#include <stdio.h>
#include "gl_core_4_3.h"
#include <SDL2/SDL.h>
#include <SDL2/SDL_video.h>
#include <SDL2/SDL_opengl.h>
#include <SDL2/SDL_events.h>
#include <SDL2/SDL_keycode.h>
#include <stdlib.h>
int *vertices;
unsigned char *pixels;
int *ivert;
int *ipixels;
float *fvert;
float *fpixels;
unsigned int max_draw;
int screen_width;
int screen_height;
SDL_Window *window;
int max_pixels;

void
init_image ( long pos )
{
    FILE *fd = fopen ( "data", "r" );
    fseek ( fd, pos, SEEK_SET );
    int width;
    int height;
    fread ( &width, sizeof ( unsigned int ), 1, fd );
    fread ( &height, sizeof ( unsigned int ), 1, fd );
    fread ( &max_pixels, sizeof ( unsigned int ), 1, fd );

    pixels = calloc ( max_pixels, sizeof ( unsigned char ) );
    fpixels = calloc ( max_pixels, sizeof ( float ) );
    ipixels = calloc ( max_pixels, sizeof ( int ) );
    fread ( &pixels[0], sizeof ( unsigned char ), max_pixels, fd );

    for ( int i = 0; i < max_pixels; i++ ) {
  float m = pixels[i];
  int b = m / 0.01;
  float c = b * 0.01;
  fpixels [ i ] = c;
  ipixels [ i ] = pixels[i];
    }

    max_draw = height * width;
    vertices = calloc ( max_draw * 2, sizeof ( unsigned int ) );
    fvert = calloc ( max_draw * 2, sizeof ( float ) );
    ivert = calloc ( max_draw * 2, sizeof ( int ) );

    for ( int y = height - 1, i = 0; y >= 0; y-- ) {
  for ( int x = 0; x < width; i += 2, x++ ) {
   vertices [ i + 0 ] = x;
   vertices [ i + 1 ] = y;
   fvert [ i + 0 ] = x;
   fvert [ i + 1 ] = y;
   ivert [ i + 0 ] = x;
   ivert [ i + 1 ] = y;
  }
    }
    fclose ( fd );
    
    
}
#if 1
GLuint program;

GLuint
load_shader ( GLenum type, const char *shader_src )
{
    GLuint shader;
    GLint compiled;
    shader = glCreateShader ( type );
    printf ( "!\n" );
    if ( shader == 0 ) return 0;
    glShaderSource ( shader, 1, &shader_src, NULL );
    glCompileShader ( shader );
    glGetShaderiv ( shader, GL_COMPILE_STATUS, &compiled );
    if ( !compiled ) {
  GLint info_len = 0;
  glGetShaderiv ( shader, GL_INFO_LOG_LENGTH, &info_len );
  if ( info_len > 1 ) {
   char *info_log = malloc ( sizeof ( char ) * info_len );
   glGetShaderInfoLog ( shader, info_len, NULL, info_log );
   printf ( "shader compile %s ", info_log );
   free ( info_log );
   switch ( type ) {
    case GL_VERTEX_SHADER:
     printf ( "vertex shader!\n" );
     break;
    case GL_FRAGMENT_SHADER:
     printf ( "fragment shader!\n" );
     break;
   }
  }
  glDeleteShader ( shader );
  return 0;
    }
    return shader;
}
GLuint
loadProgram ( const char *vshader, const char *fshader )
{
    GLuint vertex_shader, fragment_shader;
    vertex_shader = load_shader ( GL_VERTEX_SHADER, vshader );
    fragment_shader = load_shader ( GL_FRAGMENT_SHADER, fshader );
    GLuint program_object;
    program_object = glCreateProgram ( );
    glAttachShader ( program_object, vertex_shader );
    glAttachShader ( program_object, fragment_shader );
    glLinkProgram ( program_object );
    GLint linked;
    glGetProgramiv ( program_object, GL_LINK_STATUS, &linked );
    if ( !linked ) {
  GLint info_len = 0;
  glGetProgramiv ( program_object, GL_INFO_LOG_LENGTH, &info_len );
  if ( info_len > 1 ) {
   char *info_log = malloc ( sizeof ( char ) * info_len );
   glGetProgramInfoLog ( program_object, info_len, NULL, info_log );
   printf ( "%s\n", info_log );
   free ( info_log );
  }
  return -1;
    }
    return program_object;
}
#endif

void init_conf ( )
{
    const char *vShaderstr =
  "#version 430\n"
  "layout(location = 0) in vec2 position;\n"
  "layout(location = 1) in vec4 color;\n"
  "uniform mat4 transform;\n"
  "out vec4 v_color;\n"
  "void main()\n"
  "{\n"
  " v_color = vec4 ( color );\n"
  " gl_Position = transform * vec4 ( position, 0.0, 1.0 );\n"
  "}";
    const char *fShaderstr =
  "#version 430\n"
//  "precision mediump float;\n"
  "in vec4 color;\n"
  "layout ( location = 0 ) out vec4 fragColor;\n"
  "void main()\n"
  "{\n"
  " fragColor = vec4 ( color );\n"
  "}";
    program = loadProgram ( vShaderstr, fShaderstr );
#if 0
    glOrtho ( 0.0f, screen_width, 0, screen_height, 0.0f, 1.0f );
#endif
}

void
draw ( )
{
    GLfloat transform[] = {
            1.0f, 0.0f, 0.0f, 0.0f,
            0.0f, 0.0f, 0.0f, 0.0f,
            0.0f, 0.0f, -1.0f, 0.0f,
            -1.0f, -1.0f, 0.0f, 1.0f,
        };
    float prj_mat[] =
    {
      2.0f/screen_width,   0.0f,  0.0f,  0.0f,
      0.0f,       2.0f/screen_height,  0.0f,  0.0f,
      0.0f,        0.0f,        -1.0f,  0.0f,
     -1.0f,       -1.0f,         0.0f,  1.0f
    };
    glUseProgram ( program );
    GLint prj_loc = glGetUniformLocation( program, "transform" );
    glUniformMatrix4fv( prj_loc, 1, GL_FALSE, prj_mat );
//    glUniformMatrix4fv( prj_loc, 1, GL_FALSE, transform );

    GLuint vbo[2];
    GLuint vao;
    glGenBuffers ( 2, &vbo[0] );
    GLuint posbufh = vbo[0];
    GLuint colbufh = vbo[1];
    glBindBuffer ( GL_ARRAY_BUFFER, posbufh );
    glBufferData ( GL_ARRAY_BUFFER, max_draw * 2 * sizeof ( float ), fvert, GL_STATIC_DRAW );
    glBindBuffer ( GL_ARRAY_BUFFER, colbufh );
    glBufferData ( GL_ARRAY_BUFFER, max_pixels * sizeof ( float ), fpixels, GL_STATIC_DRAW );
    glGenVertexArrays ( 1, &vao );
    glBindVertexArray ( vao );
    glEnableVertexAttribArray ( 0 );
    glEnableVertexAttribArray ( 1 );
    glBindBuffer ( GL_ARRAY_BUFFER, posbufh );
    glVertexAttribPointer ( 0, 2, GL_FLOAT, GL_FALSE, 0, NULL );
    glBindBuffer ( GL_ARRAY_BUFFER, colbufh );
    glVertexAttribPointer ( 1, 4, GL_FLOAT, GL_FALSE, 0, NULL );
    glBindVertexArray ( vao );

    glDrawArrays ( GL_POINTS, 0, max_draw );
    glFlush ( );
}
SDL_GLContext glc;
void init_sdl ( )
{
    SDL_Init ( SDL_INIT_TIMER | SDL_INIT_VIDEO | SDL_INIT_EVENTS );
    SDL_DisplayMode mode;
    SDL_GetCurrentDisplayMode ( 0, &mode );
    screen_width = mode.w - 64;
    screen_height = mode.h - 128;

#if 1
    if ( ogl_LoadFunctions() == ogl_LOAD_FAILED ) {
  exit ( EXIT_FAILURE );
    }
#endif
    window = SDL_CreateWindow ( "ipsi",
   0, 0,
   screen_width,
   screen_height,
   SDL_WINDOW_OPENGL
   );

#if 0
    SDL_GL_SetAttribute ( SDL_GL_CONTEXT_MAJOR_VERSION, 4 );
    SDL_GL_SetAttribute ( SDL_GL_CONTEXT_MAJOR_VERSION, 3 );
#endif
    glc = SDL_GL_CreateContext ( window );
    SDL_GL_MakeCurrent ( window, glc );
    printf ( "!!\n");
    const char *version = glGetString ( GL_VERSION );
    printf ( "%s\n", version );

    glViewport ( 0, 0, screen_width, screen_height );
    printf ( "@\n" );
    glEnable ( GL_BLEND );
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
int input_thread ( void *data )
{
    SDL_Event event;
    while ( SDL_WaitEvent ( &event ) ) {
  switch ( event.type ) {
   case SDL_KEYDOWN:
    if ( event.key.keysym.sym == SDLK_q ) {
     exit ( EXIT_SUCCESS );
    }
    break;
   case SDL_MOUSEBUTTONDOWN:
    break;
   case SDL_MOUSEBUTTONUP:
    break;
   case SDL_MOUSEMOTION:
    break;
  }
    }
}
void print_version ( )
{
    const GLubyte *renderer = glGetString ( GL_RENDERER );
    const GLubyte *vendor = glGetString ( GL_VENDOR );
    const GLubyte *version = glGetString ( GL_VERSION );
    const GLubyte *glslVersion = glGetString ( GL_SHADING_LANGUAGE_VERSION );

    GLint major, minor;
    glGetIntegerv ( GL_MAJOR_VERSION, &major );
    glGetIntegerv ( GL_MINOR_VERSION, &minor );

    printf ( "gl renderer %s\n", renderer );
    printf ( "gl vender %s\n", vendor );
    printf ( "gl version %s %d.%d\n", version, major, minor );
    printf ( "gl glsl %s\n", glslVersion );
}
int main ( )
{
    
    init_sdl ( );
    print_version ( );
    init_conf ( );
    init_image ( 0 );
    SDL_CreateThread ( input_thread, "input_thread", NULL );

    while ( 1 ) {
  glClearColor ( 1, 1, 1, 1 );
  glClear ( GL_COLOR_BUFFER_BIT );
  draw ( );
  SDL_GL_SwapWindow ( window );
  SDL_Delay ( 0.01 );
    }

}