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

#include "pwyazh.h"
#include "pwyazh_GL.h"

#include "common.h"

U32 gen_quad_with_tan()
{
	/* Positions */
	V3F p1 = v3f(-1.0f, 1.0f, 0.0f);
	V3F p2 = v3f(-1.0f, -1.0f, 0.0f);
	V3F p3 = v3f(1.0f, -1.0f, 0.0f);
	V3F p4 = v3f(1.0f, 1.0f, 0.0f);
	/* Texture ccoordinates */
	V2F uv1 = v2f(0.0f, 1.0f);
	V2F uv2 = v2f(0.0f, 0.0f);
	V2F uv3 = v2f(1.0f, 0.0f);
	V2F uv4 = v2f(1.0f, 1.0f);
	/* Normal vector */
	V3F nm = v3f(0.0f, 0.0f, 1.0f);

	V3F edge1, edge2;
	V2F duv1, duv2;
	F32 f;
	V3F t1, bit1, t2, bit2;

	edge1 = v3f_sub(p2, p1);
	edge2 = v3f_sub(p3, p1);
	duv1 = v2f_sub(uv2, uv1);
	duv2 = v2f_sub(uv3, uv1);

	f = 1.0f/(duv1.x*duv2.y-duv2.x*duv1.y);

	t1.x = f*(duv2.y*edge1.x-duv1.y*edge2.x);
	t1.y = f*(duv2.y*edge1.y-duv1.y*edge2.y);
	t1.z = f*(duv2.y*edge1.z-duv1.y*edge2.z);

	bit1.x = f*(-duv2.x*edge1.x+duv1.x*edge2.x);
	bit1.y = f*(-duv2.x*edge1.y+duv1.x*edge2.y);
	bit1.z = f*(-duv2.x*edge1.z+duv1.x*edge2.z);

	edge1 = v3f_sub(p3, p1);
	edge2 = v3f_sub(p4, p1);
	duv1 = v2f_sub(uv3, uv1);
	duv2 = v2f_sub(uv4, uv1);

	f = 1.0f/(duv1.x*duv2.y-duv2.x*duv1.y);

	t2.x = f*(duv2.y*edge1.x-duv1.y*edge2.x);
	t2.y = f*(duv2.y*edge1.y-duv1.y*edge2.y);
	t2.z = f*(duv2.y*edge1.z-duv1.y*edge2.z);

	bit2.x = f*(-duv2.x*edge1.x+duv1.x*edge2.x);
	bit2.y = f*(-duv2.x*edge1.y+duv1.x*edge2.y);
	bit2.z = f*(-duv2.x*edge1.z+duv1.x*edge2.z);

	F32 quad_vertices[] = {
		p1.x, p1.y, p1.z, nm.x, nm.y, nm.z, uv1.x, uv1.y, t1.x, t1.y, t1.z, bit1.x, bit1.y, bit1.z,
		p2.x, p2.y, p2.z, nm.x, nm.y, nm.z, uv2.x, uv2.y, t1.x, t1.y, t1.z, bit1.x, bit1.y, bit1.z,
		p3.x, p3.y, p3.z, nm.x, nm.y, nm.z, uv3.x, uv3.y, t1.x, t1.y, t1.z, bit1.x, bit1.y, bit1.z,

		p1.x, p1.y, p1.z, nm.x, nm.y, nm.z, uv1.x, uv1.y, t2.x, t2.y, t2.z, bit2.x, bit2.y, bit2.z,
		p3.x, p3.y, p3.z, nm.x, nm.y, nm.z, uv3.x, uv3.y, t2.x, t2.y, t2.z, bit2.x, bit2.y, bit2.z,
		p4.x, p4.y, p4.z, nm.x, nm.y, nm.z, uv4.x, uv4.y, t2.x, t2.y, t2.z, bit2.x, bit2.y, bit2.z
	};
	U32 quad_vao, vbo;
	glGenVertexArrays(1, &quad_vao);
	glBindVertexArray(quad_vao);
	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(quad_vertices), quad_vertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 14*sizeof(F32), (void *)0);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 14*sizeof(F32), (void *)(3*sizeof(F32)));
	glEnableVertexAttribArray(2);
	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 14*sizeof(F32), (void *)(6*sizeof(F32)));
	glEnableVertexAttribArray(3);
	glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, 14*sizeof(F32), (void *)(8*sizeof(F32)));
	glEnableVertexAttribArray(4);
	glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, 14*sizeof(F32), (void *)(11*sizeof(F32)));
	glBindVertexArray(0);

	return quad_vao;
}

int main(void)
{
	GLFWwindow	*window;
	State		state;
	Input		input = {0};
	F64		time, last_time;
	V3F		camera_dp;
	Arena		*arena = 0;
	S32		width, height;

	U32		vao, parallax_shader, normals_debug_shader;
	U32		diffuse_texture, normal_texture, depth_texture;

	V3F		light_pos;

	width = 800;
	height = 600;

	/* NOTE(pryazha): GLFW init */
	glfwSetErrorCallback(error_callback);

	if (glfwInit() == GLFW_FALSE)
		return(1);

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	window = glfwCreateWindow(width, height, "Point shadows", 0, 0);
	if (!window)
		goto error;

	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	glfwMakeContextCurrent(window);

	if (glewInit() != GLEW_OK)
		goto error;

	/* NOTE(pryazha): Program init */
	arena = arena_alloc(Kilobytes(4));

	input.first_mouse = 1;

	state.camera = (Camera){ v3f(0.0f, 0.0f, 3.0f), 90.0f, 0.1f, 100.0f, 0.0f, 0.0f };
	camera_dp = v3f_zero();
	
	light_pos = v3f(1.0f, 2.0f, 1.0f);


	/* NOTE(pryazha): Meshes */
	vao = gen_quad_with_tan();

	diffuse_texture = load_texture("../../data/textures/bricks2.jpg");
	normal_texture = load_texture("../../data/textures/bricks2_normal.jpg");
	depth_texture = load_texture("../../data/textures/bricks2_disp.jpg");

	/* NOTE(pryazha): Shaders */
	parallax_shader = create_shader_program("shaders/parallax.vert", "shaders/parallax.frag");
	normals_debug_shader = create_shader_program_geom("shaders/normals_debug.vert",
							  "shaders/normals_debug.frag",
							  "shaders/normals_debug.geom");

	glUseProgram(parallax_shader);
	shader_set_1i(parallax_shader, "diffuse_texture", 0);
	shader_set_1i(parallax_shader, "normal_map", 1);
	shader_set_1i(parallax_shader, "depth_map", 2);
	glUseProgram(0);

	last_time = glfwGetTime();

	while (!glfwWindowShouldClose(window)) {
		glfwPollEvents();

		/* NOTE(pryazha): Update */
		F32	speed, sensitivity;
		V3F	dv;

		glfwGetFramebufferSize(window, &width, &height);
		process_glfw_keyboard(window, &input);
		process_glfw_mouse_pos(window, &input);

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

		speed = 2.0f;
		dv = get_dv_camera_first_person(&input, &state.camera, speed, state.dt);
		if (key_is_pressed(input.action_up))
			dv = v3f_scalef(dv, 3.0f);
		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);

		sensitivity = 0.1f;
		input.mouse_offset = v2f_scalef(input.mouse_offset, sensitivity);
		state.camera.yaw += input.mouse_offset.x;
		state.camera.pitch += 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;

		input_update_last_state(&input);

		/* NOTE(pryazha): Render */
		F32	ar;
		MAT4	proj, view, model;

		ar = (F32)width/(F32)height;
		proj = camera_persp(state.camera, ar);
		view = get_view_matrix(&state.camera);
		model = mat4_identity();

		glViewport(0, 0, width, height);
		glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		/* NOTE(pryazha): Draw the quad */
		glUseProgram(parallax_shader);
		shader_set_mat4fv(parallax_shader, "proj", proj); 
		shader_set_mat4fv(parallax_shader, "view", view);
		shader_set_mat4fv(parallax_shader, "model", model);
		shader_set_3fv(parallax_shader, "light_pos", light_pos);
		shader_set_3fv(parallax_shader, "view_pos", state.camera.pos);
		shader_set_1f(parallax_shader, "hscale", 0.1f);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, diffuse_texture);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, normal_texture);
		glActiveTexture(GL_TEXTURE2);
		glBindTexture(GL_TEXTURE_2D, depth_texture);
		glBindVertexArray(vao);
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindVertexArray(0);
		glUseProgram(0);

		/* NOTE(pryazha): Draw normals */
		glUseProgram(normals_debug_shader);
		shader_set_mat4fv(normals_debug_shader, "proj", proj); 
		shader_set_mat4fv(normals_debug_shader, "model", model);
		shader_set_mat4fv(normals_debug_shader, "view", view);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, diffuse_texture);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, normal_texture);
		glBindVertexArray(vao);
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindVertexArray(0);
		glUseProgram(0);

		glfwSwapBuffers(window);

		time = glfwGetTime();
		state.dt = time-last_time;
		last_time = time;
	}

	glDeleteVertexArrays(1, &vao);
	arena_release(arena);
	glfwTerminate();
	return(0);

error:
	arena_release(arena);
	glfwTerminate();
	return(1);
}