/*
	gcc -g screenTest.c -lSDL3 -lGL
	clang -g screenTest.c -L/opt/homebrew/lib -lSDL3 -framework OpenGL -I/opt/homebrew/include
*/

#define SDL_MAIN_USE_CALLBACKS 1
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include <SDL3/SDL_opengl.h>
#include <stdio.h>

SDL_Window*window;
SDL_Renderer*renderer;
SDL_GLContext glContext;
int startX;
bool glMode, altColor;
SDL_AppResult SDL_AppInit(void**appstate, int argc, char*argv[])
{
	glMode = argc == 2;
	//glMode = 1;
	
	printf(glMode ? "using gl mode\n" : "using default sdl\n");

	SDL_SetHint(SDL_HINT_NO_SIGNAL_HANDLERS, "1");
	SDL_SetHint(SDL_HINT_VIDEO_DOUBLE_BUFFER, "1");

	SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS);

	int count = SDL_GetNumVideoDrivers();
	for(int i=0; i<count; i++) {
		printf("Driver #%d %s\n", i+1, SDL_GetVideoDriver(i));
	}


	if (glMode) {
		SDL_SetHint(SDL_HINT_RENDER_DRIVER, "opengl");
		SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 0); // <-- this breaks vsync
	}

	if (!SDL_CreateWindowAndRenderer("Screen Tear Test", 640, 480, SDL_WINDOW_RESIZABLE|SDL_WINDOW_MAXIMIZED|SDL_WINDOW_HIGH_PIXEL_DENSITY, &window, &renderer)) {
		return SDL_APP_FAILURE;
	}

	if (glMode) {
		glContext = SDL_GL_CreateContext(window);
	}

	int res = SDL_SetRenderVSync(renderer, 1);
	printf("Driver %s VSync %d pixel density %f gl %p\n", SDL_GetCurrentVideoDriver(), res, SDL_GetWindowPixelDensity(window), glContext);
	if (!res) {
		printf("%s\n", SDL_GetError());
	}
	return SDL_APP_CONTINUE;
}
SDL_AppResult SDL_AppEvent(void*appstate, SDL_Event*event) {
	if (event->type == SDL_EVENT_QUIT) { return SDL_APP_SUCCESS; }
	if (event->type == SDL_EVENT_KEY_DOWN) {
		if (event->key.key == SDLK_ESCAPE)
			return SDL_APP_SUCCESS;
		printf("altColor\n");
		altColor = !altColor;
	}
	return SDL_APP_CONTINUE;
}
SDL_AppResult SDL_AppIterate(void*appstate) {
	
	SDL_SetRenderDrawColorFloat(renderer, 0.1, 0.1, 0.1, 1);
	SDL_RenderClear(renderer);

	if (altColor)
		SDL_SetRenderDrawColorFloat(renderer, .4, .5, .6, 1);
	else {
		SDL_SetRenderDrawColorFloat(renderer, .8, .8, .8, 1);
	}

	SDL_FRect r={0, 0, 25, 1080*2};
	for(int x = startX-50; x < 1920*2; x += 50) {
		r.x = x;
		SDL_RenderFillRect(renderer, &r);
	}
	startX = (startX+4) % 50;

	if (glContext) {
		SDL_FlushRenderer(renderer);
		glFlush();
		SDL_GL_SwapWindow(window);
		SDL_Delay(16);
	} else {
		SDL_RenderPresent(renderer);
	}
	// printf("Drawn at %lld\n", SDL_GetTicks());
	return SDL_APP_CONTINUE;
}
void SDL_AppQuit(void *appstate, SDL_AppResult result)
{
}