feat: add MCP server for the website chatbot over a mirrored TYPO3 content feed

src/Chatbot/Search/Excerpt.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Chatbot\Search;
+
+/**
+ * Cuts a window of about LENGTH characters out of a document, around its first match.
+ *
+ * The excerpt keeps search results small; get_document fetches the rest.
+ */
+final class Excerpt
+{
+    public const LENGTH = 600;
+
+    /**
+     * @param list<string> $terms lower-cased, matched as prefixes like the full-text search
+     */
+    public static function around(string $text, array $terms, int $length = self::LENGTH): string
+    {
+        $text = trim((string) preg_replace('/\s+/u', ' ', $text));
+        $textLength = mb_strlen($text);
+
+        if ($textLength <= $length) {
+            return $text;
+        }
+
+        $position = null;
+        $lower = mb_strtolower($text);
+        foreach ($terms as $term) {
+            $found = mb_strpos($lower, $term);
+            if (false !== $found && (null === $position || $found < $position)) {
+                $position = $found;
+            }
+        }
+
+        // Start a third of the window before the match, so it is read in context.
+        $start = max(0, min(($position ?? 0) - intdiv($length, 3), $textLength - $length));
+        $excerpt = mb_substr($text, $start, $length);
+
+        if ($start > 0) {
+            $space = mb_strpos($excerpt, ' ');
+            $excerpt = '…'.(false !== $space && $space < 40 ? mb_substr($excerpt, $space + 1) : $excerpt);
+        }
+
+        if ($start + $length < $textLength) {
+            $space = mb_strrpos($excerpt, ' ');
+            $excerpt = (false !== $space && mb_strlen($excerpt) - $space < 40 ? mb_substr($excerpt, 0, $space) : $excerpt).'…';
+        }
+
+        return $excerpt;
+    }
+}