ture 1514: improvement, impossible to activate a theme is a parent is missing

(a parent includes grand father and his own father, and his own father, and so
on... until the root theme is "default" or has no parent declared)

git-svn-id: http://piwigo.org/svn/trunk@5259 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/themes.class.php

@@ -80,6 +80,20 @@ class themes
           // the theme is already active
           break;
         }
+
+        $missing_parent = $this->missing_parent_theme($theme_id);
+        if (isset($missing_parent))
+        {
+          array_push(
+            $errors, 
+            sprintf(
+              l10n('Impossible to activate this theme, the parent theme is missing: %s'),
+              $missing_parent
+              )
+            );
+          
+          break;
+        }
         
         $query = "
 INSERT INTO ".THEMES_TABLE."
@@ -168,6 +182,28 @@ DELETE
     return $errors;
   }
 
+  function missing_parent_theme($theme_id)
+  {
+    if (!isset($this->fs_themes[$theme_id]['parent']))
+    {
+      return null;
+    }
+    
+    $parent = $this->fs_themes[$theme_id]['parent'];
+      
+    if ('default' == $parent)
+    {
+      return null;
+    }
+      
+    if (!isset($this->fs_themes[$parent]))
+    {
+      return $parent;
+    }
+
+    return $this->missing_parent_theme($parent);
+  }
+
   function get_children_themes($theme_id)
   {
     $children = array();