feat: add rss output at route /blog/feed

OliverBooth/Data/Rss/AtomLink.cs

@@ -0,0 +1,15 @@
+using System.Xml.Serialization;
+
+namespace OliverBooth.Data.Rss;
+
+public sealed class AtomLink
+{
+    [XmlAttribute("href")]
+    public string Href { get; set; } = default!;
+
+    [XmlAttribute("rel")]
+    public string Rel { get; set; } = "self";
+
+    [XmlAttribute("type")]
+    public string Type { get; set; } = "application/rss+xml";
+}

OliverBooth/Data/Rss/BlogChannel.cs

@@ -0,0 +1,33 @@
+using System.Xml.Serialization;
+
+namespace OliverBooth.Data.Rss;
+
+public sealed class BlogChannel
+{
+    [XmlElement("title")]
+    public string Title { get; set; } = default!;
+
+    [XmlElement("link", Namespace = "http://www.w3.org/2005/Atom")]
+    public AtomLink AtomLink { get; set; } = default!;
+
+    [XmlElement("link")]
+    public string Link { get; set; } = default!;
+
+    [XmlElement("description")]
+    public string Description { get; set; } = default!;
+
+    [XmlElement("lastBuildDate")]
+    public string LastBuildDate { get; set; } = default!;
+
+    [XmlElement("updatePeriod", Namespace = "http://purl.org/rss/1.0/modules/syndication/")]
+    public string UpdatePeriod { get; set; } = "hourly";
+
+    [XmlElement("updateFrequency", Namespace = "http://purl.org/rss/1.0/modules/syndication/")]
+    public string UpdateFrequency { get; set; } = "1";
+
+    [XmlElement("generator")]
+    public string Generator { get; set; } = default!;
+
+    [XmlElement("item")]
+    public List<BlogItem> Items { get; set; } = new();
+}

OliverBooth/Data/Rss/BlogItem.cs

@@ -0,0 +1,27 @@
+using System.Xml.Serialization;
+
+namespace OliverBooth.Data.Rss;
+
+public sealed class BlogItem
+{
+    [XmlElement("title")]
+    public string Title { get; set; } = default!;
+
+    [XmlElement("link")]
+    public string Link { get; set; } = default!;
+
+    [XmlElement("comments")]
+    public string Comments { get; set; } = default!;
+    
+    [XmlElement("creator", Namespace = "http://purl.org/dc/elements/1.1/")]
+    public string Creator { get; set; } = default!;
+    
+    [XmlElement("pubDate")]
+    public string PubDate { get; set; } = default!;
+    
+    [XmlElement("guid")]
+    public string Guid { get; set; } = default!;
+    
+    [XmlElement("description")]
+    public string Description { get; set; } = default!;
+}

OliverBooth/Data/Rss/BlogRoot.cs

@@ -0,0 +1,13 @@
+using System.Xml.Serialization;
+
+namespace OliverBooth.Data.Rss;
+
+[XmlRoot("rss")]
+public sealed class BlogRoot
+{
+    [XmlAttribute("version")]
+    public string Version { get; set; } = default!;
+
+    [XmlElement("channel")]
+    public BlogChannel Channel { get; set; } = default!;
+}

OliverBooth/Data/Web/Configuration/SiteConfigurationConfiguration.cs

@@ -0,0 +1,20 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace OliverBooth.Data.Web.Configuration;
+
+/// <summary>
+///     Represents the configuration for the <see cref="SiteConfiguration" /> entity.
+/// </summary>
+internal sealed class SiteConfigurationConfiguration : IEntityTypeConfiguration<SiteConfiguration>
+{
+    /// <inheritdoc />
+    public void Configure(EntityTypeBuilder<SiteConfiguration> builder)
+    {
+        builder.ToTable("SiteConfig");
+        builder.HasKey(x => x.Key);
+
+        builder.Property(x => x.Key).HasMaxLength(50).IsRequired();
+        builder.Property(x => x.Value).HasMaxLength(1000);
+    }
+}

OliverBooth/Data/Web/SiteConfiguration.cs

@@ -0,0 +1,80 @@
+namespace OliverBooth.Data.Web;
+
+/// <summary>
+///     Represents a site configuration item.
+/// </summary>
+public sealed class SiteConfiguration : IEquatable<SiteConfiguration>
+{
+    /// <summary>
+    ///     Gets or sets the name of the configuration item.
+    /// </summary>
+    /// <value>The name of the configuration item.</value>
+    public string Key { get; set; } = string.Empty;
+
+    /// <summary>
+    ///     Gets or sets the value of the configuration item.
+    /// </summary>
+    /// <value>The value of the configuration item.</value>
+    public string? Value { get; set; }
+
+    /// <summary>
+    ///     Returns a value indicating whether two instances of <see cref="SiteConfiguration" /> are equal.
+    /// </summary>
+    /// <param name="left">The first instance of <see cref="SiteConfiguration" /> to compare.</param>
+    /// <param name="right">The second instance of <see cref="SiteConfiguration" /> to compare.</param>
+    /// <returns>
+    ///     <see langword="true" /> if <paramref name="left" /> and <paramref name="right" /> are equal; otherwise,
+    ///     <see langword="false" />.
+    /// </returns>
+    public static bool operator ==(SiteConfiguration? left, SiteConfiguration? right) => Equals(left, right);
+
+    /// <summary>
+    ///     Returns a value indicating whether two instances of <see cref="SiteConfiguration" /> are not equal.
+    /// </summary>
+    /// <param name="left">The first instance of <see cref="SiteConfiguration" /> to compare.</param>
+    /// <param name="right">The second instance of <see cref="SiteConfiguration" /> to compare.</param>
+    /// <returns>
+    ///     <see langword="true" /> if <paramref name="left" /> and <paramref name="right" /> are not equal; otherwise,
+    ///     <see langword="false" />.
+    /// </returns>
+    public static bool operator !=(SiteConfiguration? left, SiteConfiguration? right) => !(left == right);
+
+    /// <summary>
+    ///     Returns a value indicating whether this instance of <see cref="SiteConfiguration" /> is equal to another
+    ///     instance.
+    /// </summary>
+    /// <param name="other">An instance to compare with this instance.</param>
+    /// <returns>
+    ///     <see langword="true" /> if <paramref name="other" /> is equal to this instance; otherwise,
+    ///     <see langword="false" />.
+    /// </returns>
+    public bool Equals(SiteConfiguration? other)
+    {
+        if (ReferenceEquals(null, other)) return false;
+        if (ReferenceEquals(this, other)) return true;
+        return Key == other.Key;
+    }
+
+    /// <summary>
+    ///     Returns a value indicating whether this instance is equal to a specified object.
+    /// </summary>
+    /// <param name="obj">An object to compare with this instance.</param>
+    /// <returns>
+    ///     <see langword="true" /> if <paramref name="obj" /> is an instance of <see cref="SiteConfiguration" /> and
+    ///     equals the value of this instance; otherwise, <see langword="false" />.
+    /// </returns>
+    public override bool Equals(object? obj)
+    {
+        return ReferenceEquals(this, obj) || obj is SiteConfiguration other && Equals(other);
+    }
+
+    /// <summary>
+    ///     Gets the hash code for this instance.
+    /// </summary>
+    /// <returns>The hash code.</returns>
+    public override int GetHashCode()
+    {
+        // ReSharper disable once NonReadonlyMemberInGetHashCode
+        return Key.GetHashCode();
+    }
+}

OliverBooth/Data/WebContext.cs

@@ -26,6 +26,12 @@ public sealed class WebContext : DbContext
     /// <value>The set of article templates.</value>
     public DbSet<ArticleTemplate> ArticleTemplates { get; private set; } = null!;
 
+    /// <summary>
+    ///     Gets the set of site configuration items.
+    /// </summary>
+    /// <value>The set of site configuration items.</value>
+    public DbSet<SiteConfiguration> SiteConfiguration { get; private set; } = null!;
+
     /// <inheritdoc />
     protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
     {
@@ -37,5 +43,6 @@ public sealed class WebContext : DbContext
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
         modelBuilder.ApplyConfiguration(new ArticleTemplateConfiguration());
+        modelBuilder.ApplyConfiguration(new SiteConfigurationConfiguration());
     }
 }

OliverBooth/Middleware/RssEndpointExtensions.cs

@@ -0,0 +1,13 @@
+namespace OliverBooth.Middleware;
+
+internal static class RssEndpointExtensions
+{
+    public static IEndpointConventionBuilder MapRssFeed(this IEndpointRouteBuilder endpoints, string pattern)
+    {
+        RequestDelegate pipeline = endpoints.CreateApplicationBuilder()
+            .UseMiddleware<RssMiddleware>()
+            .Build();
+
+        return endpoints.Map(pattern, pipeline).WithDisplayName("RSS Feed");
+    }
+}

OliverBooth/Middleware/RssMiddleware.cs

@@ -0,0 +1,93 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Xml.Serialization;
+using Microsoft.EntityFrameworkCore;
+using OliverBooth.Data;
+using OliverBooth.Data.Blog;
+using OliverBooth.Data.Rss;
+using OliverBooth.Services;
+
+namespace OliverBooth.Middleware;
+
+/// <summary>
+///     Represents the RSS middleware.
+/// </summary>
+internal sealed class RssMiddleware
+{
+    private readonly BlogService _blogService;
+    private readonly ConfigurationService _configurationService;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="RssMiddleware" /> class.
+    /// </summary>
+    /// <param name="_">The request delegate.</param>
+    /// <param name="blogService">The blog service.</param>
+    /// <param name="configurationService">The configuration service.</param>
+    public RssMiddleware(RequestDelegate _,
+        BlogService blogService,
+        ConfigurationService configurationService)
+    {
+        _blogService = blogService;
+        _configurationService = configurationService;
+    }
+
+    [SuppressMessage("Performance", "CA1822:Mark members as static", Justification = "Middleware")]
+    public async Task Invoke(HttpContext context)
+    {
+        context.Response.ContentType = "application/rss+xml";
+
+        var baseUrl = $"https://{context.Request.Host}/blog";
+        var blogItems = new List<BlogItem>();
+
+        foreach (BlogPost blogPost in _blogService.AllPosts.OrderByDescending(p => p.Published))
+        {
+            var url = $"{baseUrl}/{blogPost.Published:yyyy/MM/dd}/{blogPost.Slug}";
+            string excerpt = _blogService.GetExcerpt(blogPost, out _);
+            var description = $"{excerpt}<p><a href=\"{url}\">Read more...</a></p>";
+
+            _blogService.TryGetAuthor(blogPost, out Author? author);
+
+            var item = new BlogItem
+            {
+                Title = blogPost.Title,
+                Link = url,
+                Comments = $"{url}#disqus_thread",
+                Creator = author?.Name ?? string.Empty,
+                PubDate = blogPost.Published.ToString("R"),
+                Guid = $"{baseUrl}?pid={blogPost.Id}",
+                Description = description
+            };
+            blogItems.Add(item);
+        }
+
+        string siteTitle = _configurationService.GetSiteConfiguration("SiteTitle") ?? string.Empty;
+        var rss = new BlogRoot
+        {
+            Channel = new BlogChannel
+            {
+                AtomLink = new AtomLink
+                {
+                    Href = $"{baseUrl}/feed/",
+                },
+                Description = $"{baseUrl}/",
+                LastBuildDate = DateTimeOffset.UtcNow.ToString("R"),
+                Link = $"{baseUrl}/",
+                Title = siteTitle,
+                Generator = $"{baseUrl}/",
+                Items = blogItems
+            }
+        };
+
+        var serializer = new XmlSerializer(typeof(BlogRoot));
+        var xmlNamespaces = new XmlSerializerNamespaces();
+        xmlNamespaces.Add("content", "http://purl.org/rss/1.0/modules/content/");
+        xmlNamespaces.Add("wfw", "http://wellformedweb.org/CommentAPI/");
+        xmlNamespaces.Add("dc", "http://purl.org/dc/elements/1.1/");
+        xmlNamespaces.Add("atom", "http://www.w3.org/2005/Atom");
+        xmlNamespaces.Add("sy", "http://purl.org/rss/1.0/modules/syndication/");
+        xmlNamespaces.Add("slash", "http://purl.org/rss/1.0/modules/slash/");
+
+        await using var writer = new StreamWriter(context.Response.BodyWriter.AsStream());
+        serializer.Serialize(writer, rss, xmlNamespaces);
+        // await context.Response.WriteAsync(document.OuterXml);
+    }
+}

OliverBooth/Program.cs

@@ -2,6 +2,7 @@ using Markdig;
 using NLog.Extensions.Logging;
 using OliverBooth.Data;
 using OliverBooth.Markdown;
+using OliverBooth.Middleware;
 using OliverBooth.Services;
 using X10D.Hosting.DependencyInjection;
 
@@ -11,6 +12,7 @@ builder.Configuration.AddTomlFile("data/config.toml", true, true);
 builder.Logging.ClearProviders();
 builder.Logging.AddNLog();
 builder.Services.AddHostedSingleton<LoggingService>();
+builder.Services.AddSingleton<ConfigurationService>();
 builder.Services.AddSingleton<TemplateService>();
 
 builder.Services.AddSingleton(provider => new MarkdownPipelineBuilder()
@@ -53,5 +55,6 @@ app.UseAuthorization();
 app.MapControllers();
 app.MapControllerRoute("default", "{controller=Home}/{action=Index}/{id?}");
 app.MapRazorPages();
+app.MapRssFeed("/blog/feed");
 
 app.Run();

OliverBooth/Services/ConfigurationService.cs

@@ -0,0 +1,34 @@
+using Microsoft.EntityFrameworkCore;
+using OliverBooth.Data;
+
+namespace OliverBooth.Services;
+
+/// <summary>
+///     Represents a service for retrieving configuration values.
+/// </summary>
+public sealed class ConfigurationService
+{
+    private readonly IDbContextFactory<WebContext> _webContextFactory;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="ConfigurationService" /> class.
+    /// </summary>
+    /// <param name="webContextFactory">
+    ///     The <see cref="IDbContextFactory{TContext}" /> for the <see cref="WebContext" />.
+    /// </param>
+    public ConfigurationService(IDbContextFactory<WebContext> webContextFactory)
+    {
+        _webContextFactory = webContextFactory;
+    }
+
+    /// <summary>
+    ///     Gets the value of a site configuration key.
+    /// </summary>
+    /// <param name="key">The key of the site configuration item.</param>
+    /// <returns>The value of the site configuration item.</returns>
+    public string? GetSiteConfiguration(string key)
+    {
+        using WebContext context = _webContextFactory.CreateDbContext();
+        return context.SiteConfiguration.Find(key)?.Value;
+    }
+}