MDL-49807 mod_wiki: minimum heading level should always be <h3>

mod/wiki/parser/markups/html.php

@@ -15,22 +15,37 @@ class html_parser extends nwiki_parser {
 
     protected $section_editing = true;
 
+    /** @var int Minimum level of the headers on the page (usually tinymce uses <h1> and atto <h3>)  */
+    protected $minheaderlevel = null;
+
     public function __construct() {
         parent::__construct();
         // The order is important, headers should be parsed before links.
         $this->tagrules = array(
             // Headers are considered tags here.
             'header' => array(
-                'expression' => "/<\s*h([1-$this->maxheaderdepth])\s*>(.+?)<\/h[1-$this->maxheaderdepth]>/is"
+                'expression' => "/<\s*h([1-6])\s*>(.+?)<\/h[1-6]>/is"
             ),
             'link' => $this->tagrules['link'],
             'url' => $this->tagrules['url']
         );
     }
 
+    /**
+     * Find minimum header level used on the page (<h1>, <h3>, ...)
+     *
+     * @param string $text
+     * @return int
+     */
+    protected function find_min_header_level($text) {
+        preg_match_all($this->tagrules['header']['expression'], $text, $matches);
+        return !empty($matches[1]) ? min($matches[1]) : 1;
+    }
+
     protected function before_parsing() {
         parent::before_parsing();
 
+        $this->minheaderlevel = $this->find_min_header_level($this->string);
         $this->rules($this->string);
     }
 
@@ -40,7 +55,7 @@ class html_parser extends nwiki_parser {
      * @return string
      */
     protected function header_tag_rule($match) {
-        return $this->generate_header($match[2], $match[1]);
+        return $this->generate_header($match[2], (int)$match[1] - $this->minheaderlevel + 1);
     }
 
     /**
@@ -54,7 +69,9 @@ class html_parser extends nwiki_parser {
             $text .= "\n\n";
         }
 
-        $h1 = array("<\s*h1\s*>", "<\/h1>");
+        $minheaderlevel = $this->find_min_header_level($text);
+
+        $h1 = array("<\s*h{$minheaderlevel}\s*>", "<\/h{$minheaderlevel}>");
 
         $regex = "/(.*?)({$h1[0]}\s*".preg_quote($header, '/')."\s*{$h1[1]}.*?)((?:\n{$h1[0]}.*)|$)/is";
         preg_match($regex, $text, $match);