//------------------------------------------------------------------------------
//   Copyright (c) Microsoft Corporation. All Rights Reserved.
//------------------------------------------------------------------------------


using System;
using System.Diagnostics;
using System.Globalization;
using System.Reflection;

using Microsoft.Contracts;
using Microsoft.SingSharp.Reflection;
using Microsoft.SingSharp.Runtime;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Applications;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Configuration;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Security;
using Microsoft.Singularity.WebApps.Contracts;
using Microsoft.Singularity.WebHost;

[assembly: Transform(typeof(ApplicationResourceTransform))]
[assembly: ApplicationPublisherAttribute("singularity.microsoft.com")]
[assembly: AssertPrivilegeAttribute("$register-privilege.localhost")]

[assembly: AssemblyProduct("Microsoft Research Singularity Operating System")]
[assembly: AssemblyCompany("Microsoft Corporation")]
[assembly: AssemblyVersion("1.0.0.0")]
[assembly: AssemblyKeyFile("public.snk")]
[assembly: AssemblyDelaySign(true)]

namespace Microsoft.Singularity.WebHost
{
    [ConsoleCategory(HelpMessage="webhost [options] A web server",
                     DefaultAction=true)]
    internal sealed 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("apparg", Default="",
                         HelpMessage="Arg to pass to client app")]
        internal string appArg;

        [StringParameter("app", Mandatory=true, Default="",
                         HelpMessage="Name of the app to run")]
        internal string app;

        [StringParameter("nspath", Mandatory=false, Default="/service/webapp",
                         HelpMessage="NS path to server")]
        internal string nsPath;

        reflective internal Parameters();

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

    public sealed class WebHost
    {
        private static string[] m_childArgs;

        ///////////////////////////////////////////////////////////////////////
        //
        // The code below gets used when this webapp is compiled
        // to a stand-alone executable
        //
        internal static int AppMain(Parameters! config)
        {
            DebugStub.WriteLine("WebHost.AppMain");

            // Start up the webapp so it's ready to respond to requests
            string[] args;

            if (config.appArg != null) {
                args = new string[2];
                args[0] = config.app;
                args[1] = config.appArg;
            }
            else {
                args = new string[1];
                args[0] = config.app;
            }
            m_childArgs = args;

            if (config.nsPath != null) {
                // Publish out connection endpoint.
                DirectoryServiceContract.Imp ds = (config.nsRef).Acquire();
                if (ds == null) {
                    throw new Exception("WebHost: Unable to acquire handle to Directory Service.");
                }
                ds.RecvSuccess();

                ServiceProviderContract.Imp! nsImp;
                ServiceProviderContract.Exp! nsExp;
                ServiceProviderContract.NewChannel(out nsImp, out nsExp);

                try {
                    ds.SendRegister(Bitter.FromString2(config.nsPath), nsImp);

                    switch receive {
                        case ds.AckRegister() :
                            // All is well.
                            break;

                        case ds.NakRegister(ServiceProviderContract.Imp:Start rejectedEP, error) :
                            // All is very much not well; abort.
                            Console.WriteLine("WebHost: Failed to register endpoint as {0}: error {1}.",
                                              config.nsPath, error);
                            delete nsExp;
                            delete rejectedEP;
                            return -1;

                        case ds.ChannelClosed():
                            Console.WriteLine("WebHost: ds channel closed");
                            delete nsExp;
                            return -1;
                    }
                }
                finally {
                    delete ds;
                }

                Console.WriteLine("WebHost: Ready at {0}", config.nsPath);

                // Wait for the web server to bind to us.
                for (;;) {
                    switch receive {
                        // ------------------------------- Requests for new connections

                        case nsExp.Connect(ServiceContract.Exp:Start! newEp):
                            // We expect people to give us WebAppContract.Exp instances
                            WebAppContract.Exp appConnExp = newEp as WebAppContract.Exp;
                            if (appConnExp == null) {
                                // Invalid contract type. Fail.
                                nsExp.SendNackConnect(newEp);
                            }
                            else {
                                // Signal ready and start servicing this contract
                                nsExp.SendAckConnect();

                                Console.WriteLine("WebHost: Starting child.");
                                StartChild(appConnExp);
                            }
                            break;

                        case nsExp.ChannelClosed():
                            // The namespace channel is closed so quit.
                            delete nsExp;
                            return -1;
                    }
                }
                Console.WriteLine("WebHost: Server connected.");
                delete nsExp;
            }
            return 0;
        }

        public static void StartChild([Claims] WebAppContract.Exp:ProcessingState appConnExp)
        {
            Process child = new Process(m_childArgs, (Endpoint * in ExHeap)appConnExp);
            child.Start();
        }
    }
}