Imports System.IO
Imports System.Diagnostics
Imports System.Runtime.InteropServices

Public Class clsfilewatcher

    Public WithEvents filetimer As New Timer

    Public Filecollection As New Collection
    Dim FiletimerStoped As Boolean = True
    Public Sub AddFile(ByVal Filenr As Integer, ByVal filename As String, ByVal filedate As DateTime, ByVal indb As Boolean)
        Dim fi As New System.IO.FileInfo(filename)
        Filecollection.Add(New FileToWatch(Filenr, filename, fi.LastWriteTime, indb))
        If FiletimerStoped Then
            filetimer.Start()
            filetimer.Enabled = True
            FiletimerStoped = False
        End If
    End Sub

    Sub New()
        filetimer.Interval = 1000
    End Sub

    Private Sub filetimer_Tick(sender As Object, e As EventArgs) Handles filetimer.Tick
        If Filecollection.Count = 0 Then
            filetimer.Enabled = False
            filetimer.Stop()
            FiletimerStoped = True
        End If
        For i = 1 To Filecollection.Count
            Dim ftw As FileToWatch = Filecollection(i)
            Dim fi As New System.IO.FileInfo(ftw.Filename)
            If IsFileOpen(fi) Then Exit Sub
            Dim finew As New System.IO.FileInfo(ftw.Filename)
            If finew.LastWriteTime > ftw.Filedate Then
                If ftw.InDB = True Then
                    Dim d As New clsDok
                    If d.Save_Document(ftw.FileNr, ftw.Filename) = False Then Exit Sub
                End If
            End If

            Filecollection.Remove(i)
        Next
    End Sub

    Private Function IsFileOpen(ByVal file As FileInfo) As Boolean
        Dim stream As FileStream = Nothing
        Try
            stream = file.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None)
            stream.Close()
            Return False
        Catch ex As Exception
            Return True
            If TypeOf ex Is IOException AndAlso IsFileLocked(ex) Then
                ' do something here, either close the file if you have a handle, show a msgbox, retry  or as a last resort terminate the process - which could cause corruption and lose data
            End If
        End Try
    End Function

    Private Shared Function IsFileLocked(exception As Exception) As Boolean
        Dim errorCode As Integer = Marshal.GetHRForException(exception) And ((1 << 16) - 1)
        Return errorCode = 32 OrElse errorCode = 33
    End Function
End Class

Public Class FileToWatch
    Dim m_filenr As Integer
    Property FileNr As Integer
        Get
            Return m_filenr
        End Get
        Set(value As Integer)
            m_filenr = value
        End Set
    End Property

    Dim m_filename As String
    Property Filename As String
        Get
            Return m_filename
        End Get
        Set(value As String)
            m_filename = value
        End Set
    End Property

    Dim m_filedate As DateTime
    Property Filedate As DateTime
        Get
            Return m_filedate
        End Get
        Set(value As DateTime)
            m_filedate = value
        End Set
    End Property

    Dim m_indb As Boolean
    Property InDB As Boolean
        Get
            Return m_indb
        End Get
        Set(value As Boolean)
            m_indb = value
        End Set
    End Property
    Sub New(ByVal Filenr As Integer, ByVal Filename As String, ByVal filedate As DateTime, ByVal indb As Boolean)
        Me.FileNr = Filenr
        Me.Filename = Filename
        Me.Filedate = filedate
        Me.InDB = indb
    End Sub

End Class