Synnefo » Pithos MS Client

#region

/* -----------------------------------------------------------------------

 * <copyright file="NetworkAgent.cs" company="GRNet">

 * 

 * Copyright 2011-2012 GRNET S.A. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or

 * without modification, are permitted provided that the following

 * conditions are met:

 *

 *   1. Redistributions of source code must retain the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer.

 *

 *   2. Redistributions in binary form must reproduce the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer in the documentation and/or other materials

 *      provided with the distribution.

 *

 *

 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

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 * POSSIBILITY OF SUCH DAMAGE.

 *

 * The views and conclusions contained in the software and

 * documentation are those of the authors and should not be

 * interpreted as representing official policies, either expressed

 * or implied, of GRNET S.A.

 * </copyright>

 * -----------------------------------------------------------------------

 */

#endregion

using System;

using System.Collections.Generic;

using System.ComponentModel.Composition;

using System.Diagnostics;

using System.Diagnostics.Contracts;

using System.IO;

using System.Net;

using System.Reflection;

using System.Threading;

using System.Threading.Tasks;

using Castle.ActiveRecord;

using Pithos.Interfaces;

using Pithos.Network;

using log4net;

namespace Pithos.Core.Agents

{

    [Export]

    public class NetworkAgent

    {

        private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        private Agent<CloudAction> _agent;

        [System.ComponentModel.Composition.Import]

        private DeleteAgent _deleteAgent=new DeleteAgent();

        [System.ComponentModel.Composition.Import]

        public IStatusKeeper StatusKeeper { get; set; }

        public IStatusNotification StatusNotification { get; set; }

        [System.ComponentModel.Composition.Import]

        public IPithosSettings Settings { get; set; }

        //The Proceed signals the poll agent that it can proceed with polling. 

        //Essentially it stops the poll agent to give priority to the network agent

        //Initially the event is signalled because we don't need to pause

        private readonly AsyncManualResetEvent _proceedEvent = new AsyncManualResetEvent(true);

        public AsyncManualResetEvent ProceedEvent

        {

            get { return _proceedEvent; }

        }

        public void Start()

        {

            if (_agent != null)

                return;

            if (Log.IsDebugEnabled)

                Log.Debug("Starting Network Agent");

            _agent = Agent<CloudAction>.Start(inbox =>

            {

                Action loop = null;

                loop = () =>

                {

                    _deleteAgent.ProceedEvent.Wait();

                    var message = inbox.Receive();

                    var process=message.Then(Process,inbox.CancellationToken);

                    inbox.LoopAsync(process, loop);

                };

                loop();

            });

        }

        private async Task Process(CloudAction action)

        {

            if (action == null)

                throw new ArgumentNullException("action");

            if (action.AccountInfo==null)

                throw new ArgumentException("The action.AccountInfo is empty","action");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Operation"].Push(action.ToString()))

            {                

                var cloudFile = action.CloudFile;

                var downloadPath = action.GetDownloadPath();

                try

                {

                    StatusNotification.SetPithosStatus(PithosStatus.LocalSyncing,"Processing");

                    _proceedEvent.Reset();

                    //UpdateStatus(PithosStatus.Syncing);

                    var accountInfo = action.AccountInfo;

                    if (action.Action == CloudActionType.DeleteCloud)

                    {                        

                        //Redirect deletes to the delete agent 

                        _deleteAgent.Post((CloudDeleteAction)action);

                    }

                    if (_deleteAgent.IsDeletedFile(action))

                    {

                        //Clear the status of already deleted files to avoid reprocessing

                        if (action.LocalFile != null)

                            StatusKeeper.ClearFileStatus(action.LocalFile.FullName);

                    }

                    else

                    {

                        switch (action.Action)

                        {

                            case CloudActionType.UploadUnconditional:

                                //Abort if the file was deleted before we reached this point

                                await UploadCloudFile(action);

                                break;

                            case CloudActionType.DownloadUnconditional:

                                await DownloadCloudFile(accountInfo, cloudFile, downloadPath);

                                break;

                            case CloudActionType.RenameCloud:

                                var moveAction = (CloudMoveAction)action;

                                RenameCloudFile(accountInfo, moveAction);

                                break;

                            case CloudActionType.RenameLocal:

                                RenameLocalFile(accountInfo, action);

                                break;

                            case CloudActionType.MustSynch:

                                if (!File.Exists(downloadPath) && !Directory.Exists(downloadPath))

                                {

                                    await DownloadCloudFile(accountInfo, cloudFile, downloadPath);

                                }

                                else

                                {

                                    await SyncFiles(accountInfo, action);

                                }

                                break;

                        }

                    }

                    Log.InfoFormat("End Processing {0}:{1}->{2}", action.Action, action.LocalFile,

                                           action.CloudFile.Name);

                }

                catch (WebException exc)

                {

                    Log.ErrorFormat("[WEB ERROR] {0} : {1} -> {2} due to exception\r\n{3}", action.Action, action.LocalFile, action.CloudFile, exc);

                }

                catch (OperationCanceledException)

                {

                    throw;

                }

                catch (DirectoryNotFoundException)

                {

                    Log.ErrorFormat("{0} : {1} -> {2}  failed because the directory was not found.\n Rescheduling a delete",

                        action.Action, action.LocalFile, action.CloudFile);

                    //Post a delete action for the missing file

                    Post(new CloudDeleteAction(action));

                }

                catch (FileNotFoundException)

                {

                    Log.ErrorFormat("{0} : {1} -> {2}  failed because the file was not found.\n Rescheduling a delete",

                        action.Action, action.LocalFile, action.CloudFile);

                    //Post a delete action for the missing file

                    Post(new CloudDeleteAction(action));

                }

                catch (Exception exc)

                {

                    Log.ErrorFormat("[REQUEUE] {0} : {1} -> {2} due to exception\r\n{3}",

                                     action.Action, action.LocalFile, action.CloudFile, exc);

                    _agent.Post(action);

                }

                finally

                {

                    if (_agent.IsEmpty)

                        _proceedEvent.Set();

                    UpdateStatus(PithosStatus.LocalComplete);                                        

                }

            }

        }

        private void UpdateStatus(PithosStatus status)

        {

            StatusNotification.SetPithosStatus(status);

            //StatusNotification.Notify(new Notification());

        }

        private void RenameLocalFile(AccountInfo accountInfo, CloudAction action)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (action == null)

                throw new ArgumentNullException("action");

            if (action.LocalFile == null)

                throw new ArgumentException("The action's local file is not specified", "action");

            if (!Path.IsPathRooted(action.LocalFile.FullName))

                throw new ArgumentException("The action's local file path must be absolute", "action");

            if (action.CloudFile == null)

                throw new ArgumentException("The action's cloud file is not specified", "action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("RenameLocalFile"))

            {

                //We assume that the local file already exists, otherwise the poll agent

                //would have issued a download request

                var currentInfo = action.CloudFile;

                var previousInfo = action.CloudFile.Previous;

                var fileAgent = FileAgent.GetFileAgent(accountInfo);

                var previousRelativepath = previousInfo.RelativeUrlToFilePath(accountInfo.UserName);

                var previousFile = fileAgent.GetFileSystemInfo(previousRelativepath);

                //In every case we need to move the local file first

                MoveLocalFile(accountInfo, previousFile, fileAgent, currentInfo);

            }

        }

        private void MoveLocalFile(AccountInfo accountInfo, FileSystemInfo previousFile, FileAgent fileAgent,

                                   ObjectInfo currentInfo)

        {

            var currentRelativepath = currentInfo.RelativeUrlToFilePath(accountInfo.UserName);

            var newPath = Path.Combine(fileAgent.RootPath, currentRelativepath);

            var isFile= (previousFile is FileInfo);

            var previousFullPath = isFile? 

                FileInfoExtensions.GetProperFilePathCapitalization(previousFile.FullName):

                FileInfoExtensions.GetProperDirectoryCapitalization(previousFile.FullName);                

            using (var gateOld = NetworkGate.Acquire(previousFullPath, NetworkOperation.Renaming))

            using (var gateNew = NetworkGate.Acquire(newPath,NetworkOperation.Renaming))

            using (new SessionScope(FlushAction.Auto))

            {

                if (isFile)

                    (previousFile as FileInfo).MoveTo(newPath);

                else

                {

                    (previousFile as DirectoryInfo).MoveTo(newPath);

                }

                var state = StatusKeeper.GetStateByFilePath(previousFullPath);

                state.FilePath = newPath;

                state.SaveCopy();

                StatusKeeper.SetFileState(previousFullPath,FileStatus.Deleted,FileOverlayStatus.Deleted);

            }            

        }

        private async Task SyncFiles(AccountInfo accountInfo,CloudAction action)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (action==null)

                throw new ArgumentNullException("action");

            if (action.LocalFile==null)

                throw new ArgumentException("The action's local file is not specified","action");

            if (!Path.IsPathRooted(action.LocalFile.FullName))

                throw new ArgumentException("The action's local file path must be absolute","action");

            if (action.CloudFile== null)

                throw new ArgumentException("The action's cloud file is not specified", "action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("SyncFiles"))

            {

                var localFile = action.LocalFile;

                var cloudFile = action.CloudFile;

                var downloadPath = action.LocalFile.GetProperCapitalization();

                var cloudHash = cloudFile.Hash.ToLower();

                var previousCloudHash = cloudFile.PreviousHash.ToLower();

                var localHash = action.TreeHash.Value.TopHash.ToHashString();// LocalHash.Value.ToLower();

                //var topHash = action.TopHash.Value.ToLower();

                //At this point we know that an object has changed on the server and that a local

                //file already exists. We need to decide whether the file has only changed on 

                //the server or there is a conflicting change on the client.

                //

                //If the hashes match, we are done

                if (cloudHash == localHash)

                {

                    Log.InfoFormat("Skipping {0}, hashes match", downloadPath);

                    return;

                }

                //The hashes DON'T match. We need to sync

                // If the previous tophash matches the local tophash, the file was only changed on the server. 

                if (localHash == previousCloudHash)

                {

                    await DownloadCloudFile(accountInfo, cloudFile, downloadPath);

                }

                else

                {

                    //If the previous and local hash don't match, there was a local conflict

                    //that was not uploaded to the server. We have a conflict

                    ReportConflict(downloadPath);

                }

            }

        }

        private void ReportConflict(string downloadPath)

        {

            if (String.IsNullOrWhiteSpace(downloadPath))

                throw new ArgumentNullException("downloadPath");

            Contract.EndContractBlock();

            StatusKeeper.SetFileOverlayStatus(downloadPath, FileOverlayStatus.Conflict);

            UpdateStatus(PithosStatus.HasConflicts);

            var message = String.Format("Conflict detected for file {0}", downloadPath);

            Log.Warn(message);

            StatusNotification.NotifyChange(message, TraceLevel.Warning);

        }

        public void Post(CloudAction cloudAction)

        {

            if (cloudAction == null)

                throw new ArgumentNullException("cloudAction");

            if (cloudAction.AccountInfo==null)

                throw new ArgumentException("The CloudAction.AccountInfo is empty","cloudAction");

            Contract.EndContractBlock();

            _deleteAgent.ProceedEvent.Wait();

/*

            //If the action targets a local file, add a treehash calculation

            if (!(cloudAction is CloudDeleteAction) && cloudAction.LocalFile as FileInfo != null)

            {

                var accountInfo = cloudAction.AccountInfo;

                var localFile = (FileInfo) cloudAction.LocalFile;

                if (localFile.Length > accountInfo.BlockSize)

                    cloudAction.TopHash =

                        new Lazy<string>(() => Signature.CalculateTreeHashAsync(localFile,

                                                                                accountInfo.BlockSize,

                                                                                accountInfo.BlockHash, Settings.HashingParallelism).Result

                                                    .TopHash.ToHashString());

                else

                {

                    cloudAction.TopHash = new Lazy<string>(() => cloudAction.LocalHash.Value);

                }

            }

            else

            {

                //The hash for a directory is the empty string

                cloudAction.TopHash = new Lazy<string>(() => String.Empty);

            }

*/

            if (cloudAction is CloudDeleteAction)

                _deleteAgent.Post((CloudDeleteAction)cloudAction);

            else

                _agent.Post(cloudAction);

        }

        public IEnumerable<CloudAction> GetEnumerable()

        {

            return _agent.GetEnumerable();

        }

        public Task GetDeleteAwaiter()

        {

            return _deleteAgent.ProceedEvent.WaitAsync();

        }

        public CancellationToken CancellationToken

        {

            get { return _agent.CancellationToken; }

        }

        private static FileAgent GetFileAgent(AccountInfo accountInfo)

        {

            return AgentLocator<FileAgent>.Get(accountInfo.AccountPath);

        }

        private void RenameCloudFile(AccountInfo accountInfo,CloudMoveAction action)

        {

            if (accountInfo==null)

                throw new ArgumentNullException("accountInfo");

            if (action==null)

                throw new ArgumentNullException("action");

            if (action.CloudFile==null)

                throw new ArgumentException("CloudFile","action");

            if (action.LocalFile==null)

                throw new ArgumentException("LocalFile","action");

            if (action.OldLocalFile==null)

                throw new ArgumentException("OldLocalFile","action");

            if (action.OldCloudFile==null)

                throw new ArgumentException("OldCloudFile","action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("RenameCloudFile"))

            {

                var newFilePath = action.LocalFile.FullName;

                //How do we handle concurrent renames and deletes/uploads/downloads?

                //* A conflicting upload means that a file was renamed before it had a chance to finish uploading

                //  This should never happen as the network agent executes only one action at a time

                //* A conflicting download means that the file was modified on the cloud. While we can go on and complete

                //  the rename, there may be a problem if the file is downloaded in blocks, as subsequent block requests for the 

                //  same name will fail.

                //  This should never happen as the network agent executes only one action at a time.

                //* A conflicting delete can happen if the rename was followed by a delete action that didn't have the chance

                //  to remove the rename from the queue.

                //  We can probably ignore this case. It will result in an error which should be ignored            

                //The local file is already renamed

                StatusKeeper.SetFileOverlayStatus(newFilePath, FileOverlayStatus.Modified);

                var account = action.CloudFile.Account ?? accountInfo.UserName;

                var container = action.CloudFile.Container;

                var client = new CloudFilesClient(accountInfo);

                //TODO: What code is returned when the source file doesn't exist?

                client.MoveObject(account, container, action.OldCloudFile.Name, container, action.CloudFile.Name);

                StatusKeeper.SetFileStatus(newFilePath, FileStatus.Unchanged);

                StatusKeeper.SetFileOverlayStatus(newFilePath, FileOverlayStatus.Normal);

                NativeMethods.RaiseChangeNotification(newFilePath);

            }

        }

        //Download a file.

        private async Task DownloadCloudFile(AccountInfo accountInfo, ObjectInfo cloudFile , string filePath)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (cloudFile == null)

                throw new ArgumentNullException("cloudFile");

            if (String.IsNullOrWhiteSpace(cloudFile.Account))

                throw new ArgumentNullException("cloudFile");

            if (String.IsNullOrWhiteSpace(cloudFile.Container))

                throw new ArgumentNullException("cloudFile");

            if (String.IsNullOrWhiteSpace(filePath))

                throw new ArgumentNullException("filePath");

            if (!Path.IsPathRooted(filePath))

                throw new ArgumentException("The filePath must be rooted", "filePath");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("DownloadCloudFile"))

            {

                var localPath = Interfaces.FileInfoExtensions.GetProperFilePathCapitalization(filePath);

                var relativeUrl = new Uri(cloudFile.Name, UriKind.Relative);

                var url = relativeUrl.ToString();

                if (cloudFile.Name.EndsWith(".ignore", StringComparison.InvariantCultureIgnoreCase))

                    return;

                //Are we already downloading or uploading the file? 

                using (var gate = NetworkGate.Acquire(localPath, NetworkOperation.Downloading))

                {

                    if (gate.Failed)

                        return;

                    var client = new CloudFilesClient(accountInfo);

                    var account = cloudFile.Account;

                    var container = cloudFile.Container;

                    if (cloudFile.Content_Type == @"application/directory")

                    {

                        if (!Directory.Exists(localPath))

                            try

                            {

                                Directory.CreateDirectory(localPath);

                                if (Log.IsDebugEnabled)

                                    Log.DebugFormat("Created Directory [{0}]",localPath);

                            }

                            catch (IOException)

                            {

                                var localInfo = new FileInfo(localPath);

                                if (localInfo.Exists && localInfo.Length == 0)

                                {

                                    Log.WarnFormat("Malformed directory object detected for [{0}]",localPath);

                                    localInfo.Delete();

                                    Directory.CreateDirectory(localPath);

                                    if (Log.IsDebugEnabled)

                                        Log.DebugFormat("Created Directory [{0}]", localPath);

                                }

                            }

                    }

                    else

                    {

                        var isChanged = IsObjectChanged(cloudFile, localPath);

                        if (isChanged)

                        {

                            //Retrieve the hashmap from the server

                            var serverHash = await client.GetHashMap(account, container, url);

                            //If it's a small file

                            if (serverHash.Hashes.Count == 1)

                                //Download it in one go

                                await

                                    DownloadEntireFileAsync(accountInfo, client, cloudFile, relativeUrl, localPath,

                                                            serverHash);

                            //Otherwise download it block by block

                            else

                                await

                                    DownloadWithBlocks(accountInfo, client, cloudFile, relativeUrl, localPath,

                                                       serverHash);

                            if (cloudFile.AllowedTo == "read")

                            {

                                var attributes = File.GetAttributes(localPath);

                                File.SetAttributes(localPath, attributes | FileAttributes.ReadOnly);

                            }

                        }

                    }

                    //Now we can store the object's metadata without worrying about ghost status entries

                    StatusKeeper.StoreInfo(localPath, cloudFile);

                }

            }

        }

        private bool IsObjectChanged(ObjectInfo cloudFile, string localPath)

        {

            //If the target is a directory, there are no changes to download

            if (Directory.Exists(localPath))

                return false;

            //If the file doesn't exist, we have a chagne

            if (!File.Exists(localPath)) 

                return true;

            //If there is no stored state, we have a change

            var localState = StatusKeeper.GetStateByFilePath(localPath);

            if (localState == null)

                return true;

            var info = new FileInfo(localPath);

            var shortHash = info.ComputeShortHash();

            //If the file is different from the stored state, we have a change

            if (localState.ShortHash != shortHash)

                return true;

            //If the top hashes differ, we have a change

            return (localState.Checksum != cloudFile.Hash);

        }

        //Download a small file with a single GET operation

        private async Task DownloadEntireFileAsync(AccountInfo accountInfo, CloudFilesClient client, ObjectInfo cloudFile, Uri relativeUrl, string filePath,TreeHash serverHash)

        {

            if (client == null)

                throw new ArgumentNullException("client");

            if (cloudFile==null)

                throw new ArgumentNullException("cloudFile");

            if (relativeUrl == null)

                throw new ArgumentNullException("relativeUrl");

            if (String.IsNullOrWhiteSpace(filePath))

                throw new ArgumentNullException("filePath");

            if (!Path.IsPathRooted(filePath))

                throw new ArgumentException("The localPath must be rooted", "filePath");

            Contract.EndContractBlock();

            var localPath = Pithos.Interfaces.FileInfoExtensions.GetProperFilePathCapitalization(filePath);

            StatusNotification.SetPithosStatus(PithosStatus.LocalSyncing,String.Format("Downloading {0}",Path.GetFileName(localPath)));

            StatusNotification.Notify(new CloudNotification { Data = cloudFile });

            var fileAgent = GetFileAgent(accountInfo);

            //Calculate the relative file path for the new file

            var relativePath = relativeUrl.RelativeUriToFilePath();

            //The file will be stored in a temporary location while downloading with an extension .download

            var tempPath = Path.Combine(fileAgent.CachePath, relativePath + ".download");

            //Make sure the target folder exists. DownloadFileTask will not create the folder

            var tempFolder = Path.GetDirectoryName(tempPath);

            if (!Directory.Exists(tempFolder))

                Directory.CreateDirectory(tempFolder);

            //Download the object to the temporary location

            await client.GetObject(cloudFile.Account, cloudFile.Container, relativeUrl.ToString(), tempPath);

            //Create the local folder if it doesn't exist (necessary for shared objects)

            var localFolder = Path.GetDirectoryName(localPath);

            if (!Directory.Exists(localFolder))

                try

                {

                    Directory.CreateDirectory(localFolder);

                }

                catch (IOException)

                {

                    //A file may already exist that has the same name as the new folder.

                    //This may be an artifact of the way Pithos handles directories

                    var fileInfo = new FileInfo(localFolder);

                    if (fileInfo.Exists && fileInfo.Length == 0)

                    {

                        fileInfo.Delete();

                        Directory.CreateDirectory(localFolder);

                    }

                    else 

                        throw;

                }

            //And move it to its actual location once downloading is finished

            if (File.Exists(localPath))

                File.Replace(tempPath,localPath,null,true);

            else

                File.Move(tempPath,localPath);

            //Notify listeners that a local file has changed

            StatusNotification.NotifyChangedFile(localPath);

        }

        //Download a file asynchronously using blocks

        public async Task DownloadWithBlocks(AccountInfo accountInfo, CloudFilesClient client, ObjectInfo cloudFile, Uri relativeUrl, string filePath, TreeHash serverHash)

        {

            if (client == null)

                throw new ArgumentNullException("client");

            if (cloudFile == null)

                throw new ArgumentNullException("cloudFile");

            if (relativeUrl == null)

                throw new ArgumentNullException("relativeUrl");

            if (String.IsNullOrWhiteSpace(filePath))

                throw new ArgumentNullException("filePath");

            if (!Path.IsPathRooted(filePath))

                throw new ArgumentException("The filePath must be rooted", "filePath");

            if (serverHash == null)

                throw new ArgumentNullException("serverHash");

            Contract.EndContractBlock();

           var fileAgent = GetFileAgent(accountInfo);

            var localPath = Interfaces.FileInfoExtensions.GetProperFilePathCapitalization(filePath);

            //Calculate the relative file path for the new file

            var relativePath = relativeUrl.RelativeUriToFilePath();

            var blockUpdater = new BlockUpdater(fileAgent.CachePath, localPath, relativePath, serverHash);

            StatusNotification.SetPithosStatus(PithosStatus.LocalSyncing,String.Format("Calculating hashmap for {0} before download",Path.GetFileName(localPath)));

            //Calculate the file's treehash

            var treeHash = await Signature.CalculateTreeHashAsync(localPath, serverHash.BlockSize, serverHash.BlockHash, 2);

            //And compare it with the server's hash

            var upHashes = serverHash.GetHashesAsStrings();

            var localHashes = treeHash.HashDictionary;

            ReportDownloadProgress(Path.GetFileName(localPath),0,upHashes.Length,cloudFile.Bytes);

            for (int i = 0; i < upHashes.Length; i++)

            {

                //For every non-matching hash

                var upHash = upHashes[i];

                if (!localHashes.ContainsKey(upHash))

                {

                    StatusNotification.Notify(new CloudNotification { Data = cloudFile });

                    if (blockUpdater.UseOrphan(i, upHash))

                    {

                        Log.InfoFormat("[BLOCK GET] ORPHAN FOUND for {0} of {1} for {2}", i, upHashes.Length, localPath);

                        continue;

                    }

                    Log.InfoFormat("[BLOCK GET] START {0} of {1} for {2}", i, upHashes.Length, localPath);

                    var start = i*serverHash.BlockSize;

                    //To download the last block just pass a null for the end of the range

                    long? end = null;

                    if (i < upHashes.Length - 1 )

                        end= ((i + 1)*serverHash.BlockSize) ;

                    //Download the missing block

                    var block = await client.GetBlock(cloudFile.Account, cloudFile.Container, relativeUrl, start, end);

                    //and store it

                    blockUpdater.StoreBlock(i, block);

                    Log.InfoFormat("[BLOCK GET] FINISH {0} of {1} for {2}", i, upHashes.Length, localPath);

                }

                ReportDownloadProgress(Path.GetFileName(localPath), i, upHashes.Length, cloudFile.Bytes);

            }

            //Want to avoid notifications if no changes were made

            var hasChanges = blockUpdater.HasBlocks;

            blockUpdater.Commit();

            if (hasChanges)

                //Notify listeners that a local file has changed

                StatusNotification.NotifyChangedFile(localPath);

            Log.InfoFormat("[BLOCK GET] COMPLETE {0}", localPath);            

        }

        private async Task UploadCloudFile(CloudAction action)

        {

            if (action == null)

                throw new ArgumentNullException("action");           

            Contract.EndContractBlock();

            using(ThreadContext.Stacks["Operation"].Push("UploadCloudFile"))

            {

                try

                {

                    var accountInfo = action.AccountInfo;

                    var fileInfo = action.LocalFile;

                    if (fileInfo.Extension.Equals("ignore", StringComparison.InvariantCultureIgnoreCase))

                        return;

                    //

                    if (action.FileState == null)

                        action.FileState = StatusKeeper.GetStateByFilePath(fileInfo.FullName);

                    if (action.FileState == null)

                    {

                        Log.WarnFormat("File [{0}] has no local state. It was probably created by a download action",fileInfo.FullName);

                        return;

                    }

                    //Do not upload files in conflict

                    if (action.FileState.FileStatus == FileStatus.Conflict )

                    {

                        Log.InfoFormat("Skipping file in conflict [{0}]",fileInfo.FullName);

                        return;

                    }

                    if (action.FileState.FileStatus == FileStatus.Forbidden)

                    {

                        Log.InfoFormat("Skipping forbidden file [{0}]",fileInfo.FullName);

                        return;

                    }

                    var relativePath = fileInfo.AsRelativeTo(accountInfo.AccountPath);

                    if (relativePath.StartsWith(FolderConstants.OthersFolder))

                    {

                        var parts = relativePath.Split('\\');

                        var accountName = parts[1];

                        var oldName = accountInfo.UserName;

                        var absoluteUri = accountInfo.StorageUri.AbsoluteUri;

                        var nameIndex = absoluteUri.IndexOf(oldName, StringComparison.Ordinal);

                        var root = absoluteUri.Substring(0, nameIndex);

                        accountInfo = new AccountInfo

                                          {

                                              UserName = accountName,

                                              AccountPath = Path.Combine(accountInfo.AccountPath, parts[0], parts[1]),

                                              StorageUri = new Uri(root + accountName),

                                              BlockHash = accountInfo.BlockHash,

                                              BlockSize = accountInfo.BlockSize,

                                              Token = accountInfo.Token

                                          };

                    }

                    var fullFileName = fileInfo.GetProperCapitalization();

                    using (var gate = NetworkGate.Acquire(fullFileName, NetworkOperation.Uploading))

                    {

                        //Abort if the file is already being uploaded or downloaded

                        if (gate.Failed)

                            return;

                        var cloudFile = action.CloudFile;

                        var account = cloudFile.Account ?? accountInfo.UserName;

                        try

                        {

                        var client = new CloudFilesClient(accountInfo);

                        //Even if GetObjectInfo times out, we can proceed with the upload            

                        var cloudInfo = client.GetObjectInfo(account, cloudFile.Container, cloudFile.Name);

                        //If this is a read-only file, do not upload changes

                        if (cloudInfo.AllowedTo == "read")

                            return;

                        //TODO: Check how a directory hash is calculated -> All dirs seem to have the same hash

                            if (fileInfo is DirectoryInfo)

                            {

                                //If the directory doesn't exist the Hash property will be empty

                                if (String.IsNullOrWhiteSpace(cloudInfo.Hash))

                                    //Go on and create the directory

                                    await

                                        client.PutObject(account, cloudFile.Container, cloudFile.Name, fullFileName,

                                                         String.Empty, "application/directory");

                            }

                            else

                            {

                                var cloudHash = cloudInfo.Hash.ToLower();

                                StatusNotification.Notify(new StatusNotification(String.Format("Hashing {0} for Upload",fileInfo.Name)));

                                //TODO: This is the same as the calculation for the Local Hash!

                                //First, calculate the tree hash

/*

                                var treeHash = await Signature.CalculateTreeHashAsync(fullFileName, accountInfo.BlockSize,

                                                                                      accountInfo.BlockHash, 2);

*/

                                var treeHash = action.TreeHash.Value;

                                var topHash = treeHash.TopHash.ToHashString();

                                //var topHash = action.TopHash.Value;

                                //If the file hashes match, abort the upload

                                if (topHash == cloudHash /*|| topHash == cloudHash*/)

                                {

                                    //but store any metadata changes 

                                    StatusKeeper.StoreInfo(fullFileName, cloudInfo);

                                    Log.InfoFormat("Skip upload of {0}, hashes match", fullFileName);

                                    return;

                                }

                                //Mark the file as modified while we upload it

                                StatusKeeper.SetFileOverlayStatus(fullFileName, FileOverlayStatus.Modified);

                                //And then upload it

                                //Upload even small files using the Hashmap. The server may already contain

                                //the relevant block

                                //TODO: If the upload fails with a 403, abort it and mark conflict

                                await

                                    UploadWithHashMap(accountInfo, cloudFile, fileInfo as FileInfo, cloudFile.Name, treeHash);

                            }

                            //If everything succeeds, change the file and overlay status to normal

                            StatusKeeper.SetFileState(fullFileName, FileStatus.Unchanged, FileOverlayStatus.Normal);

                        }

                        catch (WebException exc)

                        {

                            var response=(exc.Response as HttpWebResponse);

                            if (response.StatusCode == HttpStatusCode.Forbidden)

                            {

                                StatusKeeper.SetFileState(fileInfo.FullName,FileStatus.Forbidden, FileOverlayStatus.Conflict);                                

                            }

                        }

                    }

                    //Notify the Shell to update the overlays

                    NativeMethods.RaiseChangeNotification(fullFileName);

                    StatusNotification.NotifyChangedFile(fullFileName);

                }

                catch (AggregateException ex)

                {

                    var exc = ex.InnerException as WebException;

                    if (exc == null)

                        throw ex.InnerException;

                    if (HandleUploadWebException(action, exc))

                        return;

                    throw;

                }

                catch (WebException ex)

                {

                    if (HandleUploadWebException(action, ex))

                        return;

                    throw;

                }

                catch (Exception ex)

                {

                    Log.Error("Unexpected error while uploading file", ex);

                    throw;

                }

            }

        }

        private bool HandleUploadWebException(CloudAction action, WebException exc)

        {

            var response = exc.Response as HttpWebResponse;

            if (response == null)

                throw exc;

            if (response.StatusCode == HttpStatusCode.Unauthorized)

            {

                Log.Error("Not allowed to upload file", exc);

                var message = String.Format("Not allowed to uplad file {0}", action.LocalFile.FullName);

                StatusKeeper.SetFileState(action.LocalFile.FullName, FileStatus.Unchanged, FileOverlayStatus.Normal);

                StatusNotification.NotifyChange(message, TraceLevel.Warning);

                return true;

            }

            return false;

        }

        public async Task UploadWithHashMap(AccountInfo accountInfo,ObjectInfo cloudFile,FileInfo fileInfo,string url,TreeHash treeHash)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (cloudFile==null)

                throw new ArgumentNullException("cloudFile");

            if (fileInfo == null)

                throw new ArgumentNullException("fileInfo");

            if (String.IsNullOrWhiteSpace(url))

                throw new ArgumentNullException(url);

            if (treeHash==null)

                throw new ArgumentNullException("treeHash");

            if (String.IsNullOrWhiteSpace(cloudFile.Container) )

                throw new ArgumentException("Invalid container","cloudFile");

            Contract.EndContractBlock();

            StatusNotification.Notify(new StatusNotification(String.Format("Uploading {0} for Upload", fileInfo.Name)));

            var fullFileName = fileInfo.GetProperCapitalization();

            var account = cloudFile.Account ?? accountInfo.UserName;

            var container = cloudFile.Container ;

            var client = new CloudFilesClient(accountInfo);            

            //Send the hashmap to the server            

            var missingHashes =  await client.PutHashMap(account, container, url, treeHash);

            int block = 0;

            ReportUploadProgress(fileInfo.Name,block++, missingHashes.Count, fileInfo.Length);

            //If the server returns no missing hashes, we are done

            while (missingHashes.Count > 0)

            {

                var buffer = new byte[accountInfo.BlockSize];

                foreach (var missingHash in missingHashes)

                {

                    //Find the proper block

                    var blockIndex = treeHash.HashDictionary[missingHash];

                    var offset = blockIndex*accountInfo.BlockSize;

                    var read = fileInfo.Read(buffer, offset, accountInfo.BlockSize);

                    try

                    {

                        //And upload the block                

                        await client.PostBlock(account, container, buffer, 0, read);

                        Log.InfoFormat("[BLOCK] Block {0} of {1} uploaded", blockIndex, fullFileName);

                    }

                    catch (Exception exc)

                    {

                        Log.Error(String.Format("Uploading block {0} of {1}", blockIndex, fullFileName), exc);

                    }

                    ReportUploadProgress(fileInfo.Name,block++, missingHashes.Count, fileInfo.Length);

                }

                //Repeat until there are no more missing hashes                

                missingHashes = await client.PutHashMap(account, container, url, treeHash);

            }

            ReportUploadProgress(fileInfo.Name, missingHashes.Count, missingHashes.Count, fileInfo.Length);

        }

        private void ReportUploadProgress(string fileName,int block, int totalBlocks, long fileSize)

        {

            StatusNotification.Notify(totalBlocks == 0

                                          ? new ProgressNotification(fileName, "Uploading", 1, 1, fileSize)

                                          : new ProgressNotification(fileName, "Uploading", block, totalBlocks, fileSize));

        }

        private void ReportDownloadProgress(string fileName,int block, int totalBlocks, long fileSize)

        {

            StatusNotification.Notify(totalBlocks == 0

                                          ? new ProgressNotification(fileName, "Downloading", 1, 1, fileSize)

                                          : new ProgressNotification(fileName, "Downloading", block, totalBlocks, fileSize));

        }

    }

}