#pragma once

#include <SDL.h>
// #include <GLES2/gl2.h>
#include <GL/glew.h>

#include "../util.h"
#include "../util/matrix.h"

typedef struct GL_FONT *PGL_FONT;
typedef struct GL_DATA *PGL_DATA;
typedef void(*GL_RESIZE_REPAINT_CB)( void* userdata );

struct VERTEX {
  VEC2 pos;
  VEC2 uv;
  CLR clr;
  U8 sampler = 255;
};

struct GL_SHADER_DEF {
  const char* name;
  const char* code;
  I32         type;
  U32         id;
  U8          compiled;
};

struct GL_SHADER_PROGRAM {
  const char* name;
  GL_SHADER_DEF fsh;
  GL_SHADER_DEF vsh;
  U32 id;
  U32 vbuffer;

  GL_DATA* gl;
};

struct GL_TEX2D {
  GLuint id;
  char name[256];
  U32 width;
  U32 height;
  U32 channels;
  U8* data;
};

typedef struct GL_DATA {
  SDL_Window*   window;
  SDL_GLContext ctx;
  SDL_Renderer* renderer;

  I32 canvas_size[2];

  LIST<GL_SHADER_PROGRAM*> programs;
  LIST<GL_TEX2D*>   textures;
  LIST<GL_FONT*>    fonts;

  I32 shader_texture_limit;
  U64 last_tick;
  F32 frametime;
  F32 fps;

  GLuint vbuffer;

  VEC2 clip_start;
  VEC2 clip_dim;

  VEC2 viewport_start;
  VEC2 viewport_dim;

  MAT4* proj_matrix;

  GLuint vao;

  GL_RESIZE_REPAINT_CB resize_repaint_cb{};
  void* resize_repaint_userdata{};
  U8 resize_repaint_active{};
  U8 window_constraint_active{};
} *PGL_DATA;

GL_DATA*    gl_instance();
GL_DATA*    gl_create( I32* _canvas );
void        gl_destroy( GL_DATA* gl );
void        gl_gen_buffers( GL_DATA* gl );
STAT        gl_beginframe( GL_DATA* gl );
STAT        gl_endframe( GL_DATA* gl );
STAT        gl_poll_events( GL_DATA* gl );
STAT        gl_shader_compile( GL_DATA* gl, GL_SHADER_DEF* shader );
void        gl_shader_destroy( GL_DATA* gl, GL_SHADER_DEF* shader );
GL_SHADER_PROGRAM* gl_program_create( GL_DATA* gl, const char* name, U32 size = sizeof(GL_SHADER_PROGRAM) );
STAT        gl_program_compile( GL_DATA* gl, GL_SHADER_PROGRAM* program );
void        gl_program_destroy( GL_DATA* gl, GL_SHADER_PROGRAM* program );
GL_TEX2D*   gl_texture_create( GL_DATA* gl, const char* name );
GL_TEX2D*   gl_texture_from_file( GL_DATA* gl, const char* name );
GL_TEX2D*   gl_texture_from_bitmap( GL_DATA* gl, const char* name, U8* bitmap, U32 width, U32 height );
void        gl_texture_destroy( GL_DATA* gl, GL_TEX2D* tex );
void        gl_update_window( GL_DATA* gl, I32* size );
void        gl_sync_window_size( GL_DATA* gl );
void        gl_set_resize_repaint_callback( GL_DATA* gl, GL_RESIZE_REPAINT_CB cb, void* userdata );
void        gl_set_clip( GL_DATA* gl, VEC2 start, VEC2 dim );
void        gl_get_clip( GL_DATA* gl, VEC2* start, VEC2* dim );
void        gl_set_viewport( GL_DATA* gl, VEC2 start, VEC2 dim );
void        gl_get_viewport( GL_DATA* gl, VEC2* start, VEC2* dim );
void        gl_reset_clip( GL_DATA* gl );

// special sampler id for no texture
const  U8  SAMPLER_ID_NONE = 255;
extern I32 SAMPLER_INDICES[255];

template <typename VERTEX>
LIST<VERTEX> triangle_fan_to_list( VERTEX* vertices, U32 vert_count ) {
  LIST<VERTEX> ret{};
  if( vert_count < 3 ) {
    return ret;
  }

  ret.reserve( (vert_count - 2) * 3 );
  VERTEX* start = &vertices[0];
  VERTEX* last = &vertices[1];
  for( U32 i = 2; i < vert_count; ++i ) {
    ret.push( *start );
    ret.push( *last );
    ret.push( vertices[i] );
    last = &vertices[i];
  }

  return ret;
}