#include "Backend.h"

namespace engine::Backend
{
    GLFWwindow* window;
    int SCREEN_WIDTH = 1920;
    int SCREEN_HEIGHT = 1080;

    bool Init(const char* title, int width = SCREEN_WIDTH, int height = SCREEN_HEIGHT)
    {
        SCREEN_WIDTH = width;
        SCREEN_HEIGHT = height;

        // Initialize GLFW
        glfwInit();
        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

        // Create GLFW Window
        window = glfwCreateWindow(SCREEN_WIDTH, SCREEN_HEIGHT, title, NULL, NULL);
        if (window == NULL)
        {
            std::cout << "Failed to create GLFW window" << std::endl;
            glfwTerminate();
            return false;
        }
        glfwMakeContextCurrent(window);

        // Initialize GLAD
        if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
        {
            std::cout << "Failed to initialize GLAD" << std::endl;
            return false;
        }

        // Initialize Viewport & setup resize callback
        glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
        glfwSetFramebufferSizeCallback(window, window_resize_callback);
        glfwSetCursorPosCallback(window, mouse_callback);
        glfwSetScrollCallback(window, scroll_callback);

        // depth testing
        glEnable(GL_DEPTH_TEST);

        return true;
    }


    void PreFrame()
    {
        // Input processing
        processInput(window);

        // Depth buffer
        glClearColor(0, 0, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    }

    void PostFrame()
    {
        // Call events & swap buffers
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    void Cleanup()
    {
        glfwTerminate();
    }

    bool isWindowOpen()
    {
        return !glfwWindowShouldClose(window);
    }

    void window_resize_callback(GLFWwindow* window2, int width, int height)
    {
        glViewport(0, 0, width, height);
        SCREEN_WIDTH = width;
        SCREEN_HEIGHT = height;
    }

    void processInput(GLFWwindow* window2)
    {
        // Close on Escape
        if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
            glfwSetWindowShouldClose(window, true);
    }

    void mouse_callback(GLFWwindow* window2, double xposIn, double yposIn)
    {
    }

    void scroll_callback(GLFWwindow* window2, double xoffset, double yoffset)
    {
    }
}