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

#include "eprintf.h"
#include "gldefs.h"
#include "linmath.h"
#include "loadgl.h"
#include "shaders.h"

enum {
	WIDTH = 800,
	HEIGHT = 600,
	LOGSIZE = 1024,
};

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);
}

GLuint load_shader(GLenum type, const char *data, GLint size)
{
	GLuint shdr;
	GLint success;
	char log[LOGSIZE];

	shdr = gl_shdr_create(type);
	gl_shdr_source(shdr, 1, &data, &size);
	gl_shdr_compile(shdr);
	gl_shdr_param(shdr, GL_COMPILE_STATUS, &success);

	if (!success) {
		gl_shdr_infolog(shdr, sizeof log, NULL, log);
		eprintf("Failed to compile shader:\n%s", log);
	}

	return shdr;
}

GLuint load_prog(void)
{
	GLuint vert, frag, prog;
	GLuint success;
	char log[LOGSIZE];

	vert = load_shader(GL_VERTEX_SHADER, shader_vert_data, shader_vert_size);
	frag = load_shader(GL_FRAGMENT_SHADER, shader_frag_data, shader_frag_size);
	prog = gl_prog_create();
	gl_prog_attachshdr(prog, vert);
	gl_prog_attachshdr(prog, frag);
	gl_prog_link(prog);
	gl_prog_param(prog, GL_COMPILE_STATUS, &success);
	if (!success) {
		gl_prog_infolog(prog, sizeof log, NULL, log);
		eprintf("Failed to link program:\n%s", log);
	}
	gl_shdr_del(vert);
	gl_shdr_del(frag);

	return prog;
}

int main(int argc, char **argv)
{
	GLFWwindow *win;
	int ret;
	GLuint ebo, vbo, vao, prog;
	vec3 verts[] = {
		{  0.5f,  0.5f, 0.0f },
		{  0.5f, -0.5f, 0.0f },
		{ -0.5f, -0.5f, 0.0f },
		{ -0.5f,  0.5f, 0.0f },
	};
	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, 3, GL_FLOAT, GL_FALSE, sizeof *verts, 0);
	gl_va_enable(0);

	prog = load_prog();

	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();
}