perf: cache fichier pour les rétroliens, invalidé sur create/update/delete/link

src/ArticleManager.php

@@ -117,6 +117,7 @@ class ArticleManager
         $this->writeMeta($dir, $meta);
         file_put_contents($dir . '/index.md', ltrim($content));
         $this->rebuildSearchIndex();
+        $this->rebuildBacklinksCache();
 
         return $uuid;
     }
@@ -181,6 +182,7 @@ class ArticleManager
         $this->writeMeta($dir, $meta);
         file_put_contents($dir . '/index.md', ltrim($content));
         $this->rebuildSearchIndex();
+        $this->rebuildBacklinksCache();
     }
 
     public function autosave(string $uuid, string $title, string $content, string $slug): bool
@@ -414,6 +416,7 @@ class ArticleManager
         }
         $meta['external_links'][] = $entry;
         $this->writeMeta($dir, $meta);
+        $this->rebuildBacklinksCache();
         return true;
     }
 
@@ -466,6 +469,7 @@ class ArticleManager
             static fn ($l) => $l['url'] !== $url
         ));
         $this->writeMeta($dir, $meta);
+        $this->rebuildBacklinksCache();
         return true;
     }
 
@@ -547,6 +551,75 @@ class ArticleManager
             $this->removeDir($dir);
         }
         $this->rebuildSearchIndex();
+        $this->rebuildBacklinksCache();
+    }
+
+    // ------------------------------------------------------------------ //
+    //  Cache des rétroliens
+    // ------------------------------------------------------------------ //
+
+    private function backlinksPath(): string
+    {
+        return $this->dataDir . '/_cache/backlinks.json';
+    }
+
+    /**
+     * Reconstruit le cache des rétroliens.
+     * Produit un index slug → [article minimal, ...] pour tous les articles publiés
+     * qui pointent vers un autre article interne via leurs external_links.
+     */
+    public function rebuildBacklinksCache(): void
+    {
+        $cacheDir = $this->dataDir . '/_cache';
+        if (!is_dir($cacheDir)) {
+            mkdir($cacheDir, 0755, true);
+        }
+
+        $index = [];
+        foreach ($this->getAll(publishedOnly: true) as $article) {
+            foreach ($article['external_links'] ?? [] as $link) {
+                $path = rtrim(parse_url($link['url'] ?? '', PHP_URL_PATH) ?? '', '/');
+                if (!preg_match('#^/post/([a-z0-9][a-z0-9-]*)$#', $path, $m)) {
+                    continue;
+                }
+                $target = $m[1];
+                $index[$target][] = [
+                    'uuid'         => $article['uuid'],
+                    'slug'         => $article['slug'] ?? '',
+                    'title'        => $article['title'] ?? '',
+                    'cover'        => $article['cover'] ?? '',
+                    'category'     => $article['category'] ?? '',
+                    'published_at' => $article['published_at'] ?? '',
+                    'created_at'   => $article['created_at'] ?? '',
+                ];
+            }
+        }
+
+        file_put_contents(
+            $this->backlinksPath(),
+            json_encode($index, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES)
+        );
+    }
+
+    /**
+     * Retourne les articles qui pointent vers /post/<slug>, depuis le cache.
+     * Reconstruit le cache si absent.
+     */
+    public function getBacklinks(string $slug, string $excludeUuid = ''): array
+    {
+        $path = $this->backlinksPath();
+        if (!file_exists($path)) {
+            $this->rebuildBacklinksCache();
+        }
+        $index = json_decode((string) file_get_contents($path), true);
+        if (!is_array($index)) {
+            return [];
+        }
+        $result = $index[$slug] ?? [];
+        if ($excludeUuid !== '') {
+            $result = array_values(array_filter($result, static fn ($a) => $a['uuid'] !== $excludeUuid));
+        }
+        return $result;
     }
 
     // ------------------------------------------------------------------ //
@@ -887,25 +960,6 @@ class ArticleManager
     /**
      * Retourne les articles publiés qui contiennent un lien vers /post/<slug>.
      */
-    public function getBacklinks(string $slug, string $excludeUuid = ''): array
-    {
-        $pattern = '/post/' . $slug;
-        $result  = [];
-        foreach ($this->getAll(publishedOnly: true) as $article) {
-            if ($excludeUuid !== '' && $article['uuid'] === $excludeUuid) {
-                continue;
-            }
-            foreach ($article['external_links'] ?? [] as $link) {
-                $path = parse_url($link['url'] ?? '', PHP_URL_PATH) ?? '';
-                if ($path === $pattern || rtrim($path, '/') === $pattern) {
-                    $result[] = $article;
-                    break;
-                }
-            }
-        }
-        return $result;
-    }
-
     private function removeDir(string $dir): void
     {
         foreach (scandir($dir) as $entry) {