// ----------------------------------------------------------------------------
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ----------------------------------------------------------------------------

          using System;
//using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Test.Contracts;
using Microsoft.Singularity.Xml;

using FileSystem.Utils;
using Microsoft.Singularity.Applications;
using Microsoft.Singularity.Io;
//using System.Collections;

using Microsoft.Singularity.V1.Services;
using Microsoft.SingSharp.Reflection;
using Microsoft.Singularity.Directory;
using Microsoft.Contracts;

namespace Microsoft.Singularity.Applications
{

    public class ProcessLauncher {

        internal static Process CreateSubProcess(
            Parameters! config,
            string[] args
            )
        {
            DirectoryServiceContract.Imp ds = config.nsRef.Acquire();
            if (ds == null) {
                throw new Exception("Unable to acquire handle to the Directory Service root");
            }
            ds.RecvSuccess();

            PipeMultiplexer outputMux = MuxOut();
            if (outputMux == null) {
                delete ds;
                return null;
            }

            Manifest manifest;

            Process child = Binder.CreateProcess(ds, args, outputMux, out manifest);
            if (child == null) {
                Console.WriteLine("Error creating process");
                DebugStub.Print("Error creating process");
                outputMux.Dispose();
                delete ds;
                return null;
            }

            child.Start();

            child.Join();

            outputMux.Dispose();
            delete ds;

            if (null == child) {
                return null;
            }

            // Allow the caller to the get childs exit status
            return child;
        }

        // Redirect our standard output into a multiplexer so we can interleave
        // output from child processes
        static private PipeMultiplexer MuxOut()
        {
            // Swap our real stdOut with a newly created one
            UnicodePipeContract.Exp! newOutputExp;
            UnicodePipeContract.Imp! newOutputImp;
            UnicodePipeContract.NewChannel(out newOutputImp, out newOutputExp);
            UnicodePipeContract.Imp stdOut = ConsoleOutput.Swap(newOutputImp);
            if (stdOut == null) {
                // TODO may not require stdout once we report to debugStub
                Console.WriteLine("test expects a STDOUT pipe");
                delete newOutputExp;
                return null;
            }
            // Use a mux to splice our own output together with the child
            // processes we will run.
            return PipeMultiplexer.Start(stdOut, newOutputExp);
        }
    }
}