#include "game.h"
#include "sys.h"

#include <SDL3/SDL.h>
#include <GL/glew.h>

#define DEBUG 1

typedef struct {
	SDL_Window *window;
	i32 width;
	i32 height;
	SDL_Renderer *renderer;
	u64 last_counter;
	f32 dt;
} sdl_context_t;

static sdl_context_t init_sdl(i32 width, i32 height, i32 debug)
{
	sdl_context_t ctx = {0};
	ctx.width = width;
	ctx.height = height;
	SDL_Init(SDL_INIT_VIDEO);
	u64 flags = SDL_WINDOW_OPENGL;
	SDL_CreateWindowAndRenderer("breakout", ctx.width, ctx.height, flags, &ctx.window, &ctx.renderer);
	if (debug)
		SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_DEBUG_FLAG);
	SDL_GLContext glctx = SDL_GL_CreateContext(ctx.window);
	SDL_GL_MakeCurrent(ctx.window, glctx);
	SDL_GL_SetSwapInterval(0);
	ctx.last_counter = SDL_GetPerformanceCounter();
	glewInit();
	return ctx;
}

static void process_sdl_key(input_t *input, i32 scancode, i32 pressed)
{
	switch (scancode) {
	case SDL_SCANCODE_ESCAPE:
		input->escape.current = pressed;
		break;
	case SDL_SCANCODE_RIGHT:
		input->right.current = pressed;
		break;
	case SDL_SCANCODE_LEFT:
		input->left.current = pressed;
		break;
	case SDL_SCANCODE_SPACE:
		input->space.current = pressed;
		break;
	default:
		break;
	}
}

static void process_sdl_events(game_t *game)
{
	SDL_Event event;
	while (SDL_PollEvent(&event)) {
		switch (event.type) {
		case SDL_EVENT_KEY_DOWN:
		case SDL_EVENT_KEY_UP:
			process_sdl_key(&game->input, event.key.scancode, event.key.down);
		default:
			break;
		}
	}
}

static f32 get_elapsed(u64 last_counter)
{
	u64 frequency = SDL_GetPerformanceFrequency();
	u64 current_counter = SDL_GetPerformanceCounter();
	return (f32)(current_counter - last_counter) / (f32)frequency;
}

static void lock_framerate_sdl(sdl_context_t *ctx, i32 fps)
{
	f32 elapsed = get_elapsed(ctx->last_counter) * 1000.0f;
	f32 target = 1000.0f / (f32)fps;
	f32 sleep = target - elapsed;
	if (sleep > 0)
		SDL_Delay((u32)sleep);
	do {
		elapsed = get_elapsed(ctx->last_counter) * 1000.0f;
	} while (elapsed < target);
	ctx->dt = get_elapsed(ctx->last_counter);
	ctx->last_counter = SDL_GetPerformanceCounter();
}

static void fps_info(f32 dt, i32 again)
{
	static f32 time = 0;
	static i32 lastsec = 0;
	static f32 sumdt = 0;
	static i32 sumfps = 0;
	static f32 frame_count = 0;
	time += dt;
	sumdt += dt;
	sumfps += (i32)(1.0f / dt);
	frame_count++;
	i32 sec = (i32)time;
	if (sec != 0 && sec % again == 0) {
		if (lastsec != sec) {
			f32 mean_dt = sumdt / frame_count;
			f32 mean_fps = sumfps / frame_count;
			info("time: %d dt: %f fps: %f", sec, mean_dt, mean_fps);
			lastsec = sec;
			sumdt = 0;
			sumfps = 0;
			frame_count = 0;
		}
	}
}

i32 main(void)
{
	sdl_context_t ctx = init_sdl(1600, 800, DEBUG);
	game_t game = init_game(ctx.width, ctx.height);
	while (game.running) {
		process_sdl_events(&game);
		process_input(&game);
		update_game(&game, ctx.dt);
		update_input(&game.input);
		lock_framerate_sdl(&ctx, 60);
		fps_info(ctx.dt, 10);
		render_game(game);
		SDL_GL_SwapWindow(ctx.window);
	}
	return 0;
}