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

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

#include "common.h"

int main(void)
{
	GLFWwindow *window;
	Arena *arena = 0;
	Mesh *cube;
	F32 target_fps, target_spf, last_time;
	MAT4 proj, view, model;
	U32 fbo, intermediate_fbo, color_tex,
	    screen_texture, rbo,
	    quad_vao, vbo, color_shader,
	    screen_shader;
	S32 width, height;
	State state;
	Input input;

	if (glfwInit() == GLFW_FALSE) {
		fprintf(stderr, "[ERROR] Failed to initialize glfw.\n");
		return(1);
	}

	width = 1024;
	height = 768;

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	window = glfwCreateWindow(width, height, "Anti Aliasing (Off-screen)", 0, 0);
	if (!window) {
		fprintf(stderr, "[ERROR] Failed to create window.\n");
		glfwTerminate();
		return(1);
	}

	glfwMakeContextCurrent(window);

	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	if (glewInit() != GLEW_OK) {
		fprintf(stderr, "[ERROR] Failed to initialize glew.\n");
		glfwTerminate();
		return(1);
	}

	arena = arena_alloc(Kilobytes(4));

	cube = mesh_load_obj(arena, "../../data/models/cube.obj");
	color_shader = create_shader_program("shaders/color.vert",
					     "shaders/color.frag");
	screen_shader = create_shader_program("shaders/screen.vert",
					      "shaders/screen.frag");
	glGenFramebuffers(1, &fbo);
	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
	glGenTextures(1, &color_tex);
	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, color_tex);
	glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB,
				width, height, GL_TRUE);
	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
			       GL_TEXTURE_2D_MULTISAMPLE, color_tex, 0);
	glGenRenderbuffers(1, &rbo);
	glBindRenderbuffer(GL_RENDERBUFFER, rbo);
	glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8,
					 width, height);
	glBindRenderbuffer(GL_RENDERBUFFER, 0);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
				  GL_RENDERBUFFER, rbo);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
		fprintf(stderr, "[ERROR]: Framebuffer is not complete.\n");
	fprintf(stdout, "[INFO]: Multisample fbo complete.\n");
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	glGenFramebuffers(1, &intermediate_fbo);
	glBindFramebuffer(GL_FRAMEBUFFER, intermediate_fbo);
	glGenTextures(1, &screen_texture);
	glBindTexture(GL_TEXTURE_2D, screen_texture);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height,
		     0, GL_RGB, GL_UNSIGNED_BYTE, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
			       GL_TEXTURE_2D, screen_texture, 0);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
		fprintf(stderr, "[ERROR]: Framebuffer is not complete.\n");
	fprintf(stdout, "[INFO]: Intermediate fbo complete.\n");
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	F32 quad_vertices[] = {
		-1.0f, -1.0f, 0.0f,  0.0f, 0.0f,
		 1.0f, -1.0f, 0.0f,  1.0f, 0.0f,
		 1.0f,  1.0f, 0.0f,  1.0f, 1.0f,
		-1.0f, -1.0f, 0.0f,  0.0f, 0.0f,
		 1.0f,  1.0f, 0.0f,  1.0f, 1.0f,
		-1.0f,  1.0f, 0.0f,  0.0f, 1.0f
	};

	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, 5*sizeof(F32), (void *)0);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5*sizeof(F32), (void *)(3*sizeof(F32)));
	glBindVertexArray(0);

	state.camera = (Camera) {
		v3f(0.0f, 0.0f, 3.0f),
			90.0f, 0.1f, 1000.0f,
			0.0f, 0.0f
	};
	input = input_init();

	target_fps = 60.0f;
	target_spf = 1.0f/target_fps;
	last_time = glfwGetTime();

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

		/* NOTE(pryazha): Update */
		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);

		V3F dv = get_dv_camera_first_person(&input, &state.camera,
						    4.0f, state.dt);
		state.camera.pos = v3f_add(state.camera.pos, dv);

		F32 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);

		view = get_view_matrix(&state.camera);
		proj = perspective(state.camera.fovx, (F32)width/(F32)height,
				   state.camera.near, state.camera.far);
		model = mat4_identity();

		/* NOTE(pryazha): Render */
		glBindFramebuffer(GL_FRAMEBUFFER, fbo);
		glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glEnable(GL_DEPTH_TEST);
		glUseProgram(color_shader);
		shader_set_mat4fv(color_shader, "proj", proj);
		shader_set_mat4fv(color_shader, "view", view);
		shader_set_mat4fv(color_shader, "model", model);
		mesh_draw(cube);

		glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, intermediate_fbo);
		glBlitFramebuffer(0, 0, width, height,
				  0, 0, width, height,
				  GL_COLOR_BUFFER_BIT, GL_NEAREST);

		glBindFramebuffer(GL_FRAMEBUFFER, 0);
		glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
		glUseProgram(screen_shader);
		glDisable(GL_DEPTH_TEST);
		glBindTexture(GL_TEXTURE_2D, screen_texture);
		glBindVertexArray(quad_vao);
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindVertexArray(0);

		glfwSwapBuffers(window);

		F32 elapsed = glfwGetTime()-last_time;
		if (elapsed < target_spf) {
			U32 sleep_time = (U32)(target_spf-elapsed);
			if (sleep_time > 0)
				sleep(sleep_time);
		}
		F32 current_time = glfwGetTime();
		state.dt = current_time-last_time;
		last_time = current_time;
	}

	arena_release(arena);
	glfwTerminate();
	return(0);
}