TPACK_SHOULD_HANDLE_IDC constant if set.
		 *
		 * @param bool $default Whether the site is opted in to IDC mitigation.
		 *
		 * @since 0.2.6
		 */
		return (bool) apply_filters( 'jetpack_should_handle_idc', $default );
	}

	/**
	 * Whether the site is undergoing identity crisis.
	 *
	 * @return bool
	 */
	public static function has_identity_crisis() {
		return false !== static::check_identity_crisis() && ! static::$is_safe_mode_confirmed;
	}

	/**
	 * Whether an admin has confirmed safe mode.
	 * Unlike `static::$is_safe_mode_confirmed` this function always returns the actual flag value.
	 *
	 * @return bool
	 */
	public static function safe_mode_is_confirmed() {
		return Jetpack_Options::get_option( 'safe_mode_confirmed' );
	}

	/**
	 * Returns the mismatched URLs.
	 *
	 * @return array|bool The mismatched urls, or false if the site is not connected, offline, in safe mode, or the IDC error is not valid.
	 */
	public static function get_mismatched_urls() {
		if ( ! static::has_identity_crisis() ) {
			return false;
		}

		$data = static::check_identity_crisis();

		if ( ! $data ||
			! isset( $data['error_code'] ) ||
			! isset( $data['wpcom_home'] ) ||
			! isset( $data['home'] ) ||
			! isset( $data['wpcom_siteurl'] ) ||
			! isset( $data['siteurl'] )
		) {
			// The jetpack_sync_error_idc option is missing a key.
			return false;
		}

		if ( 'jetpack_site_url_mismatch' === $data['error_code'] ) {
			return array(
				'wpcom_url'   => $data['wpcom_siteurl'],
				'current_url' => $data['siteurl'],
			);
		}

		return array(
			'wpcom_url'   => $data['wpcom_home'],
			'current_url' => $data['home'],
		);
	}

	/**
	 * Try to detect $_SERVER['HTTP_HOST'] being used within WP_SITEURL or WP_HOME definitions inside of wp-config.
	 *
	 * If `HTTP_HOST` usage is found, it's possbile (though not certain) that site URLs are dynamic.
	 *
	 * When a site URL is dynamic, it can lead to a Jetpack IDC. If potentially dynamic usage is detected,
	 * helpful support info will be shown on the IDC UI about setting a static site/home URL.
	 *
	 * @return bool True if potentially dynamic site urls were detected in wp-config, false otherwise.
	 */
	public static function detect_possible_dynamic_site_url() {
		$transient_key = 'jetpack_idc_possible_dynamic_site_url_detected';
		$transient_val = get_transient( $transient_key );

		if ( false !== $transient_val ) {
			return (bool) $transient_val;
		}

		$path      = self::locate_wp_config();
		$wp_config = $path ? file_get_contents( $path ) : false; // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
		if ( $wp_config ) {
			$matched = preg_match(
				'/define ?\( ?[\'"](?:WP_SITEURL|WP_HOME).+(?:HTTP_HOST).+\);/',
				$wp_config
			);

			if ( $matched ) {
				set_transient( $transient_key, 1, HOUR_IN_SECONDS );
				return true;
			}
		}

		set_transient( $transient_key, 0, HOUR_IN_SECONDS );
		return false;
	}

	/**
	 * Gets path to WordPress configuration.
	 * Source: https://github.com/wp-cli/wp-cli/blob/master/php/utils.php
	 *
	 * @return string
	 */
	public static function locate_wp_config() {
		static $path;

		if ( null === $path ) {
			$path = false;

			if ( getenv( 'WP_CONFIG_PATH' ) && file_exists( getenv( 'WP_CONFIG_PATH' ) ) ) {
				$path = getenv( 'WP_CONFIG_PATH' );
			} elseif ( file_exists( ABSPATH . 'wp-config.php' ) ) {
				$path = ABSPATH . 'wp-config.php';
			} elseif ( file_exists( dirname( ABSPATH ) . '/wp-config.php' ) && ! file_exists( dirname( ABSPATH ) . '/wp-settings.php' ) ) {
				$path = dirname( ABSPATH ) . '/wp-config.php';
			}

			if ( $path ) {
				$path = realpath( $path );
			}
		}

		return $path;
	}

	/**
	 * Adds `url_secret` to the `jetpack.idcUrlValidation` URL validation endpoint.
	 * Adds `url_secret_error` in case of an error.
	 *
	 * @param array $response The endpoint response that we're modifying.
	 *
	 * @return array
	 *
	 * phpcs:ignore Squiz.Commenting.FunctionCommentThrowTag -- The exception is being caught, false positive.
	 */
	public static function add_secret_to_url_validation_response( array $response ) {
		try {
			$secret = new URL_Secret();

			$secret->create();

			if ( $secret->exists() ) {
				$response['url_secret'] = $secret->get_secret();
			}
		} catch ( Exception $e ) {
			$response['url_secret_error'] = new WP_Error( 'unable_to_create_url_secret', $e->getMessage() );
		}

		return $response;
	}

	/**
	 * Check if URL is an IP.
	 *
	 * @param string $hostname The hostname to check.
	 * @return bool
	 */
	public static function url_is_ip( $hostname = null ) {

		if ( ! $hostname ) {
			$hostname = wp_parse_url( Urls::site_url(), PHP_URL_HOST );
		}

		$is_ip = filter_var( $hostname, FILTER_VALIDATE_IP ) !== false ? $hostname : false;
		return $is_ip;
	}

	/**
	 * Add IDC-related data to the registration query.
	 *
	 * @param array $params The existing query params.
	 *
	 * @return array
	 */
	public static function register_request_body( array $params ) {
		$persistent_blog_id = get_option( static::PERSISTENT_BLOG_ID_OPTION_NAME );
		if ( $persistent_blog_id ) {
			$params['persistent_blog_id'] = $persistent_blog_id;
			$params['url_secret']         = URL_Secret::create_secret( 'registration_request_url_secret_failed' );
		}

		return $params;
	}

	/**
	 * Set the necessary options when site gets registered.
	 *
	 * @param int $blog_id The blog ID.
	 *
	 * @return void
	 */
	public static function site_registered( $blog_id ) {
		update_option( static::PERSISTENT_BLOG_ID_OPTION_NAME, (int) $blog_id, false );
	}

	/**
	 * Check if we need to update the ip_requester option.
	 *
	 * @param string $hostname The hostname to check.
	 *
	 * @return void
	 */
	public static function maybe_update_ip_requester( $hostname ) {
		// Check if transient exists
		$transient_key = ip2long( $hostname );
		if ( $transient_key && ! get_transient( 'jetpack_idc_ip_requester_' . $transient_key ) ) {
			self::set_ip_requester_for_idc( $hostname, $transient_key );
		}
	}

	/**
	 * If URL is an IP, add the IP value to the ip_requester option with its expiry value.
	 *
	 * @param string $hostname The hostname to check.
	 * @param int    $transient_key The transient key.
	 */
	public static function set_ip_requester_for_idc( $hostname, $transient_key ) {
		// Check if option exists
		$data = Jetpack_Options::get_option( 'identity_crisis_ip_requester' );

		$ip_requester = array(
			'ip'         => $hostname,
			'expires_at' => time() + 360,
		);

		// If not set, initialize it
		if ( empty( $data ) ) {
			$data = array( $ip_requester );
		} else {
			$updated_data  = array();
			$updated_value = false;

			// Remove expired values and update existing IP
			foreach ( $data as $item ) {
				if ( time() > $item['expires_at'] ) {
					continue; // Skip expired IP
				}

				if ( $item['ip'] === $hostname ) {
					$item['expires_at'] = time() + 360;
					$updated_value      = true;
				}

				$updated_data[] = $item;
			}

			if ( ! $updated_value || empty( $updated_data ) ) {
				$updated_data[] = $ip_requester;
			}

			$data = $updated_data;
		}

		self::update_ip_requester( $data, $transient_key );
	}

	/**
	 * Update the ip_requester option and set a transient to expire in 5 minutes.
	 *
	 * @param array $data The data to be updated.
	 * @param int   $transient_key The transient key.
	 *
	 * @return void
	 */
	public static function update_ip_requester( $data, $transient_key ) {
		// Update the option
		$updated = Jetpack_Options::update_option( 'identity_crisis_ip_requester', $data );
		// Set a transient to expire in 5 minutes
		if ( $updated ) {
			$transient_name = 'jetpack_idc_ip_requester_' . $transient_key;
			set_transient( $transient_name, $data, 300 );
		}
	}

	/**
	 * Adds `ip_requester` to the `jetpack.idcUrlValidation` URL validation endpoint.
	 *
	 * @param array $response The enpoint response that we're modifying.
	 *
	 * @return array
	 */
	public static function add_ip_requester_to_url_validation_response( array $response ) {
		$requesters = Jetpack_Options::get_option( 'identity_crisis_ip_requester' );
		if ( $requesters ) {
			// Loop through the requesters and add the IP to the response if it's not expired
			$i = 0;
			foreach ( $requesters as $ip ) {
				if ( $ip['expires_at'] > time() ) {
					$response['ip_requester'][] = $ip['ip'];
				}
				// Limit the response to five IPs
				$i = ++$i;
				if ( $i === 5 ) {
					break;
				}
			}
		}
		return $response;
	}
}