Imports System.Data.SqlClient

Public Class cSQL

    Public Shared Sub SQL2DS(ByRef selector As String, ByRef ds As DataSet, Optional ByRef DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand
        con.ConnectionString = DBConnect 'Class1.DBConString
        cmd.Connection = con

        Dim dataadapter As New SqlDataAdapter(selector, con)
        con.Open()
        dataadapter.Fill(ds)
        con.Close()
    End Sub

    Sub UpdateDatenbankStruktur()
        Dim conn As New SqlConnection(Class1.DBDoku)
        Dim cmd As New SqlCommand("SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE'", conn)
        conn.Open()
        Dim reader As SqlDataReader = cmd.ExecuteReader()

        While reader.Read()
            Dim tableName As String = reader("TABLE_NAME").ToString()
            Console.WriteLine("CREATE TABLE " & tableName)
            ' Hier kannst du dann den CREATE TABLE Befehl generieren
            UpdateOrCreateTable(Class1.DBDoku, Class1.lokalDBDoku, tableName)
            SyncDatenbank(tableName)
        End While
        conn.Close()

    End Sub
    Sub SyncDatenbank(tabelle As String)
        Dim conn As New SqlConnection(Class1.lokalDBDoku)
        Dim cmd As New SqlCommand($"
        DELETE FROM {tabelle};
        INSERT INTO {tabelle}
        SELECT * FROM [sqlcluster.verag.ost.dmn].doku.dbo.{tabelle};", conn)

        Try
            conn.Open()
            cmd.ExecuteNonQuery()
            conn.Close()
            Console.WriteLine("Datenbank erfolgreich synchronisiert!")
        Catch ex As Exception
            Console.WriteLine("Fehler bei der Synchronisation: " & ex.Message)
        End Try
    End Sub

    Sub UpdateOrCreateTable(sqlServerConnectionString As String, localSqlServerConnectionString As String, tableName As String)
        ' SQL Server-Abfrage für die Spalteninformationen
        Dim query As String = $"SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, IS_NULLABLE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '{tableName}'"
        Dim columnDefinitions As New List(Of String)

        ' Abfrage für die Spaltenstruktur der Remote-Tabelle
        Using con As New SqlConnection(sqlServerConnectionString)
            con.Open()
            Using cmd As New SqlCommand(query, con)
                Using reader As SqlDataReader = cmd.ExecuteReader()
                    While reader.Read()
                        Dim columnName As String = reader("COLUMN_NAME").ToString()
                        Dim dataType As String = reader("DATA_TYPE").ToString()
                        If reader("CHARACTER_MAXIMUM_LENGTH") IsNot DBNull.Value Then
                            dataType &= $"({reader("CHARACTER_MAXIMUM_LENGTH").ToString()})"
                            If dataType = "varchar(-1)" Then dataType = "varchar(max)"
                        End If
                        Dim isNullable As String = If(reader("IS_NULLABLE").ToString() = "YES", "NULL", "NOT NULL")
                        columnDefinitions.Add($"{columnName} {dataType} {isNullable}")
                    End While
                End Using
            End Using
        End Using

        ' Die lokale SQL Server-Datenbank, in der die Tabelle erstellt wird
        Using localSqlCon As New SqlConnection(localSqlServerConnectionString)
            localSqlCon.Open()

            ' Prüfen, ob die Tabelle bereits existiert
            Dim tableExistsQuery As String = $"SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = '{tableName}'"
            Using cmd As New SqlCommand(tableExistsQuery, localSqlCon)
                Dim exists As Object = cmd.ExecuteScalar()
                If exists Is Nothing Then
                    ' Erstelle die Tabelle, wenn sie nicht existiert
                    Dim createTableSQL As String = $"CREATE TABLE {tableName} ({String.Join(", ", columnDefinitions)});"
                    Using createCmd As New SqlCommand(createTableSQL, localSqlCon)
                        createCmd.ExecuteNonQuery()
                    End Using
                Else
                    ' Falls die Tabelle bereits existiert, überprüfe und füge neue Spalten hinzu
                    For Each columnDef In columnDefinitions
                        Dim columnName As String = columnDef.Split(" ")(0)
                        Dim addColumnSQL As String = $"ALTER TABLE {tableName} ADD COLUMN {columnDef};"
                        Try
                            Using alterCmd As New SqlCommand(addColumnSQL, localSqlCon)
                                alterCmd.ExecuteNonQuery()
                            End Using
                        Catch ex As Exception
                            ' Falls die Spalte bereits existiert, wird die Exception ignoriert
                        End Try
                    Next
                End If
            End Using
        End Using
    End Sub

    Public Shared Sub UpdateSQL(ByRef table As String, ByRef values As String, ByRef where As String, Optional ByRef DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand
        con.ConnectionString = DBConnect ' Class1.DBConString
        cmd.Connection = con

        con.Open()
        cmd.CommandText = "UPDATE " & table & " SET " & values & " WHERE " & where & ""
        cmd.ExecuteNonQuery()
        con.Close()
    End Sub
    Public Shared Sub UpdateSQL_(ByVal table As String, ByVal values As Dictionary(Of String, Object), ByVal where As String, Optional ByVal DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString

        Using con As New SqlConnection(DBConnect),
          cmd As New SqlCommand()

            con.Open()
            cmd.Connection = con

            ' Dynamisch SQL-Zeile aufbauen
            Dim setParts As New List(Of String)
            For Each kvp In values
                setParts.Add(kvp.Key & " = @" & kvp.Key)
                cmd.Parameters.AddWithValue("@" & kvp.Key, kvp.Value)
            Next

            cmd.CommandText = $"UPDATE {table} SET {String.Join(", ", setParts)} WHERE {where}"

            cmd.ExecuteNonQuery()
        End Using
    End Sub


    Public Shared Sub InsertSQL(ByRef table As String, ByRef insert As String, Optional ByRef DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand
        con.ConnectionString = DBConnect ' Class1.DBConString
        cmd.Connection = con

        con.Open()
        cmd.CommandText = "INSERT INTO " & table & " " & insert & ""
        cmd.ExecuteNonQuery()
        con.Close()
    End Sub

    Public Shared Sub DeleteSQL(ByRef table As String, ByRef where As String, Optional ByRef DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand
        con.ConnectionString = DBConnect ' Class1.DBConString
        cmd.Connection = con

        con.Open()
        cmd.CommandText = "DELETE FROM " & table & " WHERE " & where & ""
        cmd.ExecuteNonQuery()
        con.Close()
    End Sub

    Public Shared Sub SQLCommand(command As String, Optional ByRef DBConnect As String = "")
        If DBConnect = "" Then DBConnect = Class1.DBConString
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand
        con.ConnectionString = DBConnect ' Class1.DBConString
        cmd.Connection = con

        con.Open()
        cmd.CommandText = command
        cmd.ExecuteNonQuery()
        con.Close()
    End Sub


End Class

Public Class SQLVariable
    Private Text, Value As String
    Private prim As Boolean

    Public Sub New(ByVal btext As String, ByVal bvalue As String, Optional bprim As Boolean = False)
        Me.Value = bvalue
        Me.Text = btext

    End Sub

    Public ReadOnly Property SQLText() As String
        Get
            Return Text
        End Get
    End Property

    Public ReadOnly Property SQLValue() As Object
        Get
            Return value
        End Get
    End Property

End Class