Imports NLog
Imports NLog.Config
Imports NLog.Targets
Imports NLog.Targets.Wrappers
Imports NLog.Targets.Wrappers.BufferingTargetWrapperOverflowAction

Imports System.IO

Public Class ClassLogger
    Private Const FileNameFormat As String = "${shortdate}-${var:product}.log"
    Private Const FileNameFormatDetail As String = "${shortdate}-${var:product}-Detail.log"
    Private Const FileNameFormatDebug As String = "${shortdate}-${var:product}-Debug.log"

    Private Const TARGET_DEFAULT As String = "default"
    Private Const TARGET_DEFAULT_EX As String = "defaultEx"
    Private Const TARGET_DETAIL As String = "detail"
    Private Const TARGET_DEBUG As String = "debug"

    Private Const defaultLogFormat As String = "${longdate}|${level:uppercase=true}|${logger}|${message}"
    Private Const exceptionLogFormat As String = "${longdate}|${level:uppercase=true}|${logger}|${message}|${exception:format=message}|${exception:format=toString}"

    Private config As LoggingConfiguration
    Private debugOn As Boolean = False

    Private ReadOnly failSafePath As String = Path.GetTempPath()
    Private ReadOnly basePath As String = failSafePath

    Public Enum PathType As Integer
        AppData = 0
        CurrentDirectory = 1
        CustomPath = 2
    End Enum

    Public LogFile As String


    Public Property Debug As Boolean
        Get
            Return debugOn
        End Get
        Set(value As Boolean)
            If debugOn <> value Then
                debugOn = value

                If value = True Then
                    ActivateDebugLog()
                Else
                    DeactivateDebugLog()
                End If
            End If
        End Set
    End Property

    ''' <summary>
    ''' Initializes a new Logger for a specific "Product"
    ''' </summary>
    ''' <param name="product">An name that identifies the Logs</param>
    ''' <param name="logPath">The basepath to write logs to. Can be AppData, CurrentDirectory or CustomPath.</param>
    ''' <param name="customLogPath">If `logPath` is set to custom, this defines the custom logPath</param>
    Public Sub New(product As String, logPath As PathType, Optional customLogPath As String = Nothing)
        If logPath = PathType.AppData Then
            Dim appDataDir = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)
            basePath = Path.Combine(appDataDir, "Digital Data", product)
        ElseIf logPath = PathType.CurrentDirectory Then
            basePath = "Log"
        Else 'Custom Path
            basePath = customLogPath
        End If

        config = New LoggingConfiguration()
        config.Variables("product") = product

        config.AddTarget(TARGET_DEFAULT_EX, WrapTargetInBuffered(GetDefaultLogTargetWithExceptions(basePath)))
        config.AddTarget(TARGET_DEFAULT, WrapTargetInBuffered(GetDefaultLogTarget(basePath)))
        config.AddTarget(TARGET_DETAIL, WrapTargetInBuffered(GetDetailLogTarget(basePath)))
        config.AddTarget(TARGET_DEBUG, WrapTargetInBuffered(GetDebugLogTarget(basePath)))

        AddDefaultLogTargets()

        LogManager.Configuration = config
    End Sub

    Private Function WrapTargetInBuffered(target As FileTarget) As Target
        Dim bufferedWrapper = New BufferingTargetWrapper()

        bufferedWrapper.WrappedTarget = target

        ' Number of log events to be buffered. When the limit is reached,
        ' then a synchronous flush is performed. 
        bufferedWrapper.BufferSize = 100

        ' Action to be taken when the buffer exceeds the set bufferSize.
        bufferedWrapper.OverflowAction = Flush

        ' Timeout (in milliseconds) after a write, until the entire buffer 
        ' is asynchronously flushed. Use -1 to disable timed flushes. 
        bufferedWrapper.FlushTimeout = 100

        Return bufferedWrapper
    End Function


    Private Sub ActivateDebugLog()
        ' Clear Logging Rules
        config.LoggingRules.Clear()

        ' Add default targets and debug target
        AddDefaultLogTargets()
        config.AddRuleForOneLevel(LogLevel.Debug, TARGET_DEBUG)

        ' Reload all running loggers
        LogManager.ReconfigExistingLoggers()
    End Sub

    Private Sub DeactivateDebugLog()
        ' Clear Logging Rules
        config.LoggingRules.Clear()

        ' Add default targets
        AddDefaultLogTargets()

        ' Reload all running loggers
        LogManager.ReconfigExistingLoggers()
    End Sub

    Private Sub AddDefaultLogTargets()
        config.AddRuleForOneLevel(LogLevel.Error, TARGET_DEFAULT_EX)
        config.AddRuleForOneLevel(LogLevel.Fatal, TARGET_DEFAULT_EX)
        config.AddRuleForOneLevel(LogLevel.Warn, TARGET_DEFAULT)
        config.AddRuleForOneLevel(LogLevel.Info, TARGET_DETAIL)
    End Sub

#Region "Log Targets"
    Private Function GetDefaultLogTarget(basePath As String) As FileTarget
        Dim defaultFilePath As String = Path.Combine(basePath, FileNameFormat)
        Dim defaultLog As New FileTarget() With {
            .FileName = defaultFilePath,
            .Layout = defaultLogFormat,
            .MaxArchiveFiles = 30,
            .KeepFileOpen = True
        }

        Return defaultLog
    End Function
    Private Function GetDefaultLogTargetWithExceptions(basePath As String) As FileTarget
        Dim defaultFilePath As String = Path.Combine(basePath, FileNameFormat)
        Dim defaultLogWithExceptionData As New FileTarget() With {
            .FileName = defaultFilePath,
            .Layout = exceptionLogFormat,
            .MaxArchiveFiles = 30,
            .KeepFileOpen = True
        }

        Return defaultLogWithExceptionData
    End Function
    Private Function GetDetailLogTarget(basePath As String) As FileTarget
        Dim detailFilePath As String = Path.Combine(basePath, FileNameFormatDetail)
        Dim detailLog As New FileTarget() With {
            .FileName = detailFilePath,
            .Layout = defaultLogFormat,
            .MaxArchiveFiles = 1,
            .KeepFileOpen = True
        }

        Return detailLog
    End Function
    Private Function GetDebugLogTarget(basePath As String) As FileTarget
        Dim debugFilePath As String = Path.Combine(basePath, FileNameFormatDebug)
        Dim debugLog As New FileTarget() With {
            .FileName = debugFilePath,
            .Layout = defaultLogFormat,
            .MaxArchiveFiles = 1,
            .KeepFileOpen = True
        }

        Return debugLog
    End Function
#End Region
End Class