#include "GL/glew.h"
#include "GLFW/glfw3.h"
#include "pwyazh.h"
#include "common.h"

typedef struct {
	Arena *arena;
	Input input;
	Camera camera;
	Mesh *cube;
	GLFWwindow *window;
} state_t;

static S32 width = 1600;
static S32 height = 800;

void die(const char *fmt, ...)
{
	fprintf(stderr, "error: ");
	va_list args;
	va_start(args, fmt);
	vprintf(fmt, args);
	va_end(args);
	fprintf(stderr, "\n");
	exit(1);
}

void init_glfw(state_t *state) {
	glfwSetErrorCallback(error_callback);
	if (glfwInit() == GLFW_FALSE)
		die("failed to initialize glfw");
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
	state->window = glfwCreateWindow(width, height, "prb lighting", 0, 0);
	if (!state->window)
		die("failed to create window");
	glfwSetInputMode(state->window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
	glfwMakeContextCurrent(state->window);
}

void init_gl(void)
{
	if (glewInit() != GLEW_OK)
		die("failed to initialize glew");
	glEnable(GL_DEPTH_TEST);
}

state_t init_state(void)
{
	state_t state = {
		.arena = arena_alloc(Kilobytes(256)),
		.input = input_init(),
		.camera = {
			.pos = v3f(0.0f, 2.0f, 5.0f),
			.fovx = 90.0f,
			.near = 0.1f,
			.far = 100.0f,
			.yaw = 0.0f,
			.pitch = 0.0f
		},
	};
	return state;
}

int main(void)
{
	state_t state = init_state();

	init_glfw(&state);
	init_gl();

	// meshes
	Mesh *cube = mesh_load_obj(state.arena, "../../data/models/cube.obj");

	// shaders
	U32 shader = load_shader("default.vert", "default.frag");

	F64 last_time = glfwGetTime();
	while (!glfwWindowShouldClose(state.window)) {
		F64 time = glfwGetTime();
		F32 dt = time - last_time;
		last_time = time;

		input_update_last_state(&state.input);

		glfwPollEvents();
		process_glfw_keyboard(state.window, &state.input);
		process_glfw_mouse_pos(state.window, &state.input);

		if (key_first_press(state.input.exit))
			glfwSetWindowShouldClose(state.window, GLFW_TRUE);

		F32 speed = 2.0f;
		V3F dv = get_dv_camera_first_person(&state.input, &state.camera, speed, dt);
		V3F camera_dp = v3f_add(camera_dp, dv);
		camera_dp = v3f_scalef(camera_dp, 0.8f);
		state.camera.pos = v3f_add(state.camera.pos, camera_dp);

		F32 sensitivity = 0.1f;
		state.input.mouse_offset = v2f_scalef(state.input.mouse_offset, sensitivity);
		state.camera.yaw += state.input.mouse_offset.x;
		state.camera.pitch += state.input.mouse_offset.y;
		if (state.camera.pitch > 89.0f)
			state.camera.pitch = 89.0f;
		if (state.camera.pitch < -89.0f)
			state.camera.pitch = -89.0f;

		// update

		// render
		F32 ar = (F32)width / (F32)height;
		MAT4 projection = camera_persp(state.camera, ar);
		MAT4 view = get_view_matrix(&state.camera);

		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		glUseProgram(shader);
		mesh_draw(cube);
		glUseProgram(0);

		glfwSwapBuffers(state.window);
	}

	return 0;
}