feat: Show Similiar blog posts

.editorconfig

@@ -419,6 +419,7 @@ dotnet_diagnostic.S3875.severity = none       # Remove this overload of 'operato
 dotnet_diagnostic.IDE0005.severity = none # IDE0005: Using directive is unnecessary
 dotnet_diagnostic.IDE0021.severity = suggestion # IDE0021: Use expression body for constructor
 dotnet_diagnostic.IDE0022.severity = suggestion # IDE0022: Use expression body for method
+dotnet_diagnostic.IDE0055.severity = none # IDE0055: Fix formatting
 dotnet_diagnostic.IDE0058.severity = none # IDE0058: Expression value is never used
 dotnet_diagnostic.IDE0079.severity = warning # IDE0079: Remove unnecessary suppression
 dotnet_diagnostic.IDE0290.severity = none # IDE0290: Use primary constructor
@@ -443,6 +444,7 @@ dotnet_diagnostic.CA1055.severity = none # CA1055: Uri return values should not
 dotnet_diagnostic.CA1056.severity = none # CA1056: Uri properties should not be strings
 dotnet_diagnostic.CA1812.severity = none # CA1812: Avoid uninstantiated internal classes
 dotnet_diagnostic.CA2201.severity = suggestion # CA2201: Do not raise reserved exception types
+dotnet_diagnostic.CA2227.severity = suggestion # CA2227: Collection properties should be read only
 
 # SonarAnalyzer.CSharp
 # https://rules.sonarsource.com/csharp

LinkDotNet.Blog.sln

@@ -19,6 +19,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 	ProjectSection(SolutionItems) = preProject
 		Readme.md = Readme.md
 		.editorconfig = .editorconfig
+		MIGRATION.md = MIGRATION.md
 	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{86FD0EB5-13F9-4F1C-ADA1-072EEFEFF1E9}"

MIGRATION.md

@@ -0,0 +1,26 @@
+# Migration Guide
+This document describes the changes that need to be made to migrate from one version of the blog to another.
+
+## 8.0 to 9.0
+A new `SimilarBlogPost` table is introduced to store similar blog posts.
+
+```sql
+CREATE TABLE SimilarBlogPosts
+(
+	Id [NVARCHAR](450) NOT NULL,
+	SimilarBlogPostIds NVARCHAR(1350) NOT NULL,
+)
+
+ALTER TABLE SimilarBlogPosts
+ADD CONSTRAINT PK_SimilarBlogPosts PRIMARY KEY (Id)
+```
+
+Add the following to the `appsettings.json`:
+
+```json
+{
+	"SimilarBlogPosts": true
+}
+```
+
+Or `false` if you don't want to use this feature.

docs/Setup/Configuration.md

@@ -48,7 +48,8 @@ The appsettings.json file has a lot of options to customize the content of the b
 	"KofiToken": "ABC123",
 	"GithubSponsorName": "your-tag-here",
 	"ShowReadingIndicator": true,
-	"PatreonName": "your-tag-here"
+	"PatreonName": "your-tag-here",
+	"SimlarBlogPosts": "true"
 }
 ```
 
@@ -85,3 +86,4 @@ The appsettings.json file has a lot of options to customize the content of the b
 | GithubSponsorName                             | string         | Enables the "Github Sponsor" button which redirects to GitHub. Only pass in the user name instead of the url.                                                                     |
 | ShowReadingIndicator                          | boolean        | If set to `true` (default) a circle indicates the progress when a user reads a blog post (without comments).                                                                      |
 | PatreonName                                   | string         | Enables the "Become a patreon" button that redirects to patreon.com. Only pass the user name (public profile) as user name.                                                       |
+| SimilarBlogPosts                              | boolean        | If set to `true` (default) similar blog posts are shown at the end of a blog post.                                                                                                |

src/LinkDotNet.Blog.Domain/SimilarBlogPost.cs

@@ -0,0 +1,8 @@
+using System.Collections.Generic;
+
+namespace LinkDotNet.Blog.Domain;
+
+public class SimilarBlogPost : Entity
+{
+    public IList<string> SimilarBlogPostIds { get; set; } = [];
+}

src/LinkDotNet.Blog.Infrastructure/Persistence/Sql/BlogDbContext.cs

@@ -24,6 +24,8 @@ public BlogDbContext(DbContextOptions options)
 
     public DbSet<BlogPostRecord> BlogPostRecords { get; set; }
 
+    public DbSet<SimilarBlogPost> SimilarBlogPosts { get; set; }
+
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
         ArgumentNullException.ThrowIfNull(modelBuilder);

src/LinkDotNet.Blog.Infrastructure/Persistence/Sql/Mapping/SimilarBlogPostConfiguration.cs

@@ -0,0 +1,17 @@
+using LinkDotNet.Blog.Domain;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace LinkDotNet.Blog.Infrastructure.Persistence.Sql.Mapping;
+
+internal sealed class SimilarBlogPostConfiguration : IEntityTypeConfiguration<SimilarBlogPost>
+{
+    public void Configure(EntityTypeBuilder<SimilarBlogPost> builder)
+    {
+        builder.HasKey(b => b.Id);
+        builder.Property(b => b.Id)
+            .IsUnicode(false)
+            .ValueGeneratedOnAdd();
+        builder.Property(b => b.SimilarBlogPostIds).HasMaxLength(450 * 3).IsRequired();
+    }
+}

src/LinkDotNet.Blog.Web/ApplicationConfiguration.cs

@@ -17,6 +17,7 @@ public sealed record ApplicationConfiguration
     public bool IsAboutMeEnabled { get; set; }
 
     public bool IsGiscusEnabled { get; set; }
+
     public bool IsDisqusEnabled { get; set; }
 
     public string KofiToken { get; init; }
@@ -32,4 +33,6 @@ public sealed record ApplicationConfiguration
     public string PatreonName { get; init; }
 
     public bool IsPatreonEnabled => !string.IsNullOrEmpty(PatreonName);
+
+    public bool ShowSimilarPosts { get; init; }
 }

src/LinkDotNet.Blog.Web/Features/Admin/BlogPostEditor/Components/CreateNewBlogPost.razor

@@ -1,5 +1,7 @@
 @using LinkDotNet.Blog.Domain
+@using NCronJob
 @inject IJSRuntime JSRuntime
+@inject IInstantJobRegistry InstantJobRegistry
 
 <div class="container">
 	<h3 class="fw-bold">@Title</h3>
@@ -119,6 +121,7 @@
     {
 	    canSubmit = false;
         await OnBlogPostCreated.InvokeAsync(model.ToBlogPost());
+        InstantJobRegistry.RunInstantJob<SimilarBlogPostJob>(parameter: true);
         ClearModel();
 	    canSubmit = true;
     }

src/LinkDotNet.Blog.Web/Features/BlogPostPublisher.cs

@@ -25,12 +25,15 @@ public BlogPostPublisher(IRepository<BlogPost> repository, ICacheInvalidator cac
 
     public async Task RunAsync(JobExecutionContext context, CancellationToken token)
     {
+        ArgumentNullException.ThrowIfNull(context);
+
         LogPublishStarting();
-        await PublishScheduledBlogPostsAsync();
+        var publishedPosts = await PublishScheduledBlogPostsAsync();
+        context.Output = publishedPosts;
         LogPublishStopping();
     }
 
-    private async Task PublishScheduledBlogPostsAsync()
+    private async Task<int> PublishScheduledBlogPostsAsync()
     {
         LogCheckingForScheduledBlogPosts();
 
@@ -46,6 +49,8 @@ private async Task PublishScheduledBlogPostsAsync()
         {
             cacheInvalidator.Cancel();
         }
+
+        return blogPostsToPublish.Count;
     }
 
     private async Task<IPagedList<BlogPost>> GetScheduledBlogPostsAsync()

src/LinkDotNet.Blog.Web/Features/Services/Similiarity/SimiliarityCalculator.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace LinkDotNet.Blog.Web.Features.Services.Similiarity;
+
+public static class SimilarityCalculator
+{
+    public static double CosineSimilarity(Dictionary<string, double> vectorA, Dictionary<string, double> vectorB)
+    {
+        ArgumentNullException.ThrowIfNull(vectorA);
+        ArgumentNullException.ThrowIfNull(vectorB);
+
+        var dotProduct = 0d;
+        var magnitudeA = 0d;
+
+        foreach (var term in vectorA.Keys)
+        {
+            if (vectorB.TryGetValue(term, out var value))
+            {
+                dotProduct += vectorA[term] * value;
+            }
+            magnitudeA += Math.Pow(vectorA[term], 2);
+        }
+
+        var magnitudeB = vectorB.Values.Sum(value => Math.Pow(value, 2));
+
+        return dotProduct / (Math.Sqrt(magnitudeA) * Math.Sqrt(magnitudeB));
+    }
+}

src/LinkDotNet.Blog.Web/Features/Services/Similiarity/TextProcessor.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+
+namespace LinkDotNet.Blog.Web.Features.Services.Similiarity;
+
+public static partial class TextProcessor
+{
+    private static readonly char[] Separator = [' '];
+
+    public static IReadOnlyCollection<string> TokenizeAndNormalize(IEnumerable<string> texts)
+        => texts.SelectMany(TokenizeAndNormalize).ToList();
+
+    private static IReadOnlyCollection<string> TokenizeAndNormalize(string text)
+    {
+        ArgumentNullException.ThrowIfNull(text);
+
+        text = text.ToUpperInvariant();
+        text = TokenRegex().Replace(text, " ");
+        return [..text.Split(Separator, StringSplitOptions.RemoveEmptyEntries)];
+    }
+
+    [GeneratedRegex(@"[^a-z0-9\s]")]
+    private static partial Regex TokenRegex();
+}

src/LinkDotNet.Blog.Web/Features/Services/Similiarity/TfIdfVectorizer.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace LinkDotNet.Blog.Web.Features.Services.Similiarity;
+
+public class TfIdfVectorizer
+{
+    private readonly IReadOnlyCollection<IReadOnlyCollection<string>> documents;
+    private readonly Dictionary<string, double> idfScores;
+
+    public TfIdfVectorizer(IReadOnlyCollection<IReadOnlyCollection<string>> documents)
+    {
+        this.documents = documents;
+        idfScores = CalculateIdfScores();
+    }
+
+    public Dictionary<string, double> ComputeTfIdfVector(IReadOnlyCollection<string> targetDocument)
+    {
+        ArgumentNullException.ThrowIfNull(targetDocument);
+
+        var termFrequency = targetDocument.GroupBy(t => t).ToDictionary(g => g.Key, g => g.Count());
+        var tfidfVector = new Dictionary<string, double>();
+
+        foreach (var term in termFrequency.Keys)
+        {
+            var tf = termFrequency[term] / (double)targetDocument.Count;
+            var idf = idfScores.TryGetValue(term, out var score) ? score : 0;
+            tfidfVector[term] = tf * idf;
+        }
+
+        return tfidfVector;
+    }
+
+    private Dictionary<string, double> CalculateIdfScores()
+    {
+        var termDocumentFrequency = new Dictionary<string, int>();
+        var scores = new Dictionary<string, double>();
+
+        foreach (var term in documents.Select(document => document.Distinct()).SelectMany(terms => terms))
+        {
+            if (!termDocumentFrequency.TryGetValue(term, out var value))
+            {
+                value = 0;
+                termDocumentFrequency[term] = value;
+            }
+            termDocumentFrequency[term] = ++value;
+        }
+
+        foreach (var term in termDocumentFrequency.Keys)
+        {
+            scores[term] = Math.Log(documents.Count / (double)termDocumentFrequency[term]);
+        }
+
+        return scores;
+    }
+}

src/LinkDotNet.Blog.Web/Features/ShowBlogPost/Components/BlogPostAdminActions.razor

@@ -1,14 +1,16 @@
 @using LinkDotNet.Blog.Domain
 @using LinkDotNet.Blog.Infrastructure.Persistence
+@using NCronJob
 @inject NavigationManager NavigationManager
 @inject IToastService ToastService
 @inject IRepository<BlogPost> BlogPostRepository
+@inject IInstantJobRegistry InstantJobRegistry
 
 <AuthorizeView>
     <div class="blogpost-admin">
         <button id="edit-blogpost" type="button" class="btn btn-primary" @onclick="EditBlogPost" aria-label="edit">
             <i class="pencil"></i> Edit Blogpost</button>
-        <button id="delete-blogpost" type="button" class="btn btn-danger" @onclick="ShowConfirmDialog" aria-label="delete"><i class="bin2"></i> Delete 
+        <button id="delete-blogpost" type="button" class="btn btn-danger" @onclick="ShowConfirmDialog" aria-label="delete"><i class="bin2"></i> Delete
             Blogpost</button>
     </div>
     <ConfirmDialog @ref="ConfirmDialog" Title="Delete Blog Post" Content="Do you want to delete the Blog Post?" OnYesPressed="@DeleteBlogPostAsync">
@@ -18,16 +20,17 @@
 @code {
     [Parameter]
     public string BlogPostId { get; set; }
-    
+
     private ConfirmDialog ConfirmDialog { get; set; }
 
     private async Task DeleteBlogPostAsync()
     {
         await BlogPostRepository.DeleteAsync(BlogPostId);
+        InstantJobRegistry.RunInstantJob<SimilarBlogPostJob>(true);
         ToastService.ShowSuccess("The Blog Post was successfully deleted");
         NavigationManager.NavigateTo("/");
     }
-    
+
     private void ShowConfirmDialog()
     {
         ConfirmDialog.Open();
@@ -37,4 +40,4 @@
     {
         NavigationManager.NavigateTo($"update/{BlogPostId}");
     }
-}
+}

src/LinkDotNet.Blog.Web/Features/ShowBlogPost/Components/SimilarBlogPostSection.razor

@@ -0,0 +1,49 @@
+@using LinkDotNet.Blog.Domain
+@using LinkDotNet.Blog.Infrastructure.Persistence˘
+@inject IRepository<BlogPost> BlogPostRepository
+@inject IRepository<SimilarBlogPost> SimilarBlogPostJobRepository
+
+@if (similarBlogPosts.Count > 0)
+{
+	<div class="accordion my-5" id="archiveAccordion">
+		<div class="accordion-item">
+			<h2 class="accordion-header" id="headingOne">
+				<button class="accordion-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseOne" aria-expanded="false" aria-controls="collapseOne">
+					Want to read more? Check out these related blog posts!
+				</button>
+			</h2>
+			<div id="collapseOne" class="accordion-collapse collapse" aria-labelledby="headingOne" data-bs-parent="#accordionExample">
+				<div class="row p-4">
+					@foreach (var relatedBlogPost in similarBlogPosts)
+					{
+						<div class="col pt-2">
+							<div class="card h-100">
+								<div class="card-body">
+									<h5 class="card-title fw-bold">@relatedBlogPost.Title</h5>
+									<p class="card-text">@MarkdownConverter.ToMarkupString(relatedBlogPost.ShortDescription)</p>
+								</div>
+								<a href="blogPost/@relatedBlogPost.Id/@relatedBlogPost.Slug" class="stretched-link"></a>
+							</div>
+						</div>
+					}
+				</div>
+			</div>
+		</div>
+	</div>
+}
+
+@code {
+	[Parameter] public BlogPost BlogPost { get; set; }
+
+	private IReadOnlyCollection<BlogPost> similarBlogPosts = [];
+
+	protected override async Task OnParametersSetAsync()
+	{
+		var similarBlogPostIds = await SimilarBlogPostJobRepository.GetByIdAsync(BlogPost.Id);
+		if (similarBlogPostIds is not null)
+		{
+			similarBlogPosts = await BlogPostRepository.GetAllAsync(
+				b => similarBlogPostIds.SimilarBlogPostIds.Contains(b.Id));
+		}
+	}
+}

src/LinkDotNet.Blog.Web/Features/ShowBlogPost/ShowBlogPostPage.razor

@@ -75,6 +75,10 @@ else
 				<ShareBlogPost></ShareBlogPost>
 			</div>
 			<DonationSection></DonationSection>
+			@if (AppConfiguration.Value.ShowSimilarPosts)
+			{
+				<SimilarBlogPostSection BlogPost="@BlogPost" />
+			}
 			<CommentSection></CommentSection>
 		</div>
 	</div>
@@ -109,11 +113,7 @@ else
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
         await JsRuntime.InvokeVoidAsync("hljs.highlightAll");
-
-        if (firstRender)
-        {
-	        _ = UserRecordService.StoreUserRecordAsync();
-        }
+        _ = UserRecordService.StoreUserRecordAsync();
     }
 
     private async Task UpdateLikes(bool hasLiked)