functions.php

<?php
/**
 * Main WordPress API
 *
 * @package WordPress
 */

// Don't load directly.
if ( ! defined( 'ABSPATH' ) ) {
	die( '-1' );
}

require ABSPATH . WPINC . '/option.php';

/**
 * Converts given MySQL date string into a different format.
 *
 *  - `$format` should be a PHP date format string.
 *  - 'U' and 'G' formats will return an integer sum of timestamp with timezone offset.
 *  - `$date` is expected to be local time in MySQL format (`Y-m-d H:i:s`).
 *
 * Historically UTC time could be passed to the function to produce Unix timestamp.
 *
 * If `$translate` is true then the given date and format string will
 * be passed to `wp_date()` for translation.
 *
 * @since 0.71
 *
 * @param string $format    Format of the date to return.
 * @param string $date      Date string to convert.
 * @param bool   $translate Whether the return date should be translated. Default true.
 * @return string|int|false Integer if `$format` is 'U' or 'G', string otherwise.
 *                          False on failure.
 */
function mysql2date( $format, $date, $translate = true ) {
	if ( empty( $date ) ) {
		return false;
	}

	$timezone = wp_timezone();
	$datetime = date_create( $date, $timezone );

	if ( false === $datetime ) {
		return false;
	}

	// Returns a sum of timestamp with timezone offset. Ideally should never be used.
	if ( 'G' === $format || 'U' === $format ) {
		return $datetime->getTimestamp() + $datetime->getOffset();
	}

	if ( $translate ) {
		return wp_date( $format, $datetime->getTimestamp(), $timezone );
	}

	return $datetime->format( $format );
}

/**
 * Retrieves the current time based on specified type.
 *
 *  - The 'mysql' type will return the time in the format for MySQL DATETIME field.
 *  - The 'timestamp' or 'U' types will return the current timestamp or a sum of timestamp
 *    and timezone offset, depending on `$gmt`.
 *  - Other strings will be interpreted as PHP date formats (e.g. 'Y-m-d').
 *
 * If `$gmt` is a truthy value then both types will use GMT time, otherwise the
 * output is adjusted with the GMT offset for the site.
 *
 * @since 1.0.0
 * @since 5.3.0 Now returns an integer if `$type` is 'U'. Previously a string was returned.
 *
 * @param string   $type Type of time to retrieve. Accepts 'mysql', 'timestamp', 'U',
 *                       or PHP date format string (e.g. 'Y-m-d').
 * @param int|bool $gmt  Optional. Whether to use GMT timezone. Default false.
 * @return int|string Integer if `$type` is 'timestamp' or 'U', string otherwise.
 */
function current_time( $type, $gmt = 0 ) {
	// Don't use non-GMT timestamp, unless you know the difference and really need to.
	if ( 'timestamp' === $type || 'U' === $type ) {
		return $gmt ? time() : time() + (int) ( (float) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
	}

	if ( 'mysql' === $type ) {
		$type = 'Y-m-d H:i:s';
	}

	$timezone = $gmt ? new DateTimeZone( 'UTC' ) : wp_timezone();
	$datetime = new DateTime( 'now', $timezone );

	return $datetime->format( $type );
}

/**
 * Retrieves the current time as an object using the site's timezone.
 *
 * @since 5.3.0
 *
 * @return DateTimeImmutable Date and time object.
 */
function current_datetime() {
	return new DateTimeImmutable( 'now', wp_timezone() );
}

/**
 * Retrieves the timezone of the site as a string.
 *
 * Uses the `timezone_string` option to get a proper timezone name if available,
 * otherwise falls back to a manual UTC ± offset.
 *
 * Example return values:
 *
 *  - 'Europe/Rome'
 *  - 'America/North_Dakota/New_Salem'
 *  - 'UTC'
 *  - '-06:30'
 *  - '+00:00'
 *  - '+08:45'
 *
 * @since 5.3.0
 *
 * @return string PHP timezone name or a ±HH:MM offset.
 */
function wp_timezone_string() {
	$timezone_string = get_option( 'timezone_string' );

	if ( $timezone_string ) {
		return $timezone_string;
	}

	$offset  = (float) get_option( 'gmt_offset' );
	$hours   = (int) $offset;
	$minutes = ( $offset - $hours );

	$sign      = ( $offset < 0 ) ? '-' : '+';
	$abs_hour  = abs( $hours );
	$abs_mins  = abs( $minutes * 60 );
	$tz_offset = sprintf( '%s%02d:%02d', $sign, $abs_hour, $abs_mins );

	return $tz_offset;
}

/**
 * Retrieves the timezone of the site as a `DateTimeZone` object.
 *
 * Timezone can be based on a PHP timezone string or a ±HH:MM offset.
 *
 * @since 5.3.0
 *
 * @return DateTimeZone Timezone object.
 */
function wp_timezone() {
	return new DateTimeZone( wp_timezone_string() );
}

/**
 * Retrieves the date in localized format, based on a sum of Unix timestamp and
 * timezone offset in seconds.
 *
 * If the locale specifies the locale month and weekday, then the locale will
 * take over the format for the date. If it isn't, then the date format string
 * will be used instead.
 *
 * Note that due to the way WP typically generates a sum of timestamp and offset
 * with `strtotime()`, it implies offset added at a _current_ time, not at the time
 * the timestamp represents. Storing such timestamps or calculating them differently
 * will lead to invalid output.
 *
 * @since 0.71
 * @since 5.3.0 Converted into a wrapper for wp_date().
 *
 * @param string   $format                Format to display the date.
 * @param int|bool $timestamp_with_offset Optional. A sum of Unix timestamp and timezone offset
 *                                        in seconds. Default false.
 * @param bool     $gmt                   Optional. Whether to use GMT timezone. Only applies
 *                                        if timestamp is not provided. Default false.
 * @return string The date, translated if locale specifies it.
 */
function date_i18n( $format, $timestamp_with_offset = false, $gmt = false ) {
	$timestamp = $timestamp_with_offset;

	// If timestamp is omitted it should be current time (summed with offset, unless `$gmt` is true).
	if ( ! is_numeric( $timestamp ) ) {
		// phpcs:ignore WordPress.DateTime.CurrentTimeTimestamp.Requested
		$timestamp = current_time( 'timestamp', $gmt );
	}

	/*
	 * This is a legacy implementation quirk that the returned timestamp is also with offset.
	 * Ideally this function should never be used to produce a timestamp.
	 */
	if ( 'U' === $format ) {
		$date = $timestamp;
	} elseif ( $gmt && false === $timestamp_with_offset ) { // Current time in UTC.
		$date = wp_date( $format, null, new DateTimeZone( 'UTC' ) );
	} elseif ( false === $timestamp_with_offset ) { // Current time in site's timezone.
		$date = wp_date( $format );
	} else {
		/*
		 * Timestamp with offset is typically produced by a UTC `strtotime()` call on an input without timezone.
		 * This is the best attempt to reverse that operation into a local time to use.
		 */
		$local_time = gmdate( 'Y-m-d H:i:s', $timestamp );
		$timezone   = wp_timezone();
		$datetime   = date_create( $local_time, $timezone );
		$date       = wp_date( $format, $datetime->getTimestamp(), $timezone );
	}

	/**
	 * Filters the date formatted based on the locale.
	 *
	 * @since 2.8.0
	 *
	 * @param string $date      Formatted date string.
	 * @param string $format    Format to display the date.
	 * @param int    $timestamp A sum of Unix timestamp and timezone offset in seconds.
	 *                          Might be without offset if input omitted timestamp but requested GMT.
	 * @param bool   $gmt       Whether to use GMT timezone. Only applies if timestamp was not provided.
	 *                          Default false.
	 */
	$date = apply_filters( 'date_i18n', $date, $format, $timestamp, $gmt );

	return $date;
}

/**
 * Retrieves the date, in localized format.
 *
 * This is a newer function, intended to replace `date_i18n()` without legacy quirks in it.
 *
 * Note that, unlike `date_i18n()`, this function accepts a true Unix timestamp, not summed
 * with timezone offset.
 *
 * @since 5.3.0
 *
 * @global WP_Locale $wp_locale WordPress date and time locale object.
 *
 * @param string       $format    PHP date format.
 * @param int          $timestamp Optional. Unix timestamp. Defaults to current time.
 * @param DateTimeZone $timezone  Optional. Timezone to output result in. Defaults to timezone
 *                                from site settings.
 * @return string|false The date, translated if locale specifies it. False on invalid timestamp input.
 */
function wp_date( $format, $timestamp = null, $timezone = null ) {
	global $wp_locale;

	if ( null === $timestamp ) {
		$timestamp = time();
	} elseif ( ! is_numeric( $timestamp ) ) {
		return false;
	}

	if ( ! $timezone ) {
		$timezone = wp_timezone();
	}

	$datetime = date_create( '@' . $timestamp );
	$datetime->setTimezone( $timezone );

	if ( empty( $wp_locale->month ) || empty( $wp_locale->weekday ) ) {
		$date = $datetime->format( $format );
	} else {
		// We need to unpack shorthand `r` format because it has parts that might be localized.
		$format = preg_replace( '/(?<!\\\\)r/', DATE_RFC2822, $format );

		$new_format    = '';
		$format_length = strlen( $format );
		$month         = $wp_locale->get_month( $datetime->format( 'm' ) );
		$weekday       = $wp_locale->get_weekday( $datetime->format( 'w' ) );

		for ( $i = 0; $i < $format_length; $i++ ) {
			switch ( $format[ $i ] ) {
				case 'D':
					$new_format .= addcslashes( $wp_locale->get_weekday_abbrev( $weekday ), '\\A..Za..z' );
					break;
				case 'F':
					$new_format .= addcslashes( $month, '\\A..Za..z' );
					break;
				case 'l':
					$new_format .= addcslashes( $weekday, '\\A..Za..z' );
					break;
				case 'M':
					$new_format .= addcslashes( $wp_locale->get_month_abbrev( $month ), '\\A..Za..z' );
					break;
				case 'a':
					$new_format .= addcslashes( $wp_locale->get_meridiem( $datetime->format( 'a' ) ), '\\A..Za..z' );
					break;
				case 'A':
					$new_format .= addcslashes( $wp_locale->get_meridiem( $datetime->format( 'A' ) ), '\\A..Za..z' );
					break;
				case '\\':
					$new_format .= $format[ $i ];

					// If character follows a slash, we add it without translating.
					if ( $i < $format_length ) {
						$new_format .= $format[ ++$i ];
					}
					break;
				default:
					$new_format .= $format[ $i ];
					break;
			}
		}

		$date = $datetime->format( $new_format );
		$date = wp_maybe_decline_date( $date, $format );
	}

	/**
	 * Filters the date formatted based on the locale.
	 *
	 * @since 5.3.0
	 *
	 * @param string       $date      Formatted date string.
	 * @param string       $format    Format to display the date.
	 * @param int          $timestamp Unix timestamp.
	 * @param DateTimeZone $timezone  Timezone.
	 */
	$date = apply_filters( 'wp_date', $date, $format, $timestamp, $timezone );

	return $date;
}

/**
 * Determines if the date should be declined.
 *
 * If the locale specifies that month names require a genitive case in certain
 * formats (like 'j F Y'), the month name will be replaced with a correct form.
 *
 * @since 4.4.0
 * @since 5.4.0 The `$format` parameter was added.
 *
 * @global WP_Locale $wp_locale WordPress date and time locale object.
 *
 * @param string $date   Formatted date string.
 * @param string $format Optional. Date format to check. Default empty string.
 * @return string The date, declined if locale specifies it.
 */
function wp_maybe_decline_date( $date, $format = '' ) {
	global $wp_locale;

	// i18n functions are not available in SHORTINIT mode.
	if ( ! function_exists( '_x' ) ) {
		return $date;
	}

	/*
	 * translators: If months in your language require a genitive case,
	 * translate this to 'on'. Do not translate into your own language.
	 */
	if ( 'on' === _x( 'off', 'decline months names: on or off' ) ) {

		$months          = $wp_locale->month;
		$months_genitive = $wp_locale->month_genitive;

		/*
		 * Match a format like 'j F Y' or 'j. F' (day of the month, followed by month name)
		 * and decline the month.
		 */
		if ( $format ) {
			$decline = preg_match( '#[dj]\.? F#', $format );
		} else {
			// If the format is not passed, try to guess it from the date string.
			$decline = preg_match( '#\b\d{1,2}\.? [^\d ]+\b#u', $date );
		}

		if ( $decline ) {
			foreach ( $months as $key => $month ) {
				$months[ $key ] = '# ' . preg_quote( $month, '#' ) . '\b#u';
			}

			foreach ( $months_genitive as $key => $month ) {
				$months_genitive[ $key ] = ' ' . $month;
			}

			$date = preg_replace( $months, $months_genitive, $date );
		}

		/*
		 * Match a format like 'F jS' or 'F j' (month name, followed by day with an optional ordinal suffix)
		 * and change it to declined 'j F'.
		 */
		if ( $format ) {
			$decline = preg_match( '#F [dj]#', $format );
		} else {
			// If the format is not passed, try to guess it from the date string.
			$decline = preg_match( '#\b[^\d ]+ \d{1,2}(st|nd|rd|th)?\b#u', trim( $date ) );
		}

		if ( $decline ) {
			foreach ( $months as $key => $month ) {
				$months[ $key ] = '#\b' . preg_quote( $month, '#' ) . ' (\d{1,2})(st|nd|rd|th)?([-–]\d{1,2})?(st|nd|rd|th)?\b#u';
			}

			foreach ( $months_genitive as $key => $month ) {
				$months_genitive[ $key ] = '$1$3 ' . $month;
			}

			$date = preg_replace( $months, $months_genitive, $date );
		}
	}

	// Used for locale-specific rules.
	$locale = get_locale();

	if ( 'ca' === $locale ) {
		// " de abril| de agost| de octubre..." -> " d'abril| d'agost| d'octubre..."
		$date = preg_replace( '# de ([ao])#i', " d'\\1", $date );
	}

	return $date;
}

/**
 * Converts float number to format based on the locale.
 *
 * @since 2.3.0
 *
 * @global WP_Locale $wp_locale WordPress date and time locale object.
 *
 * @param float $number   The number to convert based on locale.
 * @param int   $decimals Optional. Precision of the number of decimal places. Default 0.
 * @return string Converted number in string format.
 */
function number_format_i18n( $number, $decimals = 0 ) {
	global $wp_locale;

	if ( isset( $wp_locale ) ) {
		$formatted = number_format( $number, absint( $decimals ), $wp_locale->number_format['decimal_point'], $wp_locale->number_format['thousands_sep'] );
	} else {
		$formatted = number_format( $number, absint( $decimals ) );
	}

	/**
	 * Filters the number formatted based on the locale.
	 *
	 * @since 2.8.0
	 * @since 4.9.0 The `$number` and `$decimals` parameters were added.
	 *
	 * @param string $formatted Converted number in string format.
	 * @param float  $number    The number to convert based on locale.
	 * @param int    $decimals  Precision of the number of decimal places.
	 */
	return apply_filters( 'number_format_i18n', $formatted, $number, $decimals );
}

/**
 * Converts a number of bytes to the largest unit the bytes will fit into.
 *
 * It is easier to read 1 KB than 1024 bytes and 1 MB than 1048576 bytes. Converts
 * number of bytes to human readable number by taking the number of that unit
 * that the bytes will go into it. Supports YB value.
 *
 * Please note that integers in PHP are limited to 32 bits, unless they are on
 * 64 bit architecture, then they have 64 bit size. If you need to place the
 * larger size then what PHP integer type will hold, then use a string. It will
 * be converted to a double, which should always have 64 bit length.
 *
 * Technically the correct unit names for powers of 1024 are KiB, MiB etc.
 *
 * @since 2.3.0
 * @since 6.0.0 Support for PB, EB, ZB, and YB was added.
 *
 * @param int|string $bytes    Number of bytes. Note max integer size for integers.
 * @param int        $decimals Optional. Precision of number of decimal places. Default 0.
 * @return string|false Number string on success, false on failure.
 */
function size_format( $bytes, $decimals = 0 ) {
	$quant = array(
		/* translators: Unit symbol for yottabyte. */
		_x( 'YB', 'unit symbol' ) => YB_IN_BYTES,
		/* translators: Unit symbol for zettabyte. */
		_x( 'ZB', 'unit symbol' ) => ZB_IN_BYTES,
		/* translators: Unit symbol for exabyte. */
		_x( 'EB', 'unit symbol' ) => EB_IN_BYTES,
		/* translators: Unit symbol for petabyte. */
		_x( 'PB', 'unit symbol' ) => PB_IN_BYTES,
		/* translators: Unit symbol for terabyte. */
		_x( 'TB', 'unit symbol' ) => TB_IN_BYTES,
		/* translators: Unit symbol for gigabyte. */
		_x( 'GB', 'unit symbol' ) => GB_IN_BYTES,
		/* translators: Unit symbol for megabyte. */
		_x( 'MB', 'unit symbol' ) => MB_IN_BYTES,
		/* translators: Unit symbol for kilobyte. */
		_x( 'KB', 'unit symbol' ) => KB_IN_BYTES,
		/* translators: Unit symbol for byte. */
		_x( 'B', 'unit symbol' )  => 1,
	);

	if ( 0 === $bytes ) {
		/* translators: Unit symbol for byte. */
		return number_format_i18n( 0, $decimals ) . ' ' . _x( 'B', 'unit symbol' );
	}

	foreach ( $quant as $unit => $mag ) {
		if ( (float) $bytes >= $mag ) {
			return number_format_i18n( $bytes / $mag, $decimals ) . ' ' . $unit;
		}
	}

	return false;
}

/**
 * Converts a duration to human readable format.
 *
 * @since 5.1.0
 *
 * @param string $duration Duration will be in string format (HH:ii:ss) OR (ii:ss),
 *                         with a possible prepended negative sign (-).
 * @return string|false A human readable duration string, false on failure.
 */
function human_readable_duration( $duration = '' ) {
	if ( ( empty( $duration ) || ! is_string( $duration ) ) ) {
		return false;
	}

	$duration = trim( $duration );

	// Remove prepended negative sign.
	if ( str_starts_with( $duration, '-' ) ) {
		$duration = substr( $duration, 1 );
	}

	// Extract duration parts.
	$duration_parts = array_reverse( explode( ':', $duration ) );
	$duration_count = count( $duration_parts );

	$hour   = null;
	$minute = null;
	$second = null;

	if ( 3 === $duration_count ) {
		// Validate HH:ii:ss duration format.
		if ( ! ( (bool) preg_match( '/^([0-9]+):([0-5]?[0-9]):([0-5]?[0-9])$/', $duration ) ) ) {
			return false;
		}
		// Three parts: hours, minutes & seconds.
		list( $second, $minute, $hour ) = $duration_parts;
	} elseif ( 2 === $duration_count ) {
		// Validate ii:ss duration format.
		if ( ! ( (bool) preg_match( '/^([0-5]?[0-9]):([0-5]?[0-9])$/', $duration ) ) ) {
			return false;
		}
		// Two parts: minutes & seconds.
		list( $second, $minute ) = $duration_parts;
	} else {
		return false;
	}

	$human_readable_duration = array();

	// Add the hour part to the string.
	if ( is_numeric( $hour ) ) {
		/* translators: %s: Time duration in hour or hours. */
		$human_readable_duration[] = sprintf( _n( '%s hour', '%s hours', $hour ), (int) $hour );
	}

	// Add the minute part to the string.
	if ( is_numeric( $minute ) ) {
		/* translators: %s: Time duration in minute or minutes. */
		$human_readable_duration[] = sprintf( _n( '%s minute', '%s minutes', $minute ), (int) $minute );
	}

	// Add the second part to the string.
	if ( is_numeric( $second ) ) {
		/* translators: %s: Time duration in second or seconds. */
		$human_readable_duration[] = sprintf( _n( '%s second', '%s seconds', $second ), (int) $second );
	}

	return implode( ', ', $human_readable_duration );
}

/**
 * Gets the week start and end from the datetime or date string from MySQL.
 *
 * @since 0.71
 *
 * @param string     $mysqlstring   Date or datetime field type from MySQL.
 * @param int|string $start_of_week Optional. Start of the week as an integer. Default empty string.
 * @return int[] {
 *     Week start and end dates as Unix timestamps.
 *
 *     @type int $start The week start date as a Unix timestamp.
 *     @type int $end   The week end date as a Unix timestamp.
 * }
 */
function get_weekstartend( $mysqlstring, $start_of_week = '' ) {
	// MySQL string year.
	$my = substr( $mysqlstring, 0, 4 );

	// MySQL string month.
	$mm = substr( $mysqlstring, 8, 2 );

	// MySQL string day.
	$md = substr( $mysqlstring, 5, 2 );

	// The timestamp for MySQL string day.
	$day = mktime( 0, 0, 0, $md, $mm, $my );

	// The day of the week from the timestamp.
	$weekday = (int) gmdate( 'w', $day );

	if ( ! is_numeric( $start_of_week ) ) {
		$start_of_week = (int) get_option( 'start_of_week' );
	}

	if ( $weekday < $start_of_week ) {
		$weekday += 7;
	}

	// The most recent week start day on or before $day.
	$start = $day - DAY_IN_SECONDS * ( $weekday - $start_of_week );

	// $start + 1 week - 1 second.
	$end = $start + WEEK_IN_SECONDS - 1;

	return compact( 'start', 'end' );
}

/**
 * Serializes data, if needed.
 *
 * @since 2.0.5
 *
 * @param string|array|object $data Data that might be serialized.
 * @return mixed A scalar data.
 */
function maybe_serialize( $data ) {
	if ( is_array( $data ) || is_object( $data ) ) {
		return serialize( $data );
	}

	/*
	 * Double serialization is required for backward compatibility.
	 * See https://core.trac.wordpress.org/ticket/12930
	 * Also the world will end. See WP 3.6.1.
	 */
	if ( is_serialized( $data, false ) ) {
		return serialize( $data );
	}

	return $data;
}

/**
 * Unserializes data only if it was serialized.
 *
 * @since 2.0.0
 *
 * @param string $data Data that might be unserialized.
 * @return mixed Unserialized data can be any type.
 */
function maybe_unserialize( $data ) {
	if ( is_serialized( $data ) ) { // Don't attempt to unserialize data that wasn't serialized going in.
		return @unserialize( trim( $data ) );
	}

	return $data;
}

/**
 * Checks value to find if it was serialized.
 *
 * If $data is not a string, then returned value will always be false.
 * Serialized data is always a string.
 *
 * @since 2.0.5
 * @since 6.1.0 Added Enum support.
 *
 * @param string $data   Value to check to see if was serialized.
 * @param bool   $strict Optional. Whether to be strict about the end of the string. Default true.
 * @return bool False if not serialized and true if it was.
 */
function is_serialized( $data, $strict = true ) {
	// If it isn't a string, it isn't serialized.
	if ( ! is_string( $data ) ) {
		return false;
	}
	$data = trim( $data );
	if ( 'N;' === $data ) {
		return true;
	}
	if ( strlen( $data ) < 4 ) {
		return false;
	}
	if ( ':' !== $data[1] ) {
		return false;
	}
	if ( $strict ) {
		$lastc = substr( $data, -1 );
		if ( ';' !== $lastc && '}' !== $lastc ) {
			return false;
		}
	} else {
		$semicolon = strpos( $data, ';' );
		$brace     = strpos( $data, '}' );
		// Either ; or } must exist.
		if ( false === $semicolon && false === $brace ) {
			return false;
		}
		// But neither must be in the first X characters.
		if ( false !== $semicolon && $semicolon < 3 ) {
			return false;
		}
		if ( false !== $brace && $brace < 4 ) {
			return false;
		}
	}
	$token = $data[0];
	switch ( $token ) {
		case 's':
			if ( $strict ) {
				if ( '"' !== substr( $data, -2, 1 ) ) {
					return false;
				}
			} elseif ( ! str_contains( $data, '"' ) ) {
				return false;
			}
			// Or else fall through.
		case 'a':
		case 'O':
		case 'E':
			return (bool) preg_match( "/^{$token}:[0-9]+:/s", $data );
		case 'b':
		case 'i':
		case 'd':
			$end = $strict ? '$' : '';
			return (bool) preg_match( "/^{$token}:[0-9.E+-]+;$end/", $data );
	}
	return false;
}

/**
 * Checks whether serialized data is of string type.
 *
 * @since 2.0.5
 *
 * @param string $data Serialized data.
 * @return bool False if not a serialized string, true if it is.
 */
function is_serialized_string( $data ) {
	// if it isn't a string, it isn't a serialized string.
	if ( ! is_string( $data ) ) {
		return false;
	}
	$data = trim( $data );
	if ( strlen( $data ) < 4 ) {
		return false;
	} elseif ( ':' !== $data[1] ) {
		return false;
	} elseif ( ! str_ends_with( $data, ';' ) ) {
		return false;
	} elseif ( 's' !== $data[0] ) {
		return false;
	} elseif ( '"' !== substr( $data, -2, 1 ) ) {
		return false;
	} else {
		return true;
	}
}

/**
 * Retrieves post title from XMLRPC XML.
 *
 * If the title element is not part of the XML, then the default post title from
 * the $post_default_title will be used instead.
 *
 * @since 0.71
 *
 * @global string $post_default_title Default XML-RPC post title.
 *
 * @param string $content XMLRPC XML Request content
 * @return string Post title
 */
function xmlrpc_getposttitle( $content ) {
	global $post_default_title;
	if ( preg_match( '/<title>(.+?)<\/title>/is', $content, $matchtitle ) ) {
		$post_title = $matchtitle[1];
	} else {
		$post_title = $post_default_title;
	}
	return $post_title;
}

/**
 * Retrieves the post category or categories from XMLRPC XML.
 *
 * If the category element is not found, then the default post category will be
 * used. The return type then would be what $post_default_category. If the
 * category is found, then it will always be an array.
 *
 * @since 0.71
 *
 * @global string $post_default_category Default XML-RPC post category.
 *
 * @param string $content XMLRPC XML Request content
 * @return string|array List of categories or category name.
 */
function xmlrpc_getpostcategory( $content ) {
	global $post_default_category;
	if ( preg_match( '/<category>(.+?)<\/category>/is', $content, $matchcat ) ) {
		$post_category = trim( $matchcat[1], ',' );
		$post_category = explode( ',', $post_category );
	} else {
		$post_category = $post_default_category;
	}
	return $post_category;
}

/**
 * XMLRPC XML content without title and category elements.
 *
 * @since 0.71
 *
 * @param string $content XML-RPC XML Request content.
 * @return string XMLRPC XML Request content without title and category elements.
 */
function xmlrpc_removepostdata( $content ) {
	$content = preg_replace( '/<title>(.+?)<\/title>/si', '', $content );
	$content = preg_replace( '/<category>(.+?)<\/category>/si', '', $content );
	$content = trim( $content );
	return $content;
}

/**
 * Uses RegEx to extract URLs from arbitrary content.
 *
 * @since 3.7.0
 * @since 6.0.0 Fixes support for HTML entities (Trac 30580).
 *
 * @param string $content Content to extract URLs from.
 * @return string[] Array of URLs found in passed string.
 */
function wp_extract_urls( $content ) {
	preg_match_all(
		"#([\"']?)("
			. '(?:([\w-]+:)?//?)'
			. '[^\s()<>]+'
			. '[.]'
			. '(?:'
				. '\([\w\d]+\)|'
				. '(?:'
					. "[^`!()\[\]{}:'\".,<>«»“”‘’\s]|"
					. '(?:[:]\d+)?/?'
				. ')+'
			. ')'
		. ")\\1#",
		$content,
		$post_links
	);

	$post_links = array_unique(
		array_map(
			static function ( $link ) {
				// Decode to replace valid entities, like &amp;.
				$link = html_entity_decode( $link );
				// Maintain backward compatibility by removing extraneous semi-colons (`;`).
				return str_replace( ';', '', $link );
			},
			$post_links[2]
		)
	);

	return array_values( $post_links );
}

/**
 * Checks content for video and audio links to add as enclosures.
 *
 * Will not add enclosures that have already been added and will
 * remove enclosures that are no longer in the post. This is called as
 * pingbacks and trackbacks.
 *
 * @since 1.5.0
 * @since 5.3.0 The `$content` parameter was made optional, and the `$post` parameter was
 *              updated to accept a post ID or a WP_Post object.
 * @since 5.6.0 The `$content` parameter is no longer optional, but passing `null` to skip it
 *              is still supported.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string|null $content Post content. If `null`, the `post_content` field from `$post` is used.
 * @param int|WP_Post $post    Post ID or post object.
 * @return void|false Void on success, false if the post is not found.
 */
function do_enclose( $content, $post ) {
	global $wpdb;

	// @todo Tidy this code and make the debug code optional.
	require_once ABSPATH . WPINC . '/class-IXR.php';

	$post = get_post( $post );
	if ( ! $post ) {
		return false;
	}

	if ( null === $content ) {
		$content = $post->post_content;
	}

	$post_links = array();

	$pung = get_enclosed( $post->ID );

	$post_links_temp = wp_extract_urls( $content );

	foreach ( $pung as $link_test ) {
		// Link is no longer in post.
		if ( ! in_array( $link_test, $post_links_temp, true ) ) {
			$mids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post->ID, $wpdb->esc_like( $link_test ) . '%' ) );
			foreach ( $mids as $mid ) {
				delete_metadata_by_mid( 'post', $mid );
			}
		}
	}

	foreach ( (array) $post_links_temp as $link_test ) {
		// If we haven't pung it already.
		if ( ! in_array( $link_test, $pung, true ) ) {
			$test = parse_url( $link_test );
			if ( false === $test ) {
				continue;
			}
			if ( isset( $test['query'] ) ) {
				$post_links[] = $link_test;
			} elseif ( isset( $test['path'] ) && ( '/' !== $test['path'] ) && ( '' !== $test['path'] ) ) {
				$post_links[] = $link_test;
			}
		}
	}

	/**
	 * Filters the list of enclosure links before querying the database.
	 *
	 * Allows for the addition and/or removal of potential enclosures to save
	 * to postmeta before checking the database for existing enclosures.
	 *
	 * @since 4.4.0
	 *
	 * @param string[] $post_links An array of enclosure links.
	 * @param int      $post_id    Post ID.
	 */
	$post_links = apply_filters( 'enclosure_links', $post_links, $post->ID );

	foreach ( (array) $post_links as $url ) {
		$url = strip_fragment_from_url( $url );

		if ( '' !== $url && ! $wpdb->get_var( $wpdb->prepare( "SELECT post_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE %s", $post->ID, $wpdb->esc_like( $url ) . '%' ) ) ) {

			$headers = wp_get_http_headers( $url );
			if ( $headers ) {
				$len           = isset( $headers['Content-Length'] ) ? (int) $headers['Content-Length'] : 0;
				$type          = isset( $headers['Content-Type'] ) ? $headers['Content-Type'] : '';
				$allowed_types = array( 'video', 'audio' );

				// Check to see if we can figure out the mime type from the extension.
				$url_parts = parse_url( $url );
				if ( false !== $url_parts && ! empty( $url_parts['path'] ) ) {
					$extension = pathinfo( $url_parts['path'], PATHINFO_EXTENSION );
					if ( ! empty( $extension ) ) {
						foreach ( wp_get_mime_types() as $exts => $mime ) {
							if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
								$type = $mime;
								break;
							}
						}
					}
				}

				if ( in_array( substr( $type, 0, strpos( $type, '/' ) ), $allowed_types, true ) ) {
					add_post_meta( $post->ID, 'enclosure', "$url\n$len\n$mime\n" );
				}
			}
		}
	}
}

/**
 * Retrieves HTTP Headers from URL.
 *
 * @since 1.5.1
 *
 * @param string $url        URL to retrieve HTTP headers from.
 * @param bool   $deprecated Not Used.
 * @return \WpOrg\Requests\Utility\CaseInsensitiveDictionary|false Headers on success, false on failure.
 */
function wp_get_http_headers( $url, $deprecated = false ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.7.0' );
	}

	$response = wp_safe_remote_head( $url );

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

	return wp_remote_retrieve_headers( $response );
}