#Region "  Imports  "

Imports System
Imports System.Diagnostics.EventLog
Imports Statistics.Cdo
#End Region

Public Class AuditLogger

#Region " Instance Fields  "

    Shared _appName As String = "myApp" 'must be seven chars or less
    Shared _auditMessage = String.Empty
    Shared _auditId As Integer = 0
    Shared _auditObject As String = String.Empty
    Shared _incidentLogName As String = _appName & "Incident"
    Shared _securityLogName As String = _appName & "Security"

#End Region

#Region "  Properties  "

    Public WriteOnly Property auditId() As Integer
        Set(ByVal Value As Integer)
            _auditId = Value
        End Set
    End Property

    Public WriteOnly Property auditMessage() As String
        Set(ByVal Value As String)
            _auditMessage = Value
            _auditMessage = "{" & GetUserName() & "} " & _auditMessage
        End Set
    End Property

    Public WriteOnly Property auditObject() As String
        Set(ByVal Value As String)
            _auditObject = Value
            _auditObject = " (Row No.: " & _auditObject & ")"
        End Set
    End Property

#End Region

#Region "  Public Methods  "

    'Method to write events to the Application incident log:
    '   First argument "component" specifies the component relating to the event.
    '   Second argument "category" specifies the event category.
    '   Third argument "type" specifies the event type.
    Public Shared Sub WriteToIncidentLog(ByVal component As AuditComponent, ByVal category As AuditIncidentCategory, ByVal type As AuditIncidentType)

        Dim _source As String = String.Empty
        _source = GetComponentName(component)

        Dim _auditType As EventLogEntryType

        Select Case type
            Case AuditIncidentType.Info
                _auditType = EventLogEntryType.Information
            Case AuditIncidentType.Fault
                _auditType = EventLogEntryType.Error
            Case AuditIncidentType.Warn
                _auditType = EventLogEntryType.Warning
        End Select

        Try

            If Not EventLog.SourceExists(_source) Then

                CreateEventSource(_source, _incidentLogName)

            End If

        Catch ex As Exception

            Dim body As String
            body = "<b>Error Message:</b><br><br>" & ex.Message
            body &= "<br><br><b>Attempted to log:</b><br><br>"
            body &= "Source:" & _source.ToString() & "<br>"
            body &= "Message:" & _auditMessage.ToString() & "<br>"
            body &= "Type:" & _auditType.ToString() & "<br>"
            body &= "ID:" & _auditId & "<br>"
            body &= "Category:" & category.ToString() & "<br>"
            SendErrorMessage(body)

        End Try

        Try

            EventLog.WriteEntry(_source, _auditMessage, _auditType, _auditId, category)

        Catch ex As Exception

            Dim body As String
            body = "<b>Error Message:</b><br><br>" & ex.Message
            body &= "<br><br><b>Attempted to log:</b><br><br>"
            body &= "Source:" & _source.ToString() & "<br>"
            body &= "Message:" & _auditMessage.ToString() & "<br>"
            body &= "Type:" & _auditType.ToString() & "<br>"
            body &= "ID:" & _auditId & "<br>"
            body &= "Category:" & category.ToString() & "<br>"
            SendErrorMessage(body)

        End Try

        _auditId = 0
        _auditMessage = String.Empty

    End Sub

    'Method to write events to the Application security log:
    '   First argument "component" specifies the component relating to the event.
    '   Second argument "category" specifies the event category.
    '   Third argument "type" specifies the event type.
    Public Shared Sub WriteToSecurityLog(ByVal component As AuditComponent, ByVal category As AuditSecurityCategory, ByVal type As AuditSecurityType)

        Dim _source As String = String.Empty
        _source = GetComponentName(component)

        Dim _auditType As EventLogEntryType

        Select Case type
            Case AuditSecurityType.Failed
                _auditType = EventLogEntryType.FailureAudit
            Case AuditSecurityType.Info
                _auditType = EventLogEntryType.Information
            Case AuditSecurityType.Succeeded
                _auditType = EventLogEntryType.SuccessAudit
        End Select

        Try

            If Not EventLog.SourceExists(_source) Then

                CreateEventSource(_source, _securityLogName)

            End If

        Catch ex As Exception

            Dim body As String
            body = "<b>Error Message:</b><br><br>" & ex.Message
            body &= "<br><br><b>Attempted to log:</b><br><br>"
            body &= "Source:" & _source.ToString() & "<br>"
            body &= "Message:" & _auditMessage.ToString() & "<br>"
            body &= "Type:" & _auditType.ToString() & "<br>"
            body &= "ID:" & _auditId & "<br>"
            body &= "Category:" & category.ToString() & "<br>"
            SendErrorMessage(body)

        End Try

        Try

            EventLog.WriteEntry(_source, _auditMessage, _auditType, _auditId, category)

        Catch ex As Exception

            Dim body As String
            body = "<b>Error Message:</b><br><br>" & ex.Message
            body &= "<br><br><b>Attempted to log:</b><br><br>"
            body &= "Source:" & _source.ToString() & "<br>"
            body &= "Message:" & _auditMessage.ToString() & "<br>"
            body &= "Type:" & _auditType.ToString() & "<br>"
            body &= "ID:" & _auditId & "<br>"
            body &= "Category:" & category.ToString() & "<br>"
            SendErrorMessage(body)

        End Try

        _auditId = 0
        _auditMessage = String.Empty

    End Sub

#End Region

#Region "  Private Methods  "

    'Method to notify application support when auditing is unable to audit:
    '   First argument "errBody" specifies the message to send to support.
    '   Returns nothing.
    Private Shared Sub SendErrorMessage(ByVal errBody As String)

        Cdo.msgSubject = "Failed to audit event"
        Cdo.msgBody = errBody
        Cdo.Send()

    End Sub

    'Method to return a string representation from the AuditComponent type:
    '   First argument "component" specifies the auditComponent type to return.
    '   Returns a string corresponding with the specified type.
    Private Shared Function GetComponentName(ByVal component As AuditComponent) As String
        Select Case component
            Case AuditComponent.AD
                Return "Active Directory"
            Case AuditComponent.ADO
                Return "Active Data Object"
            Case AuditComponent.AppExceptions
                Return "Application Exceptions"
            Case AuditComponent.AuditLog
                Return "Audit Logging"
            Case AuditComponent.Cdo
                Return "Collaboration Data Object"
            Case AuditComponent.DataProvider
                Return "Data Provider"
            Case AuditComponent.Fso
                Return "File System Object"
            Case AuditComponent.Pki
                Return "Public Key Infrastructure"
            Case AuditComponent.PopupCalendar
                Return "Popup Calendar"
            Case AuditComponent.Security
                Return "Security"
            Case AuditComponent.Template
                Return "Site Template"
            Case AuditComponent.Unknown
                Return "Unknown Module"
            Case Else
                Return "INVALID AUDIT EVENT"
        End Select

    End Function

    'Method to return the current username:
    '   Returns a string containing the current "user"
    Private Shared Function GetUserName() As String
        If HttpContext.Current.Session("UserName") Is Nothing Then

            Return "session expired"

        Else

            Return LCase(HttpContext.Current.Session("UserName"))

        End If

    End Function

    'Method to return the remote IP:
    '   Returns a string containing the remote IP.
    Private Shared Function GetIP() As String
        If HttpContext.Current.Request.ServerVariables("REMOTE_ADDR") Is Nothing Then
            Return "No IP Presented"
        Else
            Return HttpContext.Current.Request.ServerVariables("REMOTE_ADDR")
        End If

    End Function

#End Region

#Region "  Enumerations  "

    Public Enum AuditComponent As Integer
        AD
        ADO
        AuditLog
        Cdo
        AppExceptions
        Fso
        Pki
        PopupCalendar
        DataProvider
        Security
        Template
        Unknown
    End Enum

    Public Enum AuditIncidentCategory As Integer
        None
        Vulnerability
        DataDeletion
        DataChange
        DataView
        General
        DataError
        AppError
    End Enum

    Public Enum AuditSecurityCategory As Integer
        None
        LoginLogout
        DataChange
        DataDeletion
        DataView
    End Enum

    Public Enum AuditIncidentType As Integer
        Info
        Warn
        Fault
    End Enum

    Public Enum AuditSecurityType As Integer
        Info
        Succeeded
        Failed
    End Enum

#End Region

End Class