_costs'][ $based_on ] ) ) {
				$tracker_data['additional_costs'][ $based_on ] = 0;
			}

			$tracker_data['additional_costs'][ $based_on ] ++;
		}

		return $tracker_data;
	}

	/**
	 * @param array  $tracker_data .
	 * @param string $special_action .
	 *
	 * @return array
	 */
	private function append_special_action_data( $tracker_data, $special_action ) {
		if ( ! isset( $tracker_data['special_actions'] ) ) {
			$tracker_data['special_actions'] = array();
		}
		if ( ! isset( $tracker_data['special_actions'][ $special_action ] ) ) {
			$tracker_data['special_actions'][ $special_action ] = 0;
		}
		$tracker_data['special_actions'][ $special_action ]++;
		if ( in_array( $special_action, array( 'stop', 'cancel' ), true ) ) {
			$tracker_data[ $special_action . '_count' ]++;
		}

		return $tracker_data;
	}

	/**
	 * @param array  $condition .
	 * @param array  $tracker_data .
	 * @param string $condition_id .
	 *
	 * @return array
	 */
	private function append_operator_data( $condition, array $tracker_data, $condition_id ) {
		if ( ! empty( $condition[ self::FIELD_OPERATOR ] ) ) {
			$operator = $condition[ self::FIELD_OPERATOR ];
			if ( ! isset( $tracker_data[ self::FIELD_OPERATOR_COUNT ] ) ) {
				$tracker_data[ self::FIELD_OPERATOR_COUNT ] = array();
			}
			if ( ! isset( $tracker_data[ self::FIELD_OPERATOR_COUNT ][ $operator ] ) ) {
				$tracker_data[ self::FIELD_OPERATOR_COUNT ][ $operator ] = 0;
			}
			$tracker_data[ self::FIELD_OPERATOR_COUNT ][ $operator ] ++;

			if ( ! isset( $tracker_data[ self::FIELD_CONDITION_OPERATOR_COUNT ] ) ) {
				$tracker_data[ self::FIELD_CONDITION_OPERATOR_COUNT ] = array();
			}
			$condition_operator = $condition_id . '-' . $operator;
			if ( ! isset( $tracker_data[ self::FIELD_CONDITION_OPERATOR_COUNT ][ $condition_operator ] ) ) {
				$tracker_data[ self::FIELD_CONDITION_OPERATOR_COUNT ][ $condition_operator ] = 0;
			}
			$tracker_data[ self::FIELD_CONDITION_OPERATOR_COUNT ][ $condition_operator ] ++;
		}

		return $tracker_data;
	}

}