AppSAV/MauiAppStock/Helpers/AsyncCommand.cs

using System;
using System.Threading.Tasks;
using System.Windows.Input;

namespace MauiAppStock.Helpers
{
    public class AsyncCommand : ICommand
    {
        private readonly Func<Task> _execute;
        private readonly Func<bool> _canExecute;
        private bool _isExecuting;

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

        public bool CanExecute(object parameter)
        {
            return !_isExecuting && (_canExecute?.Invoke() ?? true);
        }

        public async void Execute(object parameter)
        {
            if (!CanExecute(parameter))
                return;

            try
            {
                _isExecuting = true;
                RaiseCanExecuteChanged();
                await _execute();
            }
            finally
            {
                _isExecuting = false;
                RaiseCanExecuteChanged();
            }
        }

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

    public class AsyncCommand<T> : ICommand
    {
        private readonly Func<T, Task> _execute;
        private readonly Predicate<T> _canExecute;
        private bool _isExecuting;

        public AsyncCommand(Func<T, Task> execute, Predicate<T> canExecute = null)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return !_isExecuting && (_canExecute?.Invoke((T)parameter) ?? true);
        }

        public async void Execute(object parameter)
        {
            if (!CanExecute(parameter))
                return;

            try
            {
                _isExecuting = true;
                RaiseCanExecuteChanged();
                await _execute((T)parameter);
            }
            finally
            {
                _isExecuting = false;
                RaiseCanExecuteChanged();
            }
        }

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