includes/Html.php

   1 <?php
   2 /**
   3  * Collection of methods to generate HTML content
   4  *
   5  * Copyright © 2009 Aryeh Gregor
   6  * https://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  */
  25 use MediaWiki\MediaWikiServices;
  26
  27 /**
  28  * This class is a collection of static functions that serve two purposes:
  29  *
  30  * 1) Implement any algorithms specified by HTML5, or other HTML
  31  * specifications, in a convenient and self-contained way.
  32  *
  33  * 2) Allow HTML elements to be conveniently and safely generated, like the
  34  * current Xml class but a) less confused (Xml supports HTML-specific things,
  35  * but only sometimes!) and b) not necessarily confined to XML-compatible
  36  * output.
  37  *
  38  * There are two important configuration options this class uses:
  39  *
  40  * $wgMimeType: If this is set to an xml MIME type then output should be
  41  *     valid XHTML5.
  42  *
  43  * This class is meant to be confined to utility functions that are called from
  44  * trusted code paths.  It does not do enforcement of policy like not allowing
  45  * <a> elements.
  46  *
  47  * @since 1.16
  48  */
  49 class Html {
  50         // List of void elements from HTML5, section 8.1.2 as of 2016-09-19
  51         private static $voidElements = [
  52                 'area',
  53                 'base',
  54                 'br',
  55                 'col',
  56                 'embed',
  57                 'hr',
  58                 'img',
  59                 'input',
  60                 'keygen',
  61                 'link',
  62                 'meta',
  63                 'param',
  64                 'source',
  65                 'track',
  66                 'wbr',
  67         ];
  68
  69         // Boolean attributes, which may have the value omitted entirely.  Manually
  70         // collected from the HTML5 spec as of 2011-08-12.
  71         private static $boolAttribs = [
  72                 'async',
  73                 'autofocus',
  74                 'autoplay',
  75                 'checked',
  76                 'controls',
  77                 'default',
  78                 'defer',
  79                 'disabled',
  80                 'formnovalidate',
  81                 'hidden',
  82                 'ismap',
  83                 'itemscope',
  84                 'loop',
  85                 'multiple',
  86                 'muted',
  87                 'novalidate',
  88                 'open',
  89                 'pubdate',
  90                 'readonly',
  91                 'required',
  92                 'reversed',
  93                 'scoped',
  94                 'seamless',
  95                 'selected',
  96                 'truespeed',
  97                 'typemustmatch',
  98                 // HTML5 Microdata
  99                 'itemscope',
 100         ];
 101
 102         /**
 103          * Modifies a set of attributes meant for button elements
 104          * and apply a set of default attributes when $wgUseMediaWikiUIEverywhere enabled.
 105          * @param array $attrs HTML attributes in an associative array
 106          * @param string[] $modifiers classes to add to the button
 107          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 108          * @return array $attrs A modified attribute array
 109          */
 110         public static function buttonAttributes( array $attrs, array $modifiers = [] ) {
 111                 global $wgUseMediaWikiUIEverywhere;
 112                 if ( $wgUseMediaWikiUIEverywhere ) {
 113                         if ( isset( $attrs['class'] ) ) {
 114                                 if ( is_array( $attrs['class'] ) ) {
 115                                         $attrs['class'][] = 'mw-ui-button';
 116                                         $attrs['class'] = array_merge( $attrs['class'], $modifiers );
 117                                         // ensure compatibility with Xml
 118                                         $attrs['class'] = implode( ' ', $attrs['class'] );
 119                                 } else {
 120                                         $attrs['class'] .= ' mw-ui-button ' . implode( ' ', $modifiers );
 121                                 }
 122                         } else {
 123                                 // ensure compatibility with Xml
 124                                 $attrs['class'] = 'mw-ui-button ' . implode( ' ', $modifiers );
 125                         }
 126                 }
 127                 return $attrs;
 128         }
 129
 130         /**
 131          * Modifies a set of attributes meant for text input elements
 132          * and apply a set of default attributes.
 133          * Removes size attribute when $wgUseMediaWikiUIEverywhere enabled.
 134          * @param array $attrs An attribute array.
 135          * @return array $attrs A modified attribute array
 136          */
 137         public static function getTextInputAttributes( array $attrs ) {
 138                 global $wgUseMediaWikiUIEverywhere;
 139                 if ( $wgUseMediaWikiUIEverywhere ) {
 140                         if ( isset( $attrs['class'] ) ) {
 141                                 if ( is_array( $attrs['class'] ) ) {
 142                                         $attrs['class'][] = 'mw-ui-input';
 143                                 } else {
 144                                         $attrs['class'] .= ' mw-ui-input';
 145                                 }
 146                         } else {
 147                                 $attrs['class'] = 'mw-ui-input';
 148                         }
 149                 }
 150                 return $attrs;
 151         }
 152
 153         /**
 154          * Returns an HTML link element in a string styled as a button
 155          * (when $wgUseMediaWikiUIEverywhere is enabled).
 156          *
 157          * @param string $contents The raw HTML contents of the element: *not*
 158          *   escaped!
 159          * @param array $attrs Associative array of attributes, e.g., [
 160          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 161          *   further documentation.
 162          * @param string[] $modifiers classes to add to the button
 163          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 164          * @return string Raw HTML
 165          */
 166         public static function linkButton( $contents, array $attrs, array $modifiers = [] ) {
 167                 return self::element( 'a',
 168                         self::buttonAttributes( $attrs, $modifiers ),
 169                         $contents
 170                 );
 171         }
 172
 173         /**
 174          * Returns an HTML link element in a string styled as a button
 175          * (when $wgUseMediaWikiUIEverywhere is enabled).
 176          *
 177          * @param string $contents The raw HTML contents of the element: *not*
 178          *   escaped!
 179          * @param array $attrs Associative array of attributes, e.g., [
 180          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 181          *   further documentation.
 182          * @param string[] $modifiers classes to add to the button
 183          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 184          * @return string Raw HTML
 185          */
 186         public static function submitButton( $contents, array $attrs, array $modifiers = [] ) {
 187                 $attrs['type'] = 'submit';
 188                 $attrs['value'] = $contents;
 189                 return self::element( 'input', self::buttonAttributes( $attrs, $modifiers ) );
 190         }
 191
 192         /**
 193          * Returns an HTML element in a string.  The major advantage here over
 194          * manually typing out the HTML is that it will escape all attribute
 195          * values.
 196          *
 197          * This is quite similar to Xml::tags(), but it implements some useful
 198          * HTML-specific logic.  For instance, there is no $allowShortTag
 199          * parameter: the closing tag is magically omitted if $element has an empty
 200          * content model.
 201          *
 202          * @param string $element The element's name, e.g., 'a'
 203          * @param array $attribs Associative array of attributes, e.g., [
 204          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 205          *   further documentation.
 206          * @param string $contents The raw HTML contents of the element: *not*
 207          *   escaped!
 208          * @return string Raw HTML
 209          */
 210         public static function rawElement( $element, $attribs = [], $contents = '' ) {
 211                 $start = self::openElement( $element, $attribs );
 212                 if ( in_array( $element, self::$voidElements ) ) {
 213                         // Silly XML.
 214                         return substr( $start, 0, -1 ) . '/>';
 215                 } else {
 216                         return "$start$contents" . self::closeElement( $element );
 217                 }
 218         }
 219
 220         /**
 221          * Identical to rawElement(), but HTML-escapes $contents (like
 222          * Xml::element()).
 223          *
 224          * @param string $element Name of the element, e.g., 'a'
 225          * @param array $attribs Associative array of attributes, e.g., [
 226          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 227          *   further documentation.
 228          * @param string $contents
 229          *
 230          * @return string
 231          */
 232         public static function element( $element, $attribs = [], $contents = '' ) {
 233                 return self::rawElement( $element, $attribs, strtr( $contents, [
 234                         // There's no point in escaping quotes, >, etc. in the contents of
 235                         // elements.
 236                         '&' => '&amp;',
 237                         '<' => '&lt;'
 238                 ] ) );
 239         }
 240
 241         /**
 242          * Identical to rawElement(), but has no third parameter and omits the end
 243          * tag (and the self-closing '/' in XML mode for empty elements).
 244          *
 245          * @param string $element Name of the element, e.g., 'a'
 246          * @param array $attribs Associative array of attributes, e.g., [
 247          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 248          *   further documentation.
 249          *
 250          * @return string
 251          */
 252         public static function openElement( $element, $attribs = [] ) {
 253                 $attribs = (array)$attribs;
 254                 // This is not required in HTML5, but let's do it anyway, for
 255                 // consistency and better compression.
 256                 $element = strtolower( $element );
 257
 258                 // Remove invalid input types
 259                 if ( $element == 'input' ) {
 260                         $validTypes = [
 261                                 'hidden',
 262                                 'text',
 263                                 'password',
 264                                 'checkbox',
 265                                 'radio',
 266                                 'file',
 267                                 'submit',
 268                                 'image',
 269                                 'reset',
 270                                 'button',
 271
 272                                 // HTML input types
 273                                 'datetime',
 274                                 'datetime-local',
 275                                 'date',
 276                                 'month',
 277                                 'time',
 278                                 'week',
 279                                 'number',
 280                                 'range',
 281                                 'email',
 282                                 'url',
 283                                 'search',
 284                                 'tel',
 285                                 'color',
 286                         ];
 287                         if ( isset( $attribs['type'] ) && !in_array( $attribs['type'], $validTypes ) ) {
 288                                 unset( $attribs['type'] );
 289                         }
 290                 }
 291
 292                 // According to standard the default type for <button> elements is "submit".
 293                 // Depending on compatibility mode IE might use "button", instead.
 294                 // We enforce the standard "submit".
 295                 if ( $element == 'button' && !isset( $attribs['type'] ) ) {
 296                         $attribs['type'] = 'submit';
 297                 }
 298
 299                 return "<$element" . self::expandAttributes(
 300                         self::dropDefaults( $element, $attribs ) ) . '>';
 301         }
 302
 303         /**
 304          * Returns "</$element>"
 305          *
 306          * @since 1.17
 307          * @param string $element Name of the element, e.g., 'a'
 308          * @return string A closing tag
 309          */
 310         public static function closeElement( $element ) {
 311                 $element = strtolower( $element );
 312
 313                 return "</$element>";
 314         }
 315
 316         /**
 317          * Given an element name and an associative array of element attributes,
 318          * return an array that is functionally identical to the input array, but
 319          * possibly smaller.  In particular, attributes might be stripped if they
 320          * are given their default values.
 321          *
 322          * This method is not guaranteed to remove all redundant attributes, only
 323          * some common ones and some others selected arbitrarily at random.  It
 324          * only guarantees that the output array should be functionally identical
 325          * to the input array (currently per the HTML 5 draft as of 2009-09-06).
 326          *
 327          * @param string $element Name of the element, e.g., 'a'
 328          * @param array $attribs Associative array of attributes, e.g., [
 329          *   'href' => 'https://www.mediawiki.org/' ].  See expandAttributes() for
 330          *   further documentation.
 331          * @return array An array of attributes functionally identical to $attribs
 332          */
 333         private static function dropDefaults( $element, array $attribs ) {
 334                 // Whenever altering this array, please provide a covering test case
 335                 // in HtmlTest::provideElementsWithAttributesHavingDefaultValues
 336                 static $attribDefaults = [
 337                         'area' => [ 'shape' => 'rect' ],
 338                         'button' => [
 339                                 'formaction' => 'GET',
 340                                 'formenctype' => 'application/x-www-form-urlencoded',
 341                         ],
 342                         'canvas' => [
 343                                 'height' => '150',
 344                                 'width' => '300',
 345                         ],
 346                         'form' => [
 347                                 'action' => 'GET',
 348                                 'autocomplete' => 'on',
 349                                 'enctype' => 'application/x-www-form-urlencoded',
 350                         ],
 351                         'input' => [
 352                                 'formaction' => 'GET',
 353                                 'type' => 'text',
 354                         ],
 355                         'keygen' => [ 'keytype' => 'rsa' ],
 356                         'link' => [ 'media' => 'all' ],
 357                         'menu' => [ 'type' => 'list' ],
 358                         'script' => [ 'type' => 'text/javascript' ],
 359                         'style' => [
 360                                 'media' => 'all',
 361                                 'type' => 'text/css',
 362                         ],
 363                         'textarea' => [ 'wrap' => 'soft' ],
 364                 ];
 365
 366                 $element = strtolower( $element );
 367
 368                 foreach ( $attribs as $attrib => $value ) {
 369                         $lcattrib = strtolower( $attrib );
 370                         if ( is_array( $value ) ) {
 371                                 $value = implode( ' ', $value );
 372                         } else {
 373                                 $value = strval( $value );
 374                         }
 375
 376                         // Simple checks using $attribDefaults
 377                         if ( isset( $attribDefaults[$element][$lcattrib] )
 378                                 && $attribDefaults[$element][$lcattrib] == $value
 379                         ) {
 380                                 unset( $attribs[$attrib] );
 381                         }
 382
 383                         if ( $lcattrib == 'class' && $value == '' ) {
 384                                 unset( $attribs[$attrib] );
 385                         }
 386                 }
 387
 388                 // More subtle checks
 389                 if ( $element === 'link'
 390                         && isset( $attribs['type'] ) && strval( $attribs['type'] ) == 'text/css'
 391                 ) {
 392                         unset( $attribs['type'] );
 393                 }
 394                 if ( $element === 'input' ) {
 395                         $type = $attribs['type'] ?? null;
 396                         $value = $attribs['value'] ?? null;
 397                         if ( $type === 'checkbox' || $type === 'radio' ) {
 398                                 // The default value for checkboxes and radio buttons is 'on'
 399                                 // not ''. By stripping value="" we break radio boxes that
 400                                 // actually wants empty values.
 401                                 if ( $value === 'on' ) {
 402                                         unset( $attribs['value'] );
 403                                 }
 404                         } elseif ( $type === 'submit' ) {
 405                                 // The default value for submit appears to be "Submit" but
 406                                 // let's not bother stripping out localized text that matches
 407                                 // that.
 408                         } else {
 409                                 // The default value for nearly every other field type is ''
 410                                 // The 'range' and 'color' types use different defaults but
 411                                 // stripping a value="" does not hurt them.
 412                                 if ( $value === '' ) {
 413                                         unset( $attribs['value'] );
 414                                 }
 415                         }
 416                 }
 417                 if ( $element === 'select' && isset( $attribs['size'] ) ) {
 418                         if ( in_array( 'multiple', $attribs )
 419                                 || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
 420                         ) {
 421                                 // A multi-select
 422                                 if ( strval( $attribs['size'] ) == '4' ) {
 423                                         unset( $attribs['size'] );
 424                                 }
 425                         } else {
 426                                 // Single select
 427                                 if ( strval( $attribs['size'] ) == '1' ) {
 428                                         unset( $attribs['size'] );
 429                                 }
 430                         }
 431                 }
 432
 433                 return $attribs;
 434         }
 435
 436         /**
 437          * Given an associative array of element attributes, generate a string
 438          * to stick after the element name in HTML output.  Like [ 'href' =>
 439          * 'https://www.mediawiki.org/' ] becomes something like
 440          * ' href="https://www.mediawiki.org"'.  Again, this is like
 441          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 442          *
 443          * Attributes that can contain space-separated lists ('class', 'accesskey' and 'rel') array
 444          * values are allowed as well, which will automagically be normalized
 445          * and converted to a space-separated string. In addition to a numerical
 446          * array, the attribute value may also be an associative array. See the
 447          * example below for how that works.
 448          *
 449          * @par Numerical array
 450          * @code
 451          *     Html::element( 'em', [
 452          *         'class' => [ 'foo', 'bar' ]
 453          *     ] );
 454          *     // gives '<em class="foo bar"></em>'
 455          * @endcode
 456          *
 457          * @par Associative array
 458          * @code
 459          *     Html::element( 'em', [
 460          *         'class' => [ 'foo', 'bar', 'foo' => false, 'quux' => true ]
 461          *     ] );
 462          *     // gives '<em class="bar quux"></em>'
 463          * @endcode
 464          *
 465          * @param array $attribs Associative array of attributes, e.g., [
 466          *   'href' => 'https://www.mediawiki.org/' ].  Values will be HTML-escaped.
 467          *   A value of false or null means to omit the attribute.  For boolean attributes,
 468          *   you can omit the key, e.g., [ 'checked' ] instead of
 469          *   [ 'checked' => 'checked' ] or such.
 470          *
 471          * @throws MWException If an attribute that doesn't allow lists is set to an array
 472          * @return string HTML fragment that goes between element name and '>'
 473          *   (starting with a space if at least one attribute is output)
 474          */
 475         public static function expandAttributes( array $attribs ) {
 476                 $ret = '';
 477                 foreach ( $attribs as $key => $value ) {
 478                         // Support intuitive [ 'checked' => true/false ] form
 479                         if ( $value === false || is_null( $value ) ) {
 480                                 continue;
 481                         }
 482
 483                         // For boolean attributes, support [ 'foo' ] instead of
 484                         // requiring [ 'foo' => 'meaningless' ].
 485                         if ( is_int( $key ) && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 486                                 $key = $value;
 487                         }
 488
 489                         // Not technically required in HTML5 but we'd like consistency
 490                         // and better compression anyway.
 491                         $key = strtolower( $key );
 492
 493                         // https://www.w3.org/TR/html401/index/attributes.html ("space-separated")
 494                         // https://www.w3.org/TR/html5/index.html#attributes-1 ("space-separated")
 495                         $spaceSeparatedListAttributes = [
 496                                 'class', // html4, html5
 497                                 'accesskey', // as of html5, multiple space-separated values allowed
 498                                 // html4-spec doesn't document rel= as space-separated
 499                                 // but has been used like that and is now documented as such
 500                                 // in the html5-spec.
 501                                 'rel',
 502                         ];
 503
 504                         // Specific features for attributes that allow a list of space-separated values
 505                         if ( in_array( $key, $spaceSeparatedListAttributes ) ) {
 506                                 // Apply some normalization and remove duplicates
 507
 508                                 // Convert into correct array. Array can contain space-separated
 509                                 // values. Implode/explode to get those into the main array as well.
 510                                 if ( is_array( $value ) ) {
 511                                         // If input wasn't an array, we can skip this step
 512                                         $newValue = [];
 513                                         foreach ( $value as $k => $v ) {
 514                                                 if ( is_string( $v ) ) {
 515                                                         // String values should be normal `array( 'foo' )`
 516                                                         // Just append them
 517                                                         if ( !isset( $value[$v] ) ) {
 518                                                                 // As a special case don't set 'foo' if a
 519                                                                 // separate 'foo' => true/false exists in the array
 520                                                                 // keys should be authoritative
 521                                                                 $newValue[] = $v;
 522                                                         }
 523                                                 } elseif ( $v ) {
 524                                                         // If the value is truthy but not a string this is likely
 525                                                         // an [ 'foo' => true ], falsy values don't add strings
 526                                                         $newValue[] = $k;
 527                                                 }
 528                                         }
 529                                         $value = implode( ' ', $newValue );
 530                                 }
 531                                 $value = explode( ' ', $value );
 532
 533                                 // Normalize spacing by fixing up cases where people used
 534                                 // more than 1 space and/or a trailing/leading space
 535                                 $value = array_diff( $value, [ '', ' ' ] );
 536
 537                                 // Remove duplicates and create the string
 538                                 $value = implode( ' ', array_unique( $value ) );
 539                         } elseif ( is_array( $value ) ) {
 540                                 throw new MWException( "HTML attribute $key can not contain a list of values" );
 541                         }
 542
 543                         $quote = '"';
 544
 545                         if ( in_array( $key, self::$boolAttribs ) ) {
 546                                 $ret .= " $key=\"\"";
 547                         } else {
 548                                 $ret .= " $key=$quote" . Sanitizer::encodeAttribute( $value ) . $quote;
 549                         }
 550                 }
 551                 return $ret;
 552         }
 553
 554         /**
 555          * Output an HTML script tag with the given contents.
 556          *
 557          * It is unsupported for the contents to contain the sequence `<script` or `</script`
 558          * (case-insensitive). This ensures the script can be terminated easily and consistently.
 559          * It is the responsibility of the caller to avoid such character sequence by escaping
 560          * or avoiding it. If found at run-time, the contents are replaced with a comment, and
 561          * a warning is logged server-side.
 562          *
 563          * @param string $contents JavaScript
 564          * @param string|null $nonce Nonce for CSP header, from OutputPage::getCSPNonce()
 565          * @return string Raw HTML
 566          */
 567         public static function inlineScript( $contents, $nonce = null ) {
 568                 $attrs = [];
 569                 if ( $nonce !== null ) {
 570                         $attrs['nonce'] = $nonce;
 571                 } else {
 572                         if ( ContentSecurityPolicy::isNonceRequired( RequestContext::getMain()->getConfig() ) ) {
 573                                 wfWarn( "no nonce set on script. CSP will break it" );
 574                         }
 575                 }
 576
 577                 if ( preg_match( '/<\/?script/i', $contents ) ) {
 578                         wfLogWarning( __METHOD__ . ': Illegal character sequence found in inline script.' );
 579                         $contents = '/* ERROR: Invalid script */';
 580                 }
 581
 582                 return self::rawElement( 'script', $attrs, $contents );
 583         }
 584
 585         /**
 586          * Output a "<script>" tag linking to the given URL, e.g.,
 587          * "<script src=foo.js></script>".
 588          *
 589          * @param string $url
 590          * @param string|null $nonce Nonce for CSP header, from OutputPage::getCSPNonce()
 591          * @return string Raw HTML
 592          */
 593         public static function linkedScript( $url, $nonce = null ) {
 594                 $attrs = [ 'src' => $url ];
 595                 if ( $nonce !== null ) {
 596                         $attrs['nonce'] = $nonce;
 597                 } else {
 598                         if ( ContentSecurityPolicy::isNonceRequired( RequestContext::getMain()->getConfig() ) ) {
 599                                 wfWarn( "no nonce set on script. CSP will break it" );
 600                         }
 601                 }
 602
 603                 return self::element( 'script', $attrs );
 604         }
 605
 606         /**
 607          * Output a "<style>" tag with the given contents for the given media type
 608          * (if any).  TODO: do some useful escaping as well, like if $contents
 609          * contains literal "</style>" (admittedly unlikely).
 610          *
 611          * @param string $contents CSS
 612          * @param string $media A media type string, like 'screen'
 613          * @param array $attribs (since 1.31) Associative array of attributes, e.g., [
 614          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 615          *   further documentation.
 616          * @return string Raw HTML
 617          */
 618         public static function inlineStyle( $contents, $media = 'all', $attribs = [] ) {
 619                 // Don't escape '>' since that is used
 620                 // as direct child selector.
 621                 // Remember, in css, there is no "x" for hexadecimal escapes, and
 622                 // the space immediately after an escape sequence is swallowed.
 623                 $contents = strtr( $contents, [
 624                         '<' => '\3C ',
 625                         // CDATA end tag for good measure, but the main security
 626                         // is from escaping the '<'.
 627                         ']]>' => '\5D\5D\3E '
 628                 ] );
 629
 630                 if ( preg_match( '/[<&]/', $contents ) ) {
 631                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 632                 }
 633
 634                 return self::rawElement( 'style', [
 635                         'media' => $media,
 636                 ] + $attribs, $contents );
 637         }
 638
 639         /**
 640          * Output a "<link rel=stylesheet>" linking to the given URL for the given
 641          * media type (if any).
 642          *
 643          * @param string $url
 644          * @param string $media A media type string, like 'screen'
 645          * @return string Raw HTML
 646          */
 647         public static function linkedStyle( $url, $media = 'all' ) {
 648                 return self::element( 'link', [
 649                         'rel' => 'stylesheet',
 650                         'href' => $url,
 651                         'media' => $media,
 652                 ] );
 653         }
 654
 655         /**
 656          * Convenience function to produce an "<input>" element.  This supports the
 657          * new HTML5 input types and attributes.
 658          *
 659          * @param string $name Name attribute
 660          * @param string $value Value attribute
 661          * @param string $type Type attribute
 662          * @param array $attribs Associative array of miscellaneous extra
 663          *   attributes, passed to Html::element()
 664          * @return string Raw HTML
 665          */
 666         public static function input( $name, $value = '', $type = 'text', array $attribs = [] ) {
 667                 $attribs['type'] = $type;
 668                 $attribs['value'] = $value;
 669                 $attribs['name'] = $name;
 670                 if ( in_array( $type, [ 'text', 'search', 'email', 'password', 'number' ] ) ) {
 671                         $attribs = self::getTextInputAttributes( $attribs );
 672                 }
 673                 if ( in_array( $type, [ 'button', 'reset', 'submit' ] ) ) {
 674                         $attribs = self::buttonAttributes( $attribs );
 675                 }
 676                 return self::element( 'input', $attribs );
 677         }
 678
 679         /**
 680          * Convenience function to produce a checkbox (input element with type=checkbox)
 681          *
 682          * @param string $name Name attribute
 683          * @param bool $checked Whether the checkbox is checked or not
 684          * @param array $attribs Array of additional attributes
 685          * @return string Raw HTML
 686          */
 687         public static function check( $name, $checked = false, array $attribs = [] ) {
 688                 if ( isset( $attribs['value'] ) ) {
 689                         $value = $attribs['value'];
 690                         unset( $attribs['value'] );
 691                 } else {
 692                         $value = 1;
 693                 }
 694
 695                 if ( $checked ) {
 696                         $attribs[] = 'checked';
 697                 }
 698
 699                 return self::input( $name, $value, 'checkbox', $attribs );
 700         }
 701
 702         /**
 703          * Return the HTML for a message box.
 704          * @since 1.31
 705          * @param string $html of contents of box
 706          * @param string $className corresponding to box
 707          * @param string $heading (optional)
 708          * @return string of HTML representing a box.
 709          */
 710         private static function messageBox( $html, $className, $heading = '' ) {
 711                 if ( $heading !== '' ) {
 712                         $html = self::element( 'h2', [], $heading ) . $html;
 713                 }
 714                 return self::rawElement( 'div', [ 'class' => $className ], $html );
 715         }
 716
 717         /**
 718          * Return a warning box.
 719          * @since 1.31
 720          * @param string $html of contents of box
 721          * @return string of HTML representing a warning box.
 722          */
 723         public static function warningBox( $html ) {
 724                 return self::messageBox( $html, 'warningbox' );
 725         }
 726
 727         /**
 728          * Return an error box.
 729          * @since 1.31
 730          * @param string $html of contents of error box
 731          * @param string $heading (optional)
 732          * @return string of HTML representing an error box.
 733          */
 734         public static function errorBox( $html, $heading = '' ) {
 735                 return self::messageBox( $html, 'errorbox', $heading );
 736         }
 737
 738         /**
 739          * Return a success box.
 740          * @since 1.31
 741          * @param string $html of contents of box
 742          * @return string of HTML representing a success box.
 743          */
 744         public static function successBox( $html ) {
 745                 return self::messageBox( $html, 'successbox' );
 746         }
 747
 748         /**
 749          * Convenience function to produce a radio button (input element with type=radio)
 750          *
 751          * @param string $name Name attribute
 752          * @param bool $checked Whether the radio button is checked or not
 753          * @param array $attribs Array of additional attributes
 754          * @return string Raw HTML
 755          */
 756         public static function radio( $name, $checked = false, array $attribs = [] ) {
 757                 if ( isset( $attribs['value'] ) ) {
 758                         $value = $attribs['value'];
 759                         unset( $attribs['value'] );
 760                 } else {
 761                         $value = 1;
 762                 }
 763
 764                 if ( $checked ) {
 765                         $attribs[] = 'checked';
 766                 }
 767
 768                 return self::input( $name, $value, 'radio', $attribs );
 769         }
 770
 771         /**
 772          * Convenience function for generating a label for inputs.
 773          *
 774          * @param string $label Contents of the label
 775          * @param string $id ID of the element being labeled
 776          * @param array $attribs Additional attributes
 777          * @return string Raw HTML
 778          */
 779         public static function label( $label, $id, array $attribs = [] ) {
 780                 $attribs += [
 781                         'for' => $id
 782                 ];
 783                 return self::element( 'label', $attribs, $label );
 784         }
 785
 786         /**
 787          * Convenience function to produce an input element with type=hidden
 788          *
 789          * @param string $name Name attribute
 790          * @param string $value Value attribute
 791          * @param array $attribs Associative array of miscellaneous extra
 792          *   attributes, passed to Html::element()
 793          * @return string Raw HTML
 794          */
 795         public static function hidden( $name, $value, array $attribs = [] ) {
 796                 return self::input( $name, $value, 'hidden', $attribs );
 797         }
 798
 799         /**
 800          * Convenience function to produce a <textarea> element.
 801          *
 802          * This supports leaving out the cols= and rows= which Xml requires and are
 803          * required by HTML4/XHTML but not required by HTML5.
 804          *
 805          * @param string $name Name attribute
 806          * @param string $value Value attribute
 807          * @param array $attribs Associative array of miscellaneous extra
 808          *   attributes, passed to Html::element()
 809          * @return string Raw HTML
 810          */
 811         public static function textarea( $name, $value = '', array $attribs = [] ) {
 812                 $attribs['name'] = $name;
 813
 814                 if ( substr( $value, 0, 1 ) == "\n" ) {
 815                         // Workaround for T14130: browsers eat the initial newline
 816                         // assuming that it's just for show, but they do keep the later
 817                         // newlines, which we may want to preserve during editing.
 818                         // Prepending a single newline
 819                         $spacedValue = "\n" . $value;
 820                 } else {
 821                         $spacedValue = $value;
 822                 }
 823                 return self::element( 'textarea', self::getTextInputAttributes( $attribs ), $spacedValue );
 824         }
 825
 826         /**
 827          * Helper for Html::namespaceSelector().
 828          * @param array $params See Html::namespaceSelector()
 829          * @return array
 830          */
 831         public static function namespaceSelectorOptions( array $params = [] ) {
 832                 $options = [];
 833
 834                 if ( !isset( $params['exclude'] ) || !is_array( $params['exclude'] ) ) {
 835                         $params['exclude'] = [];
 836                 }
 837
 838                 if ( isset( $params['all'] ) ) {
 839                         // add an option that would let the user select all namespaces.
 840                         // Value is provided by user, the name shown is localized for the user.
 841                         $options[$params['all']] = wfMessage( 'namespacesall' )->text();
 842                 }
 843                 // Add all namespaces as options (in the content language)
 844                 $options +=
 845                         MediaWikiServices::getInstance()->getContentLanguage()->getFormattedNamespaces();
 846
 847                 $optionsOut = [];
 848                 // Filter out namespaces below 0 and massage labels
 849                 foreach ( $options as $nsId => $nsName ) {
 850                         if ( $nsId < NS_MAIN || in_array( $nsId, $params['exclude'] ) ) {
 851                                 continue;
 852                         }
 853                         if ( $nsId === NS_MAIN ) {
 854                                 // For other namespaces use the namespace prefix as label, but for
 855                                 // main we don't use "" but the user message describing it (e.g. "(Main)" or "(Article)")
 856                                 $nsName = wfMessage( 'blanknamespace' )->text();
 857                         } elseif ( is_int( $nsId ) ) {
 858                                 $nsName = MediaWikiServices::getInstance()->getContentLanguage()->
 859                                         convertNamespace( $nsId );
 860                         }
 861                         $optionsOut[$nsId] = $nsName;
 862                 }
 863
 864                 return $optionsOut;
 865         }
 866
 867         /**
 868          * Build a drop-down box for selecting a namespace
 869          *
 870          * @param array $params Params to set.
 871          * - selected: [optional] Id of namespace which should be pre-selected
 872          * - all: [optional] Value of item for "all namespaces". If null or unset,
 873          *   no "<option>" is generated to select all namespaces.
 874          * - label: text for label to add before the field.
 875          * - exclude: [optional] Array of namespace ids to exclude.
 876          * - disable: [optional] Array of namespace ids for which the option should
 877          *   be disabled in the selector.
 878          * @param array $selectAttribs HTML attributes for the generated select element.
 879          * - id:   [optional], default: 'namespace'.
 880          * - name: [optional], default: 'namespace'.
 881          * @return string HTML code to select a namespace.
 882          */
 883         public static function namespaceSelector( array $params = [],
 884                 array $selectAttribs = []
 885         ) {
 886                 ksort( $selectAttribs );
 887
 888                 // Is a namespace selected?
 889                 if ( isset( $params['selected'] ) ) {
 890                         // If string only contains digits, convert to clean int. Selected could also
 891                         // be "all" or "" etc. which needs to be left untouched.
 892                         // PHP is_numeric() has issues with large strings, PHP ctype_digit has other issues
 893                         // and returns false for already clean ints. Use regex instead..
 894                         if ( preg_match( '/^\d+$/', $params['selected'] ) ) {
 895                                 $params['selected'] = intval( $params['selected'] );
 896                         }
 897                         // else: leaves it untouched for later processing
 898                 } else {
 899                         $params['selected'] = '';
 900                 }
 901
 902                 if ( !isset( $params['disable'] ) || !is_array( $params['disable'] ) ) {
 903                         $params['disable'] = [];
 904                 }
 905
 906                 // Associative array between option-values and option-labels
 907                 $options = self::namespaceSelectorOptions( $params );
 908
 909                 // Convert $options to HTML
 910                 $optionsHtml = [];
 911                 foreach ( $options as $nsId => $nsName ) {
 912                         $optionsHtml[] = self::element(
 913                                 'option', [
 914                                         'disabled' => in_array( $nsId, $params['disable'] ),
 915                                         'value' => $nsId,
 916                                         'selected' => $nsId === $params['selected'],
 917                                 ], $nsName
 918                         );
 919                 }
 920
 921                 if ( !array_key_exists( 'id', $selectAttribs ) ) {
 922                         $selectAttribs['id'] = 'namespace';
 923                 }
 924
 925                 if ( !array_key_exists( 'name', $selectAttribs ) ) {
 926                         $selectAttribs['name'] = 'namespace';
 927                 }
 928
 929                 $ret = '';
 930                 if ( isset( $params['label'] ) ) {
 931                         $ret .= self::element(
 932                                 'label', [
 933                                         'for' => $selectAttribs['id'] ?? null,
 934                                 ], $params['label']
 935                         ) . "\u{00A0}";
 936                 }
 937
 938                 // Wrap options in a <select>
 939                 $ret .= self::openElement( 'select', $selectAttribs )
 940                         . "\n"
 941                         . implode( "\n", $optionsHtml )
 942                         . "\n"
 943                         . self::closeElement( 'select' );
 944
 945                 return $ret;
 946         }
 947
 948         /**
 949          * Constructs the opening html-tag with necessary doctypes depending on
 950          * global variables.
 951          *
 952          * @param array $attribs Associative array of miscellaneous extra
 953          *   attributes, passed to Html::element() of html tag.
 954          * @return string Raw HTML
 955          */
 956         public static function htmlHeader( array $attribs = [] ) {
 957                 $ret = '';
 958
 959                 global $wgHtml5Version, $wgMimeType, $wgXhtmlNamespaces;
 960
 961                 $isXHTML = self::isXmlMimeType( $wgMimeType );
 962
 963                 if ( $isXHTML ) { // XHTML5
 964                         // XML MIME-typed markup should have an xml header.
 965                         // However a DOCTYPE is not needed.
 966                         $ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?" . ">\n";
 967
 968                         // Add the standard xmlns
 969                         $attribs['xmlns'] = 'http://www.w3.org/1999/xhtml';
 970
 971                         // And support custom namespaces
 972                         foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
 973                                 $attribs["xmlns:$tag"] = $ns;
 974                         }
 975                 } else { // HTML5
 976                         // DOCTYPE
 977                         $ret .= "<!DOCTYPE html>\n";
 978                 }
 979
 980                 if ( $wgHtml5Version ) {
 981                         $attribs['version'] = $wgHtml5Version;
 982                 }
 983
 984                 $ret .= self::openElement( 'html', $attribs );
 985
 986                 return $ret;
 987         }
 988
 989         /**
 990          * Determines if the given MIME type is xml.
 991          *
 992          * @param string $mimetype MIME type
 993          * @return bool
 994          */
 995         public static function isXmlMimeType( $mimetype ) {
 996                 # https://html.spec.whatwg.org/multipage/infrastructure.html#xml-mime-type
 997                 # * text/xml
 998                 # * application/xml
 999                 # * Any MIME type with a subtype ending in +xml (this implicitly includes application/xhtml+xml)
1000                 return (bool)preg_match( '!^(text|application)/xml$|^.+/.+\+xml$!', $mimetype );
1001         }
1002
1003         /**
1004          * Get HTML for an info box with an icon.
1005          *
1006          * @param string $text Wikitext, get this with wfMessage()->plain()
1007          * @param string $icon Path to icon file (used as 'src' attribute)
1008          * @param string $alt Alternate text for the icon
1009          * @param string $class Additional class name to add to the wrapper div
1010          *
1011          * @return string
1012          */
1013         static function infoBox( $text, $icon, $alt, $class = '' ) {
1014                 $s = self::openElement( 'div', [ 'class' => "mw-infobox $class" ] );
1015
1016                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-left' ] ) .
1017                                 self::element( 'img',
1018                                         [
1019                                                 'src' => $icon,
1020                                                 'alt' => $alt,
1021                                         ]
1022                                 ) .
1023                                 self::closeElement( 'div' );
1024
1025                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-right' ] ) .
1026                                 $text .
1027                                 self::closeElement( 'div' );
1028                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
1029
1030                 $s .= self::closeElement( 'div' );
1031
1032                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
1033
1034                 return $s;
1035         }
1036
1037         /**
1038          * Generate a srcset attribute value.
1039          *
1040          * Generates a srcset attribute value from an array mapping pixel densities
1041          * to URLs. A trailing 'x' in pixel density values is optional.
1042          *
1043          * @note srcset width and height values are not supported.
1044          *
1045          * @see https://html.spec.whatwg.org/#attr-img-srcset
1046          *
1047          * @par Example:
1048          * @code
1049          *     Html::srcSet( [
1050          *         '1x'   => 'standard.jpeg',
1051          *         '1.5x' => 'large.jpeg',
1052          *         '3x'   => 'extra-large.jpeg',
1053          *     ] );
1054          *     // gives 'standard.jpeg 1x, large.jpeg 1.5x, extra-large.jpeg 2x'
1055          * @endcode
1056          *
1057          * @param string[] $urls
1058          * @return string
1059          */
1060         static function srcSet( array $urls ) {
1061                 $candidates = [];
1062                 foreach ( $urls as $density => $url ) {
1063                         // Cast density to float to strip 'x', then back to string to serve
1064                         // as array index.
1065                         $density = (string)(float)$density;
1066                         $candidates[$density] = $url;
1067                 }
1068
1069                 // Remove duplicates that are the same as a smaller value
1070                 ksort( $candidates, SORT_NUMERIC );
1071                 $candidates = array_unique( $candidates );
1072
1073                 // Append density info to the url
1074                 foreach ( $candidates as $density => $url ) {
1075                         $candidates[$density] = $url . ' ' . $density . 'x';
1076                 }
1077
1078                 return implode( ", ", $candidates );
1079         }
1080 }