///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   Driver.sg
//
//  Note:   The common driver-code for web apps that are compiled to standalone
//          executables
//

using System;
using Microsoft.SingSharp;
using Microsoft.SingSharp.Runtime;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.WebApps;
using Microsoft.Singularity.WebApps.Contracts;
using System.Web;
using System.Threading;

namespace Microsoft.Singularity.WebApps
{
    public class Driver
    {
#if THREAD_POOL
        private const int workerThreads = 16;
        private const int maxWorkItems = workerThreads * 128;
#endif

        internal class ThreadHelper
        {
            private IHttpRequest! m_Request;
            private IWebApp! m_WebApp;

            public ThreadHelper(IWebApp! webApp, IHttpRequest! request)
            {
                m_Request = request;
                m_WebApp = webApp;
            }

            public void Run()
            {
                m_WebApp.ProcessRequest(m_Request);
            }
        }

        public static void ServiceChannel(IWebApp! webApp, WebAppContract.Exp:ProcessingState! conn)
        {
#if THREAD_POOL
            WebAppsThreadPool threadPool =
                new WebAppsThreadPool(workerThreads, maxWorkItems);
#endif

            while (true)
            {
                switch receive
                {
                    case conn.Process(HttpRequestContract.Imp:Start! newConn) :
                    {
                        // Wrap the new connection
                        RemoteHttpRequest request = new RemoteHttpRequest(newConn);
                        ThreadHelper threadHelper = new ThreadHelper(webApp, request);

                        // Service the request on a new thread
#if THREAD_POOL
                        threadPool.QueueUserWorkItem(
                            new ThreadStart(threadHelper.Run));
#else
                        Thread newThread = new Thread(new ThreadStart(threadHelper.Run));
                        newThread.Start();
#endif

                        // Ack
                        conn.SendOK();
                    }
                    break;
                    case conn.ChannelClosed():
                        return;
                }
            }
        }
    }
}