Imports p2pTools
Public Class frmLogin
    Inherits System.Windows.Forms.Form

    Private server As New net.franklins.www.Service1

    Private Sub btnLogIn_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles btnLogIn.Click
        Dim resp As LogInReturn
        Dim bytes() As Byte = server.LogIn(txtUserName.Text, _
            txtPassword.Text)
        resp = CType(Utils.DeSerialize(bytes), LogInReturn)
        _clients = resp.Clients
        _peerid = resp.MyPeerID
        _hash = resp.UserHash
        Me.Hide()
    End Sub

    Private Sub Login_Load(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles MyBase.Load
        server.BeginHello(AddressOf GotResponse, Nothing)
    End Sub

    Private Sub GotResponse(ByVal ar As IAsyncResult)
    End Sub

    Private _hash As String
    Public ReadOnly Property UserHash() As String
        Get
            Return _hash
        End Get
    End Property

    Private _peerid As String
    Public ReadOnly Property PeerID() As String
        Get
            Return _peerid
        End Get
    End Property

    Private _clients As ClientSideUserCollection
    Public ReadOnly Property Clients() As ClientSideUserCollection
        Get
            Return _clients
        End Get
    End Property
End Class

<WebMethod()> Public Function LogIn(ByVal UserName As String, _
  ByVal Password As String) As Byte()

    '-- Do your authentication here

    '-- Does the user already exist?
    If StateManager.ExistsUserName(UserName) Then
        Throw New InvalidOperationException("User already exists")
    End If

    '-- Create a new client
    Dim PeerID As String = StateManager.AddClientAndReturnPeerID(UserName)

    '-- Return the PeerID, to be used for subsequent calls
    Dim resp As New LogInReturn
    resp.MyPeerID = PeerID
    resp.Clients = StateManager.GetClientSideUsers
    resp.UserHash = StateManager.GetHash
    Return Utils.Serialize(resp)
End Function

Public Shared Function AddClientAndReturnPeerID(ByVal UserName _
        As String) As String
    Dim obj As P2PClient
    SyncLock Clients
        obj = Clients.Add
        obj.UserName = UserName
    End SyncLock
    Return obj.PeerID
End Function

<Serializable()> Public Class P2PClient

    Private _peerid As String = Nothing
    Public ReadOnly Property PeerID() As String
        Get
            If _peerid = Nothing Then
                '-- create a random ID
                Dim g As Guid = Guid.NewGuid()
                _peerid = g.ToString
            End If
            Return _peerid
        End Get
    End Property

    '-- More here

End Class

Option Strict On

Imports System.IO
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters.Binary

Public Class Utils
    Public Shared Function Serialize(ByVal Obj As Object) As Byte()
        Dim bf As New BinaryFormatter
        Dim mem As New MemoryStream
        Try
            bf.Serialize(mem, Obj)
        Catch ex As Exception
            Throw ex
        End Try
        Return mem.ToArray
    End Function

    Public Shared Function Deserialize(ByVal bytes() As Byte) As Object
        Dim bf As New BinaryFormatter
        Dim mem As New MemoryStream(bytes)
        Dim obj As Object
        Try
            obj = bf.Deserialize(mem)
        Catch ex As Exception
            Throw ex
        End Try
        Return obj
    End Function
End Class

Public Shared Function GetHash() As String
    '-- return a unique hash string from the usernames and peerids
    Dim ret As String
    SyncLock Clients
        Dim users As ClientSideUserCollection = _
            StateManager.GetClientSideUsers
        Dim bytes() As Byte = Utils.Serialize(users)
        Dim SHA1 As New _
            System.Security.Cryptography.SHA1CryptoServiceProvider
        Dim hash() As Byte = SHA1.ComputeHash(bytes)
        ret = Convert.ToBase64String(hash)
        SHA1.Clear()
    End SyncLock
    Return ret
End Function

Private Sub frmMain_Load(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles MyBase.Load
    Me.Show()

    Dim frm As New frmLogin
    frm.ShowDialog()

    myID = frm.PeerID
    If myID Is Nothing Then Application.Exit()

    clients = frm.Clients
    With lbUsers
        .DataSource = clients
        .DisplayMember = "UserName"
        .ValueMember = "PeerID"
    End With

    server.BeginGetNextMessage(myID, myHash, AddressOf _
        ChatCallback, Nothing)

End Sub

<WebMethod()> Public Function GetNextMessage(ByVal MyPeerID As String) _
        As Byte()
    '-- Does the sender exist?
    Dim resp As New GetNextMessageReturn

    If StateManager.ClientExists(MyPeerID) Then
        resp.Message = StateManager.GetNextMessage(MyPeerID)
        If resp.Message Is Nothing Then
            resp.Response = "No new messages"
        Else
            resp.Response = "OK"
        End If
    Else
        resp.Response = "You must log in first"
    End If
    resp.UserHash = StateManager.GetHash
    Return Utils.Serialize(resp)
End Function

Private Sub ChatCallback(ByVal ar As IAsyncResult)
    Dim bytes() As Byte = server.EndGetNextMessage(ar)
    Dim resp As GetNextMessageReturn = CType(Utils.DeSerialize(bytes), _
        GetNextMessageReturn)
    If resp.Response = "OK" Then
        Dim Msg As String = "<" & resp.Message.FromUserName & "> " & _
            resp.Message.Message
        Dim args() As Object = {Msg}
        Dim dlg As New ShowMessageDelagate(AddressOf ShowMessage)
        Me.Invoke(dlg, args)
    End If
    Thread.Sleep(1000)
    server.BeginGetNextMessage(myID, AddressOf ChatCallback, Nothing)
    If resp.UserHash <> myHash Then
        '-- refresh the user list
        server.BeginGetUsers(AddressOf GetUsersCallback, Nothing)
    End If
End Sub

Public Shared Function GetNextMessage(ByVal ToID As String) As P2PMessage
    Dim msg As P2PMessage
    Dim index As Int32

    '-- Lock the clients collection
    SyncLock Clients
        '-- Retrieve the client object from its ID
        Dim toClient As P2PClient = Clients(ToID)
        If Not toClient Is Nothing Then
            '-- Reset the timestamp for last access
            toClient.LastAccess = Now
            '-- Lock the messages collection
            SyncLock toClient.Messages
                '-- Is there more than one message waiting?
                If toClient.Messages.Count > 0 Then
                    '-- Yes! Skim the first one off
                    msg = toClient.Messages(0).Clone
                    toClient.Messages.RemoveAt(0)
                End If
            End SyncLock
        End If
    End SyncLock
    '-- Return the message (or Nothing)
    Return msg
End Function