// (c) Copyright Ascensio System SIA 2010-2022
//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL 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 details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
// You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia, EU, LV-1021.
//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
// Pursuant to Section 7(b) of the License you must retain the original Product logo when
// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
//
// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

namespace ASC.Data.Storage.S3;

public class S3UploadGuard
{
    public Configuration.Storage Storage { get; }

    private readonly CoreSettings _coreSettings;
    private string _accessKey;
    private string _secretAccessKey;
    private string _bucket;
    private string _region;
    private bool _configErrors;
    private bool _configured;

    public S3UploadGuard(CoreSettings coreSettings, Configuration.Storage storage)
    {
        _coreSettings = coreSettings;
        Storage = storage;
    }

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

        task.Start();
    }

    private Task DeleteExpiredUploadsActionAsync(TimeSpan trustInterval)
    {
        Configure();

        if (_configErrors)
        {
            return Task.CompletedTask;
        }

        return InternalDeleteExpiredUploadsActionAsync(trustInterval);
    }

    private async Task InternalDeleteExpiredUploadsActionAsync(TimeSpan trustInterval)
    {
        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 = await s3.ListMultipartUploadsAsync(request);

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

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

    private async Task AbortMultipartUploadAsync(MultipartUpload u, AmazonS3Client client)
    {
        var request = new AbortMultipartUploadRequest
        {
            BucketName = _bucket,
            Key = u.Key,
            UploadId = u.UploadId,
        };

        await client.AbortMultipartUploadAsync(request);
    }

    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 handler = Storage.GetHandler("s3");
            if (handler != null)
            {
                var props = handler.GetProperties();
                _bucket = props["bucket"];
                _accessKey = props["acesskey"];
                _secretAccessKey = props["secretaccesskey"];
                _region = props["region"];
            }
            _configErrors = string.IsNullOrEmpty(_coreSettings.BaseDomain) //localhost
                            || string.IsNullOrEmpty(_accessKey)
                            || string.IsNullOrEmpty(_secretAccessKey)
                            || string.IsNullOrEmpty(_bucket)
                            || string.IsNullOrEmpty(_region);

            _configured = true;
        }
    }
}