// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Windows.Input;

namespace FancyZonesEditor.Utils
{
    public class RelayCommand : ICommand
    {
        private readonly Predicate<object> _canExecute;
        private readonly Action<object> _execute;

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

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

            _execute = execute;
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute(parameter);
        }

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

        // Ensures WPF commanding infrastructure asks all RelayCommand objects whether their
        // associated views should be enabled whenever a command is invoked
        public event EventHandler CanExecuteChanged
        {
            add
            {
                CommandManager.RequerySuggested += value;
                CanExecuteChangedInternal += value;
            }

            remove
            {
                CommandManager.RequerySuggested -= value;
                CanExecuteChangedInternal -= value;
            }
        }

        private event EventHandler CanExecuteChangedInternal;

        public void RaiseCanExecuteChanged()
        {
            CanExecuteChangedInternal.Invoke(this, null);
            /*CanExecuteChangedInternal.Raise(this);*/
        }
    }
}
