From 69a6f4a3afdc6e9d4cced304f82efda575f2a582 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Tue, 8 Aug 2023 02:06:11 +0100
Subject: [PATCH] refactor: delegate post lookup to BlogService

---
 OliverBooth/Pages/Blog/Article.cshtml.cs | 48 +++++++++++++++---------
 OliverBooth/Services/BlogService.cs      | 47 ++++++++++++++++++++++-
 2 files changed, 77 insertions(+), 18 deletions(-)

diff --git a/OliverBooth/Pages/Blog/Article.cshtml.cs b/OliverBooth/Pages/Blog/Article.cshtml.cs
index 0d1166e..b6c1086 100644
--- a/OliverBooth/Pages/Blog/Article.cshtml.cs
+++ b/OliverBooth/Pages/Blog/Article.cshtml.cs
@@ -1,24 +1,35 @@
 using Markdig;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.RazorPages;
-using Microsoft.EntityFrameworkCore;
-using OliverBooth.Data;
 using OliverBooth.Data.Blog;
+using OliverBooth.Services;
 
 namespace OliverBooth.Pages.Blog;
 
+/// <summary>
+///     Represents the page model for the <c>Article</c> page.
+/// </summary>
 public class Article : PageModel
 {
-    private readonly IDbContextFactory<BlogContext> _dbContextFactory;
+    private readonly BlogService _blogService;
     private readonly MarkdownPipeline _markdownPipeline;
 
-    public Article(IDbContextFactory<BlogContext> dbContextFactory, MarkdownPipeline markdownPipeline)
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="Article" /> class.
+    /// </summary>
+    /// <param name="blogService">The <see cref="BlogService" />.</param>
+    /// <param name="markdownPipeline">The <see cref="MarkdownPipeline" />.</param>
+    public Article(BlogService blogService, MarkdownPipeline markdownPipeline)
     {
-        _dbContextFactory = dbContextFactory;
+        _blogService = blogService;
         _markdownPipeline = markdownPipeline;
     }
 
-    public Author Author { get; private set; }
+    /// <summary>
+    ///     Gets the author of the post.
+    /// </summary>
+    /// <value>The author of the post.</value>
+    public Author Author { get; private set; } = null!;
 
     /// <summary>
     ///     Gets a value indicating whether the post is a legacy WordPress post.
@@ -26,10 +37,19 @@ public class Article : PageModel
     /// <value>
     ///     <see langword="true" /> if the post is a legacy WordPress post; otherwise, <see langword="false" />.
     /// </value>
-    public bool IsWordPressLegacyPost => Post?.WordPressId.HasValue ?? false;
+    public bool IsWordPressLegacyPost => Post.WordPressId.HasValue;
 
-    public BlogPost Post { get; private set; } = new();
+    /// <summary>
+    ///     Gets the requested blog post.
+    /// </summary>
+    /// <value>The requested blog post.</value>
+    public BlogPost Post { get; private set; } = null!;
 
+    /// <summary>
+    ///     Sanitizes the content of the blog post.
+    /// </summary>
+    /// <param name="content">The content of the blog post.</param>
+    /// <returns>The sanitized content of the blog post.</returns>
     public string SanitizeContent(string content)
     {
         content = content.Replace("<!--more-->", string.Empty);
@@ -44,20 +64,14 @@ public class Article : PageModel
 
     public IActionResult OnGet(int year, int month, int day, string slug)
     {
-        using BlogContext context = _dbContextFactory.CreateDbContext();
-        Post = context.BlogPosts.FirstOrDefault(p => p.Published.Year == year &&
-                                                     p.Published.Month == month &&
-                                                     p.Published.Day == day &&
-                                                     p.Slug == slug)!;
-
-        // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
-        if (Post is null)
+        if (!_blogService.TryGetBlogPost(year, month, day, slug, out BlogPost? post))
         {
             Response.StatusCode = 404;
             return NotFound();
         }
 
-        Author = context.Authors.FirstOrDefault(a => a.Id == Post.AuthorId)!;
+        Post = post;
+        Author = _blogService.TryGetAuthor(post, out Author? author) ? author : null!;
         return Page();
     }
 }
diff --git a/OliverBooth/Services/BlogService.cs b/OliverBooth/Services/BlogService.cs
index dc005d2..2d9ded4 100644
--- a/OliverBooth/Services/BlogService.cs
+++ b/OliverBooth/Services/BlogService.cs
@@ -1,4 +1,5 @@
-using Microsoft.EntityFrameworkCore;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.EntityFrameworkCore;
 using OliverBooth.Data;
 using OliverBooth.Data.Blog;
 
@@ -29,4 +30,48 @@ public sealed class BlogService
             return context.BlogPosts.OrderByDescending(p => p.Published).ToArray();
         }
     }
+
+    /// <summary>
+    ///     Attempts to find the author of a blog post.
+    /// </summary>
+    /// <param name="post">The blog post.</param>
+    /// <param name="author">
+    ///     When this method returns, contains the <see cref="Author" /> associated with the specified blog post, if the
+    ///     author is found; otherwise, <see langword="null" />.
+    /// <returns><see langword="true" /> if the author is found; otherwise, <see langword="false" />.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="post" /> is <see langword="null" />.</exception>
+    public bool TryGetAuthor(BlogPost post, [NotNullWhen(true)] out Author? author)
+    {
+        if (post is null) throw new ArgumentNullException(nameof(post));
+
+        using BlogContext context = _dbContextFactory.CreateDbContext();
+        author = context.Authors.FirstOrDefault(a => a.Id == post.AuthorId);
+
+        return author is not null;
+    }
+
+    /// <summary>
+    ///     Attempts to find a blog post by its publication date and slug.
+    /// </summary>
+    /// <param name="year">The year the post was published.</param>
+    /// <param name="month">The month the post was published.</param>
+    /// <param name="day">The day the post was published.</param>
+    /// <param name="slug">The slug of the post.</param>
+    /// <param name="post">
+    ///     When this method returns, contains the <see cref="BlogPost" /> associated with the specified publication
+    ///     date and slug, if the post is found; otherwise, <see langword="null" />.
+    /// </param>
+    /// <returns><see langword="true" /> if the post is found; otherwise, <see langword="false" />.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="slug" /> is <see langword="null" />.</exception>
+    public bool TryGetBlogPost(int year, int month, int day, string slug, [NotNullWhen(true)] out BlogPost? post)
+    {
+        if (slug is null) throw new ArgumentNullException(nameof(slug));
+
+        using BlogContext context = _dbContextFactory.CreateDbContext();
+        post = context.BlogPosts.FirstOrDefault(p =>
+            p.Published.Year == year && p.Published.Month == month && p.Published.Day == day &&
+            p.Slug == slug);
+
+        return post is not null;
+    }
 }