Public Class CreditCardSecurityTokenSerializer
    Inherits WSSecurityTokenSerializer

    Public Sub New(ByVal version As SecurityTokenVersion)
        MyBase.New()
    End Sub

    Protected Overrides Function CanReadTokenCore(ByVal reader As XmlReader) As Boolean
        Dim localReader = XmlDictionaryReader.CreateDictionaryReader(reader)
        If reader Is Nothing Then
            Throw New ArgumentNullException("reader")
        End If
        If reader.IsStartElement(Constants.CreditCardTokenName, _
                                 Constants.CreditCardTokenNamespace) Then
            Return True
        End If
        Return MyBase.CanReadTokenCore(reader)
    End Function

    Protected Overrides Function ReadTokenCore(ByVal reader As XmlReader, _
                                               ByVal tokenResolver As SecurityTokenResolver) As SecurityToken
        If reader Is Nothing Then
            Throw New ArgumentNullException("reader")
        End If
        If reader.IsStartElement(Constants.CreditCardTokenName, _
                                 Constants.CreditCardTokenNamespace) Then

            Dim id = reader.GetAttribute(Constants.Id, _
                                         Constants.WsUtilityNamespace)
            reader.ReadStartElement()

            ' Read the credit card number.
            Dim creditCardNumber = reader.ReadElementString(Constants.CreditCardNumberElementName, _
                                                            Constants.CreditCardTokenNamespace)

            ' Read the expiration date.
            Dim expirationTimeString = reader.ReadElementString(Constants.CreditCardExpirationElementName, _
                                                                Constants.CreditCardTokenNamespace)
            Dim expirationTime As DateTime = XmlConvert.ToDateTime(expirationTimeString, _
                                                                   XmlDateTimeSerializationMode.Utc)

            ' Read the issuer of the credit card.
            Dim creditCardIssuer = reader.ReadElementString(Constants.CreditCardIssuerElementName, _
                                                            Constants.CreditCardTokenNamespace)
            reader.ReadEndElement()

            Dim cardInfo As New CreditCardInfo(creditCardNumber, _
                                               creditCardIssuer, _
                                               expirationTime)

            Return New CreditCardToken(cardInfo, id)
        Else
            Return WSSecurityTokenSerializer.DefaultInstance.ReadToken(reader, _
                                                                       tokenResolver)
        End If
    End Function

    Protected Overrides Function CanWriteTokenCore(ByVal token As SecurityToken) As Boolean
        If TypeOf token Is CreditCardToken Then
            Return True
        Else
            Return MyBase.CanWriteTokenCore(token)
        End If
    End Function

    Protected Overrides Sub WriteTokenCore(ByVal writer As XmlWriter, _
                                           ByVal token As SecurityToken)
        If writer Is Nothing Then
            Throw New ArgumentNullException("writer")
        End If
        If token Is Nothing Then
            Throw New ArgumentNullException("token")
        End If

        Dim c = TryCast(token, CreditCardToken)
        If c IsNot Nothing Then
            With writer
                .WriteStartElement(Constants.CreditCardTokenPrefix, _
                                   Constants.CreditCardTokenName, _
                                   Constants.CreditCardTokenNamespace)
                .WriteAttributeString(Constants.WsUtilityPrefix, _
                                      Constants.Id, _
                                      Constants.WsUtilityNamespace, _
                                      token.Id)
                .WriteElementString(Constants.CreditCardNumberElementName, _
                                    Constants.CreditCardTokenNamespace, _
                                    c.CardInfo.CardNumber)
                .WriteElementString(Constants.CreditCardExpirationElementName, _
                                    Constants.CreditCardTokenNamespace, _
                                    XmlConvert.ToString(c.CardInfo.ExpirationDate, _
                                                        XmlDateTimeSerializationMode.Utc))
                .WriteElementString(Constants.CreditCardIssuerElementName, _
                                    Constants.CreditCardTokenNamespace, _
                                    c.CardInfo.CardIssuer)
                .WriteEndElement()
                .Flush()
            End With
        Else
            MyBase.WriteTokenCore(writer, token)
        End If
    End Sub

End Class