#region
/* -----------------------------------------------------------------------
 * <copyright file="FileEventIdleBatch.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.Diagnostics.Contracts;
using System.IO;
using System.Linq;
using System.Reflection;
using log4net;

namespace Pithos.Core.Agents
{
    public class FileEventIdleBatch
    {

        //Requirements
        //------------
        //* The class should group workflow actions according to file name and type
        //* The class should pass all batched actions to a continuation when
        //* the batch is triggered.
        //* Actions should not survice a trigger

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

        private readonly IdleBatch<FileSystemEventArgs> _idleBatch;
        private readonly Action<Dictionary<string, FileSystemEventArgs[]>> _callback;

        private PollAgent _pollAgent;

        public FileEventIdleBatch(PollAgent pollAgent, int idleTimeout, Action<Dictionary<string, FileSystemEventArgs[]>> callback)
        {
            _pollAgent = pollAgent;
            _callback = callback;
            _idleBatch = new IdleBatch<FileSystemEventArgs>(idleTimeout, Process);
        }

        public void Post(FileSystemEventArgs arg)
        {
            if (arg is RenamedEventArgs)
                throw new ArgumentException("arg");
            Contract.EndContractBlock();
            if (Log.IsDebugEnabled)
                Log.DebugFormat("Batch Post  {0}:{1}", arg.ChangeType.ToString("g"), arg.FullPath);
            
            _pollAgent.Pause =true;

            _idleBatch.Post(arg);
        }

        public void ForceTrigger()
        {
            _idleBatch.ForceTrigger();
        }


        protected virtual void Process(FileSystemEventArgs[] args)
        {
            var dict = new Dictionary<string, FileSystemEventArgs[]>();
            foreach (var arg in args)
            {

                if (arg.ChangeType == WatcherChangeTypes.Created )
                    dict[arg.FullPath] = new[] { arg };
                else if (arg.ChangeType == WatcherChangeTypes.Renamed)
                {
                    var renamedArg = (MovedEventArgs)arg;
                    FileSystemEventArgs[] oldValue;
                    if (dict.TryGetValue(renamedArg.OldFullPath, out oldValue))
                    {
                        dict.Remove(renamedArg.OldFullPath);
                        var last = oldValue.Last();
                        if (last.ChangeType == WatcherChangeTypes.Created)
                        {
                            var createRenamed = new FileSystemEventArgs(WatcherChangeTypes.Created, Path.GetDirectoryName(renamedArg.FullPath),
                                                                        renamedArg.Name);
                            dict[renamedArg.FullPath] = new[] {createRenamed};
                        }
                        else
                            dict[renamedArg.FullPath] = new[] { renamedArg };
                    }
                    else
                        dict[renamedArg.FullPath] = new[] { renamedArg};
                }
                else
                {
                    FileSystemEventArgs[] oldValue;
                    var hasValue=dict.TryGetValue(arg.FullPath, out oldValue);
                    var last = hasValue?oldValue.LastOrDefault():null;
                    
                    if (last==null || last.ChangeType == WatcherChangeTypes.Changed)
                    {
                        dict[arg.FullPath] = new[] { arg};
                    }
                    else if (arg.ChangeType == WatcherChangeTypes.Deleted)
                    {
                        if (last.ChangeType == WatcherChangeTypes.Created)
                            dict.Remove(arg.FullPath);
                        else
                        {
                            dict[arg.FullPath] = new[] { arg };
                        }
                    }
                    else if (last.ChangeType == WatcherChangeTypes.Renamed && arg.ChangeType == WatcherChangeTypes.Changed)
                    {
                        var newValue = oldValue.Concat(new[] { arg }).ToArray();
                        dict[arg.FullPath] = newValue;
                    }

                }
            }
            _pollAgent.Pause = false;
            _callback(dict);
        }

    }

}