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// -----------------------------------------------------------------------

// <copyright file="WorkflowAgent.cs" company="GRNET">

// Copyright 2011 GRNET S.A. All rights reserved.

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

// without modification, are permitted provided that the following

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//   2. Redistributions in binary form must reproduce the above

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

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// -----------------------------------------------------------------------

using System;

using System.Collections.Generic;

using System.ComponentModel.Composition;

using System.Diagnostics;

using System.Diagnostics.Contracts;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using Pithos.Interfaces;

using Pithos.Network;

using log4net;

namespace Pithos.Core.Agents

{

    [Export]

    public class WorkflowAgent

    {

        Agent<WorkflowState> _agent;

        public IStatusNotification StatusNotification { get; set; }

        [Import]

        public IStatusKeeper StatusKeeper { get; set; }

        [Import]

        public NetworkAgent NetworkAgent { get; set; }

        private static readonly ILog Log = LogManager.GetLogger("WorkflowAgent");

        public void Start()

        {

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

            {

                Action loop = null;

                loop = () =>

                {

                    var message = inbox.Receive();

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

                    inbox.LoopAsync(process,loop,ex=>

                            Log.ErrorFormat("[ERROR] Synch for {0}:\r{1}", message.Result.FileName, ex));

                };

                loop();

            });

        }

        private Task<object> Process(WorkflowState state)

        {

            var accountInfo = state.AccountInfo;

            using (log4net.ThreadContext.Stacks["Workflow"].Push("Process"))

            {

                try

                {

                    if (Log.IsDebugEnabled)

                        Log.DebugFormat("State {0} {1} {2}", state.FileName, state.Status, state.TriggeringChange);

                    if (state.Skip)

                    {

                        if (Log.IsDebugEnabled) Log.DebugFormat("Skipping {0}", state.FileName);

                        return CompletedTask<object>.Default;

                    }

                    string path = state.Path.ToLower();

                    FileSystemInfo info = Directory.Exists(path) ? (FileSystemInfo) new DirectoryInfo(path) : new FileInfo(path);

                    //Bypass deleted files, unless the status is Deleted

                    if (!info.Exists && state.Status != FileStatus.Deleted)

                    {

                        state.Skip = true;

                        this.StatusKeeper.ClearFileStatus(path);

                        if (Log.IsDebugEnabled) Log.DebugFormat("Skipped missing {0}", state.FileName);

                        return CompletedTask<object>.Default;

                    }

                    var fileState = FileState.FindByFilePath(path);

                    switch (state.Status)

                    {

                        case FileStatus.Created:

                        case FileStatus.Modified:

                            NetworkAgent.Post(new CloudUploadAction(accountInfo, info, fileState, accountInfo.BlockSize,

                                                                    accountInfo.BlockHash));

                            break;

                        case FileStatus.Deleted:

                            NetworkAgent.Post(new CloudDeleteAction(accountInfo, info, fileState));

                            break;

                        case FileStatus.Renamed:

                            FileSystemInfo oldInfo = Directory.Exists(state.OldPath) ? (FileSystemInfo)new DirectoryInfo(state.OldPath) : new FileInfo(state.OldPath);

                            FileSystemInfo newInfo = Directory.Exists(state.Path) ? (FileSystemInfo)new DirectoryInfo(state.Path) : new FileInfo(state.Path);

                            NetworkAgent.Post(new CloudMoveAction(accountInfo, CloudActionType.RenameCloud,

                                                                  oldInfo,

                                                                  newInfo));

                            break;

                    }

                    return CompletedTask<object>.Default;

                }

                catch (Exception ex)

                {

                    Log.Error(ex.ToString());

                    throw;

                }

            }

        }

        //Starts interrupted files for a specific account

        public void RestartInterruptedFiles(AccountInfo accountInfo)

        {

            StatusNotification.NotifyChange("Restart processing interrupted files", TraceLevel.Verbose);

            using (log4net.ThreadContext.Stacks["Workflow"].Push("Restart"))

            {

                if (Log.IsDebugEnabled)

                    Log.Debug("Starting interrupted files");

                var cachePath = Path.Combine(accountInfo.AccountPath, FolderConstants.CacheFolder)

                    .ToLower();

                var account = accountInfo;

                var pendingEntries = from state in FileState.Queryable

                                     where state.FileStatus != FileStatus.Unchanged &&

                                           !state.FilePath.StartsWith(cachePath) &&

                                           !state.FilePath.EndsWith(".ignore") &&

                                           state.FilePath.StartsWith(account.AccountPath)

                                     select state;

                var pendingStates = new List<WorkflowState>();

                foreach (var state in pendingEntries)

                {

                        pendingStates.Add(new WorkflowState(account, state));

                }

                if (Log.IsDebugEnabled)

                    Log.DebugFormat("Found {0} interrupted files", pendingStates.Count);

                foreach (var entry in pendingStates)

                {

                       Post(entry);

                }

            }

        }

        public void Post(WorkflowState workflowState)

        {

            if (Log.IsDebugEnabled)

                Log.DebugFormat("Posted {0} {1} {2}", workflowState.Path, workflowState.Status, workflowState.TriggeringChange);

            //Remove invalid state            

            //For now, ignore paths

           /* if (Directory.Exists(workflowState.Path))

                return;*/

            //TODO: Need to handle folder renames            

            Debug.Assert(workflowState.Path.StartsWith(workflowState.AccountInfo.AccountPath, StringComparison.InvariantCultureIgnoreCase), "File from wrong account posted");

            _agent.Post(workflowState);

        }     

    }

}