///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   DNSExpManager.gs
//  Note:   Provider-side helper for the IP Channel Contract
//

using System.Threading;
using System.Net.IP;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using NetStack.Contracts;
using NetStack.Runtime;
using System.Collections;
using System;

namespace NetStack.Channels.Private
{
    public class DNSExpManager
    {
        public void Run()
        {
            // Here is the channel we use to communicate with
            // the NameServer
            ServiceProviderContract.Imp! nsImp;
            ServiceProviderContract.Exp! nsExp;
            ServiceProviderContract.NewChannel(out nsImp, out nsExp);

            // Here is our NameServer connection over which we
            // receive new client channels. When we become a
            // process, this will be present automatically,
            // somehow.
            DirectoryServiceContract.Imp epNS = DirectoryService.NewClientEndpoint();

            try {
                epNS.SendRegister(Bitter.FromString2(DNSContract.ModuleName), nsImp);

                switch receive {
                    case epNS.AckRegister() :
                        // All is well.
                        break;

                    case epNS.NakRegister(ServiceProviderContract.Imp:Start rejectedEP, error) :
                        // All is very much not well; abort.
                        DebugStub.Print("Failed to register the DNS module.\n");
                        delete rejectedEP;
                        delete nsExp;
                        return;
                        break;
                }
            }
            finally {
                delete epNS;
            }

            while(true) {
                switch receive {
                    case nsExp.Connect(ServiceContract.Exp:Start! newEp) :
                        {
                            // We expect people to give us DNSContract.Exp instances
                            DNSContract.Exp newDnsEp = newEp as DNSContract.Exp;

                            if (newDnsEp == null) {
                                // Invalid contract type. Fail.
                                nsExp.SendNackConnect(newEp);
                            }
                            else {
                                // Signal ready and start servicing this contract
                                nsExp.SendAckConnect();
                                newDnsEp.SendReady();

                                // Spin up a new servicing thread
                                DNSExpConnection newConn = new DNSExpConnection(newDnsEp);
                                newConn.Start();
                            }
                        }
                        break;

                    case nsExp.ChannelClosed():
                        // Exit this thread
                        delete nsExp;
                        return;
                }
            }
        }

        public void Start()
        {
            Thread newThread = new Thread(new ThreadStart(Run));
            newThread.Start();
        }
    }
}