////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   symlink.sg
//
//  Note:
//
using System;
using System.Runtime.CompilerServices;
using System.Threading;
using Microsoft.Singularity;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.V1.Services;
using Microsoft.Singularity.Channels;

using Microsoft.SingSharp;
using Microsoft.SingSharp.Runtime;
using System.Diagnostics;

using Microsoft.Contracts;
using Microsoft.SingSharp.Reflection;
using Microsoft.Singularity.Applications;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Configuration;
[assembly: Transform(typeof(ApplicationResourceTransform))]

namespace Microsoft.Singularity.Applications {
    [ConsoleCategory(DefaultAction=true)]
    internal class Parameters {
        [InputEndpoint("data")]
        public readonly TRef<UnicodePipeContract.Exp:READY> Stdin;

        [OutputEndpoint("data")]
        public readonly TRef<UnicodePipeContract.Imp:READY> Stdout;

        [Endpoint]
        public readonly TRef<DirectoryServiceContract.Imp:Start> nsRef;

        [StringParameter( "link", Position=0, Mandatory=true)]
        internal string symPath;

        [StringParameter( "value", Position=1, Mandatory=true)]
        internal string symValue;

        reflective internal Parameters();

        internal int AppMain() {
            return SymbolicLink.AppMain(this);
        }
    }

    public class SymbolicLink
    {
        private static int symlink(DirectoryServiceContract.Imp:Ready! rootNS, string! dir, string! name, string! link)
        {
           int result = -1;

            DirectoryServiceContract.Imp! dirImp;
            DirectoryServiceContract.Exp! dirExp;
            DirectoryServiceContract.NewChannel(out dirImp, out dirExp);

            ErrorCode errorOut;
            bool ok = SdsUtils.Bind(dir, rootNS, dirExp, out errorOut);
            if (!ok) {
                Console.WriteLine("Bind of {0} failed. reason: {1}\n",
                                   dir,SdsUtils.ErrorCodeToString(errorOut) );
                delete dirImp;
                return -1;
            }
            else {
                result = 0;
            }

            switch receive {
                case dirImp.Success() :
                    break;
                case dirImp.ChannelClosed() :
                    delete dirImp;
                    return -1;
                    break;
                case unsatisfiable :
                    delete dirImp;
                    return -2;
                    break;
            }


            //Console.WriteLine("creating link in dir "+dir+" with name="+name+" whose value="+link);
            dirImp.SendCreateLink(Bitter.FromString2(name),Bitter.FromString2(link));
            switch receive
            {
                case dirImp.AckCreateLink() :
                    result = 0;
                    break;
                case dirImp.NakCreateLink(error) :
                    DebugStub.Break();
                    break;
                case dirImp.ChannelClosed():
                    throw new Exception("Channel closed unexpectedly");
            }

            delete dirImp;
            return result;
        } //symlink


        private static void tell()
        {
            Console.WriteLine("symlink <link name>  <link value>");
        }

        internal static int AppMain(Parameters! config)
        {

            string[] parts = null;
            //FIXFIX xxx is needed to make null checker happy
            string xxx = config.symPath;
            if (xxx != null)
                parts = xxx.Split('/');

            if ( (parts == null) || (parts.Length == 0) )
            {
                Console.WriteLine(" no delimiter");
                return -1;
            }

            string name = parts[parts.Length-1];
            if ( name == null)
            {
                Console.WriteLine(" no delimiter");
                return -1;
            }
            string dirName = "";
            for (int i = (parts[0] == "") ? 1 : 0;
                i < parts.Length-1; i++) {
                dirName = dirName + "/" + parts[i];
            }

            Console.WriteLine("creating link in dir "+dirName+" with name="+name+" whose value="+config.symValue);

            DirectoryServiceContract.Imp ds = (config.nsRef).Acquire(); 
            if (ds == null) { 
                throw new Exception("Unable to acquire handle to the Directory Service root"); 
            } 
            ds.RecvSuccess();
    
            int status = symlink(ds, dirName, name, config.symValue);
            //Console.WriteLine(args[0] + " returned " + status);
            delete ds;
            return status;
        }
    }//SymbolicLink
}//namespace