Imports System.ComponentModel.DataAnnotations
Imports System.Web.Mvc
Imports System.Web.Security

Public NotInheritable Class AccountNameUniqueAttribute
    Inherits ValidationAttribute
    Implements IClientValidatable

    Private Const strDefaultErrorMessage As String = "Dieser Benutzername existiert bereits"

    Public Sub New()
        MyBase.New(strDefaultErrorMessage)
    End Sub

    Protected Overrides Function IsValid(ByVal value As Object, context As ValidationContext) As ValidationResult

        '--ClientValidation: AccountController.IsAccountNameUnique

        Dim strWantedName As String = CType(value, String)

        Dim usr As MembershipUser = Membership.GetUser(strWantedName)

        If usr IsNot Nothing Then
            Return New ValidationResult(FormatErrorMessage(context.DisplayName))
        End If

        Return ValidationResult.Success

    End Function

    Public Overrides Function FormatErrorMessage(name As String) As String
        Return String.Format(ErrorMessageString, name)
    End Function

    Public Function GetClientValidationRules(metadata As System.Web.Mvc.ModelMetadata,
                                             context As System.Web.Mvc.ControllerContext) As IEnumerable(Of ModelClientValidationRule) Implements IClientValidatable.GetClientValidationRules

        Dim rule As New ModelClientValidationRule() With {.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
                                                          .ValidationType = "accountnameunique"}
        Return New ModelClientValidationRule() {rule}
    End Function

End Class