/*
 * Copyright (c) Camden Dixie O'Brien
 * SPDX-License-Identifier: AGPL-3.0-only
 */

#include "engine_hooks.h"

#include <assert.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdlib.h>

#define FRAMERATE 60
#define INTERVAL (1000 / FRAMERATE)

#define VT100_CURSORTOPLEFT "\33[H"
#define VT100_CLEAR "\33[2J"

typedef struct {
	double freq;
	uint64_t start, evt, update, render;
} perf_t;

int main(int argc, char *argv[])
{
	int err = SDL_Init(SDL_INIT_VIDEO);
	assert(0 == err);

	SDL_Window *window = SDL_CreateWindow(
	    game_conf.win.title, SDL_WINDOWPOS_UNDEFINED,
	    SDL_WINDOWPOS_UNDEFINED, game_conf.win.w, game_conf.win.h, 0);
	assert(NULL != window);

	SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);
	assert(NULL != renderer);

	void *gamemem = calloc(1, game_conf.memsize);
	game_init(argc, argv, gamemem, renderer);

	perf_t perf = { .freq = SDL_GetPerformanceFrequency() / 1000000.0 };
	uint64_t frame = 0, prevt = SDL_GetTicks64();
	while (1) {
		const uint64_t t = SDL_GetTicks64();
		const uint64_t dt = t - prevt;
		if (dt >= INTERVAL) {
			perf.start = SDL_GetPerformanceCounter();

			// Handle all events currently in queue
			SDL_Event evt;
			while (SDL_PollEvent(&evt)) {
				if (game_evthandle(gamemem, &evt) != GAMESTATUS_OK)
					goto quit;
			}
			perf.evt = SDL_GetPerformanceCounter();

			// Update game state
			if (game_update(gamemem, INTERVAL) != GAMESTATUS_OK)
				goto quit;
			perf.update = SDL_GetPerformanceCounter();

			// Render frame
			SDL_RenderClear(renderer);
			game_render(gamemem, renderer, t);
			SDL_RenderPresent(renderer);
			perf.render = SDL_GetPerformanceCounter();

			// Print performance analysis every 16 frames
			if ((frame & 15) == 0) {
				const double evt = (perf.evt - perf.start) / perf.freq;
				const double update = (perf.update - perf.evt) / perf.freq;
				const double render
				    = (perf.render - perf.update) / perf.freq;
				const double total = (perf.render - perf.start) / perf.freq;
				const double total_pc = (100 * total / (1000 * INTERVAL));
				printf(
					VT100_CLEAR VT100_CURSORTOPLEFT
				    "evt\t%10.3f μs\nupdate\t%10.3f μs\nrender\t"
				    "%10.3f μs\ntotal\t%10.3f μs (%05.2f%%)\n",
				    evt, update, render, total, total_pc);
			}

			// Increment frame counter and update time
			++frame;
			prevt = t;
		}

		SDL_Delay(INTERVAL / 8);
	}

quit:
	game_teardown(gamemem);
	SDL_DestroyRenderer(renderer);
	SDL_DestroyWindow(window);
	SDL_Quit();
}