wp_login_url()
 *
 * @return bool True if inside WordPress login screen, false otherwise.
 */
function is_login() {
	return false !== stripos( wp_login_url(), $_SERVER['SCRIPT_NAME'] );
}

/**
 * Determines whether the current request is for an administrative interface page.
 *
 * Does not check if the user is an administrator; use current_user_can()
 * for checking roles and capabilities.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 1.5.1
 *
 * @global WP_Screen $current_screen WordPress current screen object.
 *
 * @return bool True if inside WordPress administration interface, false otherwise.
 */
function is_admin() {
	if ( isset( $GLOBALS['current_screen'] ) ) {
		return $GLOBALS['current_screen']->in_admin();
	} elseif ( defined( 'WP_ADMIN' ) ) {
		return WP_ADMIN;
	}

	return false;
}

/**
 * Determines whether the current request is for a site's administrative interface.
 *
 * e.g. `/wp-admin/`
 *
 * Does not check if the user is an administrator; use current_user_can()
 * for checking roles and capabilities.
 *
 * @since 3.1.0
 *
 * @global WP_Screen $current_screen WordPress current screen object.
 *
 * @return bool True if inside WordPress site administration pages.
 */
function is_blog_admin() {
	if ( isset( $GLOBALS['current_screen'] ) ) {
		return $GLOBALS['current_screen']->in_admin( 'site' );
	} elseif ( defined( 'WP_BLOG_ADMIN' ) ) {
		return WP_BLOG_ADMIN;
	}

	return false;
}

/**
 * Determines whether the current request is for the network administrative interface.
 *
 * e.g. `/wp-admin/network/`
 *
 * Does not check if the user is an administrator; use current_user_can()
 * for checking roles and capabilities.
 *
 * Does not check if the site is a Multisite network; use is_multisite()
 * for checking if Multisite is enabled.
 *
 * @since 3.1.0
 *
 * @global WP_Screen $current_screen WordPress current screen object.
 *
 * @return bool True if inside WordPress network administration pages.
 */
function is_network_admin() {
	if ( isset( $GLOBALS['current_screen'] ) ) {
		return $GLOBALS['current_screen']->in_admin( 'network' );
	} elseif ( defined( 'WP_NETWORK_ADMIN' ) ) {
		return WP_NETWORK_ADMIN;
	}

	return false;
}

/**
 * Determines whether the current request is for a user admin screen.
 *
 * e.g. `/wp-admin/user/`
 *
 * Does not check if the user is an administrator; use current_user_can()
 * for checking roles and capabilities.
 *
 * @since 3.1.0
 *
 * @global WP_Screen $current_screen WordPress current screen object.
 *
 * @return bool True if inside WordPress user administration pages.
 */
function is_user_admin() {
	if ( isset( $GLOBALS['current_screen'] ) ) {
		return $GLOBALS['current_screen']->in_admin( 'user' );
	} elseif ( defined( 'WP_USER_ADMIN' ) ) {
		return WP_USER_ADMIN;
	}

	return false;
}

/**
 * Determines whether Multisite is enabled.
 *
 * @since 3.0.0
 *
 * @return bool True if Multisite is enabled, false otherwise.
 */
function is_multisite() {
	if ( defined( 'MULTISITE' ) ) {
		return MULTISITE;
	}

	if ( defined( 'SUBDOMAIN_INSTALL' ) || defined( 'VHOST' ) || defined( 'SUNRISE' ) ) {
		return true;
	}

	return false;
}

/**
 * Converts a value to non-negative integer.
 *
 * @since 2.5.0
 *
 * @param mixed $maybeint Data you wish to have converted to a non-negative integer.
 * @return int A non-negative integer.
 */
function absint( $maybeint ) {
	return abs( (int) $maybeint );
}

/**
 * Retrieves the current site ID.
 *
 * @since 3.1.0
 *
 * @global int $blog_id
 *
 * @return int Site ID.
 */
function get_current_blog_id() {
	global $blog_id;

	return absint( $blog_id );
}

/**
 * Retrieves the current network ID.
 *
 * @since 4.6.0
 *
 * @return int The ID of the current network.
 */
function get_current_network_id() {
	if ( ! is_multisite() ) {
		return 1;
	}

	$current_network = get_network();

	if ( ! isset( $current_network->id ) ) {
		return get_main_network_id();
	}

	return absint( $current_network->id );
}

/**
 * Attempts an early load of translations.
 *
 * Used for errors encountered during the initial loading process, before
 * the locale has been properly detected and loaded.
 *
 * Designed for unusual load sequences (like setup-config.php) or for when
 * the script will then terminate with an error, otherwise there is a risk
 * that a file can be double-included.
 *
 * @since 3.4.0
 * @access private
 *
 * @global WP_Textdomain_Registry $wp_textdomain_registry WordPress Textdomain Registry.
 * @global WP_Locale              $wp_locale              WordPress date and time locale object.
 */
function wp_load_translations_early() {
	global $wp_textdomain_registry, $wp_locale;
	static $loaded = false;

	if ( $loaded ) {
		return;
	}

	$loaded = true;

	if ( function_exists( 'did_action' ) && did_action( 'init' ) ) {
		return;
	}

	// We need $wp_local_package.
	require ABSPATH . WPINC . '/version.php';

	// Translation and localization.
	require_once ABSPATH . WPINC . '/pomo/mo.php';
	require_once ABSPATH . WPINC . '/l10n/class-wp-translation-controller.php';
	require_once ABSPATH . WPINC . '/l10n/class-wp-translations.php';
	require_once ABSPATH . WPINC . '/l10n/class-wp-translation-file.php';
	require_once ABSPATH . WPINC . '/l10n/class-wp-translation-file-mo.php';
	require_once ABSPATH . WPINC . '/l10n/class-wp-translation-file-php.php';
	require_once ABSPATH . WPINC . '/l10n.php';
	require_once ABSPATH . WPINC . '/class-wp-textdomain-registry.php';
	require_once ABSPATH . WPINC . '/class-wp-locale.php';
	require_once ABSPATH . WPINC . '/class-wp-locale-switcher.php';

	// General libraries.
	require_once ABSPATH . WPINC . '/plugin.php';

	$locales   = array();
	$locations = array();

	if ( ! $wp_textdomain_registry instanceof WP_Textdomain_Registry ) {
		$wp_textdomain_registry = new WP_Textdomain_Registry();
	}

	while ( true ) {
		if ( defined( 'WPLANG' ) ) {
			if ( '' === WPLANG ) {
				break;
			}
			$locales[] = WPLANG;
		}

		if ( isset( $wp_local_package ) ) {
			$locales[] = $wp_local_package;
		}

		if ( ! $locales ) {
			break;
		}

		if ( defined( 'WP_LANG_DIR' ) && @is_dir( WP_LANG_DIR ) ) {
			$locations[] = WP_LANG_DIR;
		}

		if ( defined( 'WP_CONTENT_DIR' ) && @is_dir( WP_CONTENT_DIR . '/languages' ) ) {
			$locations[] = WP_CONTENT_DIR . '/languages';
		}

		if ( @is_dir( ABSPATH . 'wp-content/languages' ) ) {
			$locations[] = ABSPATH . 'wp-content/languages';
		}

		if ( @is_dir( ABSPATH . WPINC . '/languages' ) ) {
			$locations[] = ABSPATH . WPINC . '/languages';
		}

		if ( ! $locations ) {
			break;
		}

		$locations = array_unique( $locations );

		foreach ( $locales as $locale ) {
			foreach ( $locations as $location ) {
				if ( file_exists( $location . '/' . $locale . '.mo' ) ) {
					load_textdomain( 'default', $location . '/' . $locale . '.mo', $locale );

					if ( defined( 'WP_SETUP_CONFIG' ) && file_exists( $location . '/admin-' . $locale . '.mo' ) ) {
						load_textdomain( 'default', $location . '/admin-' . $locale . '.mo', $locale );
					}

					break 2;
				}
			}
		}

		break;
	}

	$wp_locale = new WP_Locale();
}

/**
 * Checks or sets whether WordPress is in "installation" mode.
 *
 * If the `WP_INSTALLING` constant is defined during the bootstrap, `wp_installing()` will default to `true`.
 *
 * @since 4.4.0
 *
 * @param bool $is_installing Optional. True to set WP into Installing mode, false to turn Installing mode off.
 *                            Omit this parameter if you only want to fetch the current status.
 * @return bool True if WP is installing, otherwise false. When a `$is_installing` is passed, the function will
 *              report whether WP was in installing mode prior to the change to `$is_installing`.
 */
function wp_installing( $is_installing = null ) {
	static $installing = null;

	// Support for the `WP_INSTALLING` constant, defined before WP is loaded.
	if ( is_null( $installing ) ) {
		$installing = defined( 'WP_INSTALLING' ) && WP_INSTALLING;
	}

	if ( ! is_null( $is_installing ) ) {
		$old_installing = $installing;
		$installing     = $is_installing;

		return (bool) $old_installing;
	}

	return (bool) $installing;
}

/**
 * Determines if SSL is used.
 *
 * @since 2.6.0
 * @since 4.6.0 Moved from functions.php to load.php.
 *
 * @return bool True if SSL, otherwise false.
 */
function is_ssl() {
	if ( isset( $_SERVER['HTTPS'] ) ) {
		if ( 'on' === strtolower( $_SERVER['HTTPS'] ) ) {
			return true;
		}

		if ( '1' === (string) $_SERVER['HTTPS'] ) {
			return true;
		}
	} elseif ( isset( $_SERVER['SERVER_PORT'] ) && ( '443' === (string) $_SERVER['SERVER_PORT'] ) ) {
		return true;
	}

	return false;
}

/**
 * Converts a shorthand byte value to an integer byte value.
 *
 * @since 2.3.0
 * @since 4.6.0 Moved from media.php to load.php.
 *
 * @link https://www.php.net/manual/en/function.ini-get.php
 * @link https://www.php.net/manual/en/faq.using.php#faq.using.shorthandbytes
 *
 * @param string $value A (PHP ini) byte value, either shorthand or ordinary.
 * @return int An integer byte value.
 */
function wp_convert_hr_to_bytes( $value ) {
	$value = strtolower( trim( $value ) );
	$bytes = (int) $value;

	if ( str_contains( $value, 'g' ) ) {
		$bytes *= GB_IN_BYTES;
	} elseif ( str_contains( $value, 'm' ) ) {
		$bytes *= MB_IN_BYTES;
	} elseif ( str_contains( $value, 'k' ) ) {
		$bytes *= KB_IN_BYTES;
	}

	// Deal with large (float) values which run into the maximum integer size.
	return min( $bytes, PHP_INT_MAX );
}

/**
 * Determines whether a PHP ini value is changeable at runtime.
 *
 * @since 4.6.0
 *
 * @link https://www.php.net/manual/en/function.ini-get-all.php
 *
 * @param string $setting The name of the ini setting to check.
 * @return bool True if the value is changeable at runtime. False otherwise.
 */
function wp_is_ini_value_changeable( $setting ) {
	static $ini_all;

	if ( ! isset( $ini_all ) ) {
		$ini_all = false;
		// Sometimes `ini_get_all()` is disabled via the `disable_functions` option for "security purposes".
		if ( function_exists( 'ini_get_all' ) ) {
			$ini_all = ini_get_all();
		}
	}

	if ( isset( $ini_all[ $setting ]['access'] )
		&& ( INI_ALL === $ini_all[ $setting ]['access'] || INI_USER === $ini_all[ $setting ]['access'] )
	) {
		return true;
	}

	// If we were unable to retrieve the details, fail gracefully to assume it's changeable.
	if ( ! is_array( $ini_all ) ) {
		return true;
	}

	return false;
}

/**
 * Determines whether the current request is a WordPress Ajax request.
 *
 * @since 4.7.0
 *
 * @return bool True if it's a WordPress Ajax request, false otherwise.
 */
function wp_doing_ajax() {
	/**
	 * Filters whether the current request is a WordPress Ajax request.
	 *
	 * @since 4.7.0
	 *
	 * @param bool $wp_doing_ajax Whether the current request is a WordPress Ajax request.
	 */
	return apply_filters( 'wp_doing_ajax', defined( 'DOING_AJAX' ) && DOING_AJAX );
}

/**
 * Determines whether the current request should use themes.
 *
 * @since 5.1.0
 *
 * @return bool True if themes should be used, false otherwise.
 */
function wp_using_themes() {
	/**
	 * Filters whether the current request should use themes.
	 *
	 * @since 5.1.0
	 *
	 * @param bool $wp_using_themes Whether the current request should use themes.
	 */
	return apply_filters( 'wp_using_themes', defined( 'WP_USE_THEMES' ) && WP_USE_THEMES );
}

/**
 * Determines whether the current request is a WordPress cron request.
 *
 * @since 4.8.0
 *
 * @return bool True if it's a WordPress cron request, false otherwise.
 */
function wp_doing_cron() {
	/**
	 * Filters whether the current request is a WordPress cron request.
	 *
	 * @since 4.8.0
	 *
	 * @param bool $wp_doing_cron Whether the current request is a WordPress cron request.
	 */
	return apply_filters( 'wp_doing_cron', defined( 'DOING_CRON' ) && DOING_CRON );
}

/**
 * Checks whether the given variable is a WordPress Error.
 *
 * Returns whether `$thing` is an instance of the `WP_Error` class.
 *
 * @since 2.1.0
 *
 * @param mixed $thing The variable to check.
 * @return bool Whether the variable is an instance of WP_Error.
 */
function is_wp_error( $thing ) {
	$is_wp_error = ( $thing instanceof WP_Error );

	if ( $is_wp_error ) {
		/**
		 * Fires when `is_wp_error()` is called and its parameter is an instance of `WP_Error`.
		 *
		 * @since 5.6.0
		 *
		 * @param WP_Error $thing The error object passed to `is_wp_error()`.
		 */
		do_action( 'is_wp_error_instance', $thing );
	}

	return $is_wp_error;
}

/**
 * Determines whether file modifications are allowed.
 *
 * @since 4.8.0
 *
 * @param string $context The usage context.
 * @return bool True if file modification is allowed, false otherwise.
 */
function wp_is_file_mod_allowed( $context ) {
	/**
	 * Filters whether file modifications are allowed.
	 *
	 * @since 4.8.0
	 *
	 * @param bool   $file_mod_allowed Whether file modifications are allowed.
	 * @param string $context          The usage context.
	 */
	return apply_filters( 'file_mod_allowed', ! defined( 'DISALLOW_FILE_MODS' ) || ! DISALLOW_FILE_MODS, $context );
}

/**
 * Starts scraping edited file errors.
 *
 * @since 4.9.0
 */
function wp_start_scraping_edited_file_errors() {
	if ( ! isset( $_REQUEST['wp_scrape_key'] ) || ! isset( $_REQUEST['wp_scrape_nonce'] ) ) {
		return;
	}

	$key   = substr( sanitize_key( wp_unslash( $_REQUEST['wp_scrape_key'] ) ), 0, 32 );
	$nonce = wp_unslash( $_REQUEST['wp_scrape_nonce'] );
	if ( empty( $key ) || empty( $nonce ) ) {
		return;
	}

	$transient = get_transient( 'scrape_key_' . $key );
	if ( false === $transient ) {
		return;
	}

	if ( $transient !== $nonce ) {
		if ( ! headers_sent() ) {
			header( 'X-Robots-Tag: noindex' );
			nocache_headers();
		}
		echo "###### wp_scraping_result_start:$key ######";
		echo wp_json_encode(
			array(
				'code'    => 'scrape_nonce_failure',
				'message' => __( 'Scrape key check failed. Please try again.' ),
			)
		);
		echo "###### wp_scraping_result_end:$key ######";
		die();
	}

	if ( ! defined( 'WP_SANDBOX_SCRAPING' ) ) {
		define( 'WP_SANDBOX_SCRAPING', true );
	}

	register_shutdown_function( 'wp_finalize_scraping_edited_file_errors', $key );
}

/**
 * Finalizes scraping for edited file errors.
 *
 * @since 4.9.0
 *
 * @param string $scrape_key Scrape key.
 */
function wp_finalize_scraping_edited_file_errors( $scrape_key ) {
	$error = error_get_last();

	echo "\n###### wp_scraping_result_start:$scrape_key ######\n";

	if ( ! empty( $error )
		&& in_array( $error['type'], array( E_CORE_ERROR, E_COMPILE_ERROR, E_ERROR, E_PARSE, E_USER_ERROR, E_RECOVERABLE_ERROR ), true )
	) {
		$error = str_replace( ABSPATH, '', $error );
		echo wp_json_encode( $error );
	} else {
		echo wp_json_encode( true );
	}

	echo "\n###### wp_scraping_result_end:$scrape_key ######\n";
}

/**
 * Checks whether current request is a JSON request, or is expecting a JSON response.
 *
 * @since 5.0.0
 *
 * @return bool True if `Accepts` or `Content-Type` headers contain `application/json`.
 *              False otherwise.
 */
function wp_is_json_request() {
	if ( isset( $_SERVER['HTTP_ACCEPT'] ) && wp_is_json_media_type( $_SERVER['HTTP_ACCEPT'] ) ) {
		return true;
	}

	if ( isset( $_SERVER['CONTENT_TYPE'] ) && wp_is_json_media_type( $_SERVER['CONTENT_TYPE'] ) ) {
		return true;
	}

	return false;
}

/**
 * Checks whether current request is a JSONP request, or is expecting a JSONP response.
 *
 * @since 5.2.0
 *
 * @return bool True if JSONP request, false otherwise.
 */
function wp_is_jsonp_request() {
	if ( ! isset( $_GET['_jsonp'] ) ) {
		return false;
	}

	if ( ! function_exists( 'wp_check_jsonp_callback' ) ) {
		require_once ABSPATH . WPINC . '/functions.php';
	}

	$jsonp_callback = $_GET['_jsonp'];
	if ( ! wp_check_jsonp_callback( $jsonp_callback ) ) {
		return false;
	}

	/** This filter is documented in wp-includes/rest-api/class-wp-rest-server.php */
	$jsonp_enabled = apply_filters( 'rest_jsonp_enabled', true );

	return $jsonp_enabled;
}

/**
 * Checks whether a string is a valid JSON Media Type.
 *
 * @since 5.6.0
 *
 * @param string $media_type A Media Type string to check.
 * @return bool True if string is a valid JSON Media Type.
 */
function wp_is_json_media_type( $media_type ) {
	static $cache = array();

	if ( ! isset( $cache[ $media_type ] ) ) {
		$cache[ $media_type ] = (bool) preg_match( '/(^|\s|,)application\/([\w!#\$&-\^\.\+]+\+)?json(\+oembed)?($|\s|;|,)/i', $media_type );
	}

	return $cache[ $media_type ];
}

/**
 * Checks whether current request is an XML request, or is expecting an XML response.
 *
 * @since 5.2.0
 *
 * @return bool True if `Accepts` or `Content-Type` headers contain `text/xml`
 *              or one of the related MIME types. False otherwise.
 */
function wp_is_xml_request() {
	$accepted = array(
		'text/xml',
		'application/rss+xml',
		'application/atom+xml',
		'application/rdf+xml',
		'text/xml+oembed',
		'application/xml+oembed',
	);

	if ( isset( $_SERVER['HTTP_ACCEPT'] ) ) {
		foreach ( $accepted as $type ) {
			if ( str_contains( $_SERVER['HTTP_ACCEPT'], $type ) ) {
				return true;
			}
		}
	}

	if ( isset( $_SERVER['CONTENT_TYPE'] ) && in_array( $_SERVER['CONTENT_TYPE'], $accepted, true ) ) {
		return true;
	}

	return false;
}

/**
 * Checks if this site is protected by HTTP Basic Auth.
 *
 * At the moment, this merely checks for the present of Basic Auth credentials. Therefore, calling
 * this function with a context different from the current context may give inaccurate results.
 * In a future release, this evaluation may be made more robust.
 *
 * Currently, this is only used by Application Passwords to prevent a conflict since it also utilizes
 * Basic Auth.
 *
 * @since 5.6.1
 *
 * @global string $pagenow The filename of the current screen.
 *
 * @param string $context The context to check for protection. Accepts 'login', 'admin', and 'front'.
 *                        Defaults to the current context.
 * @return bool Whether the site is protected by Basic Auth.
 */
function wp_is_site_protected_by_basic_auth( $context = '' ) {
	global $pagenow;

	if ( ! $context ) {
		if ( 'wp-login.php' === $pagenow ) {
			$context = 'login';
		} elseif ( is_admin() ) {
			$context = 'admin';
		} else {
			$context = 'front';
		}
	}

	$is_protected = ! empty( $_SERVER['PHP_AUTH_USER'] ) || ! empty( $_SERVER['PHP_AUTH_PW'] );

	/**
	 * Filters whether a site is protected by HTTP Basic Auth.
	 *
	 * @since 5.6.1
	 *
	 * @param bool $is_protected Whether the site is protected by Basic Auth.
	 * @param string $context    The context to check for protection. One of 'login', 'admin', or 'front'.
	 */
	return apply_filters( 'wp_is_site_protected_by_basic_auth', $is_protected, $context );
}