rm to W3C's HTML spec.
					$working = 1;
					$mode    = 0;
					$attr    = preg_replace( "%^[^\s\"']+(\s+|$)%", '', $attr );
				}

				break;
		} // End switch.

		if ( 0 == $working ) { // Not well-formed, remove and try again.
			$attr = wp_kses_html_error( $attr );
			$mode = 0;
		}
	} // End while.

	if ( 1 == $mode && false === array_key_exists( $attrname, $attrarr ) ) {
		// Special case, for when the attribute list ends with a valueless
		// attribute like "selected".
		$attrarr[ $attrname ] = array(
			'name'  => $attrname,
			'value' => '',
			'whole' => $attrname,
			'vless' => 'y',
		);
	}

	return $attrarr;
}

/**
 * Finds all attributes of an HTML element.
 *
 * Does not modify input.  May return "evil" output.
 *
 * Based on `wp_kses_split2()` and `wp_kses_attr()`.
 *
 * @since 4.2.3
 *
 * @param string $element HTML element.
 * @return array|false List of attributes found in the element. Returns false on failure.
 */
function wp_kses_attr_parse( $element ) {
	$valid = preg_match( '%^(<\s*)(/\s*)?([a-zA-Z0-9]+\s*)([^>]*)(>?)$%', $element, $matches );
	if ( 1 !== $valid ) {
		return false;
	}

	$begin  = $matches[1];
	$slash  = $matches[2];
	$elname = $matches[3];
	$attr   = $matches[4];
	$end    = $matches[5];

	if ( '' !== $slash ) {
		// Closing elements do not get parsed.
		return false;
	}

	// Is there a closing XHTML slash at the end of the attributes?
	if ( 1 === preg_match( '%\s*/\s*$%', $attr, $matches ) ) {
		$xhtml_slash = $matches[0];
		$attr        = substr( $attr, 0, -strlen( $xhtml_slash ) );
	} else {
		$xhtml_slash = '';
	}

	// Split it.
	$attrarr = wp_kses_hair_parse( $attr );
	if ( false === $attrarr ) {
		return false;
	}

	// Make sure all input is returned by adding front and back matter.
	array_unshift( $attrarr, $begin . $slash . $elname );
	array_push( $attrarr, $xhtml_slash . $end );

	return $attrarr;
}

/**
 * Builds an attribute list from string containing attributes.
 *
 * Does not modify input.  May return "evil" output.
 * In case of unexpected input, returns false instead of stripping things.
 *
 * Based on `wp_kses_hair()` but does not return a multi-dimensional array.
 *
 * @since 4.2.3
 *
 * @param string $attr Attribute list from HTML element to closing HTML element tag.
 * @return array|false List of attributes found in $attr. Returns false on failure.
 */
function wp_kses_hair_parse( $attr ) {
	if ( '' === $attr ) {
		return array();
	}

	// phpcs:disable Squiz.Strings.ConcatenationSpacing.PaddingFound -- don't remove regex indentation
	$regex =
		'(?:'
		.     '[_a-zA-Z][-_a-zA-Z0-9:.]*' // Attribute name.
		. '|'
		.     '\[\[?[^\[\]]+\]\]?'        // Shortcode in the name position implies unfiltered_html.
		. ')'
		. '(?:'               // Attribute value.
		.     '\s*=\s*'       // All values begin with '='.
		.     '(?:'
		.         '"[^"]*"'   // Double-quoted.
		.     '|'
		.         "'[^']*'"   // Single-quoted.
		.     '|'
		.         '[^\s"\']+' // Non-quoted.
		.         '(?:\s|$)'  // Must have a space.
		.     ')'
		. '|'
		.     '(?:\s|$)'      // If attribute has no value, space is required.
		. ')'
		. '\s*';              // Trailing space is optional except as mentioned above.
	// phpcs:enable

	// Although it is possible to reduce this procedure to a single regexp,
	// we must run that regexp twice to get exactly the expected result.

	$validation = "%^($regex)+$%";
	$extraction = "%$regex%";

	if ( 1 === preg_match( $validation, $attr ) ) {
		preg_match_all( $extraction, $attr, $attrarr );
		return $attrarr[0];
	} else {
		return false;
	}
}

/**
 * Performs different checks for attribute values.
 *
 * The currently implemented checks are "maxlen", "minlen", "maxval", "minval",
 * and "valueless".
 *
 * @since 1.0.0
 *
 * @param string $value      Attribute value.
 * @param string $vless      Whether the attribute is valueless. Use 'y' or 'n'.
 * @param string $checkname  What $checkvalue is checking for.
 * @param mixed  $checkvalue What constraint the value should pass.
 * @return bool Whether check passes.
 */
function wp_kses_check_attr_val( $value, $vless, $checkname, $checkvalue ) {
	$ok = true;

	switch ( strtolower( $checkname ) ) {
		case 'maxlen':
			/*
			 * The maxlen check makes sure that the attribute value has a length not
			 * greater than the given value. This can be used to avoid Buffer Overflows
			 * in WWW clients and various Internet servers.
			 */

			if ( strlen( $value ) > $checkvalue ) {
				$ok = false;
			}
			break;

		case 'minlen':
			/*
			 * The minlen check makes sure that the attribute value has a length not
			 * smaller than the given value.
			 */

			if ( strlen( $value ) < $checkvalue ) {
				$ok = false;
			}
			break;

		case 'maxval':
			/*
			 * The maxval check does two things: it checks that the attribute value is
			 * an integer from 0 and up, without an excessive amount of zeroes or
			 * whitespace (to avoid Buffer Overflows). It also checks that the attribute
			 * value is not greater than the given value.
			 * This check can be used to avoid Denial of Service attacks.
			 */

			if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {
				$ok = false;
			}
			if ( $value > $checkvalue ) {
				$ok = false;
			}
			break;

		case 'minval':
			/*
			 * The minval check makes sure that the attribute value is a positive integer,
			 * and that it is not smaller than the given value.
			 */

			if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {
				$ok = false;
			}
			if ( $value < $checkvalue ) {
				$ok = false;
			}
			break;

		case 'valueless':
			/*
			 * The valueless check makes sure if the attribute has a value
			 * (like `<a href="blah">`) or not (`<option selected>`). If the given value
			 * is a "y" or a "Y", the attribute must not have a value.
			 * If the given value is an "n" or an "N", the attribute must have a value.
			 */

			if ( strtolower( $checkvalue ) != $vless ) {
				$ok = false;
			}
			break;

		case 'values':
			/*
			 * The values check is used when you want to make sure that the attribute
			 * has one of the given values.
			 */

			if ( false === array_search( strtolower( $value ), $checkvalue, true ) ) {
				$ok = false;
			}
			break;

		case 'value_callback':
			/*
			 * The value_callback check is used when you want to make sure that the attribute
			 * value is accepted by the callback function.
			 */

			if ( ! call_user_func( $checkvalue, $value ) ) {
				$ok = false;
			}
			break;
	} // End switch.

	return $ok;
}

/**
 * Sanitizes a string and removed disallowed URL protocols.
 *
 * This function removes all non-allowed protocols from the beginning of the
 * string. It ignores whitespace and the case of the letters, and it does
 * understand HTML entities. It does its work recursively, so it won't be
 * fooled by a string like `javascript:javascript:alert(57)`.
 *
 * @since 1.0.0
 *
 * @param string   $string            Content to filter bad protocols from.
 * @param string[] $allowed_protocols Array of allowed URL protocols.
 * @return string Filtered content.
 */
function wp_kses_bad_protocol( $string, $allowed_protocols ) {
	$string     = wp_kses_no_null( $string );
	$iterations = 0;

	do {
		$original_string = $string;
		$string          = wp_kses_bad_protocol_once( $string, $allowed_protocols );
	} while ( $original_string != $string && ++$iterations < 6 );

	if ( $original_string != $string ) {
		return '';
	}

	return $string;
}

/**
 * Removes any invalid control characters in a text string.
 *
 * Also removes any instance of the `\0` string.
 *
 * @since 1.0.0
 *
 * @param string $string  Content to filter null characters from.
 * @param array  $options Set 'slash_zero' => 'keep' when '\0' is allowed. Default is 'remove'.
 * @return string Filtered content.
 */
function wp_kses_no_null( $string, $options = null ) {
	if ( ! isset( $options['slash_zero'] ) ) {
		$options = array( 'slash_zero' => 'remove' );
	}

	$string = preg_replace( '/[\x00-\x08\x0B\x0C\x0E-\x1F]/', '', $string );
	if ( 'remove' === $options['slash_zero'] ) {
		$string = preg_replace( '/\\\\+0+/', '', $string );
	}

	return $string;
}

/**
 * Strips slashes from in front of quotes.
 *
 * This function changes the character sequence `\"` to just `"`. It leaves all other
 * slashes alone. The quoting from `preg_replace(//e)` requires this.
 *
 * @since 1.0.0
 *
 * @param string $string String to strip slashes from.
 * @return string Fixed string with quoted slashes.
 */
function wp_kses_stripslashes( $string ) {
	return preg_replace( '%\\\\"%', '"', $string );
}

/**
 * Converts the keys of an array to lowercase.
 *
 * @since 1.0.0
 *
 * @param array $inarray Unfiltered array.
 * @return array Fixed array with all lowercase keys.
 */
function wp_kses_array_lc( $inarray ) {
	$outarray = array();

	foreach ( (array) $inarray as $inkey => $inval ) {
		$outkey              = strtolower( $inkey );
		$outarray[ $outkey ] = array();

		foreach ( (array) $inval as $inkey2 => $inval2 ) {
			$outkey2                         = strtolower( $inkey2 );
			$outarray[ $outkey ][ $outkey2 ] = $inval2;
		}
	}

	return $outarray;
}

/**
 * Handles parsing errors in `wp_kses_hair()`.
 *
 * The general plan is to remove everything to and including some whitespace,
 * but it deals with quotes and apostrophes as well.
 *
 * @since 1.0.0
 *
 * @param string $string
 * @return string
 */
function wp_kses_html_error( $string ) {
	return preg_replace( '/^("[^"]*("|$)|\'[^\']*(\'|$)|\S)*\s*/', '', $string );
}

/**
 * Sanitizes content from bad protocols and other characters.
 *
 * This function searches for URL protocols at the beginning of the string, while
 * handling whitespace and HTML entities.
 *
 * @since 1.0.0
 *
 * @param string   $string            Content to check for bad protocols.
 * @param string[] $allowed_protocols Array of allowed URL protocols.
 * @param int      $count             Depth of call recursion to this function.
 * @return string Sanitized content.
 */
function wp_kses_bad_protocol_once( $string, $allowed_protocols, $count = 1 ) {
	$string  = preg_replace( '/(&#0*58(?![;0-9])|&#x0*3a(?![;a-f0-9]))/i', '$1;', $string );
	$string2 = preg_split( '/:|&#0*58;|&#x0*3a;|&colon;/i', $string, 2 );
	if ( isset( $string2[1] ) && ! preg_match( '%/\?%', $string2[0] ) ) {
		$string   = trim( $string2[1] );
		$protocol = wp_kses_bad_protocol_once2( $string2[0], $allowed_protocols );
		if ( 'feed:' === $protocol ) {
			if ( $count > 2 ) {
				return '';
			}
			$string = wp_kses_bad_protocol_once( $string, $allowed_protocols, ++$count );
			if ( empty( $string ) ) {
				return $string;
			}
		}
		$string = $protocol . $string;
	}

	return $string;
}

/**
 * Callback for `wp_kses_bad_protocol_once()` regular expression.
 *
 * This function processes URL protocols, checks to see if they're in the
 * list of allowed protocols or not, and returns different data depending
 * on the answer.
 *
 * @access private
 * @ignore
 * @since 1.0.0
 *
 * @param string   $string            URI scheme to check against the list of allowed protocols.
 * @param string[] $allowed_protocols Array of allowed URL protocols.
 * @return string Sanitized content.
 */
function wp_kses_bad_protocol_once2( $string, $allowed_protocols ) {
	$string2 = wp_kses_decode_entities( $string );
	$string2 = preg_replace( '/\s/', '', $string2 );
	$string2 = wp_kses_no_null( $string2 );
	$string2 = strtolower( $string2 );

	$allowed = false;
	foreach ( (array) $allowed_protocols as $one_protocol ) {
		if ( strtolower( $one_protocol ) == $string2 ) {
			$allowed = true;
			break;
		}
	}

	if ( $allowed ) {
		return "$string2:";
	} else {
		return '';
	}
}

/**
 * Converts and fixes HTML entities.
 *
 * This function normalizes HTML entities. It will convert `AT&T` to the correct
 * `AT&amp;T`, `&#00058;` to `&#058;`, `&#XYZZY;` to `&amp;#XYZZY;` and so on.
 *
 * When `$context` is set to 'xml', HTML entities are converted to their code points.  For
 * example, `AT&T&hellip;&#XYZZY;` is converted to `AT&amp;T…&amp;#XYZZY;`.
 *
 * @since 1.0.0
 * @since 5.5.0 Added `$context` parameter.
 *
 * @param string $string  Content to normalize entities.
 * @param string $context Context for normalization. Can be either 'html' or 'xml'.
 *                        Default 'html'.
 * @return string Content with normalized entities.
 */
function wp_kses_normalize_entities( $string, $context = 'html' ) {
	// Disarm all entities by converting & to &amp;
	$string = str_replace( '&', '&amp;', $string );

	// Change back the allowed entities in our list of allowed entities.
	if ( 'xml' === $context ) {
		$string = preg_replace_callback( '/&amp;([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_xml_named_entities', $string );
	} else {
		$string = preg_replace_callback( '/&amp;([A-Za-z]{2,8}[0-9]{0,2});/', 'wp_kses_named_entities', $string );
	}
	$string = preg_replace_callback( '/&amp;#(0*[0-9]{1,7});/', 'wp_kses_normalize_entities2', $string );
	$string = preg_replace_callback( '/&amp;#[Xx](0*[0-9A-Fa-f]{1,6});/', 'wp_kses_normalize_entities3', $string );

	return $string;
}

/**
 * Callback for `wp_kses_normalize_entities()` regular expression.
 *
 * This function only accepts valid named entity references, which are finite,
 * case-sensitive, and highly scrutinized by HTML and XML validators.
 *
 * @since 3.0.0
 *
 * @global array $allowedentitynames
 *
 * @param array $matches preg_replace_callback() matches array.
 * @return string Correctly encoded entity.
 */
function wp_kses_named_entities( $matches ) {
	global $allowedentitynames;

	if ( empty( $matches[1] ) ) {
		return '';
	}

	$i = $matches[1];
	return ( ! in_array( $i, $allowedentitynames, true ) ) ? "&amp;$i;" : "&$i;";
}

/**
 * Callback for `wp_kses_normalize_entities()` regular expression.
 *
 * This function only accepts valid named entity references, which are finite,
 * case-sensitive, and highly scrutinized by XML validators.  HTML named entity
 * references are converted to their code points.
 *
 * @since 5.5.0
 *
 * @global array $allowedentitynames
 * @global array $allowedxmlnamedentities
 *
 * @param array $matches preg_replace_callback() matches array.
 * @return string Correctly encoded entity.
 */
function wp_kses_xml_named_entities( $matches ) {
	global $allowedentitynames, $allowedxmlentitynames;

	if ( empty( $matches[1] ) ) {
		return '';
	}

	$i = $matches[1];

	if ( in_array( $i, $allowedxmlentitynames, true ) ) {
		return "&$i;";
	} elseif ( in_array( $i, $allowedentitynames, true ) ) {
		return html_entity_decode( "&$i;", ENT_HTML5 );
	}

	return "&amp;$i;";
}

/**
 * Callback for `wp_kses_normalize_entities()` regular expression.
 *
 * This function helps `wp_kses_normalize_entities()` to only accept 16-bit
 * values and nothing more for `&#number;` entities.
 *
 * @access private
 * @ignore
 * @since 1.0.0
 *
 * @param array $matches `preg_replace_callback()` matches array.
 * @return string Correctly encoded entity.
 */
function wp_kses_normalize_entities2( $matches ) {
	if ( empty( $matches[1] ) ) {
		return '';
	}

	$i = $matches[1];
	if ( valid_unicode( $i ) ) {
		$i = str_pad( ltrim( $i, '0' ), 3, '0', STR_PAD_LEFT );
		$i = "&#$i;";
	} else {
		$i = "&amp;#$i;";
	}

	return $i;
}

/**
 * Callback for `wp_kses_normalize_entities()` for regular expression.
 *
 * This function helps `wp_kses_normalize_entities()` to only accept valid Unicode
 * numeric entities in hex form.
 *
 * @since 2.7.0
 * @access private
 * @ignore
 *
 * @param array $matches `preg_replace_callback()` matches array.
 * @return string Correctly encoded entity.
 */
function wp_kses_normalize_entities3( $matches ) {
	if ( empty( $matches[1] ) ) {
		return '';
	}

	$hexchars = $matches[1];
	return ( ! valid_unicode( hexdec( $hexchars ) ) ) ? "&amp;#x$hexchars;" : '&#x' . ltrim( $hexchars, '0' ) . ';';
}

/**
 * Determines if a Unicode codepoint is valid.
 *
 * @since 2.7.0
 *
 * @param int $i Unicode codepoint.
 * @return bool Whether or not the codepoint is a valid Unicode codepoint.
 */
function valid_unicode( $i ) {
	return ( 0x9 == $i || 0xa == $i || 0xd == $i ||
			( 0x20 <= $i && $i <= 0xd7ff ) ||
			( 0xe000 <= $i && $i <= 0xfffd ) ||
			( 0x10000 <= $i && $i <= 0x10ffff ) );
}

/**
 * Converts all numeric HTML entities to their named counterparts.
 *
 * This function decodes numeric HTML entities (`&#65;` and `&#x41;`).
 * It doesn't do anything with named entities like `&auml;`, but we don't
 * need them in the allowed URL protocols system anyway.
 *
 * @since 1.0.0
 *
 * @param string $string Content to change entities.
 * @return string Content after decoded entities.
 */
function wp_kses_decode_entities( $string ) {
	$string = preg_replace_callback( '/&#([0-9]+);/', '_wp_kses_decode_entities_chr', $string );
	$string = preg_replace_callback( '/&#[Xx]([0-9A-Fa-f]+);/', '_wp_kses_decode_entities_chr_hexdec', $string );

	return $string;
}

/**
 * Regex callback for `wp_kses_decode_entities()`.
 *
 * @since 2.9.0
 * @access private
 * @ignore
 *
 * @param array $match preg match
 * @return string
 */
function _wp_kses_decode_entities_chr( $match ) {
	return chr( $match[1] );
}

/**
 * Regex callback for `wp_kses_decode_entities()`.
 *
 * @since 2.9.0
 * @access private
 * @ignore
 *
 * @param array $match preg match
 * @return string
 */
function _wp_kses_decode_entities_chr_hexdec( $match ) {
	return chr( hexdec( $match[1] ) );
}

/**
 * Sanitize content with allowed HTML KSES rules.
 *
 * This function expects slashed data.
 *
 * @since 1.0.0
 *
 * @param string $data Content to filter, expected to be escaped with slashes.
 * @return string Filtered content.
 */
function wp_filter_kses( $data ) {
	return addslashes( wp_kses( stripslashes( $data ), current_filter() ) );
}

/**
 * Sanitize content with allowed HTML KSES rules.
 *
 * This function expects unslashed data.
 *
 * @since 2.9.0
 *
 * @param string $data Content to filter, expected to not be escaped.
 * @return string Filtered content.
 */
function wp_kses_data( $data ) {
	return wp_kses( $data, current_filter() );
}

/**
 * Sanitizes content for allowed HTML tags for post content.
 *
 * Post content refers to the page contents of the 'post' type and not `$_POST`
 * data from forms.
 *
 * This function expects slashed data.
 *
 * @since 2.0.0
 *
 * @param string $data Post content to filter, expected to be escaped with slashes.
 * @return string Filtered post content with allowed HTML tags and attributes intact.
 */
function wp_filter_post_kses( $data ) {
	return addslashes( wp_kses( stripslashes( $data ), 'post' ) );
}

/**
 * Sanitizes global styles user content removing unsafe rules.
 *
 * @since 5.9.0
 *
 * @param string $data Post content to filter.
 * @return string Filtered post content with unsafe rules removed.
 */
function wp_filter_global_styles_post( $data ) {
	$decoded_data        = json_decode( wp_unslash( $data ), true );
	$json_decoding_error = json_last_error();
	if (
		JSON_ERROR_NONE === $json_decoding_error &&
		is_array( $decoded_data ) &&
		isset( $decoded_data['isGlobalStylesUserThemeJSON'] ) &&
		$decoded_data['isGlobalStylesUserThemeJSON']
	) {
		unset( $decoded_data['isGlobalStylesUserThemeJSON'] );

		$data_to_encode = WP_Theme_JSON::remove_insecure_properties( $decoded_data );

		$data_to_encode['isGlobalStylesUserThemeJSON'] = true;
		return wp_slash( wp_json_encode( $data_to_encode ) );
	}
	return $data;
}

/**
 * Sanitizes content for allowed HTML tags for post content.
 *
 * Post content refers to the page contents of the 'post' type and not `$_POST`
 * data from forms.
 *
 * This function expects unslashed data.
 *
 * @since 2.9.0
 *
 * @param string $data Post content to filter.
 * @return string Filtered post content with allowed HTML tags and attributes intact.
 */
function wp_kses_post( $data ) {
	return wp_kses( $data, 'post' );
}

/**
 * Navigates through an array, object, or scalar, and sanitizes content for
 * allowed HTML tags for post content.
 *
 * @since 4.4.2
 *
 * @see map_deep()
 *
 * @param mixed $data The array, object, or scalar value to inspect.
 * @return mixed The filtered content.
 */
function wp_kses_post_deep( $data ) {
	return map_deep( $data, 'wp_kses_post' );
}

/**
 * Strips all HTML from a text string.
 *
 * This function expects slashed data.
 *
 * @since 2.1.0
 *
 * @param string $data Content to strip all HTML from.
 * @return string Filtered content without any HTML.
 */
function wp_filter_nohtml_kses( $data ) {
	return addslashes( wp_kses( stripslashes( $data ), 'strip' ) );
}

/**
 * Adds all KSES input form content filters.
 *
 * All hooks have default priority. The `wp_filter_kses()` function is added to
 * the 'pre_comment_content' and 'title_save_pre' hooks.
 *
 * The `wp_filter_post_kses()` function is added to the 'content_save_pre',
 * 'excerpt_save_pre', and 'content_filtered_save_pre' hooks.
 *
 * @since 2.0.0
 */
function kses_init_filters() {
	// Normal filtering.
	add_filter( 'title_save_pre', 'wp_filter_kses' );

	// Comment filtering.
	if ( current_user_can( 'unfiltered_html' ) ) {
		add_filter( 'pre_comment_content', 'wp_filter_post_kses' );
	} else {
		add_filter( 'pre_comment_content', 'wp_filter_kses' );
	}

	// Global Styles filtering: Global Styles filters should be executed before normal post_kses HTML filters.
	add_filter( 'content_save_pre', 'wp_filter_global_styles_post', 9 );
	add_filter( 'content_filtered_save_pre', 'wp_filter_global_styles_post', 9 );

	// Post filtering.
	add_filter( 'content_save_pre', 'wp_filter_post_kses' );
	add_filter( 'excerpt_save_pre', 'wp_filter_post_kses' );
	add_filter( 'content_filtered_save_pre', 'wp_filter_post_kses' );
}

/**
 * Removes all KSES input form content filters.
 *
 * A quick procedural method to removing all of the filters that KSES uses for
 * content in WordPress Loop.
 *
 * Does not remove the `kses_init()` function from {@see 'init'} hook (priority is
 * default). Also does not remove `kses_init()` function from {@see 'set_current_user'}
 * hook (priority is also default).
 *
 * @since 2.0.6
 */
function kses_remove_filters() {
	// Normal filtering.
	remove_filter( 'title_save_pre', 'wp_filter_kses' );

	// Comment filtering.
	remove_filter( 'pre_comment_content', 'wp_filter_post_kses' );
	remove_filter( 'pre_comment_content', 'wp_filter_kses' );

	// Global Styles filtering.
	remove_filter( 'content_save_pre', 'wp_filter_global_styles_post', 9 );
	remove_filter( 'content_filtered_save_pre', 'wp_filter_global_styles_post', 9 );

	// Post filtering.
	remove_filter( 'content_save_pre', 'wp_filter_post_kses' );
	remove_filter( 'excerpt_save_pre', 'wp_filter_post_kses' );
	remove_filter( 'content_filtered_save_pre', 'wp_filter_post_kses' );
}

/**
 * Sets up most of the KSES filters for input form content.
 *
 * First removes all of the KSES filters in case the current user does not need
 * to have KSES filter the content. If the user does not have `unfiltered_html`
 * capability, then KSES filters are added.
 *
 * @since 2.0.0
 */
function kses_init() {
	kses_remove_filters();

	if ( ! current_user_can( 'unfiltered_html' ) ) {
		kses_init_filters();
	}
}

/**
 * Filters an inline style attribute and removes disallowed rules.
 *
 * @since 2.8.1
 * @since 4.4.0 Added support for `min-height`, `max-height`, `min-width`, and `max-width`.
 * @since 4.6.0 Added support for `list-style-type`.
 * @since 5.0.0 Added support for `background-image`.
 * @since 5.1.0 Added support for `text-transform`.
 * @since 5.2.0 Added support for `background-position` and `grid-template-columns`.
 * @since 5.3.0 Added support for `grid`, `flex` and `column` layout properties.
 *              Extend `background-*` support of individual properties.
 * @since 5.3.1 Added support for gradient backgrounds.
 * @since 5.7.1 Added support for `object-position`.
 * @since 5.8.0 Added support for `calc()` and `var()` values.
 *
 * @param string $css        A string of CSS rules.
 * @param string $deprecated Not used.
 * @return string Filtered string of CSS rules.
 */
function safecss_filter_attr( $css, $deprecated = '' ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.8.1' ); // Never implemented.
	}

	$css = wp_kses_no_null( $css );
	$css = str_replace( array( "\n", "\r", "\t" ), '', $css );

	$allowed_protocols = wp_allowed_protocols();

	$css_array = explode( ';', trim( $css ) );

	/**
	 * Filters the list of allowed CSS attributes.
	 *
	 * @since 2.8.1
	 *
	 * @param string[] $attr Array of allowed CSS attributes.
	 */
	$allowed_attr = apply_filters(
		'safe_style_css',
		array(
			'background',
			'background-color',
			'background-image',
			'background-position',
			'background-size',
			'background-attachment',
			'background-blend-mode',

			'border',
			'border-radius',
			'border-width',
			'border-color',
			'border-style',
			'border-right',
			'border-right-color',
			'border-right-style',
			'border-right-width',
			'border-bottom',
			'border-bottom-color',
			'border-bottom-left-radius',
			'border-bottom-right-radius',
			'border-bottom-style',
			'border-bottom-width',
			'border-bottom-right-radius',
			'border-bottom-left-radius',
			'border-left',
			'border-left-color',
			'border-left-style',
			'border-left-width',
			'border-top',
			'border-top-color',
			'border-top-left-radius',
			'border-top-right-radius',
			'border-top-style',
			'border-top-width',
			'border-top-left-radius',
			'border-top-right-radius',

			'border-spacing',
			'border-collapse',
			'caption-side',

			'columns',
			'column-count',
			'column-fill',
			'column-gap',
			'column-rule',
			'column-span',
			'column-width',

			'color',
			'filter',
			'font',
			'font-family',
			'font-size',
			'font-style',
			'font-variant',
			'font-weight',
			'letter-spacing',
			'line-height',
			'text-align',
			'text-decoration',
			'text-indent',
			'text-transform',

			'height',
			'min-height',
			'max-height',

			'width',
			'min-width',
			'max-width',

			'margin',
			'margin-right',
			'margin-bottom',
			'margin-left',
			'margin-top',

			'padding',
			'padding-right',
			'padding-bottom',
			'padding-left',
			'padding-top',

			'flex',
			'flex-basis',
			'flex-direction',
			'flex-flow',
			'flex-grow',
			'flex-shrink',

			'grid-template-columns',
			'grid-auto-columns',
			'grid-column-start',
			'grid-column-end',
			'grid-column-gap',
			'grid-template-rows',
			'grid-auto-rows',
			'grid-row-start',
			'grid-row-end',
			'grid-row-gap',
			'grid-gap',

			'justify-content',
			'justify-items',
			'justify-self',
			'align-content',
			'align-items',
			'align-self',

			'clear',
			'cursor',
			'direction',
			'float',
			'list-style-type',
			'object-fit',
			'object-position',
			'overflow',
			'vertical-align',
		)
	);

	/*
	 * CSS attributes that accept URL data types.
	 *
	 * This is in accordance to the CSS spec and unrelated to
	 * the sub-set of supported attributes above.
	 *
	 * See: https://developer.mozilla.org/en-US/docs/Web/CSS/url
	 */
	$css_url_data_types = array(
		'background',
		'background-image',

		'cursor',

		'list-style',
		'list-style-image',
	);

	/*
	 * CSS attributes that accept gradient data types.
	 *
	 */
	$css_gradient_data_types = array(
		'background',
		'background-image',
	);

	if ( empty( $allowed_attr ) ) {
		return $css;
	}

	$css = '';
	foreach ( $css_array as $css_item ) {
		if ( '' === $css_item ) {
			continue;
		}

		$css_item        = trim( $css_item );
		$css_test_string = $css_item;
		$found           = false;
		$url_attr        = false;
		$gradient_attr   = false;

		if ( strpos( $css_item, ':' ) === false ) {
			$found = true;
		} else {
			$parts        = explode( ':', $css_item, 2 );
			$css_selector = trim( $parts[0] );

			if ( in_array( $css_selector, $allowed_attr, true ) ) {
				$found         = true;
				$url_attr      = in_array( $css_selector, $css_url_data_types, true );
				$gradient_attr = in_array( $css_selector, $css_gradient_data_types, true );
			}
		}

		if ( $found && $url_attr ) {
			// Simplified: matches the sequence `url(*)`.
			preg_match_all( '/url\([^)]+\)/', $parts[1], $url_matches );

			foreach ( $url_matches[0] as $url_match ) {
				// Clean up the URL from each of the matches above.
				preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/', $url_match, $url_pieces );

				if ( empty( $url_pieces[2] ) ) {
					$found = false;
					break;
				}

				$url = trim( $url_pieces[2] );

				if ( empty( $url ) || wp_kses_bad_protocol( $url, $allowed_protocols ) !== $url ) {
					$found = false;
					break;
				} else {
					// Remove the whole `url(*)` bit that was matched above from the CSS.
					$css_test_string = str_replace( $url_match, '', $css_test_string );
				}
			}
		}

		if ( $found && $gradient_attr ) {
			$css_value = trim( $parts[1] );
			if ( preg_match( '/^(repeating-)?(linear|radial|conic)-gradient\(([^()]|rgb[a]?\([^()]*\))*\)$/', $css_value ) ) {
				// Remove the whole `gradient` bit that was matched above from the CSS.
				$css_test_string = str_replace( $css_value, '', $css_test_string );
			}
		}

		if ( $found ) {
			// Allow CSS calc().
			$css_test_string = preg_replace( '/calc\(((?:\([^()]*\)?|[^()])*)\)/', '', $css_test_string );
			// Allow CSS var().
			$css_test_string = preg_replace( '/\(?var\(--[a-zA-Z0-9_-]*\)/', '', $css_test_string );

			// Check for any CSS containing \ ( & } = or comments,
			// except for url(), calc(), or var() usage checked above.
			$allow_css = ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string );

			/**
			 * Filters the check for unsafe CSS in `safecss_filter_attr`.
			 *
			 * Enables developers to determine whether a section of CSS should be allowed or discarded.
			 * By default, the value will be false if the part contains \ ( & } = or comments.
			 * Return true to allow the CSS part to be included in the output.
			 *
			 * @since 5.5.0
			 *
			 * @param bool   $allow_css       Whether the CSS in the test string is considered safe.
			 * @param string $css_test_string The CSS string to test.
			 */
			$allow_css = apply_filters( 'safecss_filter_attr_allow_css', $allow_css, $css_test_string );

			// Only add the CSS part if it passes the regex check.
			if ( $allow_css ) {
				if ( '' !== $css ) {
					$css .= ';';
				}

				$css .= $css_item;
			}
		}
	}

	return $css;
}

/**
 * Helper function to add global attributes to a tag in the allowed HTML list.
 *
 * @since 3.5.0
 * @since 5.0.0 Add support for `data-*` wildcard attributes.
 * @access private
 * @ignore
 *
 * @param array $value An array of attributes.
 * @return array The array of attributes with global attributes added.
 */
function _wp_add_global_attributes( $value ) {
	$global_attributes = array(
		'aria-describedby' => true,
		'aria-details'     => true,
		'aria-label'       => true,
		'aria-labelledby'  => true,
		'aria-hidden'      => true,
		'class'            => true,
		'id'               => true,
		'style'            => true,
		'title'            => true,
		'role'             => true,
		'data-*'           => true,
	);

	if ( true === $value ) {
		$value = array();
	}

	if ( is_array( $value ) ) {
		return array_merge( $value, $global_attributes );
	}

	return $value;
}

/**
 * Helper function to check if this is a safe PDF URL.
 *
 * @since 5.9.0
 * @access private
 * @ignore
 *
 * @param string $url The URL to check.
 * @return bool True if the URL is safe, false otherwise.
 */
function _wp_kses_allow_pdf_objects( $url ) {
	// We're not interested in URLs that contain query strings or fragments.
	if ( str_contains( $url, '?' ) || str_contains( $url, '#' ) ) {
		return false;
	}

	// If it doesn't have a PDF extension, it's not safe.
	if ( ! str_ends_with( $url, '.pdf' ) ) {
		return false;
	}

	// If the URL host matches the current site's media URL, it's safe.
	$upload_info = wp_upload_dir( null, false );
	$parsed_url  = wp_parse_url( $upload_info['url'] );
	$upload_host = isset( $parsed_url['host'] ) ? $parsed_url['host'] : '';
	$upload_port = isset( $parsed_url['port'] ) ? ':' . $parsed_url['port'] : '';

	if ( str_starts_with( $url, "http://$upload_host$upload_port/" )
		|| str_starts_with( $url, "https://$upload_host$upload_port/" )
	) {
		return true;
	}

	return false;
}