feat: add logic for related and sequential posts

app/Http/Controllers/PostsController.php

@@ -3,6 +3,8 @@
 namespace App\Http\Controllers;
 
 use CreativeCrafts\Paginate\Facades\Paginate;
+use Illuminate\Support\Facades\Cache;
+use Illuminate\Support\Str;
 use Spatie\Sheets\Facades\Sheets;
 use Spatie\Sheets\Sheet;
 
@@ -20,6 +22,46 @@ class PostsController extends Controller
 
     public function show(Sheet $post)
     {
-        return view('posts.show', ['post' => $post]);
+        $data = Cache::remember("post_context_{$post->slug}", now()->addHours(24), function () use ($post) {
+            $allPosts = Sheets::all()
+                ->filter(fn($p) => ! $p->hidden)
+                ->sortByDesc('date')
+                ->values();
+
+            $index = $allPosts->search(fn($p) => $p->slug === $post->slug);
+
+            $next = $index !== false && $index > 0 ? $allPosts[$index - 1] : null;
+            $previous = $index !== false && $index < $allPosts->count() - 1 ? $allPosts[$index + 1] : null;
+
+            $related = $allPosts
+                ->reject(fn($p) => $p->slug === $post->slug)
+                ->map(function ($p) use ($post) {
+                    $commonTags = array_intersect($post->tags ?? [], $p->tags ?? []);
+                    $p->relevance = count($commonTags);
+                    return $p;
+                })
+                ->filter(fn($p) => $p->relevance > 0)
+                ->sortBy([
+                    ['relevance', 'desc'],
+                    ['date', 'desc'],
+                ])
+                ->take(3);
+
+            if ($related->count() < 3) {
+                $needed = 3 - $related->count();
+                $recent = $allPosts
+                    ->reject(fn($p) => $p->slug === $post->slug || $related->contains('slug', $p->slug))
+                    ->take($needed);
+                $related = $related->merge($recent);
+            }
+
+            return [
+                'previous' => $previous,
+                'next' => $next,
+                'related' => $related,
+            ];
+        });
+
+        return view('posts.show', array_merge(['post' => $post], $data));
     }
 }