feat: add CDN backend API

OliverBooth/Data/CdnAssetType.cs

@@ -0,0 +1,22 @@
+namespace OliverBooth.Data;
+
+/// <summary>
+///     An enumeration of CDN asset types.
+/// </summary>
+public enum CdnAssetType
+{
+    /// <summary>
+    ///     An image on a blog post.
+    /// </summary>
+    BlogImage,
+
+    /// <summary>
+    ///     A multimedia asset (audio and video) on a blog post.
+    /// </summary>
+    BlogMedia,
+
+    /// <summary>
+    ///     A raw (typically binary) asset on a blog post.
+    /// </summary>
+    BlogRaw
+}

OliverBooth/OliverBooth.csproj

@@ -31,6 +31,8 @@
         <PackageReference Include="Asp.Versioning.Mvc" Version="8.0.0"/>
         <PackageReference Include="AspNetCore.ReCaptcha" Version="1.8.1"/>
         <PackageReference Include="BCrypt.Net-Core" Version="1.6.0"/>
+        <PackageReference Include="FluentFTP" Version="49.0.2" />
+        <PackageReference Include="FluentFTP.Logging" Version="1.0.0" />
         <PackageReference Include="HtmlAgilityPack" Version="1.11.59"/>
         <PackageReference Include="Humanizer.Core" Version="2.14.1"/>
         <PackageReference Include="MailKit" Version="4.3.0"/>

OliverBooth/Program.cs

@@ -1,5 +1,8 @@
+using System.Security.Authentication;
 using Asp.Versioning;
 using AspNetCore.ReCaptcha;
+using FluentFTP;
+using FluentFTP.Logging;
 using Markdig;
 using OliverBooth.Data.Blog;
 using OliverBooth.Data.Web;
@@ -8,6 +11,7 @@ using OliverBooth.Markdown.Template;
 using OliverBooth.Markdown.Timestamp;
 using OliverBooth.Services;
 using Serilog;
+using Serilog.Extensions.Logging;
 using X10D.Hosting.DependencyInjection;
 
 Log.Logger = new LoggerConfiguration()
@@ -43,6 +47,25 @@ builder.Services.AddApiVersioning(options =>
 builder.Services.AddDbContextFactory<BlogContext>();
 builder.Services.AddDbContextFactory<WebContext>();
 builder.Services.AddHttpClient();
+builder.Services.AddTransient<IAsyncFtpClient, AsyncFtpClient>(provider =>
+{
+    var configuration = provider.GetRequiredService<IConfiguration>();
+    string? host = configuration["Cdn:Ftp:Host"];
+    string? username = configuration["Cdn:Ftp:Username"];
+    string? password = configuration["Cdn:Ftp:Password"];
+
+    if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(username) || string.IsNullOrWhiteSpace(password))
+    {
+        throw new AuthenticationException("Configuration value missing for CDN FTP.");
+    }
+
+    var client = new AsyncFtpClient(host, username, password);
+    var loggerFactory = new SerilogLoggerFactory(Log.Logger);
+    client.Logger = new FtpLogAdapter(loggerFactory.CreateLogger("FTP"));
+    return client;
+});
+
+builder.Services.AddSingleton<ICdnService, CdnService>();
 builder.Services.AddSingleton<IContactService, ContactService>();
 builder.Services.AddSingleton<ITemplateService, TemplateService>();
 builder.Services.AddSingleton<IBlogPostService, BlogPostService>();

OliverBooth/Services/CdnService.cs

@@ -0,0 +1,109 @@
+using System.ComponentModel;
+using FluentFTP;
+using OliverBooth.Data;
+
+namespace OliverBooth.Services;
+
+internal sealed class CdnService : ICdnService
+{
+    private readonly ILogger<CdnService> _logger;
+    private readonly IConfiguration _configuration;
+    private readonly IAsyncFtpClient _ftpClient;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="CdnService" /> class.
+    /// </summary>
+    /// <param name="logger">The logger.</param>
+    /// <param name="configuration">The configuration.</param>
+    /// <param name="ftpClient">The FTP client.</param>
+    public CdnService(ILogger<CdnService> logger, IConfiguration configuration, IAsyncFtpClient ftpClient)
+    {
+        _logger = logger;
+        _configuration = configuration;
+        _ftpClient = ftpClient;
+    }
+
+    /// <inheritdoc />
+    public Task<Uri> CreateAssetAsync(FileStream stream, CdnAssetType assetType)
+    {
+        string filename = Path.GetFileName(stream.Name);
+        return CreateAssetAsync(filename, stream, assetType);
+    }
+
+    /// <inheritdoc />
+    public async Task<Uri> CreateAssetAsync(string filename, Stream stream, CdnAssetType assetType)
+    {
+        if (filename is null)
+        {
+            throw new ArgumentNullException(nameof(filename));
+        }
+
+        if (string.IsNullOrWhiteSpace(filename))
+        {
+            throw new ArgumentException("Filename cannot be empty");
+        }
+
+        if (stream is null)
+        {
+            throw new ArgumentNullException(nameof(stream));
+        }
+
+        if (!stream.CanRead)
+        {
+            throw new ArgumentException("The provided stream cannot be read.");
+        }
+
+        if (!Enum.IsDefined(assetType))
+        {
+            throw new InvalidEnumArgumentException(nameof(assetType), (int)assetType, typeof(CdnAssetType));
+        }
+
+        DateTimeOffset now = DateTimeOffset.UtcNow;
+        string basePath = _configuration["Cdn:Ftp:ChRoot"]!;
+        string? relativePath = _configuration[$"Cdn:AssetTypeMap:{assetType:G}"];
+        string remotePath = $"{basePath}{relativePath}/{now:yyyy\\/MM}/{filename}";
+        _logger.LogDebug("Base path is {Path}", basePath);
+        _logger.LogDebug("Relative path is {Path}", relativePath);
+        _logger.LogDebug("Full remote path is {Path}", remotePath);
+
+        _logger.LogInformation("Connecting to FTP server");
+        await _ftpClient.AutoConnect();
+
+        _logger.LogInformation("Asset will be at {RemotePath}", remotePath);
+        await _ftpClient.UploadStream(stream, remotePath, FtpRemoteExists.Skip, true);
+
+        _logger.LogInformation("Asset upload complete. Disconnecting");
+        await _ftpClient.Disconnect();
+
+        return GetUri(now, filename, assetType);
+    }
+
+    /// <inheritdoc />
+    public Uri GetUri(DateOnly date, string filename, CdnAssetType assetType)
+    {
+        if (filename is null)
+        {
+            throw new ArgumentNullException(nameof(filename));
+        }
+
+        if (string.IsNullOrWhiteSpace(filename))
+        {
+            throw new ArgumentException("Filename cannot be empty");
+        }
+
+        if (!Enum.IsDefined(assetType))
+        {
+            throw new InvalidEnumArgumentException(nameof(assetType), (int)assetType, typeof(CdnAssetType));
+        }
+
+        string? relativePath = _configuration[$"Cdn:AssetTypeMap:{assetType:G}"];
+        string url = $"{_configuration["Cdn:BaseUrl"]}{relativePath}/{date:yyyy\\/MM)}/{filename}";
+        return new Uri(url);
+    }
+
+    /// <inheritdoc />
+    public Uri GetUri(DateTimeOffset date, string filename, CdnAssetType assetType)
+    {
+        return GetUri(DateOnly.FromDateTime(date.DateTime), filename, assetType);
+    }
+}

OliverBooth/Services/ICdnService.cs

@@ -0,0 +1,77 @@
+using System.ComponentModel;
+using OliverBooth.Data;
+
+namespace OliverBooth.Services;
+
+/// <summary>
+///     Represents a service which communicates with the CDN server.
+/// </summary>
+public interface ICdnService
+{
+    /// <summary>
+    ///     Asynchronously uploads a new asset to the CDN server.
+    /// </summary>
+    /// <param name="stream">A stream containing the data to upload.</param>
+    /// <param name="assetType">The type of the asset.</param>
+    /// <returns>The URI of the newly-created asset.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="stream" /> is <see langword="null" />.</exception>
+    /// <exception cref="ArgumentException">The <paramref name="stream" /> is not readable.</exception>
+    /// <exception cref="InvalidEnumArgumentException">
+    ///     <paramref name="assetType" /> is not a valid <see cref="CdnAssetType" />.
+    /// </exception>
+    Task<Uri> CreateAssetAsync(FileStream stream, CdnAssetType assetType);
+
+    /// <summary>
+    ///     Asynchronously uploads a new asset to the CDN server.
+    /// </summary>
+    /// <param name="filename">The filename of the asset.</param>
+    /// <param name="stream">A stream containing the data to upload.</param>
+    /// <param name="assetType">The type of the asset.</param>
+    /// <returns>The URI of the newly-created asset.</returns>
+    /// <exception cref="ArgumentNullException">
+    ///     <para><paramref name="filename" /> is <see langword="null" />.</para>
+    ///     -or-
+    ///     <para><paramref name="stream" /> is <see langword="null" />.</para>
+    /// </exception>
+    /// <exception cref="ArgumentException">
+    ///     <para><paramref name="filename" /> is empty, or contains only whitespace.</para>
+    ///     -or-
+    ///     <para>The <paramref name="stream" /> is not readable.</para>
+    /// </exception>
+    /// <exception cref="InvalidEnumArgumentException">
+    ///     <paramref name="assetType" /> is not a valid <see cref="CdnAssetType" />.
+    /// </exception>
+    Task<Uri> CreateAssetAsync(string filename, Stream stream, CdnAssetType assetType);
+
+    /// <summary>
+    ///     Gets the resolved asset URI for the specified date and filename.
+    /// </summary>
+    /// <param name="date">The date of the asset.</param>
+    /// <param name="filename">The filename of the asset.</param>
+    /// <param name="assetType">The type of the asset.</param>
+    /// <returns>The resolved asset URI.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="filename" /> is <see langword="null" />.</exception>
+    /// <exception cref="ArgumentException">
+    ///     <paramref name="filename" /> is empty, or contains only whitespace.
+    /// </exception>
+    /// <exception cref="InvalidEnumArgumentException">
+    ///     <paramref name="assetType" /> is not a valid <see cref="CdnAssetType" />.
+    /// </exception>
+    Uri GetUri(DateOnly date, string filename, CdnAssetType assetType);
+
+    /// <summary>
+    ///     Gets the resolved asset URI for the specified date and filename.
+    /// </summary>
+    /// <param name="date">The date of the asset.</param>
+    /// <param name="filename">The filename of the asset.</param>
+    /// <param name="assetType">The type of the asset.</param>
+    /// <returns>The resolved asset URI.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="filename" /> is <see langword="null" />.</exception>
+    /// <exception cref="ArgumentException">
+    ///     <paramref name="filename" /> is empty, or contains only whitespace.
+    /// </exception>
+    /// <exception cref="InvalidEnumArgumentException">
+    ///     <paramref name="assetType" /> is not a valid <see cref="CdnAssetType" />.
+    /// </exception>
+    Uri GetUri(DateTimeOffset date, string filename, CdnAssetType assetType);
+}