social-media/src/Infrastructure/AzureBlob/AzureBlobStorageService.cs

using Azure;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;
using Hutopy.Application.Common.Interfaces;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace Hutopy.Infrastructure.AzureBlob;

public class AzureBlobStorageService : IAzureBlobStorageService
{
    private readonly BlobServiceClient _blobServiceClient;
    private readonly ILogger<AzureBlobStorageService> _logger;
    private readonly long _maxUploadSize = 10 * 1024 * 1024;  // 10 MB in bytes

    public AzureBlobStorageService(IConfiguration configuration, ILogger<AzureBlobStorageService> logger)
    {
        _logger = logger;
        var connectionString = configuration["Azure-Blob-Connection-String"] ?? "";
        _blobServiceClient = new BlobServiceClient(connectionString);
    }

    /// <summary>
    /// Upload a file to microsoft azure blob storage.
    /// </summary>
    /// <param name="blobName">The blob name (path within the container, include the file name).</param>
    /// <param name="containerName">The name of the container where the file is stored.</param>
    /// <param name="fileStream">The stream.</param>
    /// <param name="contentType">The content type.</param>
    /// <returns></returns>
    public async Task<string> UploadFileAsync(string containerName, string blobName, Stream fileStream, string contentType)
    {
        // Read the file stream into a memory stream to determine the length
        // WATCH FOR MEMORY USAGE USING THE MEMORY STREAM.
        var memoryStream = new MemoryStream();
        await fileStream.CopyToAsync(memoryStream);
        memoryStream.Position = 0;

        // Check if the file size exceeds the maximum upload size
        if (memoryStream.Length > _maxUploadSize)
        {
            _logger.LogInformation($"Blob storage: File size exceeds the maximum allowed size of {_maxUploadSize} bytes.");
            throw new InvalidOperationException($"Blob storage: File size exceeds the maximum allowed size of {_maxUploadSize} bytes.");
        }
        
        // Validate content type
        if (!ContentTypes.IsAllowed(contentType, memoryStream))
        {
            _logger.LogInformation($"Blob storage: Unsupported file type {contentType}. Only PNG and JPEG are allowed.");
            throw new InvalidOperationException("Unsupported file type. Only PNG and JPEG are allowed.");
        }
        
        try
        {
            // Get a reference to a container
            var containerClient = _blobServiceClient.GetBlobContainerClient(containerName);

            // Create the container if it does not exist
            await containerClient.CreateIfNotExistsAsync();

            // Get a reference to a blob
            var blobClient = containerClient.GetBlobClient(blobName);

            // Define the BlobHttpHeaders to include the content type
            var blobHttpHeaders = new BlobHttpHeaders
            {
                ContentType = contentType
            };

            // Upload the file
            var response = await blobClient.UploadAsync(memoryStream, new BlobUploadOptions
            {
                HttpHeaders = blobHttpHeaders
            });

            var fileUri = blobClient.Uri.ToString();
            
            _logger.LogInformation(
                $"Blob storage: Status [   {response.GetRawResponse().Status.ToString()}   ] " +
                       $"Uploaded [  {blobName}  ] to the container [  {containerName}  ] " +
                       $"with contentType [  {contentType}  ] " +
                       $"with a length of [   {memoryStream.Length} bytes   ]" +
                       $"with the uri [   {fileUri}   ]"
                );

            // Return the URI of the uploaded blob
            return fileUri;
        }
        catch (RequestFailedException ex)
        {
            _logger.LogError($"Blob storage: Azure Storage request failed: {ex.Message}");
            throw new Exception("Error uploading file to Azure Blob Storage", ex);
        }
        catch (Exception ex)
        {
            _logger.LogError($"Blob storage: An error occurred: {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Download a file to microsoft azure blob storage.
    /// </summary>
    /// <param name="blobName">The blob name (path within the container).</param>
    /// <param name="containerName">The name of the container where the file is stored. (users)</param>
    /// <returns></returns>
    public async Task<MemoryStream> DownloadFileAsync(string containerName, string blobName)
    {
        try
        {
            // Get a reference to a container
            var containerClient = _blobServiceClient.GetBlobContainerClient(containerName);
        
            // Get a reference to a blob
            var blobClient = containerClient.GetBlobClient(blobName);

            // Download the blob to a stream
            BlobDownloadInfo download = await blobClient.DownloadAsync();
            MemoryStream memoryStream = new();
            await download.Content.CopyToAsync(memoryStream);
            memoryStream.Position = 0; // Ensure the stream is at the beginning

            return memoryStream;
        }
        catch (RequestFailedException ex)
        {
            _logger.LogError($"Azure Storage request failed: {ex.Message}");
            throw new Exception("Error downloading file from Azure Blob Storage", ex);
        }
        catch (Exception ex)
        {
            _logger.LogError($"An error occurred: {ex.Message}");
            throw new ApplicationException("Error downloading file from Azure Blob Storage.", ex);
        }
    }
}