From 0a86721db2e388df48de9a16447708cbd8ea1907 Mon Sep 17 00:00:00 2001
From: Oliver Booth <git@olivr.me>
Date: Thu, 29 Feb 2024 18:06:30 +0000
Subject: [PATCH] feat: save drafts (version history) when post is updated

---
 OliverBooth/Data/Blog/BlogContext.cs          |   7 +
 OliverBooth/Data/Blog/BlogPostDraft.cs        | 126 ++++++++++++++++++
 .../BlogPostDraftConfiguration.cs             |  36 +++++
 OliverBooth/Data/Blog/IBlogPostDraft.cs       | 103 ++++++++++++++
 OliverBooth/Services/BlogPostService.cs       |  14 ++
 OliverBooth/Services/IBlogPostService.cs      |   8 ++
 6 files changed, 294 insertions(+)
 create mode 100644 OliverBooth/Data/Blog/BlogPostDraft.cs
 create mode 100644 OliverBooth/Data/Blog/Configuration/BlogPostDraftConfiguration.cs
 create mode 100644 OliverBooth/Data/Blog/IBlogPostDraft.cs

diff --git a/OliverBooth/Data/Blog/BlogContext.cs b/OliverBooth/Data/Blog/BlogContext.cs
index 4d9db4f..1dead2e 100644
--- a/OliverBooth/Data/Blog/BlogContext.cs
+++ b/OliverBooth/Data/Blog/BlogContext.cs
@@ -25,6 +25,12 @@ internal sealed class BlogContext : DbContext
     /// <value>The collection of blog posts.</value>
     public DbSet<BlogPost> BlogPosts { get; private set; } = null!;
 
+    /// <summary>
+    ///     Gets the collection of blog posts drafts in the database.
+    /// </summary>
+    /// <value>The collection of blog post drafts.</value>
+    public DbSet<BlogPostDraft> BlogPostDrafts { get; private set; } = null!;
+
     /// <inheritdoc />
     protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
     {
@@ -37,5 +43,6 @@ internal sealed class BlogContext : DbContext
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
         modelBuilder.ApplyConfiguration(new BlogPostConfiguration());
+        modelBuilder.ApplyConfiguration(new BlogPostDraftConfiguration());
     }
 }
diff --git a/OliverBooth/Data/Blog/BlogPostDraft.cs b/OliverBooth/Data/Blog/BlogPostDraft.cs
new file mode 100644
index 0000000..3c5a027
--- /dev/null
+++ b/OliverBooth/Data/Blog/BlogPostDraft.cs
@@ -0,0 +1,126 @@
+using System.ComponentModel.DataAnnotations.Schema;
+using SmartFormat;
+
+namespace OliverBooth.Data.Blog;
+
+/// <inheritdoc />
+internal sealed class BlogPostDraft : IBlogPostDraft
+{
+    /// <inheritdoc />
+    [NotMapped]
+    public IBlogAuthor Author { get; internal set; } = null!;
+
+    /// <inheritdoc />
+    public string Body { get; set; } = string.Empty;
+
+    /// <inheritdoc />
+    public bool EnableComments { get; internal set; }
+
+    /// <inheritdoc />
+    public Guid Id { get; private set; } = Guid.NewGuid();
+
+    /// <inheritdoc />
+    public bool IsRedirect { get; internal set; }
+
+    /// <inheritdoc />
+    public string? Password { get; internal set; }
+
+    /// <inheritdoc />
+    public Uri? RedirectUrl { get; internal set; }
+
+    /// <inheritdoc />
+    public string Slug { get; internal set; } = string.Empty;
+
+    /// <inheritdoc />
+    public IReadOnlyList<string> Tags { get; internal set; } = ArraySegment<string>.Empty;
+
+    /// <inheritdoc />
+    public string Title { get; set; } = string.Empty;
+
+    /// <inheritdoc />
+    public DateTimeOffset Updated { get; internal set; }
+
+    /// <inheritdoc />
+    public BlogPostVisibility Visibility { get; internal set; }
+
+    /// <inheritdoc />
+    public int? WordPressId { get; set; }
+
+    /// <summary>
+    ///     Gets or sets the ID of the author of this blog post.
+    /// </summary>
+    /// <value>The ID of the author of this blog post.</value>
+    internal Guid AuthorId { get; set; }
+
+    /// <summary>
+    ///     Gets or sets the base URL of the Disqus comments for the blog post.
+    /// </summary>
+    /// <value>The Disqus base URL.</value>
+    internal string? DisqusDomain { get; set; }
+
+    /// <summary>
+    ///     Gets or sets the identifier of the Disqus comments for the blog post.
+    /// </summary>
+    /// <value>The Disqus identifier.</value>
+    internal string? DisqusIdentifier { get; set; }
+
+    /// <summary>
+    ///     Gets or sets the URL path of the Disqus comments for the blog post.
+    /// </summary>
+    /// <value>The Disqus URL path.</value>
+    internal string? DisqusPath { get; set; }
+
+    /// <summary>
+    ///     Constructs a <see cref="BlogPostDraft" /> by copying values from an existing <see cref="BlogPost" />.
+    /// </summary>
+    /// <param name="post">The existing <see cref="BlogPost" />.</param>
+    /// <returns>The newly-constructed <see cref="BlogPostDraft" />.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="post" /> is <see langword="null" />.</exception>
+    public static BlogPostDraft CreateFromBlogPost(BlogPost post)
+    {
+        if (post is null)
+        {
+            throw new ArgumentNullException(nameof(post));
+        }
+
+        return new BlogPostDraft
+        {
+            AuthorId = post.AuthorId,
+            Body = post.Body,
+            DisqusDomain = post.DisqusDomain,
+            DisqusIdentifier = post.DisqusIdentifier,
+            DisqusPath = post.DisqusPath,
+            EnableComments = post.EnableComments,
+            IsRedirect = post.IsRedirect,
+            Password = post.Password,
+            RedirectUrl = post.RedirectUrl,
+            Tags = post.Tags,
+            Title = post.Title,
+            Visibility = post.Visibility,
+            WordPressId = post.WordPressId
+        };
+    }
+
+    /// <summary>
+    ///     Gets the Disqus domain for the blog post.
+    /// </summary>
+    /// <returns>The Disqus domain.</returns>
+    public string GetDisqusDomain()
+    {
+        return string.IsNullOrWhiteSpace(DisqusDomain)
+            ? "https://oliverbooth.dev/blog"
+            : Smart.Format(DisqusDomain, this);
+    }
+
+    /// <inheritdoc />
+    public string GetDisqusIdentifier()
+    {
+        return string.IsNullOrWhiteSpace(DisqusIdentifier) ? $"post-{Id}" : Smart.Format(DisqusIdentifier, this);
+    }
+
+    /// <inheritdoc />
+    public string GetDisqusPostId()
+    {
+        return WordPressId?.ToString() ?? Id.ToString();
+    }
+}
diff --git a/OliverBooth/Data/Blog/Configuration/BlogPostDraftConfiguration.cs b/OliverBooth/Data/Blog/Configuration/BlogPostDraftConfiguration.cs
new file mode 100644
index 0000000..9c2f760
--- /dev/null
+++ b/OliverBooth/Data/Blog/Configuration/BlogPostDraftConfiguration.cs
@@ -0,0 +1,36 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+namespace OliverBooth.Data.Blog.Configuration;
+
+internal sealed class BlogPostDraftConfiguration : IEntityTypeConfiguration<BlogPostDraft>
+{
+    /// <inheritdoc />
+    public void Configure(EntityTypeBuilder<BlogPostDraft> builder)
+    {
+        builder.ToTable("BlogPostDraft");
+        builder.HasKey(e => new { e.Id, e.Updated });
+
+        builder.Property(e => e.Id);
+        builder.Property(e => e.Updated).IsRequired();
+        builder.Property(e => e.WordPressId).IsRequired(false);
+        builder.Property(e => e.Slug).HasMaxLength(100).IsRequired();
+        builder.Property(e => e.AuthorId).IsRequired();
+        builder.Property(e => e.Title).HasMaxLength(255).IsRequired();
+        builder.Property(e => e.Body).IsRequired();
+        builder.Property(e => e.IsRedirect).IsRequired();
+        builder.Property(e => e.RedirectUrl).HasConversion<UriToStringConverter>().HasMaxLength(255).IsRequired(false);
+        builder.Property(e => e.EnableComments).IsRequired();
+        builder.Property(e => e.DisqusDomain).IsRequired(false);
+        builder.Property(e => e.DisqusIdentifier).IsRequired(false);
+        builder.Property(e => e.DisqusPath).IsRequired(false);
+        builder.Property(e => e.Visibility).HasConversion(new EnumToStringConverter<BlogPostVisibility>()).IsRequired();
+        builder.Property(e => e.Password).HasMaxLength(255).IsRequired(false);
+        builder.Property(e => e.Tags).IsRequired()
+            .HasConversion(
+                tags => string.Join(' ', tags.Select(t => t.Replace(' ', '-'))),
+                tags => tags.Split(' ', StringSplitOptions.RemoveEmptyEntries)
+                    .Select(t => t.Replace('-', ' ')).ToArray());
+    }
+}
diff --git a/OliverBooth/Data/Blog/IBlogPostDraft.cs b/OliverBooth/Data/Blog/IBlogPostDraft.cs
new file mode 100644
index 0000000..1d66c2b
--- /dev/null
+++ b/OliverBooth/Data/Blog/IBlogPostDraft.cs
@@ -0,0 +1,103 @@
+namespace OliverBooth.Data.Blog;
+
+/// <summary>
+///     Represents a draft of a blog post.
+/// </summary>
+public interface IBlogPostDraft
+{
+    /// <summary>
+    ///     Gets the author of the post.
+    /// </summary>
+    /// <value>The author of the post.</value>
+    IBlogAuthor Author { get; }
+
+    /// <summary>
+    ///     Gets or sets the body of the post.
+    /// </summary>
+    /// <value>The body of the post.</value>
+    string Body { get; set; }
+
+    /// <summary>
+    ///     Gets a value indicating whether comments are enabled for the post.
+    /// </summary>
+    /// <value>
+    ///     <see langword="true" /> if comments are enabled for the post; otherwise, <see langword="false" />.
+    /// </value>
+    bool EnableComments { get; }
+
+    /// <summary>
+    ///     Gets the ID of the post.
+    /// </summary>
+    /// <value>The ID of the post.</value>
+    Guid Id { get; }
+
+    /// <summary>
+    ///     Gets a value indicating whether the post redirects to another URL.
+    /// </summary>
+    /// <value>
+    ///     <see langword="true" /> if the post redirects to another URL; otherwise, <see langword="false" />.
+    /// </value>
+    bool IsRedirect { get; }
+
+    /// <summary>
+    ///     Gets the password of the post.
+    /// </summary>
+    /// <value>The password of the post.</value>
+    string? Password { get; }
+
+    /// <summary>
+    ///     Gets the URL to which the post redirects.
+    /// </summary>
+    /// <value>The URL to which the post redirects, or <see langword="null" /> if the post does not redirect.</value>
+    Uri? RedirectUrl { get; }
+
+    /// <summary>
+    ///     Gets the slug of the post.
+    /// </summary>
+    /// <value>The slug of the post.</value>
+    string Slug { get; }
+
+    /// <summary>
+    ///     Gets the tags of the post.
+    /// </summary>
+    /// <value>The tags of the post.</value>
+    IReadOnlyList<string> Tags { get; }
+
+    /// <summary>
+    ///     Gets or sets the title of the post.
+    /// </summary>
+    /// <value>The title of the post.</value>
+    string Title { get; set; }
+
+    /// <summary>
+    ///     Gets the date and time the post was last updated.
+    /// </summary>
+    /// <value>The update date and time.</value>
+    DateTimeOffset Updated { get; }
+
+    /// <summary>
+    ///     Gets the visibility of the post.
+    /// </summary>
+    /// <value>The visibility of the post.</value>
+    BlogPostVisibility Visibility { get; }
+
+    /// <summary>
+    ///     Gets the WordPress ID of the post.
+    /// </summary>
+    /// <value>
+    ///     The WordPress ID of the post, or <see langword="null" /> if the post was not imported from WordPress.
+    /// </value>
+    int? WordPressId { get; }
+
+    /// <summary>
+    ///     Gets the Disqus identifier for the post.
+    /// </summary>
+    /// <returns>The Disqus identifier for the post.</returns>
+    string GetDisqusIdentifier();
+
+    /// <summary>
+    ///     Gets the Disqus post ID for the post.
+    /// </summary>
+    /// <returns>The Disqus post ID for the post.</returns>
+    string GetDisqusPostId();
+}
diff --git a/OliverBooth/Services/BlogPostService.cs b/OliverBooth/Services/BlogPostService.cs
index ef4705a..afde740 100644
--- a/OliverBooth/Services/BlogPostService.cs
+++ b/OliverBooth/Services/BlogPostService.cs
@@ -40,6 +40,18 @@ internal sealed class BlogPostService : IBlogPostService
         return context.BlogPosts.Count();
     }
 
+    /// <inheritdoc />
+    public IReadOnlyList<IBlogPostDraft> GetDrafts(IBlogPost post)
+    {
+        if (post is null)
+        {
+            throw new ArgumentNullException(nameof(post));
+        }
+
+        using BlogContext context = _dbContextFactory.CreateDbContext();
+        return context.BlogPostDrafts.Where(d => d.Id == post.Id).OrderBy(d => d.Updated).ToArray();
+    }
+
     /// <inheritdoc />
     public IReadOnlyList<IBlogPost> GetAllBlogPosts(int limit = -1,
         BlogPostVisibility visibility = BlogPostVisibility.Published)
@@ -170,6 +182,8 @@ internal sealed class BlogPostService : IBlogPostService
         }
 
         using BlogContext context = _dbContextFactory.CreateDbContext();
+        BlogPost cached = context.BlogPosts.First(p => p.Id == post.Id);
+        context.BlogPostDrafts.Add(BlogPostDraft.CreateFromBlogPost(cached));
         context.Update(post);
         context.SaveChanges();
     }
diff --git a/OliverBooth/Services/IBlogPostService.cs b/OliverBooth/Services/IBlogPostService.cs
index a8e6d6c..34a9840 100644
--- a/OliverBooth/Services/IBlogPostService.cs
+++ b/OliverBooth/Services/IBlogPostService.cs
@@ -36,6 +36,14 @@ public interface IBlogPostService
     /// <returns>A collection of blog posts.</returns>
     IReadOnlyList<IBlogPost> GetBlogPosts(int page, int pageSize = 10);
 
+    /// <summary>
+    ///     Returns the drafts of this post, sorted by their update timestamp.
+    /// </summary>
+    /// <param name="post">The post whose drafts to return.</param>
+    /// <returns>The drafts of the <paramref name="post" />.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="post" /> is <see langword="null" />.</exception>
+    IReadOnlyList<IBlogPostDraft> GetDrafts(IBlogPost post);
+
     /// <summary>
     ///     Returns the next blog post from the specified blog post.
     /// </summary>