////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  Note:
//

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

#if !SINGULARITY_PROCESS
namespace Microsoft.Singularity.Directory
#else
namespace Microsoft.Application.DSP
#endif
{
    // Although there currently are none, there might need to be access control
    // checks at Bind time.  Certainly, the Bind target can do an access check,
    // but the Bind intermediary, here, might also make a check.  See the discussion
    // below.

    public class ProviderNode : Node
    {
        public TRef<ServiceProviderContract.Imp:Start>! ServiceEndpoint;
        private bool isDead;

        public ProviderNode([Claims] ServiceProviderContract.Imp! imp, string! name, Node! parent)
            requires imp.InState(ServiceProviderContract.Start.Value);
        {
            ServiceEndpoint = new TRef<ServiceProviderContract.Imp:Start>(imp);
            isDead = false;
            base(NodeType.ServiceProvider, name, parent);
        }

        public ServiceProviderContract.Imp:Start! GetServiceEndpoint() {
                      return this.ServiceEndpoint.Acquire();
        }

        /// <returns>
        /// null on success, the service argument if it failed.
        /// </returns>
        public override ServiceContract.Exp Bind(StringBuilder! p,
                                                 Principal pr,
                                                 out bool success,
                                                 out bool linkFound,
                                                 out ErrorCode error,
                                                 out bool reparse,
                                                 out string link,
                                                 [Claims]
                                                 ServiceContract.Exp! service)
        {
            Kernel.Waypoint(3100);

            reparse = false;
            link = null;
            success = false;
            linkFound = false;

            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if  it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.NotFound;
                    reparse = true;
                    link = p.ToString();
                    return service;
                }
            }

            // There continues to be an inconsistency here with access control.
            // We might do the access control here on Bind, in which case we know
            // the caller.  However, if we require the access control operation
            // to be done on the other side of the Connect operation, then that
            // code doesn't see the original invoker and moreover there is no
            // appropriate AccessDenied failure on Connect.

            // It seems a little weird to put access controls on the provider
            // node, since such node are transient, but that is perhaps what we
            // should do.

            // If we decide to do ACL checks here, figure out how to get the
            // permissions from the service endpoint!! No access check here until we do.

            //
            //if (!CheckNodeAccess(???, pr, service)) {
            //  DebugStub.WriteLine("No access to bind");
            //  error = ErrorCode.AccessDenied;
            //  return service;
            //}
            //

            lock (this) {
                Kernel.Waypoint(3101);
                if (isDead) {
                    success = false;
                    error = ErrorCode.NotFound;
                    return service;
                }

                ServiceProviderContract.Imp ep = this.ServiceEndpoint.Acquire();
                assert ep.InState(ServiceProviderContract.Start.Value);
                Tracing.Log(Tracing.Debug, "Connecting to Service Provider");
                try {
                    ep.SendConnect(service);
                    switch receive {
                        case ep.AckConnect():
                            success = true;
                            error = ErrorCode.NoError;
                            return null;
                        case ep.NackConnect(rejectedEP):
                            Tracing.Log(Tracing.Debug,"nak connect ");
                            // REVIEW: what should be returned here?
                            error = ErrorCode.ContractNotSupported;
                            return rejectedEP;
                        case ep.ChannelClosed():
                            Tracing.Log(Tracing.Debug,"channel closed");
                            // make this a zombie node
                            isDead = true;
                            error = ErrorCode.ChannelClosed;
                            success = false;
                            return null;
                        case unsatisfiable:
                            Tracing.Log(Tracing.Debug,"Unsatisfiable!!");
                            error = ErrorCode.Unsatisfiable;
                            success = false;
                            return null;
                    }
                }
                finally {
                    this.ServiceEndpoint.Release(ep);
                }
                Kernel.Waypoint(3102);
            } // lock on node
        }

        /// <returns>
        /// null on success, the sp argument if it failed.
        /// </returns>
        public override ServiceProviderContract.Imp Register(StringBuilder! p,
                                      Principal pr,
                                      [Claims]ServiceProviderContract.Imp! sp,
                                      out bool linkFound,
                                      out ErrorCode error,
                                      out bool reparse,
                                      out string link
                                      )
        {
            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if  it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.Unknown;
                    reparse = true;
                    linkFound = false;
                    link = p.ToString();
                    return sp;
                }
            }

            // cannot register over an existing provider
            reparse = false;
            linkFound = false;
            link = null;
            error = ErrorCode.NotSupported;
            return sp;
        }

        /// <returns>
        /// The endpoint on success, null, if it fails.
        /// </returns>
        public override ServiceProviderContract.Imp:Start  Deregister(StringBuilder! p,
                                                               Principal pr,
                                                               DirectoryServiceContract.Exp! ep,
                                                               out bool linkFound,
                                                               out ErrorCode error,
                                                               out bool reparse,
                                                               out string link
                                                               )

        {
            link  = null;
            linkFound = false;
            reparse = false;

            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if  it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.Unknown;
                    reparse = true;
                    linkFound = false;
                    link = p.ToString();
                    return null;
                }
            }

            // Add the following access check on Deregister pursuant on the
            // discussion about access controls on providers above.
            //
            //if (!CheckNodeAccess(DirPermissions.AccessModeDeregister, pr, ep)) {
            //  error = ErrorCode.AccessDenied;
            //  return null;
            //}
            //

            // we are being removed
            error = ErrorCode.NoError;
            return this.ServiceEndpoint.Acquire();
        }


        /// <returns>
        /// if true returns length and node type, otherwise error
        /// </returns>
        public override bool GetAttributes(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link,
                                        out long length,
                                        out NodeType nodeType
                                        )
        {

            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if  it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.Unknown;
                    reparse = true;
                    linkFound = false;
                    length = 0;
                    link = p.ToString();
                    nodeType = NodeType.ServiceProvider;
                    return false;
                }
            }

            linkFound = false;
            reparse = false;
            link = p.ToString();
            nodeType = NodeType.ServiceProvider;
            length = 0;
            error = ErrorCode.Unknown;
            return true;
        }


        /// <returns>
        /// null on success, the imp argument if it failed.
        /// </returns>
        public override NotifyContract.Imp Notify(StringBuilder! p,
                                                  Principal pr,
                                                  string! pattern,
                                                  bool sendExisting,
                                                  out bool linkFound,
                                                  out ErrorCode error,
                                                  out bool reparse,
                                                  out string link,
                                                  [Claims] NotifyContract.Imp! notifyImp)
        {
            linkFound = false;
            error = ErrorCode.NotImplemented;
            reparse = false;
            link = null;

            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if  it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.Unknown;
                    reparse = true;
                    linkFound = false;
                    link = p.ToString();
                    return notifyImp;
                }
            }
            return notifyImp;
        }

        public override FileContract.Imp CreateAndBindFile(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            linkFound = false;
            error = ErrorCode.NotImplemented;
            reparse = false;
            link = null;

            return null;
        }

        private bool CheckForTraverse (StringBuilder! p,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            linkFound = false;
            error = ErrorCode.Unknown;
            reparse = false;
            link = null;

            if (p.Length != 0) {
                if ((p.Length == 1) && (p[0] == '/')) {
                    // pass thru if it is just the delimiter character.
                }
                else {
                    // we have hit a non-leaf service provider
                    // send back a reparse message
                    error = ErrorCode.NoError;
                    reparse = true;
                    linkFound = false;
                    link = p.ToString();
                    if (p[0] == '/') link = link.Substring(1);
                    return false;
                }
            }
            return false;

        }

        public override bool CreateDirectory(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }

        public override bool CreateFile(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }

        public override bool CreateLink(StringBuilder! p,
                                        Principal pr,
                                        string! value,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }
        public override bool DeleteDirectory(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }
        public override bool DeleteFile(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }
        public override bool DeleteLink(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )

        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }

        public override bool GetLinkValue(StringBuilder! p,
                                        Principal pr,
                                        out bool linkFound,
                                        out ErrorCode error,
                                        out bool reparse,
                                        out string link
                                        )

        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }


        public override bool QueryACL(StringBuilder! p,
                                      Principal pr,
                                      out bool linkFound,
                                      out ErrorCode error,
                                      out bool reparse,
                                      out string link,
                                      out Acl acl
                                      )
        {
            acl = new Acl();
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }

        public override bool StoreACL(StringBuilder! p,
                                      Principal pr,
                                      Acl acl,
                                      out bool linkFound,
                                      out ErrorCode error,
                                      out bool reparse,
                                      out string link
                                      )
        {
            return CheckForTraverse(p, out linkFound, out error, out reparse, out link);
        }
    }
}