// Copyright (C) 2025, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
// 
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// copy of this software and associated documentation files (the "Software"), 
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// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
// all copies or substantial portions of the Software.
// 
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
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using System.Collections.Generic;
using System.IO;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Duplicati.Library.Common.IO;
using Duplicati.Library.Interface;
using Duplicati.Library.Utility;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;

namespace Duplicati.Library.Backend.AzureBlob
{
    /// <summary>
    /// Azure blob storage facade.
    /// </summary>
    public class AzureBlobWrapper
    {
        private readonly string _containerName;
        private readonly CloudBlobContainer _container;
        private readonly OperationContext _operationContext;

        // Note: May need metadata; need to test with Azure blobs
        private const BlobListingDetails ListDetails = BlobListingDetails.None;

        public string[] DnsNames
        {
            get
            {
                var lst = new List<string>();
                if (_container != null)
                {
                    if (_container.Uri != null)
                        lst.Add(_container.Uri.Host);

                    if (_container.StorageUri != null)
                    {
                        if (_container.StorageUri.PrimaryUri != null)
                            lst.Add(_container.StorageUri.PrimaryUri.Host);
                        if (_container.StorageUri.SecondaryUri != null)
                            lst.Add(_container.StorageUri.SecondaryUri.Host);
                    }
                }

                return lst.ToArray();
            }
        }

        public AzureBlobWrapper(string accountName, string accessKey, string sasToken, string containerName)
        {
            _operationContext = new()
            {
                CustomUserAgent = string.Format(
                    "APN/1.0 Duplicati/{0} AzureBlob/2.0 {1}",
                    System.Reflection.Assembly.GetExecutingAssembly().GetName().Version,
                    Microsoft.WindowsAzure.Storage.Shared.Protocol.Constants.HeaderConstants.UserAgent
            )
            };

            string connectionString;
            if (sasToken != null)
            {
                connectionString = string.Format("DefaultEndpointsProtocol=https;AccountName={0};SharedAccessSignature={1}",
                    accountName, sasToken);
            }
            else
            {
                connectionString = string.Format("DefaultEndpointsProtocol=https;AccountName={0};AccountKey={1}",
                            accountName, accessKey);
            }

            var storageAccount = CloudStorageAccount.Parse(connectionString);
            var blobClient = storageAccount.CreateCloudBlobClient();

            _containerName = containerName;
            _container = blobClient.GetContainerReference(containerName);
        }

        public async Task AddContainerAsync(CancellationToken cancellationToken)
        {
            await _container.CreateAsync(default, default, _operationContext, cancellationToken).ConfigureAwait(false);
            await _container.SetPermissionsAsync(new BlobContainerPermissions { PublicAccess = BlobContainerPublicAccessType.Off }, default, default, _operationContext, cancellationToken).ConfigureAwait(false);
        }

        public virtual Task GetFileStreamAsync(string keyName, Stream target, CancellationToken cancellationToken)
        {
            return _container.GetBlockBlobReference(keyName).DownloadToStreamAsync(target, default, default, _operationContext, cancellationToken);
        }

        public virtual Task AddFileStream(string keyName, Stream source, CancellationToken cancelToken)
        {
            return _container.GetBlockBlobReference(keyName).UploadFromStreamAsync(source, source.Length, default, default, _operationContext, cancelToken);
        }

        public Task DeleteObjectAsync(string keyName, CancellationToken cancelToken)
        {
            return _container.GetBlockBlobReference(keyName).DeleteIfExistsAsync(default, default, default, _operationContext, cancelToken);
        }

        private async IAsyncEnumerable<IListBlobItem> ListContainerBlobEntriesAsync([EnumeratorCancellation] CancellationToken cancelToken)
        {
            BlobResultSegment segment;
            try
            {
                segment = await _container.ListBlobsSegmentedAsync(null, false, ListDetails, null, null, null, _operationContext, cancelToken).ConfigureAwait(false);
            }
            catch (StorageException ex)
            {
                if (ex.RequestInformation.HttpStatusCode == 404)
                {
                    throw new FolderMissingException(ex);
                }
                throw;
            }

            foreach (var item in segment.Results)
                yield return item;

            while (segment.ContinuationToken != null)
            {
                segment = await _container.ListBlobsSegmentedAsync(null, false, ListDetails, null, segment.ContinuationToken, null, _operationContext, cancelToken).ConfigureAwait(false);

                foreach (var item in segment.Results)
                    yield return item;
            }
        }

        public virtual async IAsyncEnumerable<IFileEntry> ListContainerEntriesAsync([EnumeratorCancellation] CancellationToken cancelToken)
        {
            await foreach (var x in ListContainerBlobEntriesAsync(cancelToken).ConfigureAwait(false))
            {
                var absolutePath = x.StorageUri.PrimaryUri.AbsolutePath;
                var containerSegment = string.Concat("/", _containerName, "/");
                var blobName = absolutePath.Substring(absolutePath.IndexOf(
                    containerSegment, System.StringComparison.Ordinal) + containerSegment.Length);

                var res = new FileEntry(Uri.UrlDecode(blobName.Replace("+", "%2B")));
                try
                {
                    if (x is CloudBlockBlob cb)
                    {
                        var lastModified = new System.DateTime();
                        if (cb.Properties.LastModified != null)
                            lastModified = new System.DateTime(cb.Properties.LastModified.Value.Ticks, System.DateTimeKind.Utc);
                        res = new FileEntry(res.Name, cb.Properties.Length, lastModified, lastModified);
                    }
                }
                catch
                {
                    // If the metadata fails to parse, return the basic entry
                }

                yield return res;
            }
        }
    }
}