using System;
using System.Windows.Input;

namespace MVVM
{
    public class ActionCommand : ICommand
    {
        private Action<object> action;
        private Predicate<object> predicate;

        public ActionCommand(Action<object> action) : this(action, null)
        { }

        public ActionCommand(Action<object> action, Predicate<object> predicate)
        {
            this.action = action ?? throw new ArgumentNullException(nameof(action));
            this.predicate = predicate;
        }

        #region ICommand members:

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public bool CanExecute(object parameter) =>
            predicate == null || predicate(parameter);

        public void Execute() => 
            Execute(null);

        public void Execute(object parameter) => 
            action(parameter);

        #endregion
    }
}