using Avalonia.Controls;
using Avalonia.Input;
using Avalonia.Threading;

namespace Lumi.Companion.App;

public sealed class HotkeyCaptureBinding
{
    private readonly Button _button;
    private readonly DispatcherTimer _timeout;
    private readonly HashSet<Key> _pressed = [];
    private string _hotkey = "";
    private string _previous = "";
    private KeyModifiers _modifiers;
    private Key? _primary;
    private bool _capturing;

    public HotkeyCaptureBinding(Button button)
    {
        _button = button;
        _button.HorizontalContentAlignment = Avalonia.Layout.HorizontalAlignment.Left;
        _button.Focusable = true;
        _timeout = new DispatcherTimer { Interval = TimeSpan.FromSeconds(7) };
        _timeout.Tick += (_, _) => CancelCapture();
        _button.Click += (_, _) => BeginCapture();
        _button.KeyDown += OnKeyDown;
        _button.KeyUp += OnKeyUp;
    }

    public string Hotkey
    {
        get => _hotkey;
        set
        {
            _hotkey = string.IsNullOrWhiteSpace(value) ? "Unassigned" : value.Trim();
            if (!_capturing) UpdateContent();
        }
    }

    private void OnKeyDown(object? sender, KeyEventArgs e)
    {
        if (!_capturing)
        {
            return;
        }

        e.Handled = true;
        if (e.Key == Key.Escape)
        {
            CancelCapture();
            return;
        }

        _pressed.Add(e.Key);
        _modifiers |= e.KeyModifiers;
        if (!IsModifier(e.Key)) _primary = e.Key;
        _button.Content = _primary is null ? "Hold modifiers, then press a key…" : $"{Format(_modifiers, _primary.Value)} · release to save";
    }

    private void OnKeyUp(object? sender, KeyEventArgs e)
    {
        if (!_capturing)
        {
            return;
        }

        e.Handled = true;
        _pressed.Remove(e.Key);
        if (_primary is not null && !_pressed.Any(key => !IsModifier(key)))
        {
            _hotkey = Format(_modifiers, _primary.Value);
            FinishCapture();
        }
    }

    private void BeginCapture()
    {
        if (_capturing) return;
        _capturing = true;
        _previous = _hotkey;
        _pressed.Clear();
        _modifiers = KeyModifiers.None;
        _primary = null;
        _button.Content = "Press a shortcut…";
        _button.Focus();
        _timeout.Start();
    }

    private void CancelCapture()
    {
        if (!_capturing) return;
        _hotkey = _previous;
        FinishCapture();
    }

    private void FinishCapture()
    {
        _capturing = false;
        _timeout.Stop();
        _pressed.Clear();
        UpdateContent();
    }

    private void UpdateContent() => _button.Content = $"{_hotkey}  (Set hotkey)";

    private static bool IsModifier(Key key) => key is
        Key.LeftCtrl or Key.RightCtrl or Key.LeftAlt or Key.RightAlt or
        Key.LeftShift or Key.RightShift or Key.LWin or Key.RWin;

    internal static string Format(KeyModifiers modifiers, Key key)
    {
        var parts = new List<string>(5);
        if (modifiers.HasFlag(KeyModifiers.Control)) parts.Add("Ctrl");
        if (modifiers.HasFlag(KeyModifiers.Alt)) parts.Add("Alt");
        if (modifiers.HasFlag(KeyModifiers.Shift)) parts.Add("Shift");
        if (modifiers.HasFlag(KeyModifiers.Meta)) parts.Add("Win");
        parts.Add(KeyName(key));
        return string.Join("+", parts);
    }

    private static string KeyName(Key key) => key switch
    {
        Key.PageUp => "PageUp",
        Key.PageDown => "PageDown",
        Key.Left => "Left",
        Key.Right => "Right",
        Key.Up => "Up",
        Key.Down => "Down",
        Key.Return => "Enter",
        Key.Space => "Space",
        Key.Back => "Backspace",
        _ => key.ToString()
    };
}