wikimedia/mediawiki-core

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includes/Html/Html.php

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<?php
/**
 * Collection of methods to generate HTML content
 *
 * Copyright © 2009 Aryeh Gregor
 * https://www.mediawiki.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

namespace MediaWiki\Html;

use FormatJson;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Request\ContentSecurityPolicy;
use UnexpectedValueException;

/**
 * This class is a collection of static functions that serve two purposes:
 *
 * 1) Implement any algorithms specified by HTML5, or other HTML
 * specifications, in a convenient and self-contained way.
 *
 * 2) Allow HTML elements to be conveniently and safely generated, like the
 * current Xml class but a) less confused (Xml supports HTML-specific things,
 * but only sometimes!) and b) not necessarily confined to XML-compatible
 * output.
 *
 * There are two important configuration options this class uses:
 *
 * $wgMimeType: If this is set to an xml MIME type then output should be
 *     valid XHTML5.
 *
 * This class is meant to be confined to utility functions that are called from
 * trusted code paths.  It does not do enforcement of policy like not allowing
 * <a> elements.
 *
 * @since 1.16
 */
class Html {
    /** @var bool[] List of void elements from HTML5, section 8.1.2 as of 2016-09-19 */
    private static $voidElements = [
        'area' => true,
        'base' => true,
        'br' => true,
        'col' => true,
        'embed' => true,
        'hr' => true,
        'img' => true,
        'input' => true,
        'keygen' => true,
        'link' => true,
        'meta' => true,
        'param' => true,
        'source' => true,
        'track' => true,
        'wbr' => true,
    ];

    /**
     * Boolean attributes, which may have the value omitted entirely.  Manually
     * collected from the HTML5 spec as of 2011-08-12.
     * @var bool[]
     */
    private static $boolAttribs = [
        'async' => true,
        'autofocus' => true,
        'autoplay' => true,
        'checked' => true,
        'controls' => true,
        'default' => true,
        'defer' => true,
        'disabled' => true,
        'formnovalidate' => true,
        'hidden' => true,
        'ismap' => true,
        'itemscope' => true,
        'loop' => true,
        'multiple' => true,
        'muted' => true,
        'novalidate' => true,
        'open' => true,
        'pubdate' => true,
        'readonly' => true,
        'required' => true,
        'reversed' => true,
        'scoped' => true,
        'seamless' => true,
        'selected' => true,
        'truespeed' => true,
        'typemustmatch' => true,
    ];

    /**
     * Modifies a set of attributes meant for button elements.
     *
     * @param array $attrs HTML attributes in an associative array
     * @param string[] $modifiers Unused
     * @return array Modified attributes array
     * @deprecated since 1.42 No-op
     */
    public static function buttonAttributes( array $attrs, array $modifiers = [] ) {
        wfDeprecated( __METHOD__, '1.42' );
        return $attrs;
    }

    /**
     * Modifies a set of attributes meant for text input elements.
     *
     * @param array $attrs An attribute array.
     * @return array Modified attributes array
     * @deprecated since 1.42 No-op
     */
    public static function getTextInputAttributes( array $attrs ) {
        wfDeprecated( __METHOD__, '1.42' );
        return $attrs;
    }

    /**
     * Returns an HTML link element in a string.
     *
     * @param string $text The text of the element. Will be escaped (not raw HTML)
     * @param array $attrs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     * @param string[] $modifiers Unused
     * @return string Raw HTML
     */
    public static function linkButton( $text, array $attrs, array $modifiers = [] ) {
        return self::element(
            'a',
            $attrs,
            $text
        );
    }

    /**
     * Returns an HTML input element in a string.
     *
     * @param string $contents Plain text label for the button value
     * @param array $attrs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     * @param string[] $modifiers Unused
     * @return string Raw HTML
     */
    public static function submitButton( $contents, array $attrs = [], array $modifiers = [] ) {
        $attrs['type'] = 'submit';
        $attrs['value'] = $contents;
        return self::element( 'input', $attrs );
    }

    /**
     * Returns an HTML element in a string.  The major advantage here over
     * manually typing out the HTML is that it will escape all attribute
     * values.
     *
     * This is quite similar to Xml::tags(), but it implements some useful
     * HTML-specific logic.  For instance, there is no $allowShortTag
     * parameter: the closing tag is magically omitted if $element has an empty
     * content model.
     *
     * @param string $element The element's name, e.g., 'a'
     * @param-taint $element tainted
     * @param array $attribs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     * @param-taint $attribs escapes_html
     * @param string $contents The raw HTML contents of the element: *not*
     *   escaped!
     * @param-taint $contents tainted
     * @return string Raw HTML
     * @return-taint escaped
     */
    public static function rawElement( $element, $attribs = [], $contents = '' ) {
        $start = self::openElement( $element, $attribs );
        if ( isset( self::$voidElements[$element] ) ) {
            return $start;
        } else {
            return $start . $contents . self::closeElement( $element );
        }
    }

    /**
     * Identical to rawElement(), but HTML-escapes $contents (like
     * Xml::element()).
     *
     * @param string $element Name of the element, e.g., 'a'
     * @param-taint $element tainted
     * @param array $attribs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     * @param-taint $attribs escapes_html
     * @param string $contents
     * @param-taint $contents escapes_html
     *
     * @return string
     * @return-taint escaped
     */
    public static function element( $element, $attribs = [], $contents = '' ) {
        return self::rawElement(
            $element,
            $attribs,
            strtr( $contents ?? '', [
                // There's no point in escaping quotes, >, etc. in the contents of
                // elements.
                '&' => '&amp;',
                '<' => '&lt;',
            ] )
        );
    }

    /**
     * Identical to rawElement(), but has no third parameter and omits the end
     * tag (and the self-closing '/' in XML mode for empty elements).
     *
     * @param string $element Name of the element, e.g., 'a'
     * @param array $attribs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     *
     * @return string
     */
    public static function openElement( $element, $attribs = [] ) {
        $attribs = (array)$attribs;
        // This is not required in HTML5, but let's do it anyway, for
        // consistency and better compression.
        $element = strtolower( $element );

        // Some people were abusing this by passing things like
        // 'h1 id="foo" to $element, which we don't want.
        if ( str_contains( $element, ' ' ) ) {
            wfWarn( __METHOD__ . " given element name with space '$element'" );
        }

        // Remove invalid input types
        if ( $element == 'input' ) {
            $validTypes = [
                'hidden' => true,
                'text' => true,
                'password' => true,
                'checkbox' => true,
                'radio' => true,
                'file' => true,
                'submit' => true,
                'image' => true,
                'reset' => true,
                'button' => true,

                // HTML input types
                'datetime' => true,
                'datetime-local' => true,
                'date' => true,
                'month' => true,
                'time' => true,
                'week' => true,
                'number' => true,
                'range' => true,
                'email' => true,
                'url' => true,
                'search' => true,
                'tel' => true,
                'color' => true,
            ];
            if ( isset( $attribs['type'] ) && !isset( $validTypes[$attribs['type']] ) ) {
                unset( $attribs['type'] );
            }
        }

        // According to standard the default type for <button> elements is "submit".
        // Depending on compatibility mode IE might use "button", instead.
        // We enforce the standard "submit".
        if ( $element == 'button' && !isset( $attribs['type'] ) ) {
            $attribs['type'] = 'submit';
        }

        return "<$element" . self::expandAttributes(
            self::dropDefaults( $element, $attribs ) ) . '>';
    }

    /**
     * Returns "</$element>"
     *
     * @since 1.17
     * @param string $element Name of the element, e.g., 'a'
     * @return string A closing tag
     */
    public static function closeElement( $element ) {
        $element = strtolower( $element );

        return "</$element>";
    }

    /**
     * Given an element name and an associative array of element attributes,
     * return an array that is functionally identical to the input array, but
     * possibly smaller.  In particular, attributes might be stripped if they
     * are given their default values.
     *
     * This method is not guaranteed to remove all redundant attributes, only
     * some common ones and some others selected arbitrarily at random.  It
     * only guarantees that the output array should be functionally identical
     * to the input array (currently per the HTML 5 draft as of 2009-09-06).
     *
     * @param string $element Name of the element, e.g., 'a'
     * @param array $attribs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ].  See expandAttributes() for
     *   further documentation.
     * @return array An array of attributes functionally identical to $attribs
     */
    private static function dropDefaults( $element, array $attribs ) {
        // Whenever altering this array, please provide a covering test case
        // in HtmlTest::provideElementsWithAttributesHavingDefaultValues
        static $attribDefaults = [
            'area' => [ 'shape' => 'rect' ],
            'button' => [
                'formaction' => 'GET',
                'formenctype' => 'application/x-www-form-urlencoded',
            ],
            'canvas' => [
                'height' => '150',
                'width' => '300',
            ],
            'form' => [
                'action' => 'GET',
                'autocomplete' => 'on',
                'enctype' => 'application/x-www-form-urlencoded',
            ],
            'input' => [
                'formaction' => 'GET',
                'type' => 'text',
            ],
            'keygen' => [ 'keytype' => 'rsa' ],
            'link' => [ 'media' => 'all' ],
            'menu' => [ 'type' => 'list' ],
            'script' => [ 'type' => 'text/javascript' ],
            'style' => [
                'media' => 'all',
                'type' => 'text/css',
            ],
            'textarea' => [ 'wrap' => 'soft' ],
        ];

        foreach ( $attribs as $attrib => $value ) {
            if ( $attrib === 'class' ) {
                if ( $value === '' || $value === [] || $value === [ '' ] ) {
                    unset( $attribs[$attrib] );
                }
            } elseif ( isset( $attribDefaults[$element][$attrib] ) ) {
                if ( is_array( $value ) ) {
                    $value = implode( ' ', $value );
                } else {
                    $value = strval( $value );
                }
                if ( $attribDefaults[$element][$attrib] == $value ) {
                    unset( $attribs[$attrib] );
                }
            }
        }

        // More subtle checks
        if ( $element === 'link'
            && isset( $attribs['type'] ) && strval( $attribs['type'] ) == 'text/css'
        ) {
            unset( $attribs['type'] );
        }
        if ( $element === 'input' ) {
            $type = $attribs['type'] ?? null;
            $value = $attribs['value'] ?? null;
            if ( $type === 'checkbox' || $type === 'radio' ) {
                // The default value for checkboxes and radio buttons is 'on'
                // not ''. By stripping value="" we break radio boxes that
                // actually wants empty values.
                if ( $value === 'on' ) {
                    unset( $attribs['value'] );
                }
            } elseif ( $type === 'submit' ) {
                // The default value for submit appears to be "Submit" but
                // let's not bother stripping out localized text that matches
                // that.
            } else {
                // The default value for nearly every other field type is ''
                // The 'range' and 'color' types use different defaults but
                // stripping a value="" does not hurt them.
                if ( $value === '' ) {
                    unset( $attribs['value'] );
                }
            }
        }
        if ( $element === 'select' && isset( $attribs['size'] ) ) {
            if ( in_array( 'multiple', $attribs )
                || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
            ) {
                // A multi-select
                if ( strval( $attribs['size'] ) == '4' ) {
                    unset( $attribs['size'] );
                }
            } else {
                // Single select
                if ( strval( $attribs['size'] ) == '1' ) {
                    unset( $attribs['size'] );
                }
            }
        }

        return $attribs;
    }

    /**
     * Given an associative array of element attributes, generate a string
     * to stick after the element name in HTML output.  Like [ 'href' =>
     * 'https://www.mediawiki.org/' ] becomes something like
     * ' href="https://www.mediawiki.org"'.  Again, this is like
     * Xml::expandAttributes(), but it implements some HTML-specific logic.
     *
     * Attributes that can contain space-separated lists ('class', 'accesskey' and 'rel') array
     * values are allowed as well, which will automagically be normalized
     * and converted to a space-separated string. In addition to a numerical
     * array, the attribute value may also be an associative array. See the
     * example below for how that works.
     *
     * @par Numerical array
     * @code
     *     Html::element( 'em', [
     *         'class' => [ 'foo', 'bar' ]
     *     ] );
     *     // gives '<em class="foo bar"></em>'
     * @endcode
     *
     * @par Associative array
     * @code
     *     Html::element( 'em', [
     *         'class' => [ 'foo', 'bar', 'foo' => false, 'quux' => true ]
     *     ] );
     *     // gives '<em class="bar quux"></em>'
     * @endcode
     *
     * @param array $attribs Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ].  Values will be HTML-escaped.
     *   A value of false or null means to omit the attribute.  For boolean attributes,
     *   you can omit the key, e.g., [ 'checked' ] instead of
     *   [ 'checked' => 'checked' ] or such.
     *
     * @return string HTML fragment that goes between element name and '>'
     *   (starting with a space if at least one attribute is output)
     */
    public static function expandAttributes( array $attribs ) {
        $ret = '';
        foreach ( $attribs as $key => $value ) {
            // Support intuitive [ 'checked' => true/false ] form
            if ( $value === false || $value === null ) {
                continue;
            }

            // For boolean attributes, support [ 'foo' ] instead of
            // requiring [ 'foo' => 'meaningless' ].
            if ( is_int( $key ) && isset( self::$boolAttribs[strtolower( $value )] ) ) {
                $key = $value;
            }

            // Not technically required in HTML5 but we'd like consistency
            // and better compression anyway.
            $key = strtolower( $key );

            // https://www.w3.org/TR/html401/index/attributes.html ("space-separated")
            // https://www.w3.org/TR/html5/index.html#attributes-1 ("space-separated")
            $spaceSeparatedListAttributes = [
                'class' => true, // html4, html5
                'accesskey' => true, // as of html5, multiple space-separated values allowed
                // html4-spec doesn't document rel= as space-separated
                // but has been used like that and is now documented as such
                // in the html5-spec.
                'rel' => true,
            ];

            // Specific features for attributes that allow a list of space-separated values
            if ( isset( $spaceSeparatedListAttributes[$key] ) ) {
                // Apply some normalization and remove duplicates

                // Convert into correct array. Array can contain space-separated
                // values. Implode/explode to get those into the main array as well.
                if ( is_array( $value ) ) {
                    // If input wasn't an array, we can skip this step
                    $arrayValue = [];
                    foreach ( $value as $k => $v ) {
                        if ( is_string( $v ) ) {
                            // String values should be normal `[ 'foo' ]`
                            // Just append them
                            if ( !isset( $value[$v] ) ) {
                                // As a special case don't set 'foo' if a
                                // separate 'foo' => true/false exists in the array
                                // keys should be authoritative
                                foreach ( explode( ' ', $v ) as $part ) {
                                    // Normalize spacing by fixing up cases where people used
                                    // more than 1 space and/or a trailing/leading space
                                    if ( $part !== '' && $part !== ' ' ) {
                                        $arrayValue[] = $part;
                                    }
                                }
                            }
                        } elseif ( $v ) {
                            // If the value is truthy but not a string this is likely
                            // an [ 'foo' => true ], falsy values don't add strings
                            $arrayValue[] = $k;
                        }
                    }
                } else {
                    $arrayValue = explode( ' ', $value );
                    // Normalize spacing by fixing up cases where people used
                    // more than 1 space and/or a trailing/leading space
                    $arrayValue = array_diff( $arrayValue, [ '', ' ' ] );
                }

                // Remove duplicates and create the string
                $value = implode( ' ', array_unique( $arrayValue ) );

                // Optimization: Skip below boolAttribs check and jump straight
                // to its `else` block. The current $spaceSeparatedListAttributes
                // block is mutually exclusive with $boolAttribs.
                // phpcs:ignore Generic.PHP.DiscourageGoto
                goto not_bool; // NOSONAR
            } elseif ( is_array( $value ) ) {
                throw new UnexpectedValueException( "HTML attribute $key can not contain a list of values" );
            }

            if ( isset( self::$boolAttribs[$key] ) ) {
                $ret .= " $key=\"\"";
            } else {
                // phpcs:ignore Generic.PHP.DiscourageGoto
                not_bool:
                // Inlined from Sanitizer::encodeAttribute() for improved performance
                $encValue = htmlspecialchars( $value, ENT_QUOTES );
                // Whitespace is normalized during attribute decoding,
                // so if we've been passed non-spaces we must encode them
                // ahead of time or they won't be preserved.
                $encValue = strtr( $encValue, [
                    "\n" => '&#10;',
                    "\r" => '&#13;',
                    "\t" => '&#9;',
                ] );
                $ret .= " $key=\"$encValue\"";
            }
        }
        return $ret;
    }

    /**
     * Output an HTML script tag with the given contents.
     *
     * It is unsupported for the contents to contain the sequence `<script` or `</script`
     * (case-insensitive). This ensures the script can be terminated easily and consistently.
     * It is the responsibility of the caller to avoid such character sequence by escaping
     * or avoiding it. If found at run-time, the contents are replaced with a comment, and
     * a warning is logged server-side.
     *
     * @param string $contents JavaScript
     * @param string|null $nonce Unused
     * @return string Raw HTML
     */
    public static function inlineScript( $contents, $nonce = null ) {
        if ( preg_match( '/<\/?script/i', $contents ) ) {
            wfLogWarning( __METHOD__ . ': Illegal character sequence found in inline script.' );
            $contents = '/* ERROR: Invalid script */';
        }

        return self::rawElement( 'script', [], $contents );
    }

    /**
     * Output a "<script>" tag linking to the given URL, e.g.,
     * "<script src=foo.js></script>".
     *
     * @param string $url
     * @param string|null $nonce Nonce for CSP header, from OutputPage->getCSP()->getNonce()
     * @return string Raw HTML
     */
    public static function linkedScript( $url, $nonce = null ) {
        $attrs = [ 'src' => $url ];
        if ( $nonce !== null ) {
            $attrs['nonce'] = $nonce;
        } elseif ( ContentSecurityPolicy::isNonceRequired( MediaWikiServices::getInstance()->getMainConfig() ) ) {
            wfWarn( "no nonce set on script. CSP will break it" );
        }

        return self::element( 'script', $attrs );
    }

    /**
     * Output a "<style>" tag with the given contents for the given media type
     * (if any).  TODO: do some useful escaping as well, like if $contents
     * contains literal "</style>" (admittedly unlikely).
     *
     * @param string $contents CSS
     * @param string $media A media type string, like 'screen'
     * @param array $attribs (since 1.31) Associative array of attributes, e.g., [
     *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
     *   further documentation.
     * @return string Raw HTML
     */
    public static function inlineStyle( $contents, $media = 'all', $attribs = [] ) {
        // Don't escape '>' since that is used
        // as direct child selector.
        // Remember, in css, there is no "x" for hexadecimal escapes, and
        // the space immediately after an escape sequence is swallowed.
        $contents = strtr( $contents, [
            '<' => '\3C ',
            // CDATA end tag for good measure, but the main security
            // is from escaping the '<'.
            ']]>' => '\5D\5D\3E '
        ] );

        if ( preg_match( '/[<&]/', $contents ) ) {
            $contents = "/*<![CDATA[*/$contents/*]]>*/";
        }

        return self::rawElement( 'style', [
            'media' => $media,
        ] + $attribs, $contents );
    }

    /**
     * Output a "<link rel=stylesheet>" linking to the given URL for the given
     * media type (if any).
     *
     * @param string $url
     * @param string $media A media type string, like 'screen'
     * @return string Raw HTML
     */
    public static function linkedStyle( $url, $media = 'all' ) {
        return self::element( 'link', [
            'rel' => 'stylesheet',
            'href' => $url,
            'media' => $media,
        ] );
    }

    /**
     * Convenience function to produce an `<input>` element.  This supports the
     * new HTML5 input types and attributes.
     *
     * @param string $name Name attribute
     * @param string $value Value attribute
     * @param string $type Type attribute
     * @param array $attribs Associative array of miscellaneous extra
     *   attributes, passed to Html::element()
     * @return string Raw HTML
     */
    public static function input( $name, $value = '', $type = 'text', array $attribs = [] ) {
        $attribs['type'] = $type;
        $attribs['value'] = $value;
        $attribs['name'] = $name;
        return self::element( 'input', $attribs );
    }

    /**
     * Convenience function to produce a checkbox (input element with type=checkbox)
     *
     * @param string $name Name attribute
     * @param bool $checked Whether the checkbox is checked or not
     * @param array $attribs Array of additional attributes
     * @return string Raw HTML
     */
    public static function check( $name, $checked = false, array $attribs = [] ) {
        if ( isset( $attribs['value'] ) ) {
            $value = $attribs['value'];
            unset( $attribs['value'] );
        } else {
            $value = 1;
        }

        if ( $checked ) {
            $attribs[] = 'checked';
        }

        return self::input( $name, $value, 'checkbox', $attribs );
    }

    /**
     * Return the HTML for a message box.
     * @since 1.31
     * @param string $html of contents of box
     * @param string|array $className corresponding to box
     * @param string $heading (optional)
     * @param string $iconClassName (optional) corresponding to box icon
     * @return string of HTML representing a box.
     */
    private static function messageBox( $html, $className, $heading = '', $iconClassName = '' ) {
        if ( $heading !== '' ) {
            $html = self::element( 'h2', [], $heading ) . $html;
        }
        $coreClasses = [
            'mw-message-box',
            'cdx-message',
            'cdx-message--block'
        ];
        if ( is_array( $className ) ) {
            $className = array_merge(
                $coreClasses,
                $className
            );
        } else {
            $className .= ' ' . implode( ' ', $coreClasses );
        }
        return self::rawElement( 'div', [ 'class' => $className ],
            self::element( 'span', [ 'class' => [
                'cdx-message__icon',
                $iconClassName
            ] ] ) .
            self::rawElement( 'div', [
                'class' => 'cdx-message__content'
            ], $html )
        );
    }

    /**
     * Return the HTML for a notice message box.
     * @since 1.38
     * @param string $html of contents of notice
     * @param string|array $className corresponding to notice
     * @param string $heading (optional)
     * @param string|array $iconClassName (optional) corresponding to notice icon
     * @return string of HTML representing the notice
     */
    public static function noticeBox( $html, $className, $heading = '', $iconClassName = '' ) {
        return self::messageBox( $html, [
            'mw-message-box-notice',
            'cdx-message--notice',
            $className
        ], $heading, $iconClassName );
    }

    /**
     * Return a warning box.
     * @since 1.31
     * @since 1.34 $className optional parameter added
     * @param string $html of contents of box
     * @param string $className (optional) corresponding to box
     * @return string of HTML representing a warning box.
     */
    public static function warningBox( $html, $className = '' ) {
        return self::messageBox( $html, [
            'mw-message-box-warning',
            'cdx-message--warning', $className ] );
    }

    /**
     * Return an error box.
     * @since 1.31
     * @since 1.34 $className optional parameter added
     * @param string $html of contents of error box
     * @param string $heading (optional)
     * @param string $className (optional) corresponding to box
     * @return string of HTML representing an error box.
     */
    public static function errorBox( $html, $heading = '', $className = '' ) {
        return self::messageBox( $html, [
            'mw-message-box-error',
            'cdx-message--error', $className ], $heading );
    }

    /**
     * Return a success box.
     * @since 1.31
     * @since 1.34 $className optional parameter added
     * @param string $html of contents of box
     * @param string $className (optional) corresponding to box
     * @return string of HTML representing a success box.
     */
    public static function successBox( $html, $className = '' ) {
        return self::messageBox( $html, [
            'mw-message-box-success',
            'cdx-message--success', $className ] );
    }

    /**
     * Convenience function to produce a radio button (input element with type=radio)
     *
     * @param string $name Name attribute
     * @param bool $checked Whether the radio button is checked or not
     * @param array $attribs Array of additional attributes
     * @return string Raw HTML
     */
    public static function radio( $name, $checked = false, array $attribs = [] ) {
        if ( isset( $attribs['value'] ) ) {
            $value = $attribs['value'];
            unset( $attribs['value'] );
        } else {
            $value = 1;
        }

        if ( $checked ) {
            $attribs[] = 'checked';
        }

        return self::input( $name, $value, 'radio', $attribs );
    }

    /**
     * Convenience function for generating a label for inputs.
     *
     * @param string $label Contents of the label
     * @param string $id ID of the element being labeled
     * @param array $attribs Additional attributes
     * @return string Raw HTML
     */
    public static function label( $label, $id, array $attribs = [] ) {
        $attribs += [
            'for' => $id,
        ];
        return self::element( 'label', $attribs, $label );
    }

    /**
     * Convenience function to produce an input element with type=hidden
     *
     * @param string $name Name attribute
     * @param mixed $value Value attribute
     * @param array $attribs Associative array of miscellaneous extra
     *   attributes, passed to Html::element()
     * @return string Raw HTML
     */
    public static function hidden( $name, $value, array $attribs = [] ) {
        return self::input( $name, $value, 'hidden', $attribs );
    }

    /**
     * Convenience function to produce a <textarea> element.
     *
     * This supports leaving out the cols= and rows= which Xml requires and are
     * required by HTML4/XHTML but not required by HTML5.
     *
     * @param string $name Name attribute
     * @param string $value Value attribute
     * @param array $attribs Associative array of miscellaneous extra
     *   attributes, passed to Html::element()
     * @return string Raw HTML
     */
    public static function textarea( $name, $value = '', array $attribs = [] ) {
        $attribs['name'] = $name;

        if ( substr( $value, 0, 1 ) == "\n" ) {
            // Workaround for T14130: browsers eat the initial newline
            // assuming that it's just for show, but they do keep the later
            // newlines, which we may want to preserve during editing.
            // Prepending a single newline
            $spacedValue = "\n" . $value;
        } else {
            $spacedValue = $value;
        }
        return self::element( 'textarea', $attribs, $spacedValue );
    }

    /**
     * Helper for Html::namespaceSelector().
     * @param array $params See Html::namespaceSelector()
     * @return array
     */
    public static function namespaceSelectorOptions( array $params = [] ) {
        if ( !isset( $params['exclude'] ) || !is_array( $params['exclude'] ) ) {
            $params['exclude'] = [];
        }

        if ( $params['in-user-lang'] ?? false ) {
            global $wgLang;
            $lang = $wgLang;
        } else {
            $lang = MediaWikiServices::getInstance()->getContentLanguage();
        }

        $optionsOut = [];
        if ( isset( $params['all'] ) ) {
            // add an option that would let the user select all namespaces.
            // Value is provided by user, the name shown is localized for the user.
            $optionsOut[$params['all']] = wfMessage( 'namespacesall' )->text();
        }
        // Add all namespaces as options
        $options = $lang->getFormattedNamespaces();
        // Filter out namespaces below 0 and massage labels
        foreach ( $options as $nsId => $nsName ) {
            if ( $nsId < NS_MAIN || in_array( $nsId, $params['exclude'] ) ) {
                continue;
            }
            if ( $nsId === NS_MAIN ) {
                // For other namespaces use the namespace prefix as label, but for
                // main we don't use "" but the user message describing it (e.g. "(Main)" or "(Article)")
                $nsName = wfMessage( 'blanknamespace' )->text();
            } elseif ( is_int( $nsId ) ) {
                $converter = MediaWikiServices::getInstance()->getLanguageConverterFactory()
                    ->getLanguageConverter( $lang );
                $nsName = $converter->convertNamespace( $nsId );
            }
            $optionsOut[$nsId] = $nsName;
        }

        return $optionsOut;
    }

    /**
     * Build a drop-down box for selecting a namespace
     *
     * @param array $params Params to set.
     * - selected: [optional] Id of namespace which should be pre-selected
     * - all: [optional] Value of item for "all namespaces". If null or unset,
     *   no "<option>" is generated to select all namespaces.
     * - label: text for label to add before the field.
     * - exclude: [optional] Array of namespace ids to exclude.
     * - disable: [optional] Array of namespace ids for which the option should
     *   be disabled in the selector.
     * @param array $selectAttribs HTML attributes for the generated select element.
     * - id:   [optional], default: 'namespace'.
     * - name: [optional], default: 'namespace'.
     * @return string HTML code to select a namespace.
     */
    public static function namespaceSelector(
        array $params = [],
        array $selectAttribs = []
    ) {
        ksort( $selectAttribs );

        // Is a namespace selected?
        if ( isset( $params['selected'] ) ) {
            // If string only contains digits, convert to clean int. Selected could also
            // be "all" or "" etc. which needs to be left untouched.
            if ( !is_int( $params['selected'] ) && ctype_digit( (string)$params['selected'] ) ) {
                $params['selected'] = (int)$params['selected'];
            }
            // else: leaves it untouched for later processing
        } else {
            $params['selected'] = '';
        }

        if ( !isset( $params['disable'] ) || !is_array( $params['disable'] ) ) {
            $params['disable'] = [];
        }

        // Associative array between option-values and option-labels
        $options = self::namespaceSelectorOptions( $params );

        // Convert $options to HTML
        $optionsHtml = [];
        foreach ( $options as $nsId => $nsName ) {
            $optionsHtml[] = self::element(
                'option',
                [
                    'disabled' => in_array( $nsId, $params['disable'] ),
                    'value' => $nsId,
                    'selected' => $nsId === $params['selected'],
                ],
                $nsName
            );
        }

        $selectAttribs['id'] ??= 'namespace';
        $selectAttribs['name'] ??= 'namespace';

        $ret = '';
        if ( isset( $params['label'] ) ) {
            $ret .= self::element(
                'label', [
                    'for' => $selectAttribs['id'],
                ], $params['label']
            ) . "\u{00A0}";
        }

        // Wrap options in a <select>
        $ret .= self::openElement( 'select', $selectAttribs )
            . "\n"
            . implode( "\n", $optionsHtml )
            . "\n"
            . self::closeElement( 'select' );

        return $ret;
    }

    /**
     * Constructs the opening html-tag with necessary doctypes depending on
     * global variables.
     *
     * @param array $attribs Associative array of miscellaneous extra
     *   attributes, passed to Html::element() of html tag.
     * @return string Raw HTML
     */
    public static function htmlHeader( array $attribs = [] ) {
        $ret = '';
        $mainConfig = MediaWikiServices::getInstance()->getMainConfig();
        $html5Version = $mainConfig->get( MainConfigNames::Html5Version );
        $mimeType = $mainConfig->get( MainConfigNames::MimeType );
        $xhtmlNamespaces = $mainConfig->get( MainConfigNames::XhtmlNamespaces );

        $isXHTML = self::isXmlMimeType( $mimeType );

        if ( $isXHTML ) { // XHTML5
            // XML MIME-typed markup should have an xml header.
            // However a DOCTYPE is not needed.
            $ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n";

            // Add the standard xmlns
            $attribs['xmlns'] = 'http://www.w3.org/1999/xhtml';

            // And support custom namespaces
            foreach ( $xhtmlNamespaces as $tag => $ns ) {
                $attribs["xmlns:$tag"] = $ns;
            }
        } else { // HTML5
            $ret .= "<!DOCTYPE html>\n";
        }

        if ( $html5Version ) {
            $attribs['version'] = $html5Version;
        }

        $ret .= self::openElement( 'html', $attribs );

        return $ret;
    }

    /**
     * Determines if the given MIME type is xml.
     *
     * @param string $mimetype
     * @return bool
     */
    public static function isXmlMimeType( $mimetype ) {
        # https://html.spec.whatwg.org/multipage/infrastructure.html#xml-mime-type
        # * text/xml
        # * application/xml
        # * Any MIME type with a subtype ending in +xml (this implicitly includes application/xhtml+xml)
        return (bool)preg_match( '!^(text|application)/xml$|^.+/.+\+xml$!', $mimetype );
    }

    /**
     * Generate a srcset attribute value.
     *
     * Generates a srcset attribute value from an array mapping pixel densities
     * to URLs. A trailing 'x' in pixel density values is optional.
     *
     * @note srcset width and height values are not supported.
     *
     * @see https://html.spec.whatwg.org/#attr-img-srcset
     *
     * @par Example:
     * @code
     *     Html::srcSet( [
     *         '1x'   => 'standard.jpeg',
     *         '1.5x' => 'large.jpeg',
     *         '3x'   => 'extra-large.jpeg',
     *     ] );
     *     // gives 'standard.jpeg 1x, large.jpeg 1.5x, extra-large.jpeg 2x'
     * @endcode
     *
     * @param string[] $urls
     * @return string
     */
    public static function srcSet( array $urls ) {
        $candidates = [];
        foreach ( $urls as $density => $url ) {
            // Cast density to float to strip 'x', then back to string to serve
            // as array index.
            $density = (string)(float)$density;
            $candidates[$density] = $url;
        }

        // Remove duplicates that are the same as a smaller value
        ksort( $candidates, SORT_NUMERIC );
        $candidates = array_unique( $candidates );

        // Append density info to the url
        foreach ( $candidates as $density => $url ) {
            $candidates[$density] = $url . ' ' . $density . 'x';
        }

        return implode( ", ", $candidates );
    }

    /**
     * Encode a variable of arbitrary type to JavaScript.
     * If the value is an HtmlJsCode object, pass through the object's value verbatim.
     *
     * @note Only use this function for generating JavaScript code. If generating output
     *       for a proper JSON parser, just call FormatJson::encode() directly.
     *
     * @since 1.41 (previously on {@link Xml})
     * @param mixed $value The value being encoded. Can be any type except a resource.
     * @param-taint $value escapes_html
     * @param bool $pretty If true, add non-significant whitespace to improve readability.
     * @return string|false String if successful; false upon failure
     * @return-taint none
     */
    public static function encodeJsVar( $value, $pretty = false ) {
        if ( $value instanceof HtmlJsCode ) {
            return $value->value;
        }
        return FormatJson::encode( $value, $pretty, FormatJson::UTF8_OK );
    }

    /**
     * Create a call to a JavaScript function. The supplied arguments will be
     * encoded using Html::encodeJsVar().
     *
     * @since 1.41 (previously on {@link Xml} since 1.17)
     * @param string $name The name of the function to call, or a JavaScript expression
     *    which evaluates to a function object which is called.
     * @param-taint $name tainted
     * @param array $args The arguments to pass to the function.
     * @param-taint $args escapes_html
     * @param bool $pretty If true, add non-significant whitespace to improve readability.
     * @return string|false String if successful; false upon failure
     * @return-taint none
     */
    public static function encodeJsCall( $name, $args, $pretty = false ) {
        $encodedArgs = self::encodeJsList( $args, $pretty );
        if ( $encodedArgs === false ) {
            return false;
        }
        return "$name($encodedArgs);";
    }

    /**
     * Encode a JavaScript comma-separated list. The supplied items will be encoded using
     * Html::encodeJsVar().
     *
     * @since 1.41.
     * @param array $args The elements of the list.
     * @param bool $pretty If true, add non-significant whitespace to improve readability.
     * @return false|string String if successful; false upon failure
     */
    public static function encodeJsList( $args, $pretty = false ) {
        foreach ( $args as &$arg ) {
            $arg = self::encodeJsVar( $arg, $pretty );
            if ( $arg === false ) {
                return false;
            }
        }
        if ( $pretty ) {
            return ' ' . implode( ', ', $args ) . ' ';
        } else {
            return implode( ',', $args );
        }
    }

    /**
     * Build options for a drop-down box from a textual list.
     *
     * The result of this function can be passed to XmlSelect::addOptions()
     * (to render a plain `<select>` dropdown box) or to Html::listDropdownOptionsOoui()
     * and then OOUI\DropdownInputWidget() (to render a pretty one).
     *
     * @param string $list Correctly formatted text (newline delimited) to be
     *   used to generate the options.
     * @param array $params Extra parameters:
     *   - string $params['other'] If set, add an option with this as text and a value of 'other'
     * @return array Array keys are textual labels, values are internal values
     */
    public static function listDropdownOptions( $list, $params = [] ) {
        $options = [];

        if ( isset( $params['other'] ) ) {
            $options[ $params['other'] ] = 'other';
        }

        $optgroup = false;
        foreach ( explode( "\n", $list ) as $option ) {
            $value = trim( $option );
            if ( $value == '' ) {
                continue;
            }
            if ( substr( $value, 0, 1 ) == '*' && substr( $value, 1, 1 ) != '*' ) {
                # A new group is starting...
                $value = trim( substr( $value, 1 ) );
                if ( $value !== '' &&
                    // Do not use the value for 'other' as option group - T251351
                    ( !isset( $params['other'] ) || $value !== $params['other'] )
                ) {
                    $optgroup = $value;
                } else {
                    $optgroup = false;
                }
            } elseif ( substr( $value, 0, 2 ) == '**' ) {
                # groupmember
                $opt = trim( substr( $value, 2 ) );
                if ( $optgroup === false ) {
                    $options[$opt] = $opt;
                } else {
                    $options[$optgroup][$opt] = $opt;
                }
            } else {
                # groupless reason list
                $optgroup = false;
                $options[$option] = $option;
            }
        }

        return $options;
    }

    /**
     * Convert options for a drop-down box into a format accepted by OOUI\DropdownInputWidget etc.
     *
     * TODO Find a better home for this function.
     *
     * @param array $options Options, as returned e.g. by Html::listDropdownOptions()
     * @return array
     */
    public static function listDropdownOptionsOoui( $options ) {
        $optionsOoui = [];

        foreach ( $options as $text => $value ) {
            if ( is_array( $value ) ) {
                $optionsOoui[] = [ 'optgroup' => (string)$text ];
                foreach ( $value as $text2 => $value2 ) {
                    $optionsOoui[] = [ 'data' => (string)$value2, 'label' => (string)$text2 ];
                }
            } else {
                $optionsOoui[] = [ 'data' => (string)$value, 'label' => (string)$text ];
            }
        }

        return $optionsOoui;
    }
}

/** @deprecated class alias since 1.40 */
class_alias( Html::class, 'Html' );