#include <SDL2/SDL.h>    
#include <SDL2/SDL2_framerate.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdint.h>

const int WINDOW_WIDTH  = 1024;
const int WINDOW_HEIGHT = 768;
const float scale_x = (float)WINDOW_WIDTH/(float)0xfff;
const float scale_y = (float)WINDOW_HEIGHT/(float)0x7ff;

struct square 
{
    Uint16 x;
    Uint16 y;
    Uint16 w;
    Uint16 h;
    Uint8 r;
    Uint8 g;
    Uint8 b;
    Uint8 a;
};

struct squares 
{
    size_t n;
    struct square * square;
};

void
square_build(struct squares * squares)
{
    int color, pos;
    for(size_t i = 0; i < squares->n; i++)
    {
        SDL_LogVerbose(SDL_LOG_CATEGORY_APPLICATION, "Build square %8d\r", i);
        color = rand();
        squares->square[i].r = (color) & 0xff;
        squares->square[i].g = (color >> 8) & 0xff;
        squares->square[i].b = (color >> 16) & 0xff;
        squares->square[i].a = (color >> 24) & 0xff;
        
        pos = rand();
        squares->square[i].x = (((pos)       & 0x7ff) << 1) * scale_x;    // 11 bits * 2
        squares->square[i].y = (((pos >> 11) & 0x3ff) << 1) * scale_y;    // 10 bits * 2
        squares->square[i].w = ((pos >> 21) & 0x1f);                      // 5 bits 
        squares->square[i].h = ((pos >> 27) & 0x1f);                      // 5 bits
    }
}

struct squares *
squares_init() 
{
    SDL_Log("Init squares\r");
    struct squares * squares = malloc(sizeof *squares);
    squares->n = 1;
    squares->square = malloc(squares->n * sizeof(struct square));
    square_build(squares);

    return squares;
}

void
squares_rebuild(struct squares * squares)
{
    SDL_Log("Rebuild squares %8d\r", squares->n);
    squares->square = realloc(squares->square, squares->n * sizeof(struct square));
    square_build(squares);
}

void
squares_destroy(struct squares * squares)
{
    if(squares)
        if(squares->square)
            free(squares->square);
        free(squares);
}

int main( int argc, char **argv )
{
    SDL_Init( SDL_INIT_EVERYTHING );
    atexit(SDL_Quit);

    SDL_Window *window = SDL_CreateWindow( "Frames",
            SDL_WINDOWPOS_UNDEFINED,
            SDL_WINDOWPOS_UNDEFINED,
            WINDOW_WIDTH, 
            WINDOW_HEIGHT, 
            SDL_WINDOW_SHOWN
            );

    SDL_Renderer *renderer = SDL_CreateRenderer( window, -1, SDL_RENDERER_ACCELERATED);
    SDL_RenderSetLogicalSize(renderer, WINDOW_WIDTH, WINDOW_HEIGHT);
    SDL_SetRenderDrawBlendMode(renderer, SDL_BLENDMODE_BLEND);
    SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0");

    int frameCount = 0;
    Uint32 time = SDL_GetTicks();
    FPSmanager fpsManager;
    SDL_initFramerate( &fpsManager );
    SDL_setFramerate( &fpsManager, 60);

    SDL_Rect rect;

    struct squares *squares = squares_init();

    bool bRunning = true;
    while (bRunning)
    {

        SDL_Event ev;

        while ( SDL_PollEvent( & ev ))  // Check event queue.
        {
            switch( ev.type )
            {
                case SDL_QUIT: // when window is closed
                    bRunning = false;
                    break;
                case SDL_KEYDOWN:
                    switch ( ev.key.keysym.sym )
                    {
                        case SDLK_1:
                            squares->n = 1;
                            squares_rebuild(squares);
                            break;
                        case SDLK_UP:
                            squares->n *= 2;
                            squares_rebuild(squares);
                            break;
                        case SDLK_DOWN:
                            squares->n /= 2;
                            squares_rebuild(squares);
                            break;
                        case SDLK_q:
                            bRunning = false;
                            break;
                    }
                    break;
            }
        }

        SDL_SetRenderDrawColor (renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
        SDL_RenderClear (renderer);
        struct square *tsq = squares->square;
        for(size_t i = 0; i < squares->n; i++) {
            SDL_SetRenderDrawColor (renderer, tsq->r, tsq->g, tsq->b, tsq->a);
            rect = (SDL_Rect) { tsq->x, tsq->y, tsq->w, tsq->h };
            SDL_RenderFillRect(renderer, &rect);
            tsq++;
        }

        // Determine when one second has passed
        if ( SDL_GetTicks() - time > 1000 )
        {
            fprintf(stdout, "FPS %8d - Rects %8d\r", frameCount, squares->n);
            fflush(stdout);
            frameCount = 0;
            time = SDL_GetTicks();
        }
        else {
            ++frameCount;
        }
        SDL_RenderPresent(renderer);
        SDL_framerateDelay(&fpsManager);

    }

    SDL_DestroyRenderer(renderer); renderer = NULL;
    SDL_DestroyWindow(window); window = NULL;
    return 0;
}