#include <fstream>
#include <iostream>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>

// glad and GLFW
#include <GLFW/glfw3.h>
#include <glad/glad.h>

// glm math
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// HPP files
#include "shader.h"

#define VERTEX_FILE "./shaders/vertex.glsl"
#define FRAGMENT_FILE "./shaders/fragment.glsl"
#define COMPUTE_FILE "./shaders/compute.glsl"

const float SCR_WIDTH = 1200.0f;
const float SCR_HEIGHT = 1200.0f;

int main(void) {
	// Initialize GLFW
	if (!glfwInit())
		return -1;

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // REQUIRED on macOS
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	glfwWindowHint(GLFW_SAMPLES, 8); // 8x MSAA

	GLFWwindow *window = glfwCreateWindow((int)SCR_WIDTH, (int)SCR_HEIGHT, "RASTER", nullptr, nullptr);
	if (!window) {
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		std::cerr << "Failed to initialize GLAD\n";
		return -1;
	}

	glViewport(0, 0, (int)SCR_WIDTH, (int)SCR_HEIGHT);

	// DEBUG
	std::cout << "OpenGL Version: " << glGetString(GL_VERSION) << std::endl;

	// ERROR: macOS does not support compute shaders in OpenGL < 4.3.
	// GLuint computeProgram = createComputeProgram(COMPUTE_FILE);

	// ----- Vertex Data -----
	// Cube
	// Positions
	float vertices[] = {// positions
	                    -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.0f, -1.0f, 1.0f, 0.0f};

	unsigned int indices[] = {0, 1, 2, 2, 3, 0};

	GLuint VAO, VBO, EBO;
	glGenVertexArrays(1, &VAO);
	glGenBuffers(1, &VBO);
	glGenBuffers(1, &EBO);

	glBindVertexArray(VAO);

	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	// position - VERTEX SHADER
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
	glEnableVertexAttribArray(0);

	// color - FRAGMENT SHADER
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	// glBindVertexArray(0);

	// Load shaders
	GLuint shaderProgram = createShaderProgram(VERTEX_FILE, FRAGMENT_FILE);

	// Check if shader program was created successfully
	if (shaderProgram == 0) {
		std::cerr << "Failed to create shader programs.\n";
		return -1;
	}

	// Caulculate model, view, projection matrices
	glm::mat4 model = glm::mat4(1.0f);
	glm::mat4 view = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, -1.0f));
	glm::mat4 projection = glm::perspective(glm::radians(45.0f), (SCR_WIDTH / SCR_HEIGHT) * 2, 0.1f, 100.0f);

	GLuint modelLoc = (unsigned int)glGetUniformLocation(shaderProgram, "model");
	GLuint viewLoc = (unsigned int)glGetUniformLocation(shaderProgram, "view");
	GLuint projLoc = (unsigned int)glGetUniformLocation(shaderProgram, "projection");

	glUseProgram(shaderProgram);
	glUniformMatrix4fv((int)modelLoc, 1, GL_FALSE, glm::value_ptr(model));
	glUniformMatrix4fv((int)viewLoc, 1, GL_FALSE, glm::value_ptr(view));
	glUniformMatrix4fv((int)projLoc, 1, GL_FALSE, glm::value_ptr(projection));

	GLint resLoc = glGetUniformLocation(shaderProgram, "u_resolution");
	glUniform2f(resLoc, SCR_WIDTH, SCR_HEIGHT); // hardcode for now

	GLint timeLoc = glGetUniformLocation(shaderProgram, "u_time");
	GLint scaleLoc = glGetUniformLocation(shaderProgram, "u_scale");
	GLint mouseLoc = glGetUniformLocation(shaderProgram, "u_mouse");

	glEnable(GL_MULTISAMPLE);

	float scale = 1.0f;
	int frameCount = 0;
	float mousePos[2] = {0.0f, 0.0f};

	// FPS tracking
	double lastTime = glfwGetTime(); // when we last printed FPS
	double fps = 0.0;

	// Render loop
	while (!glfwWindowShouldClose(window)) {
		float timeValue = (float)glfwGetTime();
		double xpos, ypos;

		// Get mouse positions
		glfwGetCursorPos(window, &xpos, &ypos);
		mousePos[0] = (float)xpos;
		mousePos[1] = (float)(SCR_HEIGHT - ypos); // Invert y-axis for OpenGL coordinates

		// Input
		glfwPollEvents();

		// Scroll to zoom in/out
		if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS) {
			scale += 0.01f;
			if (scale > 10.0f)
				scale = 10.0f; // Max zoom
		}

		if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS) {
			scale -= 0.01f;
			if (scale < 0.1f)
				scale = 0.1f; // Min zoom
		}

		// --- FPS Counter ---
		double currentTime = glfwGetTime();
		double delta = currentTime - lastTime;

		if (delta >= 1.0) { // print every ~1 second
			fps = double(frameCount) / delta;
			std::cout << "FPS: " << fps << " Time: " << timeValue << " Scale: " << scale << " Mouse: (" << mousePos[0] << ", " << mousePos[1] << ")" << std::endl;

			frameCount = 0;
			lastTime = currentTime;
		}

		glUniform1f(timeLoc, timeValue);
		glUniform1f(scaleLoc, scale);
		glUniform2f(mouseLoc, mousePos[0], mousePos[1]);

		frameCount++;

		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
		glBindVertexArray(VAO);
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

		glUseProgram(shaderProgram);

		glfwSwapBuffers(window);
	}

	glDeleteVertexArrays(1, &VAO);
	glDeleteBuffers(1, &VBO);
	glDeleteBuffers(1, &EBO);
	glDeleteProgram(shaderProgram);

	glfwDestroyWindow(window);
	glfwTerminate();
	return 0;
}