using System;
using System.Runtime.InteropServices;
using Microsoft.UI.Xaml;

namespace ClipForge
{
    public class GlobalHotkeyService
    {
        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

        [DllImport("user32.dll")]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private const int HOTKEY_CLIP = 1;
        private const uint MOD_NOREPEAT = 0x4000; // don't fire on key repeat

        public event Action? ClipRequested;

        private IntPtr _hwnd;
        private uint _modifiers;
        private uint _vk;

        /// <summary>Register the clip hotkey. Use settings values (e.g. HotkeyModifiers, HotkeyVirtualKey).</summary>
        public void Initialize(IntPtr hwnd, uint modifiers, uint vk)
        {
            _hwnd = hwnd;
            _modifiers = modifiers;
            _vk = vk;
            TryRegister();
        }

        /// <summary>Update the hotkey at runtime (e.g. after user remaps). Unregisters old and registers new.</summary>
        public bool UpdateHotkey(uint modifiers, uint vk)
        {
            UnregisterHotKey(_hwnd, HOTKEY_CLIP);
            _modifiers = modifiers;
            _vk = vk;
            return TryRegister();
        }

        private bool TryRegister()
        {
            uint mod = _modifiers | MOD_NOREPEAT;
            return RegisterHotKey(_hwnd, HOTKEY_CLIP, mod, _vk);
        }

        public void ProcessHotkey(int id)
        {
            if (id == HOTKEY_CLIP)
                ClipRequested?.Invoke();
        }

        public void Cleanup()
        {
            UnregisterHotKey(_hwnd, HOTKEY_CLIP);
        }
    }
}