/*
 *
 * (c) Copyright Ascensio System Limited 2010-2020
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


using System;
using System.Threading;
using System.Threading.Tasks;

using ASC.Common;
using ASC.Common.Caching;

using Microsoft.Extensions.DependencyInjection;

namespace ASC.Data.Storage.Encryption
{
    [Singletone]
    public class EncryptionWorker
    {
        private CancellationTokenSource TokenSource { get; set; }
        private ICache Cache { get; }
        private object Locker { get; }
        private FactoryOperation FactoryOperation { get; }

        public EncryptionWorker(FactoryOperation factoryOperation)
        {
            Cache = AscCache.Memory;
            Locker = new object();
            FactoryOperation = factoryOperation;
        }

        public void Start(EncryptionSettingsProto encryptionSettings)
        {
            EncryptionOperation encryptionOperation;
            lock (Locker)
            {
                if (Cache.Get<EncryptionOperation>(GetCacheKey()) != null) return;
                TokenSource = new CancellationTokenSource();
                encryptionOperation = FactoryOperation.CreateOperation(encryptionSettings);
                Cache.Insert(GetCacheKey(), encryptionOperation, DateTime.MaxValue);
            }

            var task = new Task(encryptionOperation.RunJob, TokenSource.Token, TaskCreationOptions.LongRunning);

            task.ConfigureAwait(false)
                .GetAwaiter()
                .OnCompleted(() =>
                {
                    lock (Locker)
                    {
                        Cache.Remove(GetCacheKey());
                    }
                });

            task.Start();
        }

        public void Stop()
        {
            TokenSource.Cancel();
        }

        public string GetCacheKey()
        {
            return typeof(EncryptionOperation).FullName;
        }
    }

    [Singletone(Additional = typeof(FactoryOperationExtension))]
    public class FactoryOperation
    {
        private IServiceProvider ServiceProvider { get; set; }

        public FactoryOperation(IServiceProvider serviceProvider)
        {
            ServiceProvider = serviceProvider;
        }

        public EncryptionOperation CreateOperation(EncryptionSettingsProto encryptionSettings)
        {
            var item = ServiceProvider.GetService<EncryptionOperation>();
            item.Init(encryptionSettings);
            return item;
        }
    }

    public class FactoryOperationExtension
    {
        public static void Register(DIHelper dIHelper)
        {
            dIHelper.TryAdd<EncryptionOperation>();
        }
    }
}