Imports System
Imports System.IO
Imports Xceed.Zip.ReaderWriter
Namespace RealTimeZipExamples
  Friend Class Examples
    Public Shared Sub TheZipReaderClass()
      ' Pick a zip file
      Dim zipFileName As String = "D:\SomeFolder\SomeZipFile.zip"
      ' Pick a base output folder, taking care not to end it with a directory separator
      Dim unzipToFolder As String = "D:\SomeOtherFolder"
      ' Open the source Zip file
      Using zipFileStream As New FileStream(zipFileName, FileMode.Open, FileAccess.Read)
        ' Create a Zip reader object around the stream.
        ' Remember that ZipReader doesn't close the underlying stream given here
        Using zipReader As New ZipReader(zipFileStream)
          ' Optional. Provide the default password for encrypted items in the archive
          zipReader.EncryptionPassword = "Password"
          ' Optional. Subscribe to available events
          AddHandler zipReader.ByteProgression, AddressOf OnByteProgression
          AddHandler zipReader.InvalidPassword, AddressOf OnInvalidPassword
          Dim zipItemLocalHeader As ZipItemLocalHeader
          ' While the reader finds local headers
          zipItemLocalHeader = zipReader.ReadItemLocalHeader()
          Do While zipItemLocalHeader IsNot Nothing
            ' The 'FileName' property contains the sub-folders and filename
            Dim outputPath As String = unzipToFolder & zipItemLocalHeader.FileName
            Dim outputFolder As String = Path.GetDirectoryName(outputPath)
            ' Make sure the output folder exists
            Directory.CreateDirectory(outputFolder)
            ' If the item isn't a folder entry
            If (Not zipItemLocalHeader.IsFolder) Then
              ' Create/overwrite an output file using our calculated filename
              Using outputFileStream As New FileStream(outputPath, FileMode.Create, FileAccess.Write)
                ' Have the reader read the item data and write it to the stream using a 64K buffer
                zipReader.ReadItemData(outputFileStream, 64 * 1024)
              End Using
            End If
              zipItemLocalHeader = zipReader.ReadItemLocalHeader()
          Loop
          ' Optional. Have the reader give us the zip ending header
          Dim endHeader As ZipEndHeader = zipReader.ReadEndHeader()
          ' If the header contains a global zip comment
          If endHeader IsNot Nothing AndAlso (Not String.IsNullOrEmpty(endHeader.ZipComment)) Then
            ' TODO: Do something with the global zip comment
          End If
        End Using
      End Using
    End Sub
    Private Shared Sub OnInvalidPassword(ByVal sender As Object, ByVal e As ZipReaderInvalidPasswordEventArgs)
      ' TODO: We have access to the current item being unzipped. We can report it's name, etc
      Dim currentItem As ZipItemLocalHeader = e.ZipItemLocalHeader
      ' TODO: We're given the password that failed. We can report it, etc
      Dim oldPassword As String = e.OldPassword
'      If 'e.NewPassword' is set to null or an empty string, or 'e.Abort' is set to true,
'      a ZipReaderException will be thrown for failure to decrypt the item.
'      Since items can't be skipped, the entire unzip process will be canceled.
'       
'      When the event is triggered, 'e.NewPassword' is set to an empty string and 'e.Abort' is set
'      to false.
      ' TODO: We have to supply a new password.
      ' If that new password is invalid, the event will be triggered again
      e.NewPassword = "Some New Password"
      ' TODO: We can ask the entire unzip operation to be aborted
      e.Abort = True
    End Sub
    Private Shared Sub OnByteProgression(ByVal sender As Object, ByVal e As ZipReaderByteProgressionEventArgs)
      ' TODO: We have access to the current item being unzipped. We can report it's name, etc
      Dim currentItem As ZipItemLocalHeader = e.ZipItemLocalHeader
      ' TODO: We're given the current amount of bytes unzipped for the item. We can report it, etc
      Dim bytesProcessed As Long = e.BytesProcessed
'      Do not assume that e.UncompressedSize and e.Percent will contain useful values.
'      Since ZipReader doesn't seek in the archive, it cannot always know the uncompressed
'      size in advance.
    End Sub
  End Class
End Namespace