#pragma once

#include "Camera.hpp"

#include <functional>

struct GLFWwindow;

namespace planetarium {

// -----------------------------------------------------------------------
// Engine
//
// Top-level owner of the GLFW window/context, the frame loop, and input
// routing between raw GLFW callbacks and the Camera. This is the only
// class that knows about GLFW directly.
//
// This is the reusable "engine" half of the original Planetarium project
// with every game-specific piece (SolarSystem, Planet, UI, picking)
// removed. Hook your own logic in via setUpdateCallback/setRenderCallback:
//
//     Engine engine;
//     engine.initialize(1600, 900, "My App");
//     engine.setUpdateCallback([](float dt) { ... });
//     engine.setRenderCallback([&](int fbWidth, int fbHeight) { ... });
//     engine.run();
//
// Left-drag orbits the camera, middle-drag pans it, scroll zooms, and R
// resets it - wire up more input in your own update/render callbacks via
// window() if you need it.
// -----------------------------------------------------------------------
class Engine {
public:
    using UpdateCallback = std::function<void(float deltaTime)>;
    using RenderCallback = std::function<void(int framebufferWidth, int framebufferHeight)>;

    ~Engine();

    bool initialize(int width, int height, const char* title);
    void run();

    void setUpdateCallback(UpdateCallback cb) { updateCallback_ = std::move(cb); }
    void setRenderCallback(RenderCallback cb) { renderCallback_ = std::move(cb); }

    Camera& camera() { return camera_; }
    const Camera& camera() const { return camera_; }
    GLFWwindow* window() const { return window_; }

private:
    void update(float deltaTime);
    void render();

    // GLFW callback trampolines (static -> instance via glfwGetWindowUserPointer).
    static void cursorPosCallback(GLFWwindow* window, double x, double y);
    static void mouseButtonCallback(GLFWwindow* window, int button, int action, int mods);
    static void scrollCallback(GLFWwindow* window, double xOffset, double yOffset);
    static void keyCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
    static void framebufferSizeCallback(GLFWwindow* window, int width, int height);

    GLFWwindow* window_ = nullptr;
    Camera camera_;

    UpdateCallback updateCallback_;
    RenderCallback renderCallback_;

    int framebufferWidth_ = 1600;
    int framebufferHeight_ = 900;

    double lastMouseX_ = 0.0;
    double lastMouseY_ = 0.0;
    bool rotating_ = false;
    bool panning_ = false;

    double lastFrameTime_ = 0.0;
};

}  // namespace planetarium