#define _SCL_SECURE_NO_WARNINGS

#include <SDL.h>
#include <stdio.h>
#include <algorithm>

//Screen dimension constants
const int SCREEN_WIDTH = 1920;
const int SCREEN_HEIGHT = 1080;

SDL_Window* gWindow;
SDL_Renderer* gRenderer;
SDL_Texture* gTexture;
SDL_Event e;

uint32_t* gPixelBuffer;
void* gPixels;
int gPitch;

bool gExitFlag;

Uint64 start;
Uint64 end;
Uint64 freq;
double seconds;

int main(int argc, char* args[])
{
    gExitFlag = false;
    gPixels = NULL;
    gPixelBuffer = new uint32_t[SCREEN_WIDTH * SCREEN_HEIGHT];
    std::fill_n(gPixelBuffer, SCREEN_WIDTH * SCREEN_HEIGHT, 0xFFFFFFFF);
    gPitch = SCREEN_WIDTH * 4;

    //Initialize SDL
    if (SDL_Init(SDL_INIT_VIDEO) < 0)
    {
        printf("SDL could not initialize! SDL Error: %s\n", SDL_GetError());
    }
    else
    {
        //Set texture filtering to linear
        if (!SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "1"))
        {
            printf("Warning: Linear texture filtering not enabled!");
        }

        //Create window
        gWindow = SDL_CreateWindow("SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
        if (gWindow == NULL)
        {
            printf("Window could not be created! SDL Error: %s\n", SDL_GetError());
        }
        else
        {
            //Create renderer for window
            gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_ACCELERATED);// | SDL_RENDERER_PRESENTVSYNC);
            if (gRenderer == NULL)
            {
                printf("Renderer could not be created! SDL Error: %s\n", SDL_GetError());
            }
            else
            {
                gTexture = SDL_CreateTexture(gRenderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, SCREEN_WIDTH, SCREEN_HEIGHT);
                if (gTexture == NULL)
                {
                    printf("Unable to create blank texture! SDL Error: %s\n", SDL_GetError());
                }
                else
                {

                    while (!gExitFlag)
                    {


                        //Handle events on queue
                        while (SDL_PollEvent(&e) != 0)
                        {
                            //User requests quit
                            if (e.type == SDL_QUIT)
                            {
                                gExitFlag = true;
                            }
                        }

                        start = SDL_GetPerformanceCounter();

                        SDL_RenderClear(gRenderer);
                        //SDL_LockTexture(gTexture, NULL, &gPixels, &gPitch);
                        //memcpy(gPixels, gPixelBuffer, gPitch * SCREEN_HEIGHT);
                        //SDL_UnlockTexture(gTexture);
                        SDL_UpdateTexture(gTexture, NULL, gPixelBuffer, gPitch);
                        SDL_RenderCopy(gRenderer, gTexture, NULL, NULL);
                        gPixels = NULL;
                        SDL_RenderPresent(gRenderer);

                        end = SDL_GetPerformanceCounter();
                        freq = SDL_GetPerformanceFrequency();
                        seconds = (end - start) / static_cast<double>(freq);
                        printf("Frame time: %fms\n", seconds * 1000.0);
                    }
                }
            }
        }
    }

    //Destroy window
    SDL_DestroyWindow(gWindow);
    SDL_DestroyRenderer(gRenderer);
    SDL_DestroyTexture(gTexture);

    delete gPixelBuffer;

    //Quit SDL subsystems
    SDL_Quit();
    return 0;
}