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

#include "camera.h"
#include "eprintf.h"
#include "gl.h"
#include "glprog.h"
#include "linmath.h"
#include "math.h"
#include "model.h"
#include "nelem.h"

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

#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, (GLfloat *)pers);
}

void loadmodel(struct model *mdl, char *name)
{
	FILE *f;
	struct fmd fmd;

	f = fopen(name, "rb");
	if (f == NULL)
		eprintf("Could not open '%s':", name);
	fmd_load(&fmd, f);
	fclose(f);
	model_load(mdl, &fmd);
	fmd_free(&fmd);
}

int main(int argc, char **argv)
{
	bool running = true;
	SDL_Window *win;
	SDL_GLContext *glc;
	struct model mdl;
	struct camera cam = { .pos = { 0.0, 0.0, 3.0 }, .yaw = -PI/2 };
	struct {
		bool w, a, s, d, spc, lct;
	} key = { 0 };
	vec4 lipos;
	float tlast;

	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, 2);
	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());

	SDL_SetRelativeMouseMode(SDL_TRUE);

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

	gl_load(SDL_GL_GetProcAddress);

	glprog_init();

	loadmodel(&mdl, "assets/utah.fmd");

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

	gl_enable(GL_DEPTH_TEST);
	gl_enable(GL_FRAMEBUFFER_SRGB);
	gl_enable(GL_CULL_FACE);

	tlast = SDL_GetTicks() * 0.0001;

	while (running) {
		mat4x4 model, view;
		vec3 dir, right, motion = { 0 }, strafe = { 0 };
		SDL_Event ev;
		float tdiff, tnow;

		while (SDL_PollEvent(&ev)) {
			bool down;
			switch (ev.type) {
			case SDL_MOUSEMOTION:
				cam.yaw += ev.motion.xrel * 0.005;
				cam.pitch += ev.motion.yrel * -0.005;
				camera_clamp(&cam);
				break;
			case SDL_KEYDOWN:
			case SDL_KEYUP:
				down = ev.key.state == SDL_PRESSED;
				switch (ev.key.keysym.sym) {
				case SDLK_w: key.w = down; break;
				case SDLK_a: key.a = down; break;
				case SDLK_s: key.s = down; break;
				case SDLK_d: key.d = down; break;
				case SDLK_SPACE: key.spc = down; break;
				case SDLK_LCTRL: key.lct = down; break;
				}
				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(prog.main.uni.proj,
						 ev.window.data1,
						 ev.window.data2);
				}
				break;
			}
		}

		tnow = SDL_GetTicks() * 0.001;
		tdiff = tnow - tlast;
		tlast = tnow;

		camera_dir(dir, &cam);
		vec3_mul_cross(right, dir, CAM_UP);
		vec3_norm(right, right);

		if (key.w != key.s) vec3_scale(motion, dir, tdiff * (key.w ? 1 : -1));
		if (key.a != key.d) vec3_scale(strafe, right, tdiff * (key.d ? 1 : -1));
		if (key.spc != key.lct) cam.pos[1] += tdiff * (key.spc ? 1 : -1);
		vec3_add(cam.pos, cam.pos, strafe);
		vec3_add(cam.pos, cam.pos, motion);

		camera_lookat(view, &cam);

		lipos[0] = 10.0 * cosf(tnow / 10) * cosf(tnow / 20);
		lipos[1] = 10.0 * sinf(tnow / 10);
		lipos[2] = 10.0 * cosf(tnow / 10) * sinf(tnow / 20);

		gl_clearcolor(0.2, 0.3, 0.3, 1.0);
		gl_clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		mat4x4_identity(model);

		gl_prog_use(prog.main.prog);
		gl_uni_setm4fv(prog.main.uni.view, 1, GL_FALSE, (GLfloat *)view);
		gl_uni_setm4fv(prog.main.uni.model, 1, GL_FALSE, (GLfloat *)model);
		gl_uni_set3fv(prog.main.uni.light, 1, lipos);
		model_render(&mdl);
		gl_va_bind(0);

		SDL_GL_SwapWindow(win);
	}

	SDL_GL_DeleteContext(glc);
	SDL_DestroyWindow(win);

	SDL_Quit();

	return 0;
}