/*
 * 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"
#include "model.h"

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

# define PI 3.14159265358979323846
#define FOV (PI * 0.5)

void viewport(GLuint proj, int width, int height)
{
	mat4x4 pers;
	gl_viewport(0, 0, width, height);
	mat4x4_perspective(pers, FOV, (float)width / (float)height, 0.1, 100);
	gl_uni_setm4fv(proj, 1, GL_FALSE, pers[0]);
}

int main(int argc, char **argv)
{
	bool running = true;
	SDL_Window *win;
	SDL_GLContext *glc;
	GLuint prog;
	struct {
		GLint model, view, proj;
	} uni;
	mat4x4 view;
	FILE *cube_file;
	struct fmd cube_fmd;
	struct model cube_model;
	vec3 pos = { 0, 0, 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);

	cube_file = fopen("cube.fmd", "rb");
	if (cube_file == NULL)
		eprintf("Could not open 'cube.fmd':");
	fmd_load(&cube_fmd, cube_file);
	model_load(&cube_model, &cube_fmd);
	fmd_free(&cube_fmd);
	fclose(cube_file);

	prog = glprog_load(2, (struct shdrdat []){
			{ GL_VERTEX_SHADER, vert_glsl.data, vert_glsl.size },
			{ GL_FRAGMENT_SHADER, frag_glsl.data, frag_glsl.size },
				},
		3, (struct unidat []){
			{ "model", &uni.model },
			{ "view", &uni.view },
			{ "proj", &uni.proj },
		});

	gl_prog_use(prog);
	viewport(uni.proj, WIDTH, HEIGHT);

	gl_enable(GL_DEPTH_TEST);

	while (running) {
		mat4x4 model;
		SDL_Event ev;
		float secs;

		secs = SDL_GetTicks() * 0.0001;

		mat4x4_look_at(view, pos, (vec3){ 0, 0, 0 }, (vec3){ 0, 1, 0 });
		gl_uni_setm4fv(uni.view, 1, GL_FALSE, view[0]);

		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:
					viewport(uni.proj,
						 ev.window.data1,
						 ev.window.data2);
				}
				break;
			}
		}

		gl_clearcolor(0.2, 0.3, 0.3, 1.0);
		gl_clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		gl_prog_use(prog);
		mat4x4_identity(model);
		mat4x4_rotate_X(model, model, secs * 3);
		mat4x4_rotate_Y(model, model, secs * 2);
		mat4x4_rotate_Z(model, model, secs * 4);
		gl_uni_setm4fv(uni.model, 1, GL_FALSE, model[0]);
		model_render(&cube_model);
		gl_va_bind(0);

		SDL_GL_SwapWindow(win);
	}

	SDL_GL_DeleteContext(glc);
	SDL_DestroyWindow(win);

	SDL_Quit();
}