using System.Windows.Input;

namespace AcDream.Launcher.ViewModels;

public sealed class RelayCommand : ICommand
{
    private readonly Action<object?> _execute;
    private readonly Func<object?, bool>? _canExecute;

    public RelayCommand(Action execute, Func<bool>? canExecute = null)
        : this(
            _ => execute(),
            canExecute is null ? null : _ => canExecute())
    {
        ArgumentNullException.ThrowIfNull(execute);
    }

    public RelayCommand(
        Action<object?> execute,
        Func<object?, bool>? canExecute = null)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        _canExecute = canExecute;
    }

    public event EventHandler? CanExecuteChanged;

    public bool CanExecute(object? parameter) => _canExecute?.Invoke(parameter) ?? true;

    public void Execute(object? parameter)
    {
        if (CanExecute(parameter))
        {
            _execute(parameter);
        }
    }

    public void NotifyCanExecuteChanged() =>
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}

public sealed class AsyncRelayCommand : ICommand
{
    private readonly Func<object?, Task> _execute;
    private readonly Func<object?, bool>? _canExecute;
    private bool _isExecuting;

    public AsyncRelayCommand(Func<Task> execute, Func<bool>? canExecute = null)
        : this(
            _ => execute(),
            canExecute is null ? null : _ => canExecute())
    {
        ArgumentNullException.ThrowIfNull(execute);
    }

    public AsyncRelayCommand(
        Func<object?, Task> execute,
        Func<object?, bool>? canExecute = null)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        _canExecute = canExecute;
    }

    public event EventHandler? CanExecuteChanged;

    public bool CanExecute(object? parameter) =>
        !_isExecuting && (_canExecute?.Invoke(parameter) ?? true);

    public async void Execute(object? parameter) =>
        await ExecuteAsync(parameter).ConfigureAwait(true);

    public async Task ExecuteAsync(object? parameter = null)
    {
        if (!CanExecute(parameter))
        {
            return;
        }

        _isExecuting = true;
        NotifyCanExecuteChanged();
        try
        {
            await _execute(parameter).ConfigureAwait(true);
        }
        finally
        {
            _isExecuting = false;
            NotifyCanExecuteChanged();
        }
    }

    public void NotifyCanExecuteChanged() =>
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}