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

#include "assets.h"
#include "eprintf.h"
#include "gl.h"
#include "glprog.h"
#include "linmath.h"
#include "nelem.h"

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

int main(int argc, char **argv)
{
	bool running = true;
	SDL_Window *win;
	SDL_GLContext *glc;
	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] : "faqe");

	if (SDL_Init(SDL_INIT_VIDEO) != 0)
		eprintf("Failed to initialise SDL: %s", SDL_GetError());

	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

	win = SDL_CreateWindow("faqe",
			       SDL_WINDOWPOS_UNDEFINED,
			       SDL_WINDOWPOS_UNDEFINED,
			       WIDTH, HEIGHT,
			       SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
	if (win == NULL)
		eprintf("Failed to create window: %s", SDL_GetError());

	glc = SDL_GL_CreateContext(win);
	if (glc == NULL)
		eprintf("Failed to create OpenGL context: %s", SDL_GetError());

	gl_load((gl_loadfunc *)SDL_GL_GetProcAddress);

	gl_viewport(0, 0, 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 (running) {
		SDL_Event ev;

		while (SDL_PollEvent(&ev)) {
			switch (ev.type) {
			case SDL_KEYDOWN:
			case SDL_KEYUP:
				if (ev.key.state != SDL_RELEASED
				    || ev.key.keysym.sym != SDLK_ESCAPE)
					break;
				/* fallthrough */
			case SDL_QUIT:
				running = false;
				break;
			case SDL_WINDOWEVENT:
				switch (ev.window.event) {
				case SDL_WINDOWEVENT_SIZE_CHANGED:
					gl_viewport(0, 0,
						    ev.window.data1,
						    ev.window.data2);
				}
				break;
			}
		}

		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);

		SDL_GL_SwapWindow(win);
	}

	SDL_GL_DeleteContext(glc);
	SDL_DestroyWindow(win);

	SDL_Quit();
}