using System.Windows.Input;

namespace TeamsISO.App.ViewModels;

/// <summary>
/// Synchronous command that delegates execution to an <see cref="Action"/>.
/// </summary>
public sealed class RelayCommand : ICommand
{
    private readonly Action _execute;
    private readonly Func<bool>? _canExecute;

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

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

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

/// <summary>
/// Async command that suppresses re-entrancy while running.
/// </summary>
public sealed class AsyncRelayCommand : ICommand
{
    private readonly Func<Task> _execute;
    private readonly Func<bool>? _canExecute;
    private bool _isRunning;

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

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

    public async void Execute(object? parameter)
    {
        if (_isRunning) return;
        _isRunning = true;
        RaiseCanExecuteChanged();
        try { await _execute(); }
        finally
        {
            _isRunning = false;
            RaiseCanExecuteChanged();
        }
    }

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