turn boolean True if it is a bad bot.
	 */
	private function isBadBot() {
		$botList = aioseo()->options->deprecated->tools->blocker->custom->enable
			? explode( "\n", aioseo()->options->deprecated->tools->blocker->custom->bots )
			: $this->botList;
		$botList = apply_filters( 'aioseo_bad_bot_list', $botList );
		if ( ! empty( $botList ) ) {
			if ( ! isset( $_SERVER['HTTP_USER_AGENT'] ) ) {
				return false;
			}
			$ua  = ! empty( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';
			$uas = $this->prepareList( $botList );
			if ( preg_match( '/' . $uas . '/i', $ua ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Is this a bad referer?
	 *
	 * @since 4.0.0
	 *
	 * @return boolean True if this is a bad referer.
	 */
	private function isBadReferer() {
		$refererList = aioseo()->options->deprecated->tools->blocker->custom->enable
			? explode( "\n", aioseo()->options->deprecated->tools->blocker->custom->referer )
			: $this->refererList;
		$refererList = apply_filters( 'aioseo_bad_referer_list', $refererList );

		if ( ! empty( $refererList ) && ! empty( $_SERVER ) && ! empty( $_SERVER['HTTP_REFERER'] ) ) {
			$referer = esc_url_raw( sanitize_text_field( wp_unslash( $_SERVER['HTTP_REFERER'] ) ) );
			$regex   = $this->prepareList( $refererList );
			if ( preg_match( '/' . $regex . '/i', $referer ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Quote List for Regex
	 *
	 * @since 4.0.0
	 *
	 * @param        $list
	 * @param string $quote
	 * @return string
	 */
	private function prepareList( $list, $quote = '/' ) {
		$regex = '';
		$cont  = 0;
		foreach ( $list as $l ) {
			$trim_l = trim( $l );
			if ( ! empty( $trim_l ) ) {
				if ( $cont ) {
					$regex .= '|';
				}
				$cont   = 1;
				$regex .= preg_quote( trim( $l ), $quote );
			}
		}

		return $regex;
	}

	/**
	 * Tracks the bad bot that was blocked.
	 *
	 * @since 4.0.0
	 *
	 * @param  string $message The message to log.
	 * @return void
	 */
	public function track( $message ) {
		if ( $this->log ) {
			$this->log->info( $message );
		}
	}
}