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

#ifdef PERFMON
#define GETPERF(x) x = SDL_GetPerformanceCounter()
#else
#define GETPERF(x)
#endif

typedef struct {
	double freq;
	uint64_t start, evt, update, render;
	double max_start, max_evt, max_update, max_render, max_total;
} 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, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
	assert(NULL != renderer);

	SDL_DisplayMode mode;
	assert(SDL_GetWindowDisplayMode(window, &mode) == 0);
	const double interval = 1.0 / mode.refresh_rate;

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

#ifdef PERFMON
	perf_t perf = { .freq = SDL_GetPerformanceFrequency() / 1000000.0 };
	uint64_t frame = 0;
#endif
	while (1) {
		GETPERF(perf.start);

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

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

		// Render frame
		SDL_RenderClear(renderer);
		game_render(gamemem, renderer, SDL_GetTicks64());
		GETPERF(perf.render);

#ifdef PERFMON
		// Print performance analysis every 16 frames
		if ((frame & 15) == 0) {
			const double evt = (perf.evt - perf.start) / perf.freq;
			if (evt > perf.max_evt)
				perf.max_evt = evt;
			const double update = (perf.update - perf.evt) / perf.freq;
			if (update > perf.max_update)
				perf.max_update = update;
			const double render = (perf.render - perf.update) / perf.freq;
			if (render > perf.max_render)
				perf.max_render = render;
			const double total = (perf.render - perf.start) / perf.freq;
			if (total > perf.max_total)
				perf.max_total = total;
			const double total_pc = 100 * total / (1000000 * interval);
			printf(
			    VT100_CLEAR VT100_CURSORTOPLEFT
			    "evt\t[max %10.3f μs] %10.3f μs\n"
			    "update\t[max %10.3f μs] %10.3f μs\n"
			    "render\t[max %10.3f μs] %10.3f μs\n"
			    "total\t[max %10.3f μs] %10.3f μs -- %.2f%% of %.3f ms\n",
			    perf.max_evt, evt, perf.max_update, update, perf.max_render,
			    render, perf.max_total, total, total_pc, 1000 * interval);
		}
		++frame;
#endif

		// Present frame
		SDL_RenderPresent(renderer);
	}

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