////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   FSDirectoryInstanceWorker.sg
//
//  Note:   Handles servicing directory requests for all active directories
//

using System;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Security;
using Microsoft.Singularity;


using Iso9660;

namespace Microsoft.Singularity.FileSystem
{
    public class FSDirectoryInstanceWorker
    {
        private static string location;
        private static bool started = false;
        private static bool terminating = false;
        private static bool success = false;
        private static bool endpointCaptured = false;
        private static bool endpointAvailable = true;
        private static object lockToken = new Object();
        private static Iso9660DirectoryInfo pendingDir;
        private static TRef<DirectoryServiceContract.Exp:Ready>
            pendingEPT = null;
        private static TRef<ThreadPoolControlContract.Imp:Start> signalEPT;
        public  static FSThreadPool threadPool;

        public static bool Start(string mountLocation)
        {
            started = false;
            terminating = false;
            location = mountLocation;
            threadPool =
                new FSThreadPool(1, new FSThreadPoolCallback(ProcessRequest));
            Thread t = new Thread(new ThreadStart(Run));
            t.Start();
            lock (lockToken) {
                while (!started) Monitor.Wait(lockToken);
            }

            return success;
        }

        public static bool TrackEndpoint(
            [Claims] DirectoryServiceContract.Exp:Ready s,
            Iso9660DirectoryInfo dir) {

            Monitoring.Log(Monitoring.Provider.Iso9660,
                (ushort)FileSystemEvent.StartTrackEndpoint);

            lock (lockToken) {
                while (!endpointAvailable && !terminating) {
                    Monitor.Wait(lockToken);
                }
                if (terminating) {
                    delete s;
                    return false;
                }

                endpointAvailable = false;
                endpointCaptured = false;
                pendingDir = dir;
                pendingEPT = new TRef<DirectoryServiceContract.Exp:Ready>(s);
                ThreadPoolControlContract.Imp signalEP = signalEPT.Acquire();
                signalEP.SendTrackEndpoint();
                //signalEP.RecvAckTrackEndpoint();
                while (!endpointCaptured && !terminating) {
                    Monitor.Wait(lockToken);
                }

                endpointAvailable = true;
                Monitor.PulseAll(lockToken);
                if (pendingEPT != null) {
                    signalEPT.Release(signalEP);
                    delete pendingEPT.Acquire();
                    return false;
                }
                else {
                    signalEP.RecvAckTrackEndpoint();
                    signalEPT.Release(signalEP);
                    return true;
                }
            }
            Monitoring.Log(Monitoring.Provider.Iso9660,
                (ushort)FileSystemEvent.StopTrackEndpoint);

        }

        public static void Terminate() {
            lock (lockToken) {
                ThreadPoolControlContract.Imp signalEP = signalEPT.Acquire();
                signalEP.SendTerminate();
                while (!terminating) {
                    Monitor.Wait(lockToken);
                }
                signalEP.RecvAckTerminate();
                started = false;
                delete signalEP;
            }
        }

        // worker thread that actually services requests
        protected static void Run()
        {
            ServiceProviderContract.Imp! spClient;
            ServiceProviderContract.Exp! spServer;
            ServiceProviderContract.NewChannel(out spClient, out spServer);

            DirectoryServiceContract.Imp systemNS = DirectoryService.NewClientEndpoint();
            systemNS.SendRegister(Bitter.FromString2(location), spClient);

            switch receive {
                case systemNS.AckRegister():
                    success = true;
                    break;

                case systemNS.NakRegister(rejected, error):
                    delete rejected;
                    success = false;
                    break;
            }

            delete systemNS;

            lock (lockToken) {
                started = true;
                Monitor.Pulse(lockToken);
            }

            if (!success) {
                delete spServer;
                return;
            }

            EMap<DirectoryServiceContract.Exp:Ready,
                Iso9660DirectoryInfo> dirSet =
                    new EMap<DirectoryServiceContract.Exp:Ready,
                        Iso9660DirectoryInfo>();
            ThreadPoolControlContract.Imp! imp;
            ThreadPoolControlContract.Exp! exp;
            ThreadPoolControlContract.NewChannel(out imp, out exp);
            signalEPT = new TRef<ThreadPoolControlContract.Imp:Start>(imp);
            //EMap<FileContract.Exp:Ready, Iso9660DirectoryInfo> dirSet;

            lock (lockToken) {
                endpointAvailable = true;
                started = true;
                Monitor.Pulse(lockToken);
            }

            for (bool run = true; run;) {
                //dirSet = dirSetT.Acquire();
                byte[] buf;
                switch receive {
                    case spServer.Connect(candidate) :
                        // the directory server is trying to connect
                        // with a DirectoryServiceContract endpoint
                        DirectoryServiceContract.Exp dsClient = candidate as DirectoryServiceContract.Exp;
                        if (null == dsClient) {
                            spServer.SendNackConnect(candidate);
                            break;
                        }
                        spServer.SendAckConnect();
                        dsClient.SendSuccess();
                        dirSet.Add(dsClient, SuperBlock.Root);
                        break;

                    case exp.TrackEndpoint():
                        lock (lockToken) {

                            endpointCaptured = true;
                            if (!terminating) {
                                DirectoryServiceContract.Exp newEP = pendingEPT.Acquire();
                                dirSet.Add(newEP, pendingDir);
                                pendingEPT = null;
                            }
                            exp.SendAckTrackEndpoint();
                            Monitor.PulseAll(lockToken);
                        }
                        break;

                    case exp.Terminate():
                        lock (lockToken) {
                            terminating = true;
                            threadPool.KillPool();
                            Monitor.PulseAll(lockToken);
                        }
                        exp.SendAckTerminate();
                        run = false;
                        break;

                    case ep.Bind(char[]! in ExHeap pathTemp,
                        ServiceContract.Exp:Start! serviceServer) in dirSet~>dir :

                        string path = Bitter.ToString(pathTemp);
                        delete pathTemp;

                        if (path == null) {
                            path = "";
                        }

                        threadPool.EnqueueItem(
                            new FSBindRequestInfo(
                                FSRequestAction.Bind,
                                new TRef<DirectoryServiceContract.Exp:Ready>(ep),
                                new TRef<ServiceContract.Exp:Start>(serviceServer),
                                dir,
                                path));
                        break;
                        
                    case ep.BeginEnumeration()
                        in dirSet~>dir:

                        threadPool.EnqueueItem(
                            new FSDirectoryRequestInfo(
                                FSRequestAction.BeginEnumeration,
                                new TRef<
                                    DirectoryServiceContract.Exp:Ready>(ep),
                                dir,
                                null));
                        break;

                    case ep.GetAttributes(char []! in ExHeap fileNameTemp)
                        in dirSet~>dir:
                        Iso9660FileSystemInfo info;
                        string fileName = Bitter.ToString(fileNameTemp);
                        delete fileNameTemp;

                        threadPool.EnqueueItem(
                            new FSDirectoryRequestInfo(
                                FSRequestAction.GetAttributes,
                                new TRef<DirectoryServiceContract.Exp:Ready>(ep),
                                dir,
                                fileName));
                        break;

                    case ep.ChannelClosed() in dirSet~>dir:
                        delete ep;
                        break;

                    case unsatisfiable:
                        //DebugStub.Print("FSFileWorker shutting down\n");
                        run = false;
                        break;
                        //return;
                }//switch
                //dirSetT.Release(dirSet);
            } //for

            dirSet.Dispose();
            delete exp;
            delete spServer;
        } //run

        protected static void ProcessRequest(FSRequestInfo request) {
            FSDirectoryRequestInfo info;
            DirectoryServiceContract.Exp ep;
            Iso9660FileSystemInfo child;

            switch (request.action) {
                    case FSRequestAction.Bind:

                    Monitoring.Log(Monitoring.Provider.Iso9660,
                        (ushort)FileSystemEvent.StartBind);
                    FSBindRequestInfo bindInfo = (FSBindRequestInfo)request;
                    ep = bindInfo.endpointT.Acquire();
                    Iso9660FileSystemInfo fsInfo = Iso9660FileSystemInfo.InstantiatePath
                                                   (bindInfo.path, bindInfo.startingDir);

                    // This var serves to track whether we have given away the
                    // endpoint or not.
                    ServiceContract.Exp localServiceServer =
                        bindInfo.bindEndpointT.Acquire();

                    if (fsInfo is Iso9660FileInfo) {
                        FileContract.Exp fileServer =
                            localServiceServer as FileContract.Exp;

                        if (fileServer != null) {
                            Iso9660FileStream fileStream =
                                ((Iso9660FileInfo)fsInfo).Open(
                                    System.IO.FileMode.Open,
                                    System.IO.FileAccess.Read);

                            fileServer.SendSuccess();
                            FSFileInstanceWorker.TrackEndpoint(
                                fileServer, fileStream);
                            localServiceServer = null; // Gave it away
                        }
                    }
                    else if (fsInfo is Iso9660DirectoryInfo) {
                        DirectoryServiceContract.Exp dirServer =
                            localServiceServer as DirectoryServiceContract.Exp;

                        if (dirServer != null) {
                            dirServer.SendSuccess();
                            //FSDirectoryInstanceWorker.TrackEndpoint(
                            //    dirServer, (Iso9660DirectoryInfo)fsInfo);
                            TrackEndpoint(dirServer, (Iso9660DirectoryInfo)fsInfo);
                            localServiceServer = null; // Gave it away
                        }
                    }

                    if (localServiceServer == null) { // Did we give it away?
                        // If so, success
                        ep.SendAckBind();
                    }
                    else {
                        // We didn't give it away, so give it back.
                        ep.SendNakBind(localServiceServer, ErrorCode.NotFound);
                    }
                    TrackEndpoint(ep, bindInfo.startingDir);
                    Monitoring.Log(Monitoring.Provider.Iso9660,
                        (ushort)FileSystemEvent.StopBind);
                    break;
                    
                case FSRequestAction.BeginEnumeration :
                    info = (FSDirectoryRequestInfo)request;
                    ep = info.endpointT.Acquire();
                    EnumerationRecords[] in ExHeap responses = null;

                    // use the root
                    ErrorCode errorOut;
                    responses = info.dir.Enumerate(out errorOut);
                    if (null == responses) {
                        ep.SendEnumerationTerminated(errorOut);
                        delete responses;
                    }
                    else {
                        ep.SendEnumerationEntries(responses,false);
                    }
                    TrackEndpoint(ep, info.dir);
                    break;

                case FSRequestAction.GetAttributes:
                    info = (FSDirectoryRequestInfo)request;
                    ep = info.endpointT.Acquire();
                    Iso9660FileSystemInfo file = Iso9660FileSystemInfo.InstantiatePath(info.name, info.dir);
                    if (file == null) {
                    //if (!info.dir.FindChild(info.name, true, out file)) {
                        ep.SendNakGetAttributes(ErrorCode.Unknown);
                    }
                    else {
                        long len = 0;
                        if (file is Iso9660FileInfo) {
#if WHAT_FOR?
                            Iso9660FileStream fileStream =
                            ((Iso9660FileInfo)file).Open(
                                System.IO.FileMode.Open,
                                System.IO.FileAccess.Read);
                            len = fileStream.Length;
#else
                            len = (long)((Iso9660FileInfo)file).size;
#endif
                        }

                        NodeType nodeType = NodeType.File;

                        // Translate flags
                        if ((file.flags & (byte)Iso9660FileFlags.Directory) != 0) {
                            nodeType = NodeType.Directory;
                        }

                        // Unprocessed: System, Archive

                        FileAttributesRecord fileAttributes =
                            new FileAttributesRecord();
                        fileAttributes.FileSize = len;
                        fileAttributes.Type = nodeType;
                        // TODO: FIXFIX what about timestamp info

                        ep.SendAckGetAttributes(fileAttributes);
                    }

                    TrackEndpoint(ep, info.dir);
                    break;

                default:
                    // Should be impossible
                    System.Diagnostics.Debug.Assert(false);
                    break;
            } // switch
        } // ProcessRequest
    } //FSFileWorker class
} //namespace