module Neo4j
  module Wrapper
    module Rule
      class EventListener
        class << self
          # ----------------------------------------------------------------------------------------------------------------
          # Event handling methods
          # ----------------------------------------------------------------------------------------------------------------

          def on_relationship_created(rel, *)
            Rule.trigger_rules(rel._start_node) if Rule.trigger?(rel._start_node)
            Rule.trigger_rules(rel._end_node) if Rule.trigger?(rel._end_node)
          end

          def on_property_changed(node, *changes)
            Rule.trigger_rules(node, *changes) if Rule.trigger?(node)
          end

          def on_node_deleted(node, old_properties, deleted_relationship_set, deleted_identity_map)
            # have we deleted a rule node ?
            del_rule_node = Rule.find_rule_node(node)
            del_rule_node && del_rule_node.clear_rule_node
            return if del_rule_node

            # do we have prop_aggregations for this
            clazz = old_properties['_classname']
            rule_node = Rule.rule_node_for(clazz)
            return if rule_node.nil?

            id = node.neo_id
            rule_node.rules.each do |rule|
              next if rule.functions.nil? || rule.bulk_update?
              rule_name = rule.rule_name.to_s

              # is the rule node deleted ?
              deleted_rule_node = deleted_identity_map.get(rule_node.rule_node.neo_id)
              next if deleted_rule_node

              rule.functions.each do |function|
                next unless deleted_relationship_set.contains?(id, rule_name)
                previous_value = old_properties[function.function_id]
                function.delete(rule_name, rule_node.rule_node, previous_value) if previous_value
              end if rule.functions
            end
          end

          def classes_changed(changed_class_map)
            changed_class_map.each_pair do |clazz, class_change|
              Rule.bulk_trigger_rules(clazz, class_change, changed_class_map)
            end
          end

          def on_neo4j_started(db)
            if not Neo4j::Config[:enable_rules]
              db.event_handler.remove(self)
            end
          end
        end


      end
      Neo4j.unstarted_db.event_handler.add(EventListener) unless Neo4j.read_only?

    end
  end
end