CancellationCommandAsync.cs

    public class CommandAsync<T> : ICommand

    {
        private  CancellationTokenSource cancellationTokenSource;
        private readonly Func<T, CancellationToken, Task> _executeTask;

        private readonly Predicate<T> _canExecute;

        private bool _locked;

        public CommandAsync(Func<T,CancellationToken, Task> executeTask) : this(executeTask, o => true)

        {

        }



        public CommandAsync(Func<T, CancellationToken, Task> executeTask, Predicate<T> canExecute)

        {
            cancellationTokenSource = new CancellationTokenSource();
            _executeTask = executeTask;

            _canExecute = canExecute;

        }



        public bool CanExecute(object parameter)

        {

            return _canExecute.Invoke((T)parameter);

        }



        public async void Execute(object parameter)

        {

            try

            {
                if (_locked)
                {
                    cancellationTokenSource.Cancel();
                    cancellationTokenSource = new CancellationTokenSource();
                }

                _locked = true;

                CanExecuteChanged?.Invoke(this, EventArgs.Empty);

                await _executeTask.Invoke((T)parameter, cancellationTokenSource.Token);

            }

            finally
            {

                _locked = false;

                CanExecuteChanged?.Invoke(this, EventArgs.Empty);

            }

        }



        public event EventHandler CanExecuteChanged;

        public void ChangeCanExecute()

        {

            CanExecuteChanged?.Invoke(this, EventArgs.Empty);

        }

    }