* @return false|void
	 */
	public function remove_all() {
		// Get the database interface.
		$db = $this->get_db();

		// Bail if no database interface is available.
		if ( empty( $db ) ) {
			return false;
		}

		$prefixed_table_name = $db->prefix . $this->table_name;

		$db->query( "DELETE FROM `$prefixed_table_name` WHERE 1 = 1" );
	}

	/**
	 * Lock a URL.
	 *
	 * @param string $url URL to lock.
	 *
	 * @return void
	 */
	public function lock( string $url ) {
		$this->create_or_update(
			[
				'url'       => $url,
				'is_locked' => true,
			]
			);
	}

	/**
	 * Unlock a URL.
	 *
	 * @param string $url URL to unlock.
	 *
	 * @return void
	 */
	public function unlock( string $url ) {
		$this->create_or_update(
			[
				'url'       => $url,
				'is_locked' => false,
			]
			);
	}

	/**
	 * Check if the url is rejected.
	 *
	 * @param string $url url to check.
	 * @return bool
	 */
	protected function is_rejected( string $url ): bool {
		$extensions = [
			'php' => 1,
			'xml' => 1,
			'xsl' => 1,
			'kml' => 1,
		];

		$extension = pathinfo( $url, PATHINFO_EXTENSION );

		return $extension && isset( $extensions[ $extension ] );
	}
}