Display a list of related post titles

References #3

web/modules/custom/blog/src/Plugin/Block/RelatedPostsBlock.php

@@ -3,6 +3,13 @@
 namespace Drupal\opdavies_blog\Plugin\Block;
 
 use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Link;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Routing\CurrentRouteMatch;
+use Drupal\opdavies_blog\Entity\Node\Post;
+use Drupal\opdavies_blog\Repository\RelatedPostsRepository;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Tightenco\Collect\Support\Collection;
 
 /**
  * @Block(
@@ -11,14 +18,69 @@ use Drupal\Core\Block\BlockBase;
  *   category = @Translation("Blog")
  * )
  */
-class RelatedPostsBlock extends BlockBase {
+class RelatedPostsBlock extends BlockBase implements ContainerFactoryPluginInterface {
+
+  private CurrentRouteMatch $currentRouteMatch;
+
+  private RelatedPostsRepository $relatedPostsRepository;
+
+  public function __construct(
+    array $configuration,
+    string $pluginId,
+    array $pluginDefinition,
+    CurrentRouteMatch $currentRouteMatch,
+    RelatedPostsRepository $relatedPostsRepository
+  ) {
+    parent::__construct($configuration, $pluginId, $pluginDefinition);
+
+    $this->currentRouteMatch = $currentRouteMatch;
+    $this->relatedPostsRepository = $relatedPostsRepository;
+  }
+
+  public static function create(
+    ContainerInterface $container,
+    array $configuration,
+    $pluginId,
+    $pluginDefinition
+  ): self {
+    // @phpstan-ignore-next-line
+    return new self(
+      $configuration,
+      $pluginId,
+      $pluginDefinition,
+      $container->get('current_route_match'),
+      $container->get(RelatedPostsRepository::class)
+    );
+  }
 
   public function build(): array {
+    $currentPost = $this->currentRouteMatch->getParameter('node');
+
+    /** @var Collection|Post[] $relatedPosts */
+    $relatedPosts = $this->relatedPostsRepository->getFor($currentPost);
+
+    if ($relatedPosts->isEmpty()) {
+      return [];
+    }
+
     $build['content'] = [
-      '#markup' => $this->t('It works!'),
+      '#theme' => 'item_list',
+      '#items' => $relatedPosts
+        ->sortByDesc(fn(Post $post) => $post->getCreatedTime())
+        ->map(fn(Post $post) => $this->generateLinkToPost($post))
+        ->slice(0, 3)
+        ->toArray(),
     ];
 
     return $build;
   }
 
+  private function generateLinkToPost(Post $post): Link {
+    return Link::createFromRoute(
+      $post->getTitle(),
+      'entity.node.canonical',
+      ['node' => $post->id()]
+    );
+  }
+
 }

web/modules/custom/blog/src/Repository/RelatedPostsRepository.php

@@ -9,7 +9,7 @@ use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\opdavies_blog\Entity\Node\Post;
 use Drupal\taxonomy\TermInterface;
-use Illuminate\Support\Collection;
+use Tightenco\Collect\Support\Collection;
 
 final class RelatedPostsRepository {