Zipper

Imports System.IO
Imports System.IO.Compression

Public Class Zipper
    Public Event Progress(percent As Integer)
    Public Event StatusChanged(status As String)
    Public Event Complete()
    Public Event Canceled()

    Public Enum Overwrite
        Always
        Never
    End Enum

    Private _cancel As Boolean

    Public Property Cancel As Boolean
        Get
            Return _cancel
        End Get
        Set(value As Boolean)
            If _cancel = True Then Exit Property
            _cancel = value
        End Set
    End Property

    Private _compression As CompressionLevel
    Public Property CompressionLevel As CompressionLevel
        Get
            Return _compression
        End Get
        Set(value As CompressionLevel)
            _compression = value
        End Set
    End Property

    Private _target As String
    Public Property TargetURL As String
        Get
            Return _target
        End Get
        Set(value As String)
            _target = value
        End Set
    End Property

    Private _source As String
    Public Property SourceURL As String
        Get
            Return _source
        End Get
        Set(value As String)
            _source = value
        End Set
    End Property

    Private _isDir As Boolean
    Public ReadOnly Property SourceIsDirectory
        Get
            Return _isDir
        End Get
    End Property

    Private _includeRootDir As Boolean
    Public Property IncludeRootDir As Boolean
        Get
            Return _includeRootDir
        End Get
        Set(value As Boolean)
            _includeRootDir = value
        End Set
    End Property

    Private _overwrite As Overwrite
    Private _sessionLength As Int64
    Private _sessionFiles As String()
    Private _rootDir As String

    Private Function GetSessionLength() As Int64
        Dim sLen As Int64 = 0
        For Each sessionFile As String In _sessionFiles
            sLen += New FileInfo(sessionFile).Length
            If Cancel = True Then Exit For
        Next
        Return sLen
    End Function

    Private Function GetEntriesLength() As Int64
        Dim sLen As Int64 = _sessionFiles.Sum(Function(file) New FileInfo(file).Length)
        Return sLen
    End Function

    Private Function IsDir(source As String) As Int16
        If File.Exists(source) Then
            Return 0
        ElseIf Directory.Exists(source) Then
            Return -1
        Else
            Return 1
        End If
    End Function

    Private Function InlineAssignHelper(Of T)(ByRef target As T, value As T) As T
        target = value
        Return value
    End Function

    Public Sub Compress(source As String, target As String, compressionLevel As CompressionLevel, overwrite As Overwrite)
        RaiseEvent StatusChanged("Gathering required information")

        _overwrite = False
        _includeRootDir = True
        _target = target
        _compression = compressionLevel
        _cancel = False

        If IsDir(source) <> 1 Then
            _isDir = IsDir(source)
            _source = source
        Else
            Throw New Exception("Source file or directory doesn't exist or cannot be accessed.")
        End If

        If SourceIsDirectory Then
            _sessionFiles = Directory.GetFiles(SourceURL, "*", SearchOption.AllDirectories)
        Else
            _sessionFiles = New String() {SourceURL}
        End If

        RaiseEvent StatusChanged("Examining files")

        _sessionLength = GetSessionLength()

        If SourceIsDirectory And IncludeRootDir = False Then
            _rootDir = SourceURL & "\"
        Else
            _rootDir = String.Join("\", SourceURL.Split("\").ToArray, _
                                   0, SourceURL.Split("\").ToArray.Length - 1) & "\"
        End If

        RaiseEvent StatusChanged("Compressing")

        Try
            Zip()
        Catch ex As Exception
            MsgBox(ex.Message)
            Exit Sub
        End Try

        If Cancel = True Then
            RaiseEvent Canceled()
            RaiseEvent StatusChanged("Cancelled")
            RaiseEvent Progress(100)
        Else
            RaiseEvent Complete()
            RaiseEvent StatusChanged("Complete")
        End If
    End Sub

    Public Sub Decompress(source As String, target As String, overwrite As Overwrite)
        RaiseEvent StatusChanged("Gathering required information")

        _overwrite = overwrite
        _source = source
        _cancel = False
        _target = target

        RaiseEvent StatusChanged("Examining files")

        _sessionLength = GetEntriesLength()

        RaiseEvent StatusChanged("Decompressing")

        Try
            Unzip()
        Catch ex As Exception
            MsgBox(ex.Message)
            Exit Sub
        End Try

        If Cancel = True Then
            RaiseEvent Canceled()
            RaiseEvent StatusChanged("Cancelled")
            RaiseEvent Progress(100)
        Else
            RaiseEvent Complete()
            RaiseEvent StatusChanged("Complete")
        End If
    End Sub

    Private Sub Zip()
        If Cancel = True Then Exit Sub
        Dim blockSizeToRead As Int32 = 1048576 '1Mib Buffer
        Dim buffer As Byte() = New Byte(blockSizeToRead - 1) {}
        Dim bytesRead As Int64, totalBytesRead As Int64
        Dim liveProg As Int16 = 0
        Dim prevProg As Int16 = 0

        If File.Exists(_target) And _overwrite = Overwrite.Never Then
            Throw New Exception("Target file already exists")
        Else
            File.Delete(_target)
        End If

        Using fs As FileStream = New FileStream(_target, FileMode.CreateNew, FileAccess.Write)
            Using archive As ZipArchive = New ZipArchive(fs, ZipArchiveMode.Create)
                Dim entry As ZipArchiveEntry = Nothing
                For Each sessionFile As String In _sessionFiles
                    Try
                        Using reader As FileStream = File.Open(sessionFile, FileMode.Open, FileAccess.Read)
                            entry = archive.CreateEntry(sessionFile.Replace(_rootDir, ""), _compression)
                            Using writer As Stream = entry.Open()
                                While (InlineAssignHelper(bytesRead, _
                                    reader.Read(buffer, 0, buffer.Length - 1))) > 0
                                    writer.Write(buffer, 0, bytesRead)
                                    totalBytesRead += bytesRead
                                    liveProg = CInt((100 / _sessionLength) * totalBytesRead)

                                    If liveProg <> prevProg Then
                                        prevProg = liveProg
                                        RaiseEvent Progress(liveProg)
                                    End If
                                    If Cancel = True Then Exit While
                                End While
                            End Using
                        End Using
                    Catch ex As Exception
                        totalBytesRead += New FileInfo(sessionFile).Length
                        Console.WriteLine(String.Format("Unable to add file to archive: {0} Error:{1}", sessionFile, ex.Message))
                    End Try
                    If Cancel = True Then Exit For
                Next
            End Using
        End Using
        If Cancel = True Then
            File.Delete(_target)
        End If
    End Sub

    Private Sub Unzip()
        If Cancel = True Then Exit Sub
        Dim blockSizeToRead As Int32 = 1048576 '1Mib Buffer
        Dim buffer As Byte() = New Byte(blockSizeToRead - 1) {}
        Dim bytesRead As Int64, totalBytesRead As Int64
        Dim liveProg As Int16 = 0
        Dim prevProg As Int16 = 0

        Using fs As FileStream = New FileStream(_source, FileMode.Open)
            Using archive As ZipArchive = New ZipArchive(fs, ZipArchiveMode.Read)
                For Each entry As ZipArchiveEntry In archive.Entries
                    Dim output As String = String.Format("{0}{1}\{2}", _target, _
                                                            Path.GetFileNameWithoutExtension(_source), _
                                                            entry.FullName.Replace("/", "\"))

                    Dim directoryPath As String = IIf(output.EndsWith("\"), output, Directory.GetParent(output).ToString)

                    If output.EndsWith("\") Then
                        Continue For
                    Else
                        If File.Exists(output) Then
                            Select Case _overwrite
                                Case Overwrite.Always
                                    File.Delete(output)
                                Case Overwrite.Never
                                    Throw New Exception("Target file already exists")
                            End Select
                        End If
                    End If

                    If Directory.Exists(directoryPath) = False Then
                        Directory.CreateDirectory(directoryPath)
                    End If

                    Using reader As Stream = entry.Open()
                        Using writer As FileStream = New FileStream(output, FileMode.Create)
                            While (InlineAssignHelper(bytesRead, reader.Read(buffer, 0, buffer.Length - 1))) > 0
                                writer.Write(buffer, 0, bytesRead)
                                totalBytesRead += bytesRead
                                liveProg = CInt((100 / _sessionLength) * totalBytesRead)
                                If liveProg <> prevProg Then
                                    prevProg = liveProg
                                    RaiseEvent Progress(liveProg)
                                End If
                                If Cancel = True Then Exit While
                            End While
                        End Using
                    End Using
                    If Cancel = True Then Exit For
                Next
            End Using
        End Using
    End Sub
End Class