Option Explicit On

Imports System.Collections.Generic
Imports System.Data
Imports System.IO
Imports System.Linq
Imports DigitalData.Modules.Base
Imports DigitalData.Modules.Config
Imports DigitalData.Modules.Database
Imports DigitalData.Modules.Interfaces
Imports DigitalData.Modules.Jobs.GraphQL
Imports DigitalData.Modules.Logging
Imports Newtonsoft.Json.Linq

Public Class GraphQLJob
    Inherits JobBase
    Implements IJob(Of GraphQLArgs)

    Private _GraphQL As GraphQLInterface = Nothing

    Private Const PLACEHOLDER_STATIC = "STATIC:"
    Private Const JOB_NAME = "GraphQL Job"

    Public Sub New(LogConfig As LogConfig, MSSQL As MSSQLServer)
        MyBase.New(LogConfig, Nothing, MSSQL)
    End Sub

    Public Sub Start(Args As GraphQLArgs) Implements IJob(Of GraphQLArgs).Start
        Try
            Dim oConfigPath As String = Args.QueryConfigPath
            Dim oConfigManager As New ConfigManager(Of GraphQLConfig)(_LogConfig, oConfigPath)

            With oConfigManager.Config
                _GraphQL = New GraphQLInterface(_LogConfig, .BaseUrl, .Email, .Password, .CertificateFingerprint)
            End With

            ' Login to get cookie
            _Logger.Debug("Logging in")
            Dim oLoginResponse = _GraphQL.Login()

            ' save cookie for future requests
            _GraphQL.SaveCookies(oLoginResponse.Cookies.Item(0))

            _Logger.Debug("Loading Queries")

            ' Load query data from TBCUST_JOBRUNNER_QUERY
            Dim oQueryTable As DataTable = _MSSQL.GetDatatable("SELECT * FROM TBCUST_JOBRUNNER_QUERY ORDER BY SEQUENCE")
            Dim oQueryList As New List(Of Query)

            ' Save query data to business objects
            For Each oRow As DataRow In oQueryTable.Rows
                Dim oQuery As New Query With {
                    .Id = oRow.Item("GUID"),
                    .Name = oRow.Item("TITLE"),
                    .ClearBeforeFill = oRow.ItemEx("CLEAR_BEFORE_FILL", False),
                    .ConnectionId = oRow.ItemEx("CON_ID", 1), ' TODO: Connection String?
                    .DestinationTable = oRow.ItemEx("DESTINATION_TABLE", String.Empty),
                    .OperationName = oRow.ItemEx("OPERATION_NAME", String.Empty),
                    .MappingBasePath = oRow.ItemEx("MAPPING_BASE_PATH", String.Empty),
                    .QueryString = oRow.ItemEx("QUERY_STRING", String.Empty)
                }

                If oQuery.DestinationTable = String.Empty Then
                    _Logger.Warn("Value [DestinationTable] could not be read. Configuration incomplete.")
                End If

                If oQuery.OperationName = String.Empty Then
                    _Logger.Warn("Value [OperationName] could not be read. Configuration incomplete.")
                End If

                If oQuery.MappingBasePath = String.Empty Then
                    _Logger.Warn("Value [MappingBasePath] could not be read. Configuration incomplete.")
                End If

                If oQuery.QueryString = String.Empty Then
                    _Logger.Warn("Value [QueryString] could not be read. Configuration incomplete.")
                End If

                oQueryList.Add(oQuery)
            Next

            _Logger.Debug("Running [{0}] queries.", oQueryList.Count)

            ' run
            For Each oQuery As Query In oQueryList
                _Logger.Debug("Running Query [{0}].", oQuery.Name)
                Dim oQueryResult = RunQuery(oQuery)
                _Logger.Info("Query [{0}] finished with Result [{1}]", oQuery.Name, oQueryResult)
            Next

            ' logout
            _Logger.Debug("Logging out")
            Dim oLogoutResponse = _GraphQL.Logout()

            _Logger.Info("Finished GraphQL Job")

        Catch ex As Exception
            _Logger.Warn("Finished GraphQL Job with errors")
            _Logger.Error(ex)
            Throw ex
        End Try
    End Sub

    Private Function RunQuery(pQuery As Query)
        Try
            _Logger.Info("Executing Query [{0}]", pQuery.Name)

            Dim oConnectionId As Integer = pQuery.ConnectionId
            Dim oConnectionString = _MSSQL.Get_ConnectionStringforID(oConnectionId)

            If oConnectionString = String.Empty Then
                _Logger.Warn("Could not get Connection String for ConnectionId [{0}]", oConnectionId)
            End If

            Dim oDatabase As New MSSQLServer(_LogConfig, oConnectionString)

            'TODO: ONly set status when clear before fill is false
            'TODO: ADDED_WHO which contains the query id which inserted the rows

            ' Clear Table before inserting
            If pQuery.ClearBeforeFill = True Then
                If DeleteWithQueryName(pQuery) = False Then
                    Throw New ApplicationException($"Error while dropping history table before fill for Query [{pQuery.Name}]")
                End If

                If CreateHistoryTable(pQuery) = False Then
                    Throw New ApplicationException($"Error while creating history table before fill for Query [{pQuery.Name}]")
                End If
            End If

            ' Reset all records to status = 0
            If pQuery.ClearBeforeFill = False Then
                _Logger.Info("Resetting data for Query [{0}]", pQuery.Name)
                If UpdateWithStatus(pQuery, 0) = False Then
                    Throw New ApplicationException($"Error while resetting status of current Records for Query [{pQuery.Name}]")
                End If
            End If

            ' get the data from GraphQL
            _Logger.Info("Getting data..", pQuery.Name)
            Dim oDataResponse = _GraphQL.GetData(pQuery.QueryString, pQuery.OperationName)
            Dim oResult As String

            ' write data to string
            Using oStream = oDataResponse.GetResponseStream()
                Using oReader As New StreamReader(oStream)
                    oResult = oReader.ReadToEnd()
                End Using
            End Using

            ' Fill the query object with field mapping data from TBCUST_JOBRUNNER_QUERY_MAPPING
            Dim oSQL As String = "SELECT t2.* FROM TBCUST_JOBRUNNER_QUERY_MAPPING t
                                          JOIN TBCUST_JOBRUNNER_MAPPING t2 ON t.MAPPING_ID = t2.GUID
                                          WHERE t.QUERY_ID = {0}"
            Dim oMappingTable As DataTable = _MSSQL.GetDatatable(String.Format(oSQL, pQuery.Id))
            For Each oMapping As DataRow In oMappingTable.Rows
                pQuery.MappingFields.Add(New GraphQL.FieldMapping With {
                    .DestinationColumn = oMapping.Item("DestinationColumn"),
                    .SourcePath = oMapping.Item("SourcePath")
                })
            Next

            ' Handle the response from GraphQL and insert Data
            Dim oWriteDataResult As GraphQL.Query = WriteNewQueryData(oResult, pQuery, oDatabase)

            If IsNothing(oWriteDataResult) Then
                Throw New ApplicationException($"Error while handling Result of Query [{pQuery.Name}]")
            End If

            _Logger.Info("New Data successfully inserted for Query [{0}]", pQuery.Name)

            ' Finally delete all old records
            If pQuery.ClearBeforeFill = False Then
                _Logger.Info("Deleting old records for Query [{0}].", pQuery.Name)
                If DeleteWithStatus(pQuery, 0) = False Then
                    Throw New ApplicationException($"Error while deleting current Records for Query [{pQuery.Name}]")
                End If
            End If

            Return True

        Catch ex As Exception
            _Logger.Warn("Error while getting Data for Name/OperationName [{0}]/[{1}]", pQuery.Name, pQuery.OperationName)
            _Logger.Error(ex)

            ' If a crash happens, delete all records which were inserted in this run,
            ' thus going back to the previous state
            _Logger.Info("Failure, deleting new records..", pQuery.Name)

            If pQuery.ClearBeforeFill = False Then
                If DeleteWithStatus(pQuery, 1) = False Then
                    Throw New ApplicationException($"Error while deleting new Records for Query [{pQuery.Name}]")
                End If
            End If

            Return False

        Finally
            _Logger.Debug("Finished running Query [{0}].", pQuery.Name)
        End Try
    End Function

    Private Function DeleteWithQueryName(pQuery As GraphQL.Query) As Boolean
        Dim oHistoryTableName = $"{pQuery.DestinationTable}_HISTORY"
        Dim oDeleteHistorySQL = $"
            IF (EXISTS (SELECT *
            FROM INFORMATION_SCHEMA.TABLES
            WHERE TABLE_SCHEMA = 'dbo'
            AND TABLE_NAME = '{oHistoryTableName}'))
            BEGIN
            DROP TABLE {oHistoryTableName};
            END"

        Return _MSSQL.ExecuteNonQuery(oDeleteHistorySQL)
    End Function

    Private Function CreateHistoryTable(pQuery As Query) As Boolean
        Dim oHistoryTableName = $"{pQuery.DestinationTable}_HISTORY"
        Dim oFillHistorySQL = $"SELECT * INTO {oHistoryTableName} FROM {pQuery.DestinationTable}"

        Return _MSSQL.ExecuteNonQuery(oFillHistorySQL)
    End Function

    Private Function DeleteWithStatus(pQuery As Query, pStatus As Integer) As Boolean
        Dim oDeleteSQL = $"DELETE FROM {pQuery.DestinationTable} WHERE STATUS = {pStatus} AND ADDED_QUERY_ID = '{pQuery.Id}'"
        Return _MSSQL.ExecuteNonQuery(oDeleteSQL)
    End Function

    Private Function UpdateWithStatus(pQuery As Query, pStatus As Integer)
        Dim oResetSQL = $"UPDATE {pQuery.DestinationTable} SET STATUS = {pStatus} WHERE ADDED_QUERY_ID = '{pQuery.Id}'"
        Return _MSSQL.ExecuteNonQuery(oResetSQL)
    End Function

    Private Function WriteNewQueryData(JsonString As String, QueryData As GraphQL.Query, DB As Database.MSSQLServer) As GraphQL.Query
        Dim oObj As JObject = JObject.Parse(JsonString)
        Dim oResultList As JToken

        If _GraphQL.ReadJSONPathFragmented(oObj, QueryData.MappingBasePath) = False Then
            _Logger.Warn("There is an error in the MappingBasePath [{1}] configuration of query [{0}]", QueryData.Name, QueryData.MappingBasePath)
        End If

        Try
            oResultList = oObj.SelectToken(QueryData.MappingBasePath, errorWhenNoMatch:=True)
        Catch ex As Exception
            _Logger.Warn("WriteNewQueryData: Could not find BasePath: [{0}] for query [{1}]", QueryData.MappingBasePath, QueryData.Name)
            _Logger.Error(ex)
            Return Nothing
        End Try

        If oResultList Is Nothing Then
            _Logger.Warn("WriteNewQueryData: Could not find BasePath: [{0}] for query [{1}]", QueryData.MappingBasePath, QueryData.Name)
            Return Nothing
        End If

        _Logger.Info("WriteNewQueryData: Processing Queue [{0}] with [{1}] Items", QueryData.Name, oResultList.Count)

        For Each oResultItem As JToken In oResultList
            Try
                ' ADDED_WHO, ADDED_QUERY_ID are system fields which are used to correctly fill
                ' and delete rows in the destination table without touching rows from other queries
                Dim oKeys As New List(Of String) From {"ADDED_WHO", "ADDED_QUERY_ID", "STATUS"}
                Dim oValues As New List(Of String) From {JOB_NAME, QueryData.Id, "1"}

                For Each oMapping In QueryData.MappingFields
                    Dim oValue As String = String.Empty

                    If oMapping.SourcePath.StartsWith(PLACEHOLDER_STATIC) Then
                        oValue = oMapping.SourcePath.Replace(PLACEHOLDER_STATIC, String.Empty)
                    Else
                        Dim oToken = oResultItem.SelectToken(oMapping.SourcePath)

                        If oToken Is Nothing Then
                            _Logger.Warn("WriteNewQueryData: Could not find value at SourcePath: {0}", oMapping.SourcePath)
                            oValue = String.Empty
                        Else
                            oValue = oToken.ToString
                        End If
                    End If

                    oValues.Add(oValue)
                    oKeys.Add(oMapping.DestinationColumn)
                Next

                Dim oColumnString = String.Join(",", oKeys.ToArray)

                Dim oValueList = oValues.Select(Function(Value) $"'{Value.EscapeForSQL}'").ToList()
                Dim oValueString = String.Join(",", oValueList)

                Dim oSQL As String = $"INSERT INTO {QueryData.DestinationTable} ({oColumnString}) VALUES ({oValueString})"

                DB.ExecuteNonQuery(oSQL)
            Catch ex As Exception
                _Logger.Error(ex)
            End Try
        Next

        Return QueryData
    End Function

    Public Function ShouldStart(Arguments As GraphQLArgs) As Boolean Implements IJob(Of GraphQLArgs).ShouldStart
        Return Arguments.Enabled
    End Function
End Class