Imports System.Timers
Imports System.IO
Imports System.ComponentModel
Imports DigitalData.Modules.Base
Imports DigitalData.Modules.Logging
Imports DigitalData.Modules.Database
Imports DigitalData.Modules.Messaging
Imports DigitalData.Modules.Config
Imports FirebirdSql.Data

Public Class EmailService
    Private _Logger As Logger
    Private _LogConfig As LogConfig
    Private _ConfigManager As ConfigManager(Of Config)
    Private _Config As Config

    Private _Firebird As Firebird
    Private _MSSQL As MSSQLServer
    Private _MSSQL_Test As MSSQLServer
    Private _Encryption As EncryptionLegacy
    Private _EmailQueue As BackgroundWorker
    Private _QueueTimer As Timer
    Private _TempFiles As TempFiles
    Private _AnyDatabaseInitialized As Boolean = False
    Private _limilab As Limilab
    Private _MailSender As Mail.MailSender
    Private _AttachmentByteData As Byte()
    Private _RecentAttachmentByteData As Byte()
    Private ReadOnly _messageSend As Boolean = False


    Private Enum DatabaseType
        Firebird
        MSSQL
    End Enum

    Protected Overrides Sub OnStart(ByVal args() As String)
        Try
            ' === Initialize Logger ===
            Dim oLogPath = Path.Combine(My.Application.Info.DirectoryPath, "Log")
            _LogConfig = New LogConfig(LogConfig.PathType.CustomPath, oLogPath, Nothing, "Digital Data", "EmailService")

            ' === Initialize Config ===
            _ConfigManager = New ConfigManager(Of Config)(_LogConfig, My.Application.Info.DirectoryPath)
            _Config = _ConfigManager.Config

            _LogConfig.Debug = _Config.Debug


            Dim oCurrentDomain As AppDomain = AppDomain.CurrentDomain
            AddHandler oCurrentDomain.UnhandledException, AddressOf AppDomain_UnhandledException

            _Logger = _LogConfig.GetLogger()
            _Logger.Info($"DEBUG = {_LogConfig.Debug}")

            _Logger.Info("Starting {0}", ServiceName)

            ' === Inititalize Encryption ===

            _Logger.Debug("Inititalize Encryption")
            _Encryption = New EncryptionLegacy()

            ' === Initialize Databases ===

            _Logger.Info("Inititalize Databases")

            If _Config.SQLServerConnectionString <> String.Empty Then
                _MSSQL = New MSSQLServer(_LogConfig, _Config.SQLServerConnectionString)

                If _MSSQL.DBInitialized = False Then
                    _Logger.Warn("MSSQL Connection could not be established. Check the Error Log")
                End If
            End If

            If _Config.SQLServerTestConnectionString <> String.Empty Then

                _MSSQL_Test = New MSSQLServer(_LogConfig, _Config.SQLServerTestConnectionString)

                If _MSSQL_Test.DBInitialized = False Then
                    _Logger.Warn("MSSQL Test Connection could not be established. Check the Error Log")
                End If
            End If

            _AnyDatabaseInitialized = _Firebird?._DBInitialized Or _MSSQL?.DBInitialized Or _MSSQL_Test?.DBInitialized
            _TempFiles = New TempFiles(_LogConfig)
            _TempFiles.Create()
            ' === Initialize Email ===

            _Logger.Debug("Inititalize Email")

            _limilab = New Limilab(_LogConfig)

            ' === Initialize Queue ===

            _Logger.Debug("Inititalize Queue")

            If _AnyDatabaseInitialized Then
                _EmailQueue = New BackgroundWorker() With {
                    .WorkerReportsProgress = True,
                    .WorkerSupportsCancellation = True
                }

                AddHandler _EmailQueue.DoWork, AddressOf EmailQueue_DoWork
                AddHandler _EmailQueue.RunWorkerCompleted, AddressOf EmailQueue_Completed
            End If

            ' === Initialize & Start Timer ===

            _Logger.Debug("Initialize & Start Timer")

            If _AnyDatabaseInitialized Then
                _QueueTimer = New Timer With {
                   .Interval = 60000,
                   .Enabled = True
                }

                AddHandler _QueueTimer.Elapsed, AddressOf QueueTimer_Elapsed
            End If

            ' === Initial Run ===

            If _AnyDatabaseInitialized Then
                _Logger.Info("Starting Initial Run...")
                _EmailQueue.RunWorkerAsync()
            End If
        Catch ex As Exception
            _Logger.Error(ex)
        End Try
    End Sub

    Private Sub AppDomain_UnhandledException(sender As Object, e As UnhandledExceptionEventArgs)
        Dim oException As Exception = e.ExceptionObject
        _Logger.Warn("An unhandled exception has occurred.")
        _Logger.Error(oException)
    End Sub

    Private Sub QueueTimer_Elapsed(sender As Object, e As ElapsedEventArgs)
        Try
            If Not _EmailQueue.IsBusy Then
                _EmailQueue.RunWorkerAsync()
                _Logger.Debug("Worker is ready, executing.")
            Else
                _Logger.Info("Worker is busy, skipping execution.")
            End If
        Catch ex As Exception
            _Logger.Warn("Error while starting the Worker!")
            _Logger.Error(ex)
        End Try
    End Sub

    Private Sub EmailQueue_DoWork(sender As Object, e As DoWorkEventArgs)
        Try
            If _MSSQL?.DBInitialized Then
                _Logger.Debug("Starting MSSQL Sending")
                SendEmailFrom(DatabaseType.MSSQL, _MSSQL)
            End If

            If _MSSQL_Test?.DBInitialized Then
                _Logger.Debug("Starting MSSQL Test Sending")
                SendEmailFrom(DatabaseType.MSSQL, _MSSQL_Test)
            End If
        Catch ex As Exception
            _Logger.Error(ex)
        End Try
    End Sub

    Private Sub EmailQueue_Completed(sender As Object, e As RunWorkerCompletedEventArgs)
        Try
            If e.Cancelled Then
                _Logger.Warn("EmailQueue has been cancelled manually!")
            ElseIf e.Error IsNot Nothing Then
                _Logger.Warn("Unexpected Error in EmailQueue: {0}", e.Error.Message)
                _Logger.Error(e.Error)
            Else
                _Logger.Debug("Email Queue successfully processed.")
            End If
        Catch ex As Exception
            _Logger.Warn("Error while processing result of Worker!")
            _Logger.Error(e.Error)
        End Try
    End Sub

    Private Class EmailAccount
        Public Guid As Integer
        Public Sender As String
        Public Server As String
        Public Port As String
        Public Username As String
        Public Password As String
        Public AuthType As String

        Public AddedWhen As String
        Public ErrorMessage As String
    End Class

    Private Function GetAccounts(Database As DatabaseType, MSSQLInstance As MSSQLServer) As List(Of EmailAccount)
        Try
            Dim oSQL As String = String.Empty
            Dim oEmailAccounts As DataTable = Nothing
            Dim oAccounts As New List(Of EmailAccount)

            Select Case Database
                Case DatabaseType.Firebird
                    oSQL = "SELECT * FROM TBEDM_EMAIL_ACCOUNT WHERE ACTIVE = True"
                    oEmailAccounts = _Firebird.GetDatatable(oSQL)
                Case DatabaseType.MSSQL
                    oSQL = "SELECT * FROM TBDD_EMAIL_ACCOUNT WHERE ACTIVE = 1"
                    oEmailAccounts = MSSQLInstance.GetDatatable(oSQL)
            End Select

            If IsNothing(oEmailAccounts) Then
                _Logger.Warn("Error in TBEDM_EMAIL_ACCOUNT Query. Exiting.")
                _Logger.Warn("Query: {0}", oSQL)
                Return Nothing
            End If

            If oEmailAccounts.Rows.Count = 0 Then
                _Logger.Warn("No Active Email Accounts Configured! Exiting.")
                Return Nothing
            End If

            _Logger.Debug("Found [{0}] active Accounts.", oEmailAccounts.Rows.Count)

            For Each oRow As DataRow In oEmailAccounts.Rows
                Dim oAccount As EmailAccount = Nothing

                Select Case Database
                    Case DatabaseType.Firebird
                        oAccount = New EmailAccount With {
                            .Guid = oRow.Item("GUID"),
                            .Sender = oRow.Item("EMAIL_FROM"),
                            .Server = oRow.Item("SERVER_OUT"),
                            .Port = oRow.Item("PORT_OUT"),
                            .Username = oRow.Item("EMAIL_USER"),
                            .Password = oRow.Item("EMAIL_PW"),
                            .AuthType = oRow.Item("AUTH_TYPE"),
                            .AddedWhen = ""
                        }

                    Case DatabaseType.MSSQL
                        oAccount = New EmailAccount With {
                            .Guid = oRow.Item("GUID"),
                            .Sender = oRow.Item("EMAIL_FROM"),
                            .Server = oRow.Item("EMAIL_SMTP"),
                            .Port = oRow.Item("PORT"),
                            .Username = oRow.Item("EMAIL_USER"),
                            .Password = oRow.Item("EMAIL_PW"),
                            .AuthType = oRow.Item("AUTH_TYPE"),
                            .AddedWhen = oRow.Item("ADDED_WHEN").ToString,
                            .ErrorMessage = oRow.ItemEx("ERROR_MSG", String.Empty)
                        }

                End Select

                If oAccount Is Nothing Then
                    _Logger.Warn("Account could not be created. Unknown Database type.")
                    Continue For
                End If

                Dim oPasswordPlain = _Encryption.DecryptData(oAccount.Password)

                If IsNothing(oPasswordPlain) Then
                    _Logger.Warn("Could not decrypt email password for Account [{0}]. Skipping.", oAccount.Sender)
                    Continue For
                End If

                oAccount.Password = oPasswordPlain
                oAccounts.Add(oAccount)

            Next

            Return oAccounts
        Catch ex As Exception
            _Logger.Warn("Error while getting Accounts!")
            _Logger.Error(ex)
            Return Nothing
        End Try
    End Function

    Private Function SendEmailFrom(Database As DatabaseType, MSSQLInstance As MSSQLServer)
        Try
            Dim oSQL As String = String.Empty
            Dim oEmailAccounts As List(Of EmailAccount) = GetAccounts(Database, MSSQLInstance)
            Dim oEmailQueue As DataTable = Nothing

            If IsNothing(oEmailAccounts) Then
                _Logger.Warn("Error in getting Accounts Query. Exiting.")
                Return False
            End If

            If oEmailAccounts.Count = 0 Then
                _Logger.Warn("No Active Email Accounts Configured! Exiting.")
                Return False
            End If

            Select Case Database
                Case DatabaseType.Firebird
                    oSQL = "SELECT * FROM TBEDM_EMAIL_QUEUE WHERE EMAIL_SENT IS NULL and EMAIL_TO <> ''"
                    oEmailQueue = _Firebird.GetDatatable(oSQL)
                Case DatabaseType.MSSQL
                    If My.Settings.MSSQL_SELECT <> String.Empty Then
                        _Logger.Debug("My.Settings.MSSQL_SELECT will be used..")
                        oSQL = My.Settings.MSSQL_SELECT
                    Else
                        oSQL = "SELECT * FROM TBEMLP_EMAIL_OUT WHERE EMAIL_SENT IS NULL and EMAIL_ADRESS <> ''"
                    End If

                    oEmailQueue = MSSQLInstance.GetDatatable(oSQL)
            End Select

            If IsNothing(oEmailQueue) Then
                _Logger.Warn("Error in EmailQueue Query. Exiting.")
                _Logger.Warn("Query: {0}", oSQL)
                Return False
            End If

            If oEmailQueue.Rows.Count = 0 Then
                _Logger.Debug("Email Queue is empty. Exiting.")
                Return False
            End If

            Dim oGuid, oJobId As Integer

            For Each oAccount In oEmailAccounts

                Try
                    _Logger.Debug("Sending mails for Account [{0}]", oAccount.Guid)

                    Dim oAccountQueue As DataRow()

                    Select Case Database
                        Case DatabaseType.Firebird
                            oAccountQueue = oEmailQueue.Select($"EMAIL_ACCOUNT_ID = {oAccount.Guid}", "GUID ASC")
                        Case Else
                            oAccountQueue = oEmailQueue.Select($"SENDING_PROFILE = {oAccount.Guid}", "GUID ASC")
                    End Select

                    ' No mails for this profile
                    If oAccountQueue.Count = 0 Then
                        _Logger.Debug("No mails for Account [{0}]", oAccount.Guid)
                        Continue For
                    End If

                    _Logger.Debug("Preparing to send [{0}] mails..", oAccountQueue.Count)

                    ' ======= Initialize Sender =======

                    _MailSender = New Mail.MailSender(_LogConfig)

                    ' ======= Connect to server =======

                    Dim oOptions As New Mail.MailSession.MailSessionOptions() With {
                        .EnableTls1_1 = _Config.TlsVersion.EnableTls1_1,
                        .EnableTls1_2 = _Config.TlsVersion.EnableTls1_2,
                        .EnableDefault = _Config.TlsVersion.EnableDefault
                    }

                    Dim oResult As Mail.MailSession.SessionInfo = _MailSender.Connect(oAccount.Server, oAccount.Port, oAccount.Username, oAccount.Password, oAccount.AuthType, oOptions)

                    If oResult.Connected = False Then
                        _Logger.Warn("Could not connect to server. Skipping.")
                        Continue For

                    End If

                    ' ======= Connect to server =======

                    Dim oSuccessfulSent As New List(Of String)
                    Dim oFailedSent As New List(Of String)
                    Dim oTotalSent As New List(Of String)

                    For Each oRow As DataRow In oAccountQueue
                        'Dim oAccountMatch As Boolean = False
                        Dim oComment As String = String.Empty

                        Dim oAttachment = String.Empty
                        Dim oEmailTo = String.Empty
                        Dim oSubject = String.Empty
                        Dim oBody = String.Empty
                        Dim oAddedWhen = Now
                        Dim ATT1_RELATED_ID = String.Empty
                        Dim ATT1_REL_TYPE = String.Empty

                        Select Case Database
                            Case DatabaseType.Firebird
                                oGuid = oRow.Item("GUID")

                                oEmailTo = oRow.Item("EMAIL_TO")
                                _Logger.Debug("EMAIL_TO: {0}", oEmailTo)

                                oSubject = oRow.Item("EMAIL_SUBJ")
                                _Logger.Debug("EMAIL_SUBJ: {0}", oSubject)

                                oBody = oRow.Item("EMAIL_BODY")
                                _Logger.Debug("EMAIL_BODY: {0}", oBody)

                                oJobId = oRow.Item("JOB_ID")
                                _Logger.Debug("JOB_ID: {0}", oJobId)

                                oAttachment = oRow.ItemEx("EMAIL_ATTMT1", String.Empty)

                            Case DatabaseType.MSSQL
                                oGuid = oRow.ItemEx("GUID", 0)

                                oEmailTo = oRow.ItemEx("EMAIL_ADRESS", String.Empty)
                                _Logger.Debug($"EMAIL_ADRESS: {oEmailTo}")

                                oSubject = oRow.ItemEx("EMAIL_SUBJ", String.Empty)
                                _Logger.Debug($"EMAIL_SUBJ: {oSubject}")

                                oBody = oRow.ItemEx("EMAIL_BODY", String.Empty)
                                _Logger.Debug($"EMAIL_BODY: {oBody}")

                                oJobId = oRow.ItemEx("REFERENCE_ID", 0)
                                _Logger.Debug($"REFERENCE_ID: {oJobId}")

                                oAddedWhen = oRow.ItemEx("ADDED_WHEN", Now)

                                oAttachment = oRow.ItemEx("EMAIL_ATTMT1", String.Empty)
                                ATT1_RELATED_ID = oRow.ItemEx("ATT1_RELATED_ID", String.Empty)
                                ATT1_REL_TYPE = oRow.ItemEx("ATT1_REL_TYPE", String.Empty)
                        End Select
                        If ATT1_RELATED_ID <> String.Empty And ATT1_REL_TYPE <> String.Empty Then
                            _Logger.Info($"Attachment via byte/ID [{ATT1_RELATED_ID}]...")
                            If ATT1_REL_TYPE = "EnvelopeResult" Then
                                GetEnvelope_Result_FileStreamByte(ATT1_RELATED_ID, MSSQLInstance)
                            End If
                            If IsNothing(_AttachmentByteData) = False Then
                                Dim oTempFolder = _TempFiles.TempPath
                                Dim oTempFilename = String.Concat(oTempFolder, "\", $"SigningReport_{ATT1_RELATED_ID}.pdf")
                                Dim oFileFromByteData = CreateTempFileFromByte(oTempFilename)
                                If Not IsNothing(oFileFromByteData) Then
                                    _Logger.Info($"oFileFromByteData is  [{oFileFromByteData}]!")
                                    oAttachment = oFileFromByteData
                                End If
                            End If
                        End If
                        If oAttachment <> String.Empty Then
                            If oAttachment.ToString.Contains("\") Then
                                If File.Exists(oAttachment) = False Then
                                    _Logger.Warn($"Email Attachment [{oAttachment}] Not existing!")
                                    oComment = $"Email Attachment [{oAttachment}] Not existing!"
                                    oAttachment = String.Empty
                                Else
                                    _Logger.Debug("Email Attachment Is:  {0}", oAttachment)
                                End If
                            End If

                        End If

                        Dim oAddresses As List(Of String) = oEmailTo.Split(";").ToList()
                        Dim oAttachments As New List(Of String) From {oAttachment}
                        Dim oMessageSent = _MailSender.SendMail(oAddresses, oAccount.Sender, oSubject, oBody, oAddedWhen, oAttachments, False)


                        If oMessageSent Then
                            oTotalSent.Add(oEmailTo)
                            oSuccessfulSent.Add(oEmailTo)

                            Select Case Database
                                Case DatabaseType.Firebird
                                    oSQL = GetFirebirdUpdateString(oComment, oGuid)
                                    _Firebird.ExecuteNonQuery(oSQL)
                                Case DatabaseType.MSSQL
                                    oSQL = GetSQLUpdateString(oComment, oGuid)
                                    MSSQLInstance.ExecuteNonQuery(oSQL)
                            End Select
                            _Logger.Info($"EmailID [{oGuid.ToString}] has been send to: {oEmailTo}")

                        Else
                            oTotalSent.Add(oEmailTo)
                            oFailedSent.Add(oEmailTo)

                            Select Case Database
                                Case DatabaseType.MSSQL
                                    oSQL = $"UPDATE TBEMLP_EMAIL_OUT SET ERROR_TIMESTAMP = GETDATE(),ERROR_MSG = '{_limilab.ErrorMessage}' WHERE GUID = {oGuid} "
                                    MSSQLInstance.ExecuteNonQuery(oSQL)

                                    If _messageSend = True Then
                                        oSQL = GetSQLUpdateString(oComment, oGuid)
                                        MSSQLInstance.ExecuteNonQuery(oSQL)
                                        _Logger.Info($"EmailID [{oGuid.ToString}] has been send to: {oEmailTo} - although there was an error in connection close!")
                                    End If

                            End Select
                        End If

                    Next ' Account Queue

                    Dim oDisconnected = _MailSender.Disconnect()
                    If oDisconnected = False Then
                        _Logger.Warn("Error while disconnecting from Server. Continuing.")
                    End If

                    _Logger.Info("Sent [{0}] mails for account [{1}]", oTotalSent.Count, oAccount.Guid)
                    _Logger.Info("Successful: [{0}], Failed: [{1}]", oSuccessfulSent.Count, oFailedSent.Count)
                Catch ex As Exception

                    _Logger.Warn("Could not send mails for account [{0}]", oAccount.Guid)
                    _Logger.Error(ex)

                End Try

            Next ' Accounts

            Return True
        Catch ex As Exception
            _Logger.Warn("Error in SendEmailFrom. Email was not sent.")
            _Logger.Error(ex)
            Return False
        End Try
    End Function

    Private Function GetSQLUpdateString(pComment As String, pGuid As Integer) As String
        Dim oSQL As String = "UPDATE TBEMLP_EMAIL_OUT SET "
        oSQL += " EMAIL_SENT = GETDATE() "

        If String.IsNullOrWhiteSpace(pComment) = False Then
            oSQL += $", COMMENT = '{pComment}' "
        End If

        oSQL += $" WHERE Guid = {pGuid}"

        Return oSQL
    End Function

    Private Function GetFirebirdUpdateString(pComment As String, pGuid As Integer) As String
        ' Vermutlich wird das nicht mehr gebraucht?
        Dim oSQL As String = $"UPDATE TBEDM_EMAIL_QUEUE SET EMAIL_SENT = CURRENT_TIMESTAMP,COMMENT = '{pComment}' WHERE GUID = {pGuid}"
        If oSQL.Contains(",COMMENT = ''") Then
            oSQL.Replace(",COMMENT = ''", "")
        End If

        Return oSQL
    End Function

    Private Sub GetEnvelope_Result_FileStreamByte(ByVal pEnvID As Long, pMSSQL As MSSQLServer)

        Dim strSql As String
        'For Document
        Try
            'Get image data from gridview column. 
            strSql = "Select [DOC_RESULT] from [TBSIG_ENVELOPE] WHERE GUID = " & pEnvID
            Dim obyteDB = pMSSQL.GetScalarValue(strSql)
            If Not IsDBNull(obyteDB) Then
                'Get image data from DB
                Dim fileData As Byte() = DirectCast(obyteDB, Byte())
                If Not fileData Is Nothing Then
                    _AttachmentByteData = fileData
                Else
                    _AttachmentByteData = Nothing
                End If
            Else
                _AttachmentByteData = Nothing
            End If


        Catch ex As Exception
            _Logger.Warn($"Error in GetEnvelope_Result_FileStreamByte [{ex.Message}]")
            _Logger.Error(ex)
            _AttachmentByteData = Nothing
        End Try
    End Sub
    Private Function CreateTempFileFromByte(ByVal sFileName As String) As String
        Try
            If Not _AttachmentByteData Is Nothing Then
                'Read image data into a file stream 
                Using fs As New FileStream(sFileName, FileMode.OpenOrCreate, FileAccess.Write)
                    fs.Write(_AttachmentByteData, 0, _AttachmentByteData.Length)
                    'Set image variable value using memory stream. 
                    fs.Flush()
                    fs.Close()
                End Using
                'Open File
                Return sFileName
            Else
                _Logger.Warn($"Error in CreateTempFileFromByte - _AttachmentByteData is nothing!")
                Return Nothing
            End If
        Catch ex As Exception
            _Logger.Warn($"Error in CreateTempFileFromByte [{ex.Message}]")
            _Logger.Error(ex)
            Return Nothing
        End Try
    End Function


    Protected Overrides Sub OnStop()
        Try
            _Logger.Warn("Service {0} was stopped.", ServiceName)
            _TempFiles.CleanUp()
        Catch ex As Exception
            _Logger.Warn("Error while stopping service!")
            _Logger.Error(ex)
        End Try
    End Sub
End Class