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

using System;
using System.IO;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Security;
using Microsoft.Singularity.FileSystem;
using Microsoft.Singularity.Configuration;
using Microsoft.Singularity.ServiceManager;
using Iso9660;

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

namespace Microsoft.Singularity.FileSystem
{
    [Category("Service")]
    internal class ServiceParameters
    {
        [CustomEndpoint]
        public readonly TRef<ServiceProcessContract.Exp:Starting> ControlEndpointRef;
        
        [CustomEndpoint]
        public readonly TRef<ServiceEventContract.Imp:Ready> EventEndpointRef;
        
        reflective internal ServiceParameters();
    }
    
    public class Iso9660Service : ITracked
    {    
        internal static int AppMain(ServiceParameters! parameters) {
        
            ServiceProcessContract.Exp! svcontrol = ((!)parameters.ControlEndpointRef).Acquire();
            ServiceEventContract.Imp! svevent = ((!)parameters.EventEndpointRef).Acquire();

            Iso9660Service service = new Iso9660Service(svcontrol, svevent);
            try {
                service.Run();
            }
            finally {
                service.Dispose();
            }
            return 0;
        }
        
        
        #region Data Fields
        
        private string mountPath;
        
        private bool mounted;
        
        readonly string dbgprefix;

        readonly ServiceProcessContract.Exp! svcontrol;
        readonly ServiceEventContract.Imp! svevent;
            
        readonly ESet<FileSystemControllerContract.Exp:Ready>! controllers =
            new ESet<FileSystemControllerContract.Exp:Ready>();


        readonly ArrayList/*<Iso9660Fs>*/ filesystems = new ArrayList();
            
        #endregion
        
        Iso9660Service(
            [Claims]ServiceProcessContract.Exp! svcontrol,
            [Claims]ServiceEventContract.Imp! svevent)
        {
            this.svcontrol = svcontrol;
            this.svevent = svevent;
            this.dbgprefix = "ISO9660Service: ";
            this.mounted = false;
            this.mountPath = null;
        }
        
        public void Dispose()
        {
            delete controllers;
            delete svcontrol;
            delete svevent;
        }
        
        void Dbg(string! line)
        {
            DebugStub.WriteLine(dbgprefix + line);
        }
        
        void Dbg(string! format, params object[]! args)
        {
            Dbg(String.Format(format, args));
        }

        internal void Run()
        {
            expose (this) {
            
            svcontrol.SendStartSucceeded();

            for (;;) {
                switch receive {
                    case svcontrol.Connect(char[] in ExHeap expath, ServiceContract.Exp:Start! candidate):
                    {
                        if (expath != null) {
                            string! path = Bitter.ToString2(expath);
                            delete expath;
                            Dbg("Received 'Connect' with subpath '{0}'.  This service does not support subpaths; rejecting.", path);
                            svcontrol.SendNakConnect(ErrorCode.NotFound, candidate);
                            break;
                        }
                        
                        FileSystemControllerContract.Exp client = candidate as FileSystemControllerContract.Exp;
                        if (client != null) {
                            Dbg("Received 'Connect' with contract FileSystemControllerContract.");
                            svcontrol.SendAckConnect();
                            client.SendSuccess();
                            controllers.Add(client);
                        }
                        else {
                            Dbg("Received 'Connect', but the client did not provide a supported contract.");
                            svcontrol.SendNakConnect(ErrorCode.ContractNotSupported, candidate);
                        }
                        break;
                    }
                    
                    case svcontrol.Knock():
                        svcontrol.SendAlive();
                        break;
                    
                    case svcontrol.Stop():
                        Dbg("Service Manager has requested that this service stop.");
                        return;
                        
                    case svcontrol.ChannelClosed():
                        Dbg("Service control channel has closed!  Not good!");
                        return;

                    case controller.Mount(char[]! in ExHeap exdevice, char[]! in ExHeap expath) in controllers:
                    {
                        string! device = Bitter.ToString2(exdevice);
                        string! path = Bitter.ToString2(expath);
                        delete exdevice;
                        delete expath;
                        Dbg("Received mount request, device '{0}' mount path '{1}'.", device, path);
                        ErrorCode error = ProcessMountRequest(device, path);
                        if (error == ErrorCode.NoError) {
                            Dbg("Successfully mounted filesystem.");
                            controller.SendOk();
                        }
                        else {
                            Dbg("Failed to mount filesystem.");
                            controller.SendRequestFailed(error);
                        }
                        controllers.Add(controller);
                        break;
                    }
                    
                    case controller.Unmount(char[]! in ExHeap expath) in controllers:
                    {
                        string! path = Bitter.ToString2(expath);
                        delete expath;
                        
                        ErrorCode error = Unmount(path);
                        if (error == ErrorCode.NoError) {
                            controller.SendOk();
                        }
                        else {
                            controller.SendRequestFailed(error);
                        }
                        Dbg("Received request to unmount '{0}'.");
                        
                        controllers.Add(controller);
                        break;
                    }
                        
                    case controller.ChannelClosed() in controllers:
                        Dbg("A controller client has disconnected.");
                        delete controller;
                        break;
                    }
            }
            }
        }

        Iso9660Fs FindFileSystemByMountPath(string! mountPath)
        {
            foreach (Iso9660Fs! fs in filesystems) {
                if (fs.MountPath == mountPath) {
                    return fs;
                }
            }
            
            return null;
        }

        ErrorCode Unmount(string! mountPath)
        {
            Iso9660Fs fs = FindFileSystemByMountPath(mountPath);
            if (fs == null) {
                Dbg("Cannot unmount filesystem at '{0}'; no such filesystem.", mountPath);
                return ErrorCode.NotFound;
            }
                
            
            if (path != mountPath) {
                Dbg("We are not mounted at that location.  Rejecting request.");
                controller.SendRequestFailed(ErrorCode.NotFound);
                controllers.Add(controller);
                break;
            }

            Shutdown();
            Dbg("Filesystem dismounted.");
            mounted = false;
            controller.SendOk();
        }

        ErrorCode ProcessMountRequest(string! device, string! location)
        {
            expose(this)
            {
                if (mounted) {
                    Dbg("This service cannot yet handle more than one volume concurrently.");
                    return ErrorCode.NotSupported;
                }

                long unit = Iso9660.Stdio.RawDevice.LoadDisk(device);
                if (unit < 0) {
                    Dbg("LoadDisk failed with unit = " + unit);
                    return ErrorCode.Unknown;
                }
                
                Dbg("Successfully loaded disk '{0}'.", device);
                Dbg("Reading root...");
                
                byte[] superBlock = new byte[2048];
                Iso9660.Stdio.RawDevice.ReadBlock(superBlock,16);
                // 0x01 + "CD001"
                if (superBlock[0] != (byte)0x01 ||
                    superBlock[1] != (byte)0x43 ||
                    superBlock[2] != (byte)0x44 ||
                    superBlock[3] != (byte)0x30 ||
                    superBlock[4] != (byte)0x30 ||
                    superBlock[5] != (byte)0x31)
                {
                    Dbg("The filesystem does not contain a valid ISO9660 signature of 'CD001'.  Rejecting mount request.");
                    return ErrorCode.Unknown;
                }
                
                //
                //  1. check media & show label
                //
                
                ushort set = ByteArray.ToUshort(superBlock, SuperBlock.SET_SIZE);
                ushort seq = ByteArray.ToUshort(superBlock, SuperBlock.SEQ_NO);
                ushort blk = ByteArray.ToUshort(superBlock, SuperBlock.BLK_SIZE);

                if (set != 1 || seq != 1 || blk != 2048) {
                    Dbg("The disk does not contain a valid ISO9660 superblock.");
                    if (set != 1)
                        Dbg("    The set size is {0}; expected 1.", set);
                    if (seq != 1)
                        Dbg("    The seq size is {0}; expected 1.", seq);
                    if (blk != 1)
                        Dbg("    The block size is {0}; expected 2048.", blk);
                    return ErrorCode.Unknown;
                }
                string label = ByteArray.ToString(superBlock, SuperBlock.LABEL, 32);

                //
                //  2. "unmarshall" & init root
                //
                
                Iso9660DirectoryInfo root = new Iso9660DirectoryInfo();
                root.InitializeMe(superBlock, SuperBlock.ROOT_DIR);
                root.myPrefix = "";
                Dbg("Superblock looks ok.");
                Dbg("Label: '{0}'.", label);
                SuperBlock.root = root;
                

                mountPath = location;
                
                Dbg("Starting file instance worker...");
                FSFileInstanceWorker.Start();

                Dbg("Starting directory instance worker...");
                bool result = FSDirectoryInstanceWorker.Start(location);
                
                if (!result) {
                    Dbg("The directory instance worker failed to initialize.");
                    Shutdown();
                    return ErrorCode.Unknown;
                }
                
                Dbg("done.");
                
                mounted = true;
                return ErrorCode.NoError;
            }
        }
        
        void Shutdown()
        {
            Dbg("Terminating directory instance worker...");
            FSDirectoryInstanceWorker.Terminate();
            Dbg("done.");

            Dbg("Terminating file instance worker...");
            FSFileInstanceWorker.Terminate();
            Dbg("done.");
        }
        
        void ITracked.Expose() {}
        void ITracked.UnExpose() {}
        void ITracked.Acquire() {}
        void ITracked.Release() {}
    }
    
    class Iso9660Fs
    {
        public string! MountPath;
        public string! DevicePath;
        public Process! Process;
        
        public bool IsControlEndpointReady;
        
        public TRef<FileSystemControlContract.Imp> ControlEndpointRef;
    }
}