../ui/elements.h"
#include "r_gl.h"
#include "interface.h"

void r_gl_Init() {
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

  if ((screen = SDL_SetVideoMode(g_video_width, g_video_height, 32, SDL_HWSURFACE|SDL_OPENGL|SDL_RESIZABLE|g_video_fullscreen)) == NULL) 
    return; // TODO: handle error

  glEnable( GL_TEXTURE_2D );
   
  glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
   
  glViewport( 0, 0, g_video_width, g_video_height);
   
  glClear( GL_COLOR_BUFFER_BIT );
   
  glMatrixMode( GL_PROJECTION );
  glLoadIdentity();
   
  glOrtho(0.0f, g_video_width, g_video_height, 1.0f, -1.0f, 1.0f);
  //glOrtho(0.0f, g_video_width, 0, g_video_height, -1.0f, 1.0f);
   
  glMatrixMode( GL_MODELVIEW );
  glLoadIdentity();
}

void r_gl_Reinit() {

}

void r_gl_clearScreen() {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void r_gl_renderScreen() {
  SDL_GL_SwapBuffers();
}

void r_gl_renderElements(struct ElementList *list) {
  struct Element *current = list->first;
  while(current != NULL) {
    struct Element *next = current->next;
    r_gl_renderElement(current);
    current = next;
  }
}

void r_gl_renderElement(struct Element *element) {
  if (element == NULL)
    return;
  if (element->flags & E_FLAG_HIDE || element->target == NULL)
    return;
  if (element->flags & E_FLAG_UPDATE) {
    if (element->type == E_TYPE_TEXT) {
      r_gl_renderText(element->font, ((struct TextElement*)element->data)->string, element->dimen.x, element->dimen.y);
    }
  }
}

void r_gl_renderText(struct Font *font, const char *string, int x, int y) {
  if (font == NULL) { 
    printf("font is null\n");
    return;
  }
  if (font->texture == 0) {
    r_gl_createTexture(&font->texture, font->surface);
  }
  int i = 0;
  int x_offset, y_offset;
  int x_render = 0;
  int y_render = 0;

  /* get the width and height of each sprite in gl texture terms */
  double sx = 1.0f/(font->surface->w / font->width);
  double sy = 1.0f/(font->surface->h / font->height);
  glBindTexture(GL_TEXTURE_2D, font->texture);
  while(string[i] != '\0') {
    switch(string[i]) {
      case '\n':
        y_render += font->height*font->scale_y;
        x_render = 0;
        break;
      default:
        y_offset = string[i] / 16;
        x_offset = string[i] - (y_offset*16);
        /* get the texture offsets for the target sprite */
        double tx = (x_offset == 0 ? 0.0f : 1.0f/((float)(16.0f/x_offset)));
        double ty = (y_offset == 0 ? 0.0f : 1.0f/(8.0f/y_offset));
        /* draw a clipped portion of our font texture to a quad*/
        glLoadIdentity();
        glTranslated(x+x_render, y+y_render, 1.0f);
        //glTranslated(font->width, y_render, 0.0f);
        glBegin(GL_QUADS);
          // tl
          //glTexCoord2d(tx,ty+sy); glVertex2f(0,0);
          glTexCoord2d(tx,ty); glVertex2f(0,0);
          // tr
          //glTexCoord2d(tx+sx,ty+sy); glVertex2f(font->width, 0);
          glTexCoord2d(tx+sx,ty); glVertex2f(font->width*font->scale_x, 0);
          // br
          //glTexCoord2d(tx+sx,ty); glVertex2f(font->width, font->height);
          glTexCoord2d(tx+sx,ty+sy); glVertex2f(font->width*font->scale_x, font->height*font->scale_y);
          // bl
          //glTexCoord2d(tx,ty); glVertex2f(0,font->height);
          glTexCoord2d(tx,ty+sy); glVertex2f(0,font->height*font->scale_y);
        glEnd();
        x_render += font->width*font->scale_x;
        break;
    }
    i++;
  }
  glLoadIdentity();
}

GLuint r_gl_createTexture(GLuint *texture, SDL_Surface *surface) {
  GLenum format;
  GLint colors = surface->format->BytesPerPixel;
  if (colors == 4) { // with alpha
    if (surface->format->Rmask == 0x000000ff) {
      format = GL_RGBA;
    } else {
      format = GL_BGRA;
    }
  } else if (colors == 3) {
    if (surface->format->Rmask == 0x000000ff) {
      format = GL_RGB;
    } else {
      format = GL_BGR;
    }
  } else {
    // non truecolor, handle error or convert
  }
  // generate texture handle
  glGenTextures(1, texture);
  // bind the texture object
  glBindTexture(GL_TEXTURE_2D, *texture);
  // set stretching properties
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  // get the appropriate endianness for data packing
  int num = 1;
  int pack_type = ( (*(char*)&num == 1) ? GL_UNSIGNED_INT_8_8_8_8 : GL_UNSIGNED_INT_8_8_8_8_REV);
  // copy it over! :)
  glTexImage2D(GL_TEXTURE_2D, 0, colors, surface->w, surface->h, 0, format, pack_type, surface->pixels);
  return *texture;
}