Imports System
Imports System.IO

Namespace CGS
    ''' <summary>
    ''' Wraps another stream and provides reporting for when bytes are read or written to the stream.
    ''' </summary>
    Public Class ProgressStream
        Inherits Stream
#Region "Private Data Members"
        Private innerStream As Stream
#End Region

#Region "Constructor"
        ''' <summary>
        ''' Creates a new ProgressStream supplying the stream for it to report on.
        ''' </summary>
        ''' <param name="streamToReportOn">The underlying stream that will be reported on when bytes are read or written.</param>
        Public Sub New(ByVal streamToReportOn As Stream)
            If streamToReportOn IsNot Nothing Then
                Me.innerStream = streamToReportOn
            Else
                Throw New ArgumentNullException("streamToReportOn")
            End If
        End Sub
#End Region

#Region "Events"
        ''' <summary>
        ''' Raised when bytes are read from the stream.
        ''' </summary>
        Public Event BytesRead As ProgressStreamReportDelegate

        ''' <summary>
        ''' Raised when bytes are written to the stream.
        ''' </summary>
        Public Event BytesWritten As ProgressStreamReportDelegate

        ''' <summary>
        ''' Raised when bytes are either read or written to the stream.
        ''' </summary>
        Public Event BytesMoved As ProgressStreamReportDelegate

        Protected Overridable Sub OnBytesRead(ByVal bytesMoved As Integer)
            Dim args = New ProgressStreamReportEventArgs(bytesMoved, innerStream.Length, innerStream.Position, True)
            RaiseEvent BytesRead(Me, args)
        End Sub

        Protected Overridable Sub OnBytesWritten(ByVal bytesMoved As Integer)
            Dim args = New ProgressStreamReportEventArgs(bytesMoved, innerStream.Length, innerStream.Position, False)
            RaiseEvent BytesRead(Me, args)
        End Sub

        Protected Overridable Sub OnBytesMoved(ByVal bytesMoved__1 As Integer, ByVal isRead As Boolean)
            Dim args = New ProgressStreamReportEventArgs(bytesMoved__1, innerStream.Length, innerStream.Position, isRead)
            RaiseEvent BytesRead(Me, args)
        End Sub
#End Region

#Region "Stream Members"

        Public Overloads Overrides ReadOnly Property CanRead() As Boolean
            Get
                Return innerStream.CanRead
            End Get
        End Property

        Public Overloads Overrides ReadOnly Property CanSeek() As Boolean
            Get
                Return innerStream.CanSeek
            End Get
        End Property

        Public Overloads Overrides ReadOnly Property CanWrite() As Boolean
            Get
                Return innerStream.CanWrite
            End Get
        End Property

        Public Overloads Overrides Sub Flush()
            innerStream.Flush()
        End Sub

        Public Overloads Overrides ReadOnly Property Length() As Long
            Get
                Return innerStream.Length
            End Get
        End Property

        Public Overloads Overrides Property Position() As Long
            Get
                Return innerStream.Position
            End Get
            Set(ByVal value As Long)
                innerStream.Position = value
            End Set
        End Property

        Public Overloads Overrides Function Read(ByVal buffer As Byte(), ByVal offset As Integer, ByVal count As Integer) As Integer
            Dim bytesRead = innerStream.Read(buffer, offset, count)

            OnBytesRead(bytesRead)
            OnBytesMoved(bytesRead, True)

            Return bytesRead
        End Function

        Public Overloads Overrides Function Seek(ByVal offset As Long, ByVal origin As SeekOrigin) As Long
            Return innerStream.Seek(offset, origin)
        End Function

        Public Overloads Overrides Sub SetLength(ByVal value As Long)
            innerStream.SetLength(value)
        End Sub

        Public Overloads Overrides Sub Write(ByVal buffer As Byte(), ByVal offset As Integer, ByVal count As Integer)
            innerStream.Write(buffer, offset, count)

            OnBytesWritten(count)
            OnBytesMoved(count, False)
        End Sub

        Public Overloads Overrides Sub Close()
            innerStream.Close()
            MyBase.Close()
        End Sub
#End Region
    End Class

    ''' <summary>
    ''' Contains the pertinent data for a ProgressStream Report event.
    ''' </summary>
    Public Class ProgressStreamReportEventArgs
        Inherits EventArgs
        ''' <summary>
        ''' The number of bytes that were read/written to/from the stream.
        ''' </summary>
        Private _BytesMoved As Integer
        Public Property BytesMoved() As Integer
            Get
                Return _BytesMoved
            End Get
            Private Set(ByVal value As Integer)
                _BytesMoved = value
            End Set
        End Property

        ''' <summary>
        ''' The total length of the stream in bytes.
        ''' </summary>
        Private _StreamLength As Long
        Public Property StreamLength() As Long
            Get
                Return _StreamLength
            End Get
            Private Set(ByVal value As Long)
                _StreamLength = value
            End Set
        End Property

        ''' <summary>
        ''' The current position in the stream.
        ''' </summary>
        Private _StreamPosition As Long
        Public Property StreamPosition() As Long
            Get
                Return _StreamPosition
            End Get
            Private Set(ByVal value As Long)
                _StreamPosition = value
            End Set
        End Property

        ''' <summary>
        ''' True if the bytes were read from the stream, false if they were written.
        ''' </summary>
        Private _WasRead As Boolean
        Public Property WasRead() As Boolean
            Get
                Return _WasRead
            End Get
            Private Set(ByVal value As Boolean)
                _WasRead = value
            End Set
        End Property

        ''' <summary>
        ''' Default constructor for ProgressStreamReportEventArgs.
        ''' </summary>
        Public Sub New()
            MyBase.New()
        End Sub

        ''' <summary>
        ''' Creates a new ProgressStreamReportEventArgs initializing its members.
        ''' </summary>
        ''' <param name="bytesMoved">The number of bytes that were read/written to/from the stream.</param>
        ''' <param name="streamLength">The total length of the stream in bytes.</param>
        ''' <param name="streamPosition">The current position in the stream.</param>
        ''' <param name="wasRead">True if the bytes were read from the stream, false if they were written.</param>
        Public Sub New(ByVal bytesMoved As Integer, ByVal streamLength As Long, ByVal streamPosition As Long, ByVal wasRead__1 As Boolean)
            Me.New()
            Me.BytesMoved = bytesMoved
            Me.StreamLength = streamLength
            Me.StreamPosition = streamPosition
            Me.WasRead = WasRead
        End Sub
    End Class

    ''' <summary>
    ''' The delegate for handling a ProgressStream Report event.
    ''' </summary>
    ''' <param name="sender">The object that raised the event, should be a ProgressStream.</param>
    ''' <param name="args">The arguments raised with the event.</param>
    Public Delegate Sub ProgressStreamReportDelegate(ByVal sender As Object, ByVal args As ProgressStreamReportEventArgs)
End Namespace