/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * 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.Linq;
using System.Threading.Tasks;
using Amazon;
using Amazon.S3;
using Amazon.S3.Model;
using ASC.Core;
using ASC.Data.Storage.Configuration;

namespace ASC.Data.Storage.S3
{
    public class S3UploadGuard
    {
        private string accessKey;
        private string secretAccessKey;
        private string bucket;
        private string region;
        private bool configErrors;
        private bool configured;

        public void DeleteExpiredUploadsAsync(TimeSpan trustInterval)
        {
            var task = new Task(() =>
            {
                DeleteExpiredUploads(trustInterval);
            }, TaskCreationOptions.LongRunning);

            task.Start();
        }

        private void DeleteExpiredUploads(TimeSpan trustInterval)
        {
            Configure();

            if (configErrors)
            {
                return;
            }

            using (var s3 = GetClient())
            {
                var nextKeyMarker = string.Empty;
                var nextUploadIdMarker = string.Empty;
                bool isTruncated;

                do
                {
                    var request = new ListMultipartUploadsRequest { BucketName = bucket };

                    if (!string.IsNullOrEmpty(nextKeyMarker))
                    {
                        request.KeyMarker = nextKeyMarker;
                    }

                    if (!string.IsNullOrEmpty(nextUploadIdMarker))
                    {
                        request.UploadIdMarker = nextUploadIdMarker;
                    }

                    var response = s3.ListMultipartUploadsAsync(request).Result;

                    foreach (var u in response.MultipartUploads.Where(x => x.Initiated + trustInterval <= DateTime.UtcNow))
                    {
                        AbortMultipartUpload(u, s3);
                    }

                    isTruncated = response.IsTruncated;
                    nextKeyMarker = response.NextKeyMarker;
                    nextUploadIdMarker = response.NextUploadIdMarker;
                }
                while (isTruncated);
                
            }
        }

        private void AbortMultipartUpload(MultipartUpload u, AmazonS3Client client)
        {
            var request = new AbortMultipartUploadRequest
            {
                BucketName = bucket,
                Key = u.Key,
                UploadId = u.UploadId,
            };

            client.AbortMultipartUploadAsync(request).Wait();
        }

        private AmazonS3Client GetClient()
        {
            var s3Config = new AmazonS3Config {UseHttp = true, MaxErrorRetry = 3, RegionEndpoint = RegionEndpoint.GetBySystemName(region)};
            return new AmazonS3Client(accessKey, secretAccessKey, s3Config);
        }

        private void Configure()
        {
            if (!configured)
            {
                var config = StorageConfigFactory.Instance;
                var handler = config.GetHandler("s3");
                if (handler != null)
                {
                    var props = handler.GetProperties();
                    bucket = props["bucket"];
                    accessKey = props["acesskey"];
                    secretAccessKey = props["secretaccesskey"];
                    region = props["region"];
                }
                configErrors = string.IsNullOrEmpty(CoreContext.Configuration.BaseDomain) //localhost
                                || string.IsNullOrEmpty(accessKey)
                                || string.IsNullOrEmpty(secretAccessKey)
                                || string.IsNullOrEmpty(bucket)
                                || string.IsNullOrEmpty(region);

                configured = true;
            }
        }
    }
}