/**
  * @return MetaConfiguration
  **/
 public function buildSchemaChanges()
 {
     $out = $this->getOutput();
     $out->newLine()->infoLine('Suggested DB-schema changes: ');
     require ONPHP_META_AUTO_DIR . 'schema.php';
     foreach ($this->classes as $class) {
         if ($class->getTypeId() == MetaClassType::CLASS_ABSTRACT || $class->getPattern() instanceof EnumerationClassPattern) {
             continue;
         }
         try {
             $target = $schema->getTableByName($class->getTableName());
         } catch (MissingElementException $e) {
             // dropped or tableless
             continue;
         }
         try {
             $db = DBPool::me()->getLink($class->getSourceLink());
         } catch (BaseException $e) {
             $out->errorLine('Can not connect using source link in \'' . $class->getName() . '\' class, skipping this step.');
             break;
         }
         try {
             $source = $db->getTableInfo($class->getTableName());
         } catch (UnsupportedMethodException $e) {
             $out->errorLine(get_class($db) . ' does not support tables introspection yet.', true);
             break;
         } catch (ObjectNotFoundException $e) {
             $out->errorLine("table '{$class->getTableName()}' not found, skipping.");
             continue;
         }
         $diff = DBTable::findDifferences($db->getDialect(), $source, $target);
         if ($diff) {
             foreach ($diff as $line) {
                 $out->warningLine($line);
             }
             $out->newLine();
         }
     }
     return $this;
 }