#include <glad/glad.h> // Include GLAD before GLFW
#include <GLFW/glfw3.h>
#include <iostream>

#include "io.h"

// ImGui includes
#include "imgui/imgui.h"
#include "imgui/imgui_impl_glfw.h"
#include "imgui/imgui_impl_opengl3.h"

char* fragmentShaderFile = "./source/shader/fragment.glsl";
char* vertexShaderFile = "./source/shader/vertex.glsl";

const unsigned int SCR_WIDTH = 1920;
const unsigned int SCR_HEIGHT = 1080;

// Callback to resize the viewport when the window is resized
void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
	(void)window; // Unused parameter
	glViewport(0, 0, width, height);
}

int main() {
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
    const char* glsl_version = "#version 330";
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
#endif

	GLFWwindow *window = glfwCreateWindow( SCR_WIDTH, SCR_HEIGHT , "OpenGLTemplate", NULL, NULL);
	if (window == NULL) {
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

	if (!gladLoadGLLoader(reinterpret_cast<GLADloadproc>(glfwGetProcAddress))) {
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

    // Compile shaders
    char* vertexShaderSource = readFile(vertexShaderFile);
    char* fragmentShaderSource = readFile(fragmentShaderFile);

    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);

    unsigned int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    delete[] vertexShaderSource;
    delete[] fragmentShaderSource;

    // --- ImGui Setup Start ---
	IMGUI_CHECKVERSION();
	ImGui::CreateContext();
	ImGuiIO &io = ImGui::GetIO();
	(void)io;
	ImGui::StyleColorsDark();
	ImGui_ImplGlfw_InitForOpenGL(window, true);
	ImGui_ImplOpenGL3_Init(glsl_version);

	while (!glfwWindowShouldClose(window)) {
		if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
			glfwSetWindowShouldClose(window, true);

        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        ImGui::Begin("Settings");
        ImGui::Text("FPS: %.1f", static_cast<double>(ImGui::GetIO().Framerate));
        ImGui::End();
        glUseProgram(shaderProgram);

		glClearColor(0.01f, 0.01f, 0.01f, 1.0f); // Set clear color (Dark Gray)
		glClear(GL_COLOR_BUFFER_BIT);         // Clear the screen


        ImGui::Render();
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	// 5. Clean up
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();
	glfwTerminate();
	return 0;
}