e() {
		$api_key = $this->get_api_key();

		if ( is_wp_error( $api_key ) ) {
			return $api_key;
		}

		$response = $this->request_api(
			[
				'a' => 'clear_cache',
				'k' => $api_key['k'],
				's' => $api_key['s'],
			]
		);

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		Logger::info(
			'Sucuri firewall cache cleared.',
			[
				'sucuri firewall cache',
			]
		);

		return true;
	}

	/**
	 * Get the API key.
	 *
	 * @since 3.2
	 *
	 * @return array|WP_Error An array with the keys 'k' and 's', required by the API. A WP_Error object if no key or invalid key.
	 */
	private function get_api_key() {
		$api_key = trim( $this->options->get( 'sucury_waf_api_key', '' ) );

		if ( ! $api_key ) {
			Logger::error(
				'API key was not found.',
				[
					'sucuri firewall cache',
				]
			);

			return new WP_Error( 'no_sucuri_api_key', __( 'Sucuri firewall API key was not found.', 'rocket' ) );
		}

		$matches = self::is_api_key_valid( $api_key );

		if ( ! $matches ) {
			Logger::error(
				'API key is invalid.',
				[
					'sucuri firewall cache',
				]
			);

			return new WP_Error( 'invalid_sucuri_api_key', __( 'Sucuri firewall API key is invalid.', 'rocket' ) );
		}

		return [
			'k' => $matches['k'],
			's' => $matches['s'],
		];
	}

	/**
	 * Request against the API.
	 *
	 * @since 3.2
	 *
	 * @param array $params Parameters to send.
	 *
	 * @return array|WP_Error The response data on success. A WP_Error object on failure.
	 */
	private function request_api( $params = [] ) {
		$params['time'] = time();
		$params         = $this->build_query( $params );
		$url            = sprintf( static::API_URL, $params );

		/**
		 * Filters the arguments for the Sucuri API request
		 *
		 * @since 3.3.4
		 *
		 * @param array $args Arguments for the request.
		 */
		$args = apply_filters(
			'rocket_sucuri_api_request_args',
			[
				'timeout'     => 5,
				'redirection' => 5,
				'httpversion' => '1.1',
				'blocking'    => true,
				// This filter is documented in wp-includes/class-wp-http-streams.php.
				'sslverify'   => apply_filters( 'https_ssl_verify', true ), // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound
			]
		);

		$response = wp_remote_get( $url, $args );

		if ( is_wp_error( $response ) ) {
			Logger::error(
				'Error when contacting the API.',
				[
					'sucuri firewall cache',
					'url'      => $url,
					'response' => $response->get_error_message(),
				]
			);

			// translators: %s is an error message.
			return new WP_Error( 'wp_error_sucuri_api', sprintf( __( 'Error when contacting Sucuri firewall API. Error message was: %s', 'rocket' ), $response->get_error_message() ) );
		}

		$contents = wp_remote_retrieve_body( $response );

		if ( empty( $contents ) ) {
			Logger::error(
				'Could not get a response from the API.',
				[
					'sucuri firewall cache',
					'url'      => $url,
					'response' => $response,
				]
			);

			return new WP_Error( 'sucuri_api_no_response', __( 'Could not get a response from the Sucuri firewall API.', 'rocket' ) );
		}

		$data = json_decode( $contents, true );

		if ( ! $data || ! is_array( $data ) ) {
			Logger::error(
				'Invalid response from the API.',
				[
					'sucuri firewall cache',
					'url'           => $url,
					'response_body' => $contents,
				]
			);

			return new WP_Error( 'sucuri_api_invalid_response', __( 'Got an invalid response from the Sucuri firewall API.', 'rocket' ) );
		}

		if ( empty( $data['status'] ) ) {
			Logger::error(
				'The action failed.',
				[
					'sucuri firewall cache',
					'url'           => $url,
					'response_data' => $data,
				]
			);

			if ( empty( $data['messages'] ) || ! is_array( $data['messages'] ) ) {
				return new WP_Error( 'sucuri_api_error_status', __( 'The Sucuri firewall API returned an unknown error.', 'rocket' ) );
			}

			// translators: %s is an error message.
			$message = _n( 'The Sucuri firewall API returned the following error: %s', 'The Sucuri firewall API returned the following errors: %s', count( $data['messages'] ), 'rocket' );
			$message = sprintf( $message, '<br/>' . implode( '<br/>', $data['messages'] ) );

			return new WP_Error( 'sucuri_api_error_status', $message );
		}

		return $data;
	}

	/**
	 * Add the helper message on the CDN settings.
	 *
	 * @param string[] $addons Name from the addon that requires the helper message.
	 * @return string[]
	 */
	public function add_cdn_helper_message( array $addons ): array {

		if ( ! $this->options->get( 'sucury_waf_cache_sync', false ) ) {
			return $addons;
		}

		$addons[] = 'Sucuri';
		return $addons;
	}

	/**
	 * An i18n-friendly alternative to the built-in PHP method `http_build_query()`.
	 *
	 * @param array|object $params An array or object containing properties.
	 *
	 * @return string An URL-encoded string.
	 */
	private function build_query( $params ): string {
		if ( ! $params ) {
			return '';
		}

		$params = (array) $params;

		foreach ( $params as $param => $value ) {
			$params[ $param ] = $param . '=' . rawurlencode( (string) $value );
		}

		return implode( '&', $params );
	}
}