MDL-44747 editor_atto: Improved validation of toolbar config

This ensures that:
- Plugins are only used once,
- Group names are unique,
- Lines match: group = plugin[, plugin[, plugin ...]],
- There are some groups and plugins defined,
- The plugins used are installed.

lib/editor/atto/adminlib.php

@@ -24,6 +24,78 @@
 
 defined('MOODLE_INTERNAL') || die();
 
+/**
+ * Admin setting for toolbar.
+ *
+ * @package    editor_atto
+ * @copyright  2014 Frédéric Massart
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class editor_atto_toolbar_setting extends admin_setting_configtextarea {
+
+    /**
+     * Validate data.
+     *
+     * This ensures that:
+     * - Plugins are only used once,
+     * - Group names are unique,
+     * - Lines match: group = plugin[, plugin[, plugin ...]],
+     * - There are some groups and plugins defined,
+     * - The plugins used are installed.
+     *
+     * @param string $data
+     * @return mixed True on success, else error message.
+     */
+    public function validate($data) {
+        $result = parent::validate($data);
+        if ($result !== true) {
+            return $result;
+        }
+
+        $lines = explode("\n", $data);
+        $groups = array();
+        $plugins = array();
+
+        foreach ($lines as $line) {
+            if (empty(trim($line))) {
+                continue;
+            }
+
+            $matches = array();
+            if (!preg_match('/^\s*([a-z0-9]+)\s*=\s*([a-z0-9]+(\s*,\s*[a-z0-9]+)*)+\s*$/', $line, $matches)) {
+                $result = get_string('errorcannotparseline', 'editor_atto', $line);
+                break;
+            }
+
+            $group = $matches[1];
+            if (isset($groups[$group])) {
+                $result = get_string('errorgroupisusedtwice', 'editor_atto', $group);
+                break;
+            }
+            $groups[$group] = true;
+
+            $lineplugins = array_map('trim', explode(',', $matches[2]));
+            foreach ($lineplugins as $plugin) {
+                if (isset($plugins[$plugin])) {
+                    $result = get_string('errorpluginisusedtwice', 'editor_atto', $plugin);
+                    break 2;
+                } else if (!core_component::get_component_directory('atto_' . $plugin)) {
+                    $result = get_string('errorpluginnotfound', 'editor_atto', $plugin);
+                    break 2;
+                }
+                $plugins[$plugin] = true;
+            }
+        }
+
+        // We did not find any groups or plugins.
+        if (empty($groups) || empty($plugins)) {
+            $result = get_string('errornopluginsorgroupsfound', 'editor_atto');
+        }
+
+        return $result;
+    }
+
+}
 
 /**
  * Special class for Atto plugins administration.