/*
Notes I kept while testing:

try-1/ - 2000 frames in 11 seconds
- works but uses surfaces rather than rendering
  - seems rendering may be better as uses GPU:
    - https://gamedev.stackexchange.com/questions/180077/in-sdl-what-is-the-difference-between-using-a-surfaces-and-a-renderer
- started here which was surfaces:
  - https://lazyfoo.net/tutorials/SDL/01_hello_SDL/index2.php
- also looked at this which is rendering:
  - https://www.geeksforgeeks.org/sdl-library-in-c-c-with-examples/

try-2/ - 2000 frames in 5.2 seconds - NOTE MAY NEED LockSurface!!!
- surfaces accessing pixels directly:
  - https://stackoverflow.com/questions/20070155/how-to-set-a-pixel-in-a-sdl-surface?rq=3

try-3/ - 200 (not 2000) frames in 10.7 seconds (ie 2000 frames in ~107 seconds)
- switch to renderer from surfaces
  - https://stackoverflow.com/questions/20579658/how-to-draw-pixels-in-sdl-2-0

try-4/ - 2000 frames in 1 second - BEST result and stretches to match window!
- render accessing pixels directly:
  - https://gist.github.com/mmozeiko/729860eeb414f1a2ee345d9d3ab4dd4e
  - https://stackoverflow.com/questions/62379457/how-to-draw-a-grid-of-pixels-fast-with-sdl2#comment110428713_62394835
*/

//try-4/main.c
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <SDL2/SDL.h>

//Constants
//=========
#define WINDOW_TITLE        "SDL2 test"

#define CALC_SCREEN_WIDTH   384
#define CALC_SCREEN_HEIGHT  216
#define SCALE_FACTOR        3
#define SCREEN_WIDTH        CALC_SCREEN_WIDTH*SCALE_FACTOR
#define SCREEN_HEIGHT       CALC_SCREEN_HEIGHT*SCALE_FACTOR

//Commented out below but see SDL_Delay below to set framerate
//#define FPS 24

//Globals
//=======
uint32_t screen[CALC_SCREEN_HEIGHT][CALC_SCREEN_WIDTH];

int main(int argc, char *argv[])
{
    //Set up pixel data
    for (int y=0;y<CALC_SCREEN_HEIGHT;y++)
    {
        for (int x=0;x<CALC_SCREEN_WIDTH;x++)
        {
            screen[y][x]=((y<<16)|(x/2)|0xFF000000);
        }
    }

    //Initialize SDL
    SDL_Window *window=NULL;
    SDL_Renderer *renderer=NULL;
    SDL_Texture *texture=NULL;
    if (SDL_Init(SDL_INIT_VIDEO)<0)
    {
        printf("Error: SDL2 did not initialize. SDL error: %s\n", SDL_GetError());
        exit(1);
    }

    //Create window
    window=SDL_CreateWindow(WINDOW_TITLE,SDL_WINDOWPOS_UNDEFINED,SDL_WINDOWPOS_UNDEFINED,SCREEN_WIDTH,SCREEN_HEIGHT,SDL_WINDOW_SHOWN);
    if (window==NULL)
    {
        printf("Error: SDL2 could not create window. SDL error: %s\n", SDL_GetError());
        exit(1);
    }

    //Draw to texture
    renderer=SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED);
    texture=SDL_CreateTexture(renderer,SDL_PIXELFORMAT_ARGB8888,SDL_TEXTUREACCESS_STREAMING,CALC_SCREEN_WIDTH,CALC_SCREEN_HEIGHT);

    //Keep track of frames drawn and exit after 2000
    unsigned int debug_counter=0;

    //Event loop
    SDL_Event event;
    bool done=false;
    while (done==false)
    {
        while (SDL_PollEvent(&event))
        {
            switch (event.type)
            {
                case SDL_QUIT:
                    //User closed window
                    done=true;
                    break;
                case SDL_KEYDOWN:
                    switch (event.key.keysym.scancode)
                    {
                        case SDL_SCANCODE_ESCAPE:
                            //User pressed escape
                            done=true;
                            break;
                    }
            }
        }

        //Logic goes here

        //Update window with drawn pixels
        SDL_UpdateTexture(texture,NULL,screen,CALC_SCREEN_WIDTH*sizeof(uint32_t));
        SDL_RenderCopy(renderer,texture,NULL,NULL);
        SDL_RenderPresent(renderer);

        //End test after 2000 frames drwn
        if (debug_counter==2000) done=true;
        else debug_counter++;

        //Delay to limit FPS
        //SDL_Delay(1000/FPS);
    }

    //Free memory
    SDL_DestroyTexture(texture);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}




//build script
#!/bin/bash
FILENAME=main

gcc -O3 ${FILENAME}.c -o $FILENAME `sdl2-config --cflags --libs`
ret=$?
if [ $ret -eq 0 ]; then
    ./$FILENAME
fi