Imports System.Data.SqlClient

Public Class MSSQLServer
    Private Shared Logger As NLog.Logger = NLog.LogManager.GetCurrentClassLogger
    Public DBInitialized As Boolean = False
    Public CurrentSQLConnectionString As String = ""
    Private CurrentSQLConnection As SqlClient.SqlConnection
    Public Sub New(CONSTRING As String)
        Init(CONSTRING)
    End Sub
    Public Function Init(CONSTRING As String)
        Try
            Dim oSQLconnect As New SqlClient.SqlConnection
            oSQLconnect.ConnectionString = CONSTRING
            oSQLconnect.Open()
            oSQLconnect.Close()
            CurrentSQLConnectionString = CONSTRING
            DBInitialized = True
            Return True
        Catch ex As Exception
            DBInitialized = False
            Logger.Error(ex)
            'clsLogger.Add("Error in DatabaseInit: " & ex.Message, True)
            Return False
        End Try
    End Function
    Private Function GetSQLConnection()
        Try
            If IsNothing(CurrentSQLConnection) Then
                Dim oSQLconnect As New SqlClient.SqlConnection
                oSQLconnect.ConnectionString = CurrentSQLConnectionString
                CurrentSQLConnection = oSQLconnect
                CurrentSQLConnection.Open()

            Else
                If CurrentSQLConnection.State <> ConnectionState.Open Then
                    Logger.Warn($"Actual ConnectionState is: '{CurrentSQLConnection.State.ToString}'")
                    Try
                        CurrentSQLConnection.Open()
                        Return True
                    Catch ex As Exception
                        Logger.Warn("Could not reconnect to database!")
                        Return False
                    End Try
                End If
            End If
            Return True
        Catch ex As Exception
            Logger.Error(ex)
            Return False
        End Try
    End Function
    ''' <summary>
    ''' Returns a datatable for a sql-statement 
    ''' </summary>
    ''' <param name="sqlcommand">sqlcommand for datatable (select XYZ from TableORView)</param>
    ''' <param name="commandtimeout">Optional Timeout</param>
    ''' <returns>Returns a datatable</returns>
    ''' <remarks></remarks>
    Public Function GetDatatable(sqlcommand As String, Optional commandtimeout As Integer = 120) As DataTable
        Try
            Dim dt As DataTable = New DataTable()
            If GetSQLConnection() = False Then
                Return Nothing
            End If

            Dim oSQLCOmmand As SqlClient.SqlCommand

            oSQLCOmmand = CurrentSQLConnection.CreateCommand()
            oSQLCOmmand.CommandText = sqlcommand
            oSQLCOmmand.CommandTimeout = commandtimeout
            Dim adapter1 As SqlClient.SqlDataAdapter = New SqlClient.SqlDataAdapter(oSQLCOmmand)
            adapter1.Fill(dt)

            Return dt
        Catch ex As Exception
            Logger.Error(ex)
            Logger.Debug("sqlcommand: " & sqlcommand)
            Return Nothing
        End Try
    End Function
    ''' <summary>
    ''' Executes the passed sql-statement 
    ''' </summary>
    ''' <param name="executeStatement">the sql statement</param>
    ''' <param name="commandtimeout">Optional Timeout</param>
    ''' <returns>Returns true if properly executed, else false</returns>
    ''' <remarks></remarks>
    Public Function NewExecutenonQuery(executeStatement As String, Optional commandtimeout As Integer = 120) As Boolean
        Try
            If GetSQLConnection() = False Then
                Return Nothing
            End If
            'Dim oSQLconnect As New SqlClient.SqlConnection
            Dim oSQLCOmmand As SqlClient.SqlCommand

            oSQLCOmmand = CurrentSQLConnection.CreateCommand()
            oSQLCOmmand.CommandText = executeStatement
            oSQLCOmmand.CommandTimeout = commandtimeout
            oSQLCOmmand.ExecuteNonQuery()
            oSQLCOmmand.Dispose()
            Return True
        Catch ex As Exception
            Logger.Error(ex)
            Logger.Debug("executeStatement: " & executeStatement)
            Return False
        End Try
    End Function
    ''' <summary>
    ''' Executes the passed sql-statement in asyncmode
    ''' </summary>
    ''' <param name="executeStatement">the sql statement</param>
    ''' <param name="commandtimeout">Optional Timeout</param>
    ''' <remarks></remarks>
    Public Sub NewExecuteNonQueryAsync(executeStatement As String, Optional commandtimeout As Integer = 120)
        If GetSQLConnection() = False Then
            Exit Sub
        End If

        Dim oSQLCOmmand As SqlClient.SqlCommand
        Dim callback As New AsyncCallback(AddressOf Execute_non_Query_Async_Callback)
        Try
            oSQLCOmmand = CurrentSQLConnection.CreateCommand()
            oSQLCOmmand.CommandText = executeStatement
            oSQLCOmmand.CommandTimeout = commandtimeout
            oSQLCOmmand.BeginExecuteNonQuery(callback, oSQLCOmmand)
            oSQLCOmmand.Dispose()
        Catch ex As Exception
            Logger.Error(ex)
            Logger.Debug("executeStatement: " & executeStatement)
        End Try
    End Sub

    Private Sub Execute_non_Query_Async_Callback(ByVal result As IAsyncResult)
        Dim command As SqlClient.SqlCommand = CType(result.AsyncState, SqlClient.SqlCommand)
        Dim res = command.EndExecuteNonQuery(result)
        Logger.Info(String.Format("Finished executing Async database operation: {0}", command.CommandText))
    End Sub
    ''' <summary>
    ''' Executes the passed sql-statement as Scalar
    ''' </summary>
    ''' <param name="executeStatement">the sql statement</param>
    ''' <param name="commandtimeout">Optional Timeout</param>
    ''' <returns>Returns true if properly executed, else false</returns>
    ''' <remarks></remarks>
    Public Function NewExecuteScalar(executeStatement As String, Optional commandtimeout As Integer = 120)
        Dim result
        Try
            If GetSQLConnection() = False Then
                Return Nothing
            End If

            Dim oSQLCOmmand As SqlClient.SqlCommand
            oSQLCOmmand = CurrentSQLConnection.CreateCommand()
            oSQLCOmmand.CommandText = executeStatement
            oSQLCOmmand.CommandTimeout = commandtimeout
            result = oSQLCOmmand.ExecuteScalar()
            oSQLCOmmand.Dispose()
            Return result
        Catch ex As Exception
            Logger.Error(ex)
            Logger.Debug("executeStatement: " & executeStatement)
            Return Nothing
        End Try
    End Function
End Class