Markdown: Add the 'meta-tag' .nomarkdown which prevent a shaare from being parsed with markdown

Also add the tag in tag list in edit_link, so it will appear on autocompletion.

plugins/markdown/markdown.php

@@ -8,6 +8,12 @@
 
 require_once 'Parsedown.php';
 
+/*
+ * If this tag is used on a shaare, the description won't be processed by Parsedown.
+ * Using a private tag so it won't appear for visitors.
+ */
+define('NO_MD_TAG', '.nomarkdown');
+
 /**
  * Parse linklist descriptions.
  *
@@ -18,6 +24,9 @@ require_once 'Parsedown.php';
 function hook_markdown_render_linklist($data)
 {
     foreach ($data['links'] as &$value) {
+        if (!empty($value['tags']) && noMarkdownTag($value['tags'])) {
+            continue;
+        }
         $value['description'] = process_markdown($value['description']);
     }
 
@@ -36,6 +45,9 @@ function hook_markdown_render_daily($data)
     // Manipulate columns data
     foreach ($data['cols'] as &$value) {
         foreach ($value as &$value2) {
+            if (!empty($value2['tags']) && noMarkdownTag($value2['tags'])) {
+                continue;
+            }
             $value2['formatedDescription'] = process_markdown($value2['formatedDescription']);
         }
     }
@@ -43,6 +55,18 @@ function hook_markdown_render_daily($data)
     return $data;
 }
 
+/**
+ * Check if noMarkdown is set in tags.
+ *
+ * @param string $tags tag list
+ *
+ * @return bool true if markdown should be disabled on this link.
+ */
+function noMarkdownTag($tags)
+{
+    return strpos($tags, NO_MD_TAG) !== false;
+}
+
 /**
  * When link list is displayed, include markdown CSS.
  *
@@ -75,6 +99,12 @@ function hook_markdown_render_editlink($data)
 {
     // Load help HTML into a string
     $data['edit_link_plugin'][] = file_get_contents(PluginManager::$PLUGINS_PATH .'/markdown/help.html');
+
+    // Add no markdown 'meta-tag' in tag list if it was never used, for autocompletion.
+    if (! in_array(NO_MD_TAG, $data['tags'])) {
+        $data['tags'][NO_MD_TAG] = 0;
+    }
+
     return $data;
 }