/*-
 * Copyright (C) 2025  Alessandro Iezzi <aiezzi AT alessandroiezzi PERIOD it>
 *
 * This file is part of Tris Game.
 *
 * Tris Game is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Tris Game is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Tris Game.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <time.h>
#include <GL/gl.h>
#include "../ui/ui.h"

#define RANGE_GL 2.0f

static float xstep;
static float ystep;
static int width;
static int height;

typedef struct Engine {
	void (*draw_frame)();
} Engine;

static Engine engine;

/* FPS */
static time_t start;
static int frames;
static time_t end;

void
engine_init(int w, int h)
{
	width = w;
	height = h;
	ui_init(w, h);

	xstep = RANGE_GL / (float) w;
	ystep = RANGE_GL / (float) h;
}

void
engine_draw_line(int x1, int y1, int x2, int y2)
{
	float _x1 = x1 * xstep - 1; float _y1 = (height - y1) * ystep - 1;
	float _x2 = x2 * xstep - 1; float _y2 = (height - y2) * ystep - 1;

	glVertex2f(_x1, _y1);
	glVertex2f(_x2, _y2);
}

static void
engine_calculate_fps()
{
	frames ++;

	end = time(NULL);
	if (end - start >= 1.0) {
		printf("FPS: %d\n", frames);
		frames = 0;
		start = time(NULL);
	}
}

static void
draw_frames()
{
	glClearColor(0.0f, 0.0f, 0.2f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	glEnable(GL_LINE_SMOOTH);
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	engine.draw_frame();
	engine_calculate_fps();
}

void
engine_loop(void (*draw_frame)())
{
	engine.draw_frame = draw_frame;

	ui_set_loop_listener(draw_frames);

	/* FPS calculation */
	start = time(NULL);
	frames = 0;

	ui_loop();
}