﻿// The MIT License (MIT)
//
// Copyright (c) 2017 Smart&Soft
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// SOFTWARE.

using System;
using System.Windows.Input;

namespace ModernApp4Me.Universal.LifeCycle
{

  /// <author>Ludovic Roland</author>
  /// <since>2015.04.02</since>
  /// <summary>
  /// A command whose sole purpose is to relay its functionality 
  /// to other objects by invoking delegates. 
  /// The default return value for the CanExecute method is 'true'.
  /// <see cref="RaiseCanExecuteChanged"/> needs to be called whenever
  /// <see cref="CanExecute"/> is expected to return a different value.
  /// </summary>
  // Taken from the HubPage template
  public class M4MRelayCommand : ICommand
  {

    private readonly Action execute;

    private readonly Func<bool> canExecute;

    /// <summary>
    /// Raised when RaiseCanExecuteChanged is called.
    /// </summary>
    public event EventHandler CanExecuteChanged;

    /// <summary>
    /// Creates a new command that can always execute.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    public M4MRelayCommand(Action execute) : this(execute, null)
    {
    }

    /// <summary>
    /// Creates a new command.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    /// <param name="canExecute">The execution status logic.</param>
    public M4MRelayCommand(Action execute, Func<bool> canExecute)
    {
      if (execute == null)
      {
        throw new ArgumentNullException("execute");
      }

      this.execute = execute;
      this.canExecute = canExecute;
    }

    /// <summary>
    /// Determines whether this <see cref="M4MRelayCommand"/> can execute in its current state.
    /// </summary>
    /// <param name="parameter">
    /// Data used by the command. If the command does not require data to be passed, this object can be set to null.
    /// </param>
    /// <returns>true if this command can be executed; otherwise, false.</returns>
    public bool CanExecute(object parameter)
    {
      return canExecute == null ? true : canExecute();
    }

    /// <summary>
    /// Executes the <see cref="M4MRelayCommand"/> on the current command target.
    /// </summary>
    /// <param name="parameter">
    /// Data used by the command. If the command does not require data to be passed, this object can be set to null.
    /// </param>
    public void Execute(object parameter)
    {
        execute();
    }

    /// <summary>
    /// Method used to raise the <see cref="CanExecuteChanged"/> event
    /// to indicate that the return value of the <see cref="CanExecute"/>
    /// method has changed.
    /// </summary>
    public void RaiseCanExecuteChanged()
    {
      var handler = CanExecuteChanged;

      if (handler != null)
      {
        handler(this, EventArgs.Empty);
      }
    }

  }

}