using System;
using AcDream.UI.Abstractions.Input;
using Silk.NET.Input;

namespace AcDream.App.Input;

/// <summary>
/// Bridges a Silk.NET <see cref="IKeyboard"/> to the test-fakeable
/// <see cref="IKeyboardSource"/> interface used by
/// <see cref="InputDispatcher"/>. K.1a wiring: GameWindow constructs
/// one of these wrapping the first keyboard from
/// <c>IInputContext.Keyboards</c>; the dispatcher fans events out to
/// subscribers without ever touching Silk types directly.
/// </summary>
public sealed class SilkKeyboardSource : IKeyboardSource
{
    private readonly IKeyboard _keyboard;

    public event Action<Key, ModifierMask>? KeyDown;
    public event Action<Key, ModifierMask>? KeyUp;

    public SilkKeyboardSource(IKeyboard keyboard)
    {
        _keyboard = keyboard ?? throw new ArgumentNullException(nameof(keyboard));
        _keyboard.KeyDown += (_, key, _) => KeyDown?.Invoke(key, ReadModifiers());
        _keyboard.KeyUp   += (_, key, _) => KeyUp?.Invoke(key, ReadModifiers());
    }

    public bool IsHeld(Key key) => _keyboard.IsKeyPressed(key);

    public ModifierMask CurrentModifiers => ReadModifiers();

    private ModifierMask ReadModifiers()
    {
        ModifierMask m = ModifierMask.None;
        if (_keyboard.IsKeyPressed(Key.ShiftLeft) || _keyboard.IsKeyPressed(Key.ShiftRight))
            m |= ModifierMask.Shift;
        if (_keyboard.IsKeyPressed(Key.ControlLeft) || _keyboard.IsKeyPressed(Key.ControlRight))
            m |= ModifierMask.Ctrl;
        if (_keyboard.IsKeyPressed(Key.AltLeft) || _keyboard.IsKeyPressed(Key.AltRight))
            m |= ModifierMask.Alt;
        if (_keyboard.IsKeyPressed(Key.SuperLeft) || _keyboard.IsKeyPressed(Key.SuperRight))
            m |= ModifierMask.Win;
        return m;
    }
}