#region
/* -----------------------------------------------------------------------
 * <copyright file="WorkflowAgent.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
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * 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.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using Castle.ActiveRecord;
using Pithos.Interfaces;
using Pithos.Network;
using log4net;

namespace Pithos.Core.Agents
{
    [Export]
    public class WorkflowAgent
    {
        private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        readonly Agent<WorkflowState> _agent;
                
        public IStatusNotification StatusNotification { get; set; }
        [System.ComponentModel.Composition.Import]
        public IStatusKeeper StatusKeeper { get; set; }

        [System.ComponentModel.Composition.Import]
        public NetworkAgent NetworkAgent { get; set; }

        [System.ComponentModel.Composition.Import]
        public IPithosSettings Settings { get; set; }


        public WorkflowAgent()
        {
            _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;
                    }                    

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

                    //Bypass deleted files, unless the status is Deleted
                    if (!info.Exists && state.Status != FileStatus.Deleted)
                    {
                        state.Skip = true;
                        this.StatusKeeper.ClearFileStatus(state.Path);

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

                        return CompletedTask<object>.Default;
                    }

                    using (new SessionScope(FlushAction.Never))
                    {

                        var fileState = StatusKeeper.GetStateByFilePath(state.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:
                                DeleteChildObjects(state, fileState);
                                NetworkAgent.Post(new CloudDeleteAction(accountInfo, info, fileState));
                                break;
                            case FileStatus.Renamed:
                                if (state.OldPath == null)
                                {
                                    //We reach this point only if the app closed before propagating a rename to the server
                                    Log.WarnFormat("Unfinished rename [{0}]",state.Path);
                                    StatusKeeper.SetFileState(state.Path,FileStatus.Conflict,FileOverlayStatus.Conflict, "Rename without old path");
                                    break;
                                }
                                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));                                
                                //TODO: Do I have to move children as well or will Pithos handle this?
                               //Need to find all children of the OLD filepath
                                //MoveChildObjects(state);
                                break;
                        }
                    }

                    return CompletedTask<object>.Default;
                }
                catch (Exception ex)
                {
                    Log.Error(ex.ToString());
                    throw;
                }
            }
        }


        private void DeleteChildObjects(WorkflowState state, FileState fileState)
        {
            if (fileState != null)
            {
                var children = StatusKeeper.GetChildren(fileState);
                foreach (var child in children)
                {
                    var childInfo = child.IsFolder
                                        ? (FileSystemInfo) new DirectoryInfo(child.FilePath)
                                        : new FileInfo(child.FilePath);
                    NetworkAgent.Post(new CloudDeleteAction(state.AccountInfo, childInfo, child));
                }
            }
        }

        /*private void MoveChildObjects(WorkflowState state)
        {
            var oldFileState = StatusKeeper.GetStateByFilePath(state.OldPath);
            if (oldFileState != null)
            {
                var children = StatusKeeper.GetChildren(oldFileState);
                foreach (var child in children)
                {
                    var newPath = Path.Combine(state.Path, child.FilePath.Substring(state.OldPath.Length+1));

                    var oldMoveInfo = child.IsFolder
                                          ? (FileSystemInfo) new DirectoryInfo(child.FilePath)
                                          : new FileInfo(child.FilePath);
                    var newMoveInfo = child.IsFolder
                                          ? (FileSystemInfo) new DirectoryInfo(newPath)
                                          : new FileInfo(newPath);
                    //The new file path will be created by trimming the old root path
                    //and substituting the new root path

                    NetworkAgent.Post(new CloudMoveAction(state.AccountInfo, CloudActionType.RenameCloud,
                                                          oldMoveInfo, newMoveInfo));
                }
            }
        }*/


        //Starts interrupted files for a specific account
        public void RestartInterruptedFiles(AccountInfo accountInfo)
        {
            
            StatusKeeper.CleanupOrphanStates();
            using (log4net.ThreadContext.Stacks["Operation"].Push("RestartInterrupted"))
            {
                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.FileStatus != FileStatus.Forbidden &&
                                            state.FileStatus != FileStatus.Conflict &&
                                           !state.FilePath.StartsWith(cachePath) &&
                                           !state.FilePath.EndsWith(".ignore") &&
                                           state.FilePath.StartsWith(account.AccountPath)                                            
                                     select state).ToList();
                if (pendingEntries.Count>0)
                    StatusNotification.NotifyChange("Restart processing interrupted files", TraceLevel.Verbose);

                var pendingStates = pendingEntries
                    .Select(state => new WorkflowState(account, state))
                    .ToList();

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

                pendingStates.ForEach(Post);
            }
        }



        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);
        }     

    }
}