// Displays all contacts and asssociated peer endpoints (PeerEndPoint) in the PeerContactCollection.
   private static void DisplayContacts(PeerContactCollection peerContactsCollection)
   {
       if (peerContactsCollection == null ||
           peerContactsCollection.Count == 0)
       {
           Console.WriteLine("No contacts to display. To add a contact select option 0 from the menu.");
       }
       else
       {
           foreach (PeerContact pc in peerContactsCollection)
           {
               Console.WriteLine("The contact is: {0}", pc.DisplayName);
               DisplayEndpoints(pc.PeerEndPoints);
           }
       }
       return;
   }
   
   //------------------------------------------------------------------------------------------------------
   //------------------------------------------------------------------------------------------------------
   // Displays all peer end points (PeerEndPoint) in the PeerEndPointCollection.

   private static void DisplayEndpoints(PeerEndPointCollection endpointCollection)
   {
       if (endpointCollection == null ||  endpointCollection.Count == 0)
       {
           Console.WriteLine("No peer endpoints in the collection to display.");
       }
       else
       {
           foreach (PeerEndPoint pep in endpointCollection)
           {
               Console.WriteLine("PeerEndPoint is: {0}", pep);
               Console.WriteLine("PeerEndPoint data is:\n  Name: {0}\n EndPoint IP address: {1}\n . Port: {2}\n",
                   pep.Name,
                   pep.EndPoint.Address,
                   pep.EndPoint.Port);
           }
       }
       return;
   }
   
   //------------------------------------------------------------------------------------------------------
   //------------------------------------------------------------------------------------------------------
   //List PeerNearMe objects that may be added as contacts.
   
   private static void AddContact()
   {
       PeerNearMeCollection pnmc = null;
       PeerContactCollection peerContacts = null;            
       bool peerNameFound = false;

       PeerApplication application = null;

       try
       {
           Console.WriteLine("Listing the existing contacts...");
           peerContacts = PeerCollaboration.ContactManager.GetContacts();
       }
       catch (PeerToPeerException p2pEx)
       {
           Console.WriteLine("The Peer Collaboration Infrastructure is not responding to the contact enumeration request: {0}", p2pEx.Message);
       }
       catch (Exception ex)
       {
           Console.WriteLine("An unexpected error occurred while attempting to obtain the contact list: {0}", ex.Message);
       }

       DisplayContacts(peerContacts);

       try
       {
           //Adds one of the PeerNearMe objects as a contact.                               
           pnmc = GetPeersNearMe();
           Console.WriteLine("Please enter the nickname of the peer you wish to add as a contact:");
           string peerNameToAdd = Console.ReadLine();

           application = RegisterCollabApp();

           foreach (PeerNearMe pnm in pnmc)
           {
               PeerInvitationResponse res = null;
               if (pnm.Nickname.Contains(peerNameToAdd))
               {
                   peerNameFound = true;
                   if (!peerContacts.ToString().Contains(pnm.Nickname))
                   {
                       Console.WriteLine("Adding peer {0} to the contact list.", pnm.Nickname);
                       pnm.AddToContactManager();
                   }
                   else
                   {
                       Console.WriteLine("This peer already exists in your contact list.");
                       Console.WriteLine("Sending invitation using the Contact structure instead of the PeerNearMe.");
                       foreach (PeerContact pc in peerContacts)
                       {
                           if (pc.Nickname.Equals(pnm.Nickname))
                           {
                               res = pnm.Invite(application, "Peer Collaboration Sample", application.Data);
                               if (res.PeerInvitationResponseType == PeerInvitationResponseType.Accepted)
                               {
                                   Console.WriteLine("Invitation to contact succeeded.");
                               }
                               else
                               {
                                   Console.WriteLine("Invitation to contact {0}.", res.PeerInvitationResponseType);
                               }
                           }
                       }
                   }
               }
           }

           if (!peerNameFound)
           {
               Console.WriteLine("No such peer exists near you. Cannot add to contacts.");
               return;
           }

           peerContacts = PeerCollaboration.ContactManager.GetContacts();

           Console.WriteLine("Listing the contacts again...");
           DisplayContacts(peerContacts);
       }
       catch (Exception ex)
       {
           Console.WriteLine("Error adding a contact: {0}", ex.Message);
       }
       finally
       {
           application.Dispose();
       }
       return;
   }