using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Windows.Forms;

namespace PlayingWithWinForms {
	public partial class PhoneNumberView : Form {
		public PhoneNumberView( ) {
			InitializeComponent( );
			_aggregator = new DelegateAggregator( );

			uxPhoneNumberTextBox.Leave +=
				_aggregator.CreateHandler( new FormatPhoneNumberCommand( uxPhoneNumberTextBox ).Execute );
		}

		private readonly IDelegateAggregator _aggregator;
	}

	public interface IPhoneNumber {
		string Number { get; }

		bool IsValid( );
	}

	internal interface IFormatPhoneNumberCommand {
		void Execute( );
	}

	internal interface IDelegateAggregator {
		EventHandler CreateHandler( MethodInvoker command );
	}

	public class PhoneNumber : IPhoneNumber {
		public PhoneNumber( string number ) {
			const string expression = @"[\(\)\-\ ]";
			_number = ( null != number ) ? Regex.Replace( number, expression, String.Empty ) : string.Empty;
		}

		public string Number {
			get { return _number; }
		}

		public bool IsValid( ) {
			string tenDigitNumberExpression = @"^(\d{10})*$";
			return !string.IsNullOrEmpty( _number ) && Regex.IsMatch( _number, tenDigitNumberExpression );
		}

		public override string ToString( ) {
			return _number;
		}

		private readonly string _number;
	}

	internal class FormatPhoneNumberCommand : IFormatPhoneNumberCommand {
		public FormatPhoneNumberCommand( Control control ) {
			_control = control;
		}

		public void Execute( ) {
			_control.Text = new PhoneNumber( _control.Text ).Number;
		}

		private readonly Control _control;
	}

	internal class DelegateAggregator : IDelegateAggregator {
		public DelegateAggregator( ) : this( new List< Delegate >( ) ) {}

		private DelegateAggregator( IList< Delegate > delegates ) {
			_delegates = delegates;
		}

		public EventHandler CreateHandler( MethodInvoker command ) {
			_delegates.Add( command );
			//return delegate( object sender, EventArgs e ) { command( ); }; // same as line below
			return delegate { command( ); }; // c# compiler implicitly adds the sender and e params.
		}

		private readonly IList< Delegate > _delegates;
	}
}