using System.Windows.Input;

namespace Zcbot.WindowsNode;

internal sealed class AsyncCommand : ObservableObject, ICommand
{
    private readonly Func<Task> execute;
    private readonly Func<bool>? canExecute;
    private bool isRunning;

    internal AsyncCommand(Func<Task> execute, Func<bool>? canExecute = null)
    {
        this.execute = execute;
        this.canExecute = canExecute;
    }

    public event EventHandler? CanExecuteChanged;

    internal event Action<Exception>? Failed;

    internal bool IsRunning
    {
        get => isRunning;
        private set
        {
            if (SetProperty(ref isRunning, value))
            {
                CanExecuteChanged?.Invoke(this, EventArgs.Empty);
            }
        }
    }

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

    public async void Execute(object? parameter)
    {
        if (!CanExecute(parameter)) return;
        IsRunning = true;
        try
        {
            await execute();
        }
        catch (Exception exception)
        {
            Failed?.Invoke(exception);
        }
        finally
        {
            IsRunning = false;
        }
    }

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