Imports System.Collections.Specialized
Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Windows.Forms
Imports CefSharp
Imports CefSharp.Callback

Public Class ResourceHandler
   Implements IResourceHandler

   Public Const DefaultMimeType As String = "text/html"
   Private tempBuffer As Byte()
   Public Property Charset As String
   Public Property MimeType As String
   Public Property Stream As Stream
   Public Property StatusCode As Integer
   Public Property StatusText As String
   Public Property m_ResponseLength As Long?
   Public Property Headers As NameValueCollection
   Public Property AutoDisposeStream As Boolean
   Public Property ErrorCode As CefErrorCode?
   Private disposedValue As Boolean

   Public Sub New(ByVal Optional mimeType As String = DefaultMimeType, ByVal Optional stream As Stream = Nothing, ByVal Optional autoDisposeStream As Boolean = False, ByVal Optional charset As String = Nothing)
      If String.IsNullOrEmpty(mimeType) Then
         Throw New ArgumentNullException("mimeType", "Please provide a valid mimeType")
      End If

      StatusCode = 200
      StatusText = "OK"
      mimeType = "application/pdf"
      Headers = New NameValueCollection()
      stream = stream
      autoDisposeStream = autoDisposeStream
      charset = charset
      Headers.Add("Access-Control-Allow-Origin", "*")
   End Sub
   Public Sub GetResponseHeaders(response As IResponse, ByRef responseLength As Long, ByRef redirectUrl As String) Implements IResourceHandler.GetResponseHeaders
      redirectUrl = Nothing
      responseLength = -1
      'response.MimeType = MimeType
      response.MimeType = "application/pdf"
      response.StatusCode = StatusCode
      response.StatusText = StatusText
      response.Headers = Headers

      If Not String.IsNullOrEmpty(Charset) Then
         response.Charset = Charset
      End If

      If Not IsNothing(m_ResponseLength) Then
         responseLength = m_ResponseLength
      End If

      If Stream IsNot Nothing AndAlso Stream.CanSeek Then

         If m_ResponseLength Is Nothing OrElse responseLength = 0 Then
            responseLength = Stream.Length
         End If

         Stream.Position = 0
      End If
   End Sub

   Public Sub Cancel() Implements IResourceHandler.Cancel
      Return
   End Sub

   Public Function Open(request As IRequest, ByRef handleRequest As Boolean, callback As ICallback) As Boolean Implements IResourceHandler.Open
      Dim assembly = Reflection.Assembly.GetExecutingAssembly()
      Dim resourceName = "Icarus.Icarus.pdf"

      Stream = assembly.GetManifestResourceStream(resourceName)
      callback.Continue()
      Return True
   End Function

   Public Function ProcessRequest(request As IRequest, callback As ICallback) As Boolean Implements IResourceHandler.ProcessRequest
      Return True
   End Function

   Public Function Skip(bytesToSkip As Long, ByRef bytesSkipped As Long, callback As IResourceSkipCallback) As Boolean Implements IResourceHandler.Skip
      callback.Dispose()

      If Stream Is Nothing OrElse Not Stream.CanSeek Then
         bytesSkipped = -2
         Return False
      End If

      bytesSkipped = bytesToSkip
      Stream.Seek(bytesToSkip, SeekOrigin.Current)
      Return True
   End Function

   Public Function Read(dataOut As Stream, ByRef bytesRead As Integer, callback As IResourceReadCallback) As Boolean Implements IResourceHandler.Read
      bytesRead = 0
      callback.Dispose()

      If Stream Is Nothing Then
         Return False
      End If

      If tempBuffer Is Nothing OrElse tempBuffer.Length < dataOut.Length Then
         tempBuffer = New Byte(dataOut.Length - 1) {}
      End If

      bytesRead = Stream.Read(tempBuffer, 0, CInt(dataOut.Length))

      If bytesRead = 0 Then
         Return False
      End If

      dataOut.Write(tempBuffer, 0, bytesRead)
      Return bytesRead > 0
   End Function

   Public Function ReadResponse(dataOut As Stream, ByRef bytesRead As Integer, callback As ICallback) As Boolean Implements IResourceHandler.ReadResponse
      Throw New NotImplementedException()
   End Function

   Protected Overridable Sub Dispose(disposing As Boolean)
      If Not disposedValue Then
         If disposing Then
            ' TODO: dispose managed state (managed objects)
         End If

         ' TODO: free unmanaged resources (unmanaged objects) and override finalizer
         ' TODO: set large fields to null
         disposedValue = True
      End If
   End Sub

   ' ' TODO: override finalizer only if 'Dispose(disposing As Boolean)' has code to free unmanaged resources
   ' Protected Overrides Sub Finalize()
   '     ' Do not change this code. Put cleanup code in 'Dispose(disposing As Boolean)' method
   '     Dispose(disposing:=False)
   '     MyBase.Finalize()
   ' End Sub

   Public Sub Dispose() Implements IDisposable.Dispose
      ' Do not change this code. Put cleanup code in 'Dispose(disposing As Boolean)' method
      Dispose(disposing:=True)
      GC.SuppressFinalize(Me)
   End Sub
End Class