Add filter for normalize label - Close #5

Author: sandrokeil

src/Filter/NormalizeLabel.php

@@ -0,0 +1,34 @@
+<?php
+
+/**
+ * @see       https://github.com/open-code-modeling/php-filter for the canonical source repository
+ * @copyright https://github.com/open-code-modeling/php-filter/blob/master/COPYRIGHT.md
+ * @license   https://github.com/open-code-modeling/php-filter/blob/master/LICENSE.md MIT License
+ */
+
+declare(strict_types=1);
+
+namespace OpenCodeModeling\Filter\Filter;
+
+final class NormalizeLabel extends AbstractFilter
+{
+    public function __invoke(string $value): string
+    {
+        // Special rule: Remove everything after the first horizontal line
+        $matches = [];
+        if (\preg_match('/<hr id="null"[^>]*>/', $value, $matches)) {
+            return \explode($matches[0], $value)[0];
+        }
+
+        // Remove all html tags and styles
+        $normalizedName = \strip_tags(\html_entity_decode($value));
+
+        // Replace the decoded nbsp UTF-8 space with a "normal" space
+        $normalizedName = \str_replace("\xc2\xa0", ' ', $normalizedName);
+
+        // Strip multi-spaces and tabs with a single space
+        $normalizedName = \preg_replace(['/\s{2,}/', '/[\t\n]/'], ' ', $normalizedName);
+
+        return \trim($normalizedName);
+    }
+}