namespace Common.Commands
{
    using System;
    using System.Diagnostics;
    using System.Windows.Input;

    public class RelayCommand : ICommand
    {
        private readonly Predicate<object> _canExecute;

        private readonly Action<object> _execute;

        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;
        }

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

            remove
            {
                CommandManager.RequerySuggested -= value;
            }
        }

        [DebuggerStepThrough]
        public bool CanExecute(object parameter)
        {
            return _canExecute == null ? true : _canExecute(parameter);
        }

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