class TriggerMigrator:
    def __init__(self, bind, target):
        self.bind = bind
        self.target = target

    def upgrade(self):
        self.bind.execute(
            f"""
                CREATE OR REPLACE FUNCTION {self.target.function_name}()
                RETURNS TRIGGER
                LANGUAGE  PLPGSQL
                AS
                $$
                    BEGIN
                        IF (TG_OP = 'DELETE') THEN
                            {self.target.on_delete()}
                        RETURN OLD;
                        ELSIF (TG_OP = 'UPDATE') THEN
                            {self.target.on_update()}
                        RETURN NEW;
                        ELSIF (TG_OP = 'INSERT') THEN
                            {self.target.on_insert()}
                        RETURN NEW;
                        END IF;
                    END
                $$;
            """
        )

        self.bind.execute(
            f"""
                CREATE TRIGGER {self.target.function_name}_trigger
                    AFTER INSERT OR UPDATE OR DELETE
                    ON "{self.target.table}"
                    FOR EACH ROW
                    EXECUTE PROCEDURE {self.target.function_name}();
            """
        )

    def rollback(self):
        self.bind.execute(
            f"""
                DROP TRIGGER IF EXISTS {self.target.function_name}_trigger ON "{self.target.table}";
                DROP FUNCTION IF EXISTS {self.target.function_name}();
            """
        )