EmailAddress.cs :  » Email » SharpWebMail » EricDaugherty » CSES » Common » C# / CSharp Open Source

using System;
using System.Text.RegularExpressions;

namespace EricDaugherty.CSES.Common{  
  /// <summary>
  /// Stores a single EmailAddress.  The class will only
  /// represent valid email addresses, and will never contain
  /// an invalid address.
  /// </summary>
  /// <remarks>
  /// This class provides a way to store and pass a valid email address
  /// within the system.  This class can not be created with an invalid address,
  /// so if parameter of this type is not null, the address can be assumed to
  /// be valid.
  /// </remarks>
  public class EmailAddress
  {
    #region Constants
    
    private Regex ILLEGAL_CHARACTERS = new Regex( "[][)(@><\\\",;:]" );
    
    #endregion
    
    #region Variables
    
    private string username;
    private string domain;
    
    #endregion
    
    #region Constructors
    
    /// <summary>
    /// Creates a new EmailAddress using a valid address.
    /// </summary>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the username or domain is invalid.
    /// </exception>
    public EmailAddress( string address )
    {
      Address = address;
    }
    
    /// <summary>
    /// Creates a new EmailAddress using valid name and domain.
    /// </summary>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the username or domain is invalid.
    /// </exception>
    public EmailAddress( string username, string domain )
    {
      Username = username;
      Domain = domain;
    }
    
    #endregion
    
    #region Properties
    
    /// <summary>
    /// The username component of the EmailAddress.  This
    /// consists of everything before the @.
    /// </summary>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the username is invalid.
    /// </exception>
    public string Username
    {
      get
      {
        return username;
      }
      set
      {
        if( value == null || value.Length == 0 )
        {
          throw new InvalidEmailAddressException( "Invalid username.  Username must be at least one charecter" );
        }
        
        // Verify that the username does not contain illegal characters.
        VerifySpecialCharacters( value );
        
        username = value;
      }
    }
    
    /// <summary>
    /// The domain component of the EmailAddress.  This
    /// consists of everything after the @.
    /// </summary>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the domain is invalid.
    /// </exception>
    public string Domain
    {
      get
      {
        return domain;
      }
      set
      {
        if( value == null || value.Length < 5 )
        {
          throw new InvalidEmailAddressException( "Invalid domian.  Domain must be at least 5 charecters (a.com, a.edu, etc...)" );
        }
        
        // Verify that the username does not contain illegal characters.
        VerifySpecialCharacters( value );
        
        domain = value;
      }
    }
    
    /// <summary>
    /// The entire EmailAddress (username@domian)
    /// </summary>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the address is invalid.
    /// </exception>
    public string Address
    {
      get
      {
        return username + "@" + domain;
      }
      set
      {
        // Verify it isn't null/empty.
        if( value == null || value.Length == 0 )
        {
          throw new InvalidEmailAddressException( "Invalid address.  Specified address is empty" );
        }
        
        String[] addressParts = value.Split( "@".ToCharArray() );
        if( addressParts.Length != 2 )
        {
          throw new InvalidEmailAddressException( "Invalid address.  The address must be formatted as: username@domain." );
        }
        
        // Store the individual parts.  These methods will
        // verify that the individual parts are valid or will
        // throw their own InvalidEmailAddressException        
        Username = addressParts[0];
        Domain = addressParts[1];
      }
    }
    
    #endregion
    
    #region Object Methods
    
    /// <summary>
    /// Returns the email address as: "user@domain.com".;
    /// </summary>
    /// <returns>Value of Address Property.</returns>
    public override string ToString()
    {
      return Address;
    }
    
    #endregion
    
    #region Private Methods
    
    /// <summary>
    /// Checks the specified string to verify it does not
    /// contain any of the following characters: ( ) &lt; &gt; @ , ; : \ " . [ ]  
    /// </summary>
    /// <param name="data">The string to test</param>
    /// <exception cref="InvalidEmailAddressException">
    /// Thrown if the data contains any illegal special characters.
    /// </exception>
    private void VerifySpecialCharacters( String data )
    {
      if( ILLEGAL_CHARACTERS.IsMatch( data ) ) 
      {
        throw new InvalidEmailAddressException( "Invalid address.  The username and domain address parts can not contain any of the following characters: ( ) < > @ , ; : \\ \" . [ ]" );
      }
    }
    
    #endregion
  }
}