using System;
using System.Diagnostics;
using System.Windows.Input;

namespace Dominion.NET_WPF.ViewModel
{
	public class RelayCommand : ICommand
	{
		#region Fields

	    private readonly Action<object> _execute;
	    private readonly Predicate<object> _canExecute;

		#endregion // Fields

		#region Constructors

		public RelayCommand(Action<object> execute)
			: this(execute, null)
		{
		}

		public RelayCommand(Action<object> execute, Predicate<object> canExecute)
		{
			if (execute == null)
				throw new ArgumentNullException("execute");

			_execute = execute;
			_canExecute = canExecute;
		}
		#endregion // Constructors

		#region ICommand Members

		[DebuggerStepThrough]
		public bool CanExecute(object parameter)
		{
			return _canExecute?.Invoke(parameter) ?? true;
		}

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

		public void Execute(object parameter)
		{
			_execute(parameter);
		}

		#endregion // ICommand Members
	}
}