/*
 * Copyright (C) 2018 Tomasz Kramkowski <tk@the-tk.com>
 * SPDX-License-Identifier: MIT
 */
#include <GLFW/glfw3.h>
#include <stdbool.h>

#include "assets.h"
#include "eprintf.h"
#include "gldefs.h"
#include "glprog.h"
#include "linmath.h"
#include "loadgl.h"
#include "nelem.h"

enum {
	WIDTH = 800,
	HEIGHT = 600,
};

void fb_size_cb(GLFWwindow *win, int width, int height)
{
	(void)win;
	gl_viewport(0, 0, width, height);
}

void take_input(GLFWwindow *win)
{
	if (glfwGetKey(win, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(win, true);
}

int main(int argc, char **argv)
{
	GLFWwindow *win;
	int ret;
	GLuint ebo, vbo, vao, prog;
	GLint ucolor;
	struct vertex {
		vec3 pos;
		vec3 col;
		vec2 uv;
	} verts[] = {
		{{  0.5,  0.5, 0.0 }, { 1.0, 0.0, 0.0 }, { 1.0, 1.0 }},
		{{  0.5, -0.5, 0.0 }, { 0.0, 1.0, 0.0 }, { 1.0, 0.0 }},
		{{ -0.5, -0.5, 0.0 }, { 0.0, 0.0, 1.0 }, { 0.0, 0.0 }},
		{{ -0.5,  0.5, 0.0 }, { 1.0, 1.0, 0.0 }, { 0.0, 1.0 }},
	};
	GLuint idxs[] = {
		0, 1, 3,
		1, 2, 3,
	};

	setprogname(argc >= 1 && argv[0] != NULL ? argv[0] : "gltest");

	glfwInit();

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	win = glfwCreateWindow(WIDTH, HEIGHT, "gltest", NULL, NULL);
	if (win == NULL)
		eprintf("Failed to create GLFW window");
	glfwMakeContextCurrent(win);

	ret = lgl_load((lgl_loadfunc *)glfwGetProcAddress);
	if (ret != 0)
		eprintf("Failed to load GL: %s", lgl_strerror(ret));
	glfwSetFramebufferSizeCallback(win, &fb_size_cb);
	fb_size_cb(win, WIDTH, HEIGHT);

	gl_buf_gen(1, &vbo);
	gl_buf_gen(1, &ebo);
	gl_va_gen(1, &vao);

	gl_va_bind(vao);

	gl_buf_bind(GL_ARRAY_BUFFER, vbo);
	gl_buf_data(GL_ARRAY_BUFFER, sizeof verts, verts, GL_STATIC_DRAW);

	gl_buf_bind(GL_ELEMENT_ARRAY_BUFFER, ebo);
	gl_buf_data(GL_ELEMENT_ARRAY_BUFFER, sizeof idxs, idxs, GL_STATIC_DRAW);

	gl_va_define(0, NELEM(verts[0].pos), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, pos));
	gl_va_enable(0);
	gl_va_define(1, NELEM(verts[0].col), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, col));
	gl_va_enable(1);
	gl_va_define(2, NELEM(verts[0].uv), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, uv));
	gl_va_enable(2);

	prog = glprog_load(2, (struct shdrdat []){
			{ GL_VERTEX_SHADER, vert_glsl.data, vert_glsl.size },
			{ GL_FRAGMENT_SHADER, frag_glsl.data, frag_glsl.size },
				},
		1, &(struct unidat){ "ucolor", &ucolor });

	gl_poly_mode(GL_FRONT_AND_BACK, GL_LINE);

	while (!glfwWindowShouldClose(win)) {
		take_input(win);

		gl_clearcolor(0.2, 0.3, 0.3, 1.0);
		gl_clear(GL_COLOR_BUFFER_BIT);
		gl_prog_use(prog);
		gl_va_bind(vao);
		gl_draw_elems(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
		gl_va_bind(0);

		glfwSwapBuffers(win);
		glfwPollEvents();
	}

	glfwTerminate();
}