<?php

/**

 * WordPress implementation for PHP functions either missing from older PHP versions or not included by default.

 *

 * @package PHP

 * @access private

 */

// If gettext isn't available.

if ( ! function_exists( '_' ) ) {

	function _( $string ) {

		return $string;

	}

}

/**

 * Returns whether PCRE/u (PCRE_UTF8 modifier) is available for use.

 *

 * @ignore

 * @since 4.2.2

 * @access private

 *

 * @param bool $set - Used for testing only

 *             null   : default - get PCRE/u capability

 *             false  : Used for testing - return false for future calls to this function

 *             'reset': Used for testing - restore default behavior of this function

 */

function _wp_can_use_pcre_u( $set = null ) {

	static $utf8_pcre = 'reset';

	if ( null !== $set ) {

		$utf8_pcre = $set;

	}

	if ( 'reset' === $utf8_pcre ) {

		// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- intentional error generated to detect PCRE/u support.

		$utf8_pcre = @preg_match( '/^./u', 'a' );

	}

	return $utf8_pcre;

}

if ( ! function_exists( 'mb_substr' ) ) :

	/**

	 * Compat function to mimic mb_substr().

	 *

	 * @ignore

	 * @since 3.2.0

	 *

	 * @see _mb_substr()

	 *

	 * @param string      $str      The string to extract the substring from.

	 * @param int         $start    Position to being extraction from in `$str`.

	 * @param int|null    $length   Optional. Maximum number of characters to extract from `$str`.

	 *                              Default null.

	 * @param string|null $encoding Optional. Character encoding to use. Default null.

	 * @return string Extracted substring.

	 */

	function mb_substr( $str, $start, $length = null, $encoding = null ) {

		return _mb_substr( $str, $start, $length, $encoding );

	}

endif;

/**

 * Internal compat function to mimic mb_substr().

 *

 * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.

 * For $encoding === UTF-8, the $str input is expected to be a valid UTF-8 byte sequence.

 * The behavior of this function for invalid inputs is undefined.

 *

 * @ignore

 * @since 3.2.0

 *

 * @param string      $str      The string to extract the substring from.

 * @param int         $start    Position to being extraction from in `$str`.

 * @param int|null    $length   Optional. Maximum number of characters to extract from `$str`.

 *                              Default null.

 * @param string|null $encoding Optional. Character encoding to use. Default null.

 * @return string Extracted substring.

 */

function _mb_substr( $str, $start, $length = null, $encoding = null ) {

	if ( null === $encoding ) {

		$encoding = get_option( 'blog_charset' );

	}

	/*

	 * The solution below works only for UTF-8, so in case of a different

	 * charset just use built-in substr().

	 */

	if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ), true ) ) {

		return is_null( $length ) ? substr( $str, $start ) : substr( $str, $start, $length );

	}

	if ( _wp_can_use_pcre_u() ) {

		// Use the regex unicode support to separate the UTF-8 characters into an array.

		preg_match_all( '/./us', $str, $match );

		$chars = is_null( $length ) ? array_slice( $match[0], $start ) : array_slice( $match[0], $start, $length );

		return implode( '', $chars );

	}

	$regex = '/(

		[\x00-\x7F]                  # single-byte sequences   0xxxxxxx

		| [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx

		| \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2

		| [\xE1-\xEC][\x80-\xBF]{2}

		| \xED[\x80-\x9F][\x80-\xBF]

		| [\xEE-\xEF][\x80-\xBF]{2}

		| \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3

		| [\xF1-\xF3][\x80-\xBF]{3}

		| \xF4[\x80-\x8F][\x80-\xBF]{2}

	)/x';

	// Start with 1 element instead of 0 since the first thing we do is pop.

	$chars = array( '' );

	do {

		// We had some string left over from the last round, but we counted it in that last round.

		array_pop( $chars );

		/*

		 * Split by UTF-8 character, limit to 1000 characters (last array element will contain

		 * the rest of the string).

		 */

		$pieces = preg_split( $regex, $str, 1000, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );

		$chars = array_merge( $chars, $pieces );

		// If there's anything left over, repeat the loop.

	} while ( count( $pieces ) > 1 && $str = array_pop( $pieces ) );

	return implode( '', array_slice( $chars, $start, $length ) );

}

if ( ! function_exists( 'mb_strlen' ) ) :

	/**

	 * Compat function to mimic mb_strlen().

	 *

	 * @ignore

	 * @since 4.2.0

	 *

	 * @see _mb_strlen()

	 *

	 * @param string      $str      The string to retrieve the character length from.

	 * @param string|null $encoding Optional. Character encoding to use. Default null.

	 * @return int String length of `$str`.

	 */

	function mb_strlen( $str, $encoding = null ) {

		return _mb_strlen( $str, $encoding );

	}

endif;

/**

 * Internal compat function to mimic mb_strlen().

 *

 * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.

 * For $encoding === UTF-8, the `$str` input is expected to be a valid UTF-8 byte

 * sequence. The behavior of this function for invalid inputs is undefined.

 *

 * @ignore

 * @since 4.2.0

 *

 * @param string      $str      The string to retrieve the character length from.

 * @param string|null $encoding Optional. Character encoding to use. Default null.

 * @return int String length of `$str`.

 */

function _mb_strlen( $str, $encoding = null ) {

	if ( null === $encoding ) {

		$encoding = get_option( 'blog_charset' );

	}

	/*

	 * The solution below works only for UTF-8, so in case of a different charset

	 * just use built-in strlen().

	 */

	if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ), true ) ) {

		return strlen( $str );

	}

	if ( _wp_can_use_pcre_u() ) {

		// Use the regex unicode support to separate the UTF-8 characters into an array.

		preg_match_all( '/./us', $str, $match );

		return count( $match[0] );

	}

	$regex = '/(?:

		[\x00-\x7F]                  # single-byte sequences   0xxxxxxx

		| [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx

		| \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2

		| [\xE1-\xEC][\x80-\xBF]{2}

		| \xED[\x80-\x9F][\x80-\xBF]

		| [\xEE-\xEF][\x80-\xBF]{2}

		| \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3

		| [\xF1-\xF3][\x80-\xBF]{3}

		| \xF4[\x80-\x8F][\x80-\xBF]{2}

	)/x';

	// Start at 1 instead of 0 since the first thing we do is decrement.

	$count = 1;

	do {

		// We had some string left over from the last round, but we counted it in that last round.

		$count--;

		/*

		 * Split by UTF-8 character, limit to 1000 characters (last array element will contain

		 * the rest of the string).

		 */

		$pieces = preg_split( $regex, $str, 1000 );

		// Increment.

		$count += count( $pieces );

		// If there's anything left over, repeat the loop.

	} while ( $str = array_pop( $pieces ) );

	// Fencepost: preg_split() always returns one extra item in the array.

	return --$count;

}

if ( ! function_exists( 'hash_hmac' ) ) :

	/**

	 * Compat function to mimic hash_hmac().

	 *

	 * The Hash extension is bundled with PHP by default since PHP 5.1.2.

	 * However, the extension may be explicitly disabled on select servers.

	 * As of PHP 7.4.0, the Hash extension is a core PHP extension and can no

	 * longer be disabled.

	 * I.e. when PHP 7.4.0 becomes the minimum requirement, this polyfill

	 * and the associated `_hash_hmac()` function can be safely removed.

	 *

	 * @ignore

	 * @since 3.2.0

	 *

	 * @see _hash_hmac()

	 *

	 * @param string $algo       Hash algorithm. Accepts 'md5' or 'sha1'.

	 * @param string $data       Data to be hashed.

	 * @param string $key        Secret key to use for generating the hash.

	 * @param bool   $raw_output Optional. Whether to output raw binary data (true),

	 *                           or lowercase hexits (false). Default false.

	 * @return string|false The hash in output determined by `$raw_output`. False if `$algo`

	 *                      is unknown or invalid.

	 */

	function hash_hmac( $algo, $data, $key, $raw_output = false ) {

		return _hash_hmac( $algo, $data, $key, $raw_output );

	}

endif;

/**

 * Internal compat function to mimic hash_hmac().

 *

 * @ignore

 * @since 3.2.0

 *

 * @param string $algo       Hash algorithm. Accepts 'md5' or 'sha1'.

 * @param string $data       Data to be hashed.

 * @param string $key        Secret key to use for generating the hash.

 * @param bool   $raw_output Optional. Whether to output raw binary data (true),

 *                           or lowercase hexits (false). Default false.

 * @return string|false The hash in output determined by `$raw_output`. False if `$algo`

 *                      is unknown or invalid.

 */

function _hash_hmac( $algo, $data, $key, $raw_output = false ) {

	$packs = array(

		'md5'  => 'H32',

		'sha1' => 'H40',

	);

	if ( ! isset( $packs[ $algo ] ) ) {

		return false;

	}

	$pack = $packs[ $algo ];

	if ( strlen( $key ) > 64 ) {

		$key = pack( $pack, $algo( $key ) );

	}

	$key = str_pad( $key, 64, chr( 0 ) );

	$ipad = ( substr( $key, 0, 64 ) ^ str_repeat( chr( 0x36 ), 64 ) );

	$opad = ( substr( $key, 0, 64 ) ^ str_repeat( chr( 0x5C ), 64 ) );

	$hmac = $algo( $opad . pack( $pack, $algo( $ipad . $data ) ) );

	if ( $raw_output ) {

		return pack( $pack, $hmac );

	}

	return $hmac;

}

if ( ! function_exists( 'hash_equals' ) ) :

	/**

	 * Timing attack safe string comparison

	 *

	 * Compares two strings using the same time whether they're equal or not.

	 *

	 * Note: It can leak the length of a string when arguments of differing length are supplied.

	 *

	 * This function was added in PHP 5.6.

	 * However, the Hash extension may be explicitly disabled on select servers.

	 * As of PHP 7.4.0, the Hash extension is a core PHP extension and can no

	 * longer be disabled.

	 * I.e. when PHP 7.4.0 becomes the minimum requirement, this polyfill

	 * can be safely removed.

	 *

	 * @since 3.9.2

	 *

	 * @param string $a Expected string.

	 * @param string $b Actual, user supplied, string.

	 * @return bool Whether strings are equal.

	 */

	function hash_equals( $a, $b ) {

		$a_length = strlen( $a );

		if ( strlen( $b ) !== $a_length ) {

			return false;

		}

		$result = 0;

		// Do not attempt to "optimize" this.

		for ( $i = 0; $i < $a_length; $i++ ) {

			$result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );

		}

		return 0 === $result;

	}

endif;

// random_int() was introduced in PHP 7.0.

if ( ! function_exists( 'random_int' ) ) {

	require ABSPATH . WPINC . '/random_compat/random.php';

}

// sodium_crypto_box() was introduced in PHP 7.2.

if ( ! function_exists( 'sodium_crypto_box' ) ) {

	require ABSPATH . WPINC . '/sodium_compat/autoload.php';

}

if ( ! function_exists( 'is_countable' ) ) {

	/**

	 * Polyfill for is_countable() function added in PHP 7.3.

	 *

	 * Verify that the content of a variable is an array or an object

	 * implementing the Countable interface.

	 *

	 * @since 4.9.6

	 *

	 * @param mixed $var The value to check.

	 * @return bool True if `$var` is countable, false otherwise.

	 */

	function is_countable( $var ) {

		return ( is_array( $var )

			|| $var instanceof Countable

			|| $var instanceof SimpleXMLElement

			|| $var instanceof ResourceBundle

		);

	}

}

if ( ! function_exists( 'is_iterable' ) ) {

	/**

	 * Polyfill for is_iterable() function added in PHP 7.1.

	 *

	 * Verify that the content of a variable is an array or an object

	 * implementing the Traversable interface.

	 *

	 * @since 4.9.6

	 *

	 * @param mixed $var The value to check.

	 * @return bool True if `$var` is iterable, false otherwise.

	 */

	function is_iterable( $var ) {

		return ( is_array( $var ) || $var instanceof Traversable );

	}

}