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
  26 /**
  27  * This class is a collection of static functions that serve two purposes:
  28  *
  29  * 1) Implement any algorithms specified by HTML5, or other HTML
  30  * specifications, in a convenient and self-contained way.
  31  *
  32  * 2) Allow HTML elements to be conveniently and safely generated, like the
  33  * current Xml class but a) less confused (Xml supports HTML-specific things,
  34  * but only sometimes!) and b) not necessarily confined to XML-compatible
  35  * output.
  36  *
  37  * There are two important configuration options this class uses:
  38  *
  39  * $wgMimeType: If this is set to an xml MIME type then output should be
  40  *     valid XHTML5.
  41  *
  42  * This class is meant to be confined to utility functions that are called from
  43  * trusted code paths.  It does not do enforcement of policy like not allowing
  44  * <a> elements.
  45  *
  46  * @since 1.16
  47  */
  48 class Html {
  49         // List of void elements from HTML5, section 8.1.2 as of 2016-09-19
  50         private static $voidElements = [
  51                 'area',
  52                 'base',
  53                 'br',
  54                 'col',
  55                 'embed',
  56                 'hr',
  57                 'img',
  58                 'input',
  59                 'keygen',
  60                 'link',
  61                 'meta',
  62                 'param',
  63                 'source',
  64                 'track',
  65                 'wbr',
  66         ];
  67
  68         // Boolean attributes, which may have the value omitted entirely.  Manually
  69         // collected from the HTML5 spec as of 2011-08-12.
  70         private static $boolAttribs = [
  71                 'async',
  72                 'autofocus',
  73                 'autoplay',
  74                 'checked',
  75                 'controls',
  76                 'default',
  77                 'defer',
  78                 'disabled',
  79                 'formnovalidate',
  80                 'hidden',
  81                 'ismap',
  82                 'itemscope',
  83                 'loop',
  84                 'multiple',
  85                 'muted',
  86                 'novalidate',
  87                 'open',
  88                 'pubdate',
  89                 'readonly',
  90                 'required',
  91                 'reversed',
  92                 'scoped',
  93                 'seamless',
  94                 'selected',
  95                 'truespeed',
  96                 'typemustmatch',
  97                 // HTML5 Microdata
  98                 'itemscope',
  99         ];
 100
 101         /**
 102          * Modifies a set of attributes meant for button elements
 103          * and apply a set of default attributes when $wgUseMediaWikiUIEverywhere enabled.
 104          * @param array $attrs HTML attributes in an associative array
 105          * @param string[] $modifiers classes to add to the button
 106          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 107          * @return array $attrs A modified attribute array
 108          */
 109         public static function buttonAttributes( array $attrs, array $modifiers = [] ) {
 110                 global $wgUseMediaWikiUIEverywhere;
 111                 if ( $wgUseMediaWikiUIEverywhere ) {
 112                         if ( isset( $attrs['class'] ) ) {
 113                                 if ( is_array( $attrs['class'] ) ) {
 114                                         $attrs['class'][] = 'mw-ui-button';
 115                                         $attrs['class'] = array_merge( $attrs['class'], $modifiers );
 116                                         // ensure compatibility with Xml
 117                                         $attrs['class'] = implode( ' ', $attrs['class'] );
 118                                 } else {
 119                                         $attrs['class'] .= ' mw-ui-button ' . implode( ' ', $modifiers );
 120                                 }
 121                         } else {
 122                                 // ensure compatibility with Xml
 123                                 $attrs['class'] = 'mw-ui-button ' . implode( ' ', $modifiers );
 124                         }
 125                 }
 126                 return $attrs;
 127         }
 128
 129         /**
 130          * Modifies a set of attributes meant for text input elements
 131          * and apply a set of default attributes.
 132          * Removes size attribute when $wgUseMediaWikiUIEverywhere enabled.
 133          * @param array $attrs An attribute array.
 134          * @return array $attrs A modified attribute array
 135          */
 136         public static function getTextInputAttributes( array $attrs ) {
 137                 global $wgUseMediaWikiUIEverywhere;
 138                 if ( $wgUseMediaWikiUIEverywhere ) {
 139                         if ( isset( $attrs['class'] ) ) {
 140                                 if ( is_array( $attrs['class'] ) ) {
 141                                         $attrs['class'][] = 'mw-ui-input';
 142                                 } else {
 143                                         $attrs['class'] .= ' mw-ui-input';
 144                                 }
 145                         } else {
 146                                 $attrs['class'] = 'mw-ui-input';
 147                         }
 148                 }
 149                 return $attrs;
 150         }
 151
 152         /**
 153          * Returns an HTML link element in a string styled as a button
 154          * (when $wgUseMediaWikiUIEverywhere is enabled).
 155          *
 156          * @param string $contents The raw HTML contents of the element: *not*
 157          *   escaped!
 158          * @param array $attrs Associative array of attributes, e.g., [
 159          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 160          *   further documentation.
 161          * @param string[] $modifiers classes to add to the button
 162          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 163          * @return string Raw HTML
 164          */
 165         public static function linkButton( $contents, array $attrs, array $modifiers = [] ) {
 166                 return self::element( 'a',
 167                         self::buttonAttributes( $attrs, $modifiers ),
 168                         $contents
 169                 );
 170         }
 171
 172         /**
 173          * Returns an HTML link element in a string styled as a button
 174          * (when $wgUseMediaWikiUIEverywhere is enabled).
 175          *
 176          * @param string $contents The raw HTML contents of the element: *not*
 177          *   escaped!
 178          * @param array $attrs Associative array of attributes, e.g., [
 179          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 180          *   further documentation.
 181          * @param string[] $modifiers classes to add to the button
 182          * @see https://tools.wmflabs.org/styleguide/desktop/index.html for guidance on available modifiers
 183          * @return string Raw HTML
 184          */
 185         public static function submitButton( $contents, array $attrs, array $modifiers = [] ) {
 186                 $attrs['type'] = 'submit';
 187                 $attrs['value'] = $contents;
 188                 return self::element( 'input', self::buttonAttributes( $attrs, $modifiers ) );
 189         }
 190
 191         /**
 192          * Returns an HTML element in a string.  The major advantage here over
 193          * manually typing out the HTML is that it will escape all attribute
 194          * values.
 195          *
 196          * This is quite similar to Xml::tags(), but it implements some useful
 197          * HTML-specific logic.  For instance, there is no $allowShortTag
 198          * parameter: the closing tag is magically omitted if $element has an empty
 199          * content model.
 200          *
 201          * @param string $element The element's name, e.g., 'a'
 202          * @param array $attribs Associative array of attributes, e.g., [
 203          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 204          *   further documentation.
 205          * @param string $contents The raw HTML contents of the element: *not*
 206          *   escaped!
 207          * @return string Raw HTML
 208          */
 209         public static function rawElement( $element, $attribs = [], $contents = '' ) {
 210                 $start = self::openElement( $element, $attribs );
 211                 if ( in_array( $element, self::$voidElements ) ) {
 212                         // Silly XML.
 213                         return substr( $start, 0, -1 ) . '/>';
 214                 } else {
 215                         return "$start$contents" . self::closeElement( $element );
 216                 }
 217         }
 218
 219         /**
 220          * Identical to rawElement(), but HTML-escapes $contents (like
 221          * Xml::element()).
 222          *
 223          * @param string $element
 224          * @param array $attribs
 225          * @param string $contents
 226          *
 227          * @return string
 228          */
 229         public static function element( $element, $attribs = [], $contents = '' ) {
 230                 return self::rawElement( $element, $attribs, strtr( $contents, [
 231                         // There's no point in escaping quotes, >, etc. in the contents of
 232                         // elements.
 233                         '&' => '&amp;',
 234                         '<' => '&lt;'
 235                 ] ) );
 236         }
 237
 238         /**
 239          * Identical to rawElement(), but has no third parameter and omits the end
 240          * tag (and the self-closing '/' in XML mode for empty elements).
 241          *
 242          * @param string $element
 243          * @param array $attribs
 244          *
 245          * @return string
 246          */
 247         public static function openElement( $element, $attribs = [] ) {
 248                 $attribs = (array)$attribs;
 249                 // This is not required in HTML5, but let's do it anyway, for
 250                 // consistency and better compression.
 251                 $element = strtolower( $element );
 252
 253                 // Remove invalid input types
 254                 if ( $element == 'input' ) {
 255                         $validTypes = [
 256                                 'hidden',
 257                                 'text',
 258                                 'password',
 259                                 'checkbox',
 260                                 'radio',
 261                                 'file',
 262                                 'submit',
 263                                 'image',
 264                                 'reset',
 265                                 'button',
 266
 267                                 // HTML input types
 268                                 'datetime',
 269                                 'datetime-local',
 270                                 'date',
 271                                 'month',
 272                                 'time',
 273                                 'week',
 274                                 'number',
 275                                 'range',
 276                                 'email',
 277                                 'url',
 278                                 'search',
 279                                 'tel',
 280                                 'color',
 281                         ];
 282                         if ( isset( $attribs['type'] ) && !in_array( $attribs['type'], $validTypes ) ) {
 283                                 unset( $attribs['type'] );
 284                         }
 285                 }
 286
 287                 // According to standard the default type for <button> elements is "submit".
 288                 // Depending on compatibility mode IE might use "button", instead.
 289                 // We enforce the standard "submit".
 290                 if ( $element == 'button' && !isset( $attribs['type'] ) ) {
 291                         $attribs['type'] = 'submit';
 292                 }
 293
 294                 return "<$element" . self::expandAttributes(
 295                         self::dropDefaults( $element, $attribs ) ) . '>';
 296         }
 297
 298         /**
 299          * Returns "</$element>"
 300          *
 301          * @since 1.17
 302          * @param string $element Name of the element, e.g., 'a'
 303          * @return string A closing tag
 304          */
 305         public static function closeElement( $element ) {
 306                 $element = strtolower( $element );
 307
 308                 return "</$element>";
 309         }
 310
 311         /**
 312          * Given an element name and an associative array of element attributes,
 313          * return an array that is functionally identical to the input array, but
 314          * possibly smaller.  In particular, attributes might be stripped if they
 315          * are given their default values.
 316          *
 317          * This method is not guaranteed to remove all redundant attributes, only
 318          * some common ones and some others selected arbitrarily at random.  It
 319          * only guarantees that the output array should be functionally identical
 320          * to the input array (currently per the HTML 5 draft as of 2009-09-06).
 321          *
 322          * @param string $element Name of the element, e.g., 'a'
 323          * @param array $attribs Associative array of attributes, e.g., [
 324          *   'href' => 'https://www.mediawiki.org/' ].  See expandAttributes() for
 325          *   further documentation.
 326          * @return array An array of attributes functionally identical to $attribs
 327          */
 328         private static function dropDefaults( $element, array $attribs ) {
 329                 // Whenever altering this array, please provide a covering test case
 330                 // in HtmlTest::provideElementsWithAttributesHavingDefaultValues
 331                 static $attribDefaults = [
 332                         'area' => [ 'shape' => 'rect' ],
 333                         'button' => [
 334                                 'formaction' => 'GET',
 335                                 'formenctype' => 'application/x-www-form-urlencoded',
 336                         ],
 337                         'canvas' => [
 338                                 'height' => '150',
 339                                 'width' => '300',
 340                         ],
 341                         'form' => [
 342                                 'action' => 'GET',
 343                                 'autocomplete' => 'on',
 344                                 'enctype' => 'application/x-www-form-urlencoded',
 345                         ],
 346                         'input' => [
 347                                 'formaction' => 'GET',
 348                                 'type' => 'text',
 349                         ],
 350                         'keygen' => [ 'keytype' => 'rsa' ],
 351                         'link' => [ 'media' => 'all' ],
 352                         'menu' => [ 'type' => 'list' ],
 353                         'script' => [ 'type' => 'text/javascript' ],
 354                         'style' => [
 355                                 'media' => 'all',
 356                                 'type' => 'text/css',
 357                         ],
 358                         'textarea' => [ 'wrap' => 'soft' ],
 359                 ];
 360
 361                 $element = strtolower( $element );
 362
 363                 foreach ( $attribs as $attrib => $value ) {
 364                         $lcattrib = strtolower( $attrib );
 365                         if ( is_array( $value ) ) {
 366                                 $value = implode( ' ', $value );
 367                         } else {
 368                                 $value = strval( $value );
 369                         }
 370
 371                         // Simple checks using $attribDefaults
 372                         if ( isset( $attribDefaults[$element][$lcattrib] )
 373                                 && $attribDefaults[$element][$lcattrib] == $value
 374                         ) {
 375                                 unset( $attribs[$attrib] );
 376                         }
 377
 378                         if ( $lcattrib == 'class' && $value == '' ) {
 379                                 unset( $attribs[$attrib] );
 380                         }
 381                 }
 382
 383                 // More subtle checks
 384                 if ( $element === 'link'
 385                         && isset( $attribs['type'] ) && strval( $attribs['type'] ) == 'text/css'
 386                 ) {
 387                         unset( $attribs['type'] );
 388                 }
 389                 if ( $element === 'input' ) {
 390                         $type = isset( $attribs['type'] ) ? $attribs['type'] : null;
 391                         $value = isset( $attribs['value'] ) ? $attribs['value'] : null;
 392                         if ( $type === 'checkbox' || $type === 'radio' ) {
 393                                 // The default value for checkboxes and radio buttons is 'on'
 394                                 // not ''. By stripping value="" we break radio boxes that
 395                                 // actually wants empty values.
 396                                 if ( $value === 'on' ) {
 397                                         unset( $attribs['value'] );
 398                                 }
 399                         } elseif ( $type === 'submit' ) {
 400                                 // The default value for submit appears to be "Submit" but
 401                                 // let's not bother stripping out localized text that matches
 402                                 // that.
 403                         } else {
 404                                 // The default value for nearly every other field type is ''
 405                                 // The 'range' and 'color' types use different defaults but
 406                                 // stripping a value="" does not hurt them.
 407                                 if ( $value === '' ) {
 408                                         unset( $attribs['value'] );
 409                                 }
 410                         }
 411                 }
 412                 if ( $element === 'select' && isset( $attribs['size'] ) ) {
 413                         if ( in_array( 'multiple', $attribs )
 414                                 || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
 415                         ) {
 416                                 // A multi-select
 417                                 if ( strval( $attribs['size'] ) == '4' ) {
 418                                         unset( $attribs['size'] );
 419                                 }
 420                         } else {
 421                                 // Single select
 422                                 if ( strval( $attribs['size'] ) == '1' ) {
 423                                         unset( $attribs['size'] );
 424                                 }
 425                         }
 426                 }
 427
 428                 return $attribs;
 429         }
 430
 431         /**
 432          * Given an associative array of element attributes, generate a string
 433          * to stick after the element name in HTML output.  Like [ 'href' =>
 434          * 'https://www.mediawiki.org/' ] becomes something like
 435          * ' href="https://www.mediawiki.org"'.  Again, this is like
 436          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 437          *
 438          * Attributes that can contain space-separated lists ('class', 'accesskey' and 'rel') array
 439          * values are allowed as well, which will automagically be normalized
 440          * and converted to a space-separated string. In addition to a numerical
 441          * array, the attribute value may also be an associative array. See the
 442          * example below for how that works.
 443          *
 444          * @par Numerical array
 445          * @code
 446          *     Html::element( 'em', [
 447          *         'class' => [ 'foo', 'bar' ]
 448          *     ] );
 449          *     // gives '<em class="foo bar"></em>'
 450          * @endcode
 451          *
 452          * @par Associative array
 453          * @code
 454          *     Html::element( 'em', [
 455          *         'class' => [ 'foo', 'bar', 'foo' => false, 'quux' => true ]
 456          *     ] );
 457          *     // gives '<em class="bar quux"></em>'
 458          * @endcode
 459          *
 460          * @param array $attribs Associative array of attributes, e.g., [
 461          *   'href' => 'https://www.mediawiki.org/' ].  Values will be HTML-escaped.
 462          *   A value of false means to omit the attribute.  For boolean attributes,
 463          *   you can omit the key, e.g., [ 'checked' ] instead of
 464          *   [ 'checked' => 'checked' ] or such.
 465          *
 466          * @throws MWException If an attribute that doesn't allow lists is set to an array
 467          * @return string HTML fragment that goes between element name and '>'
 468          *   (starting with a space if at least one attribute is output)
 469          */
 470         public static function expandAttributes( array $attribs ) {
 471                 $ret = '';
 472                 foreach ( $attribs as $key => $value ) {
 473                         // Support intuitive [ 'checked' => true/false ] form
 474                         if ( $value === false || is_null( $value ) ) {
 475                                 continue;
 476                         }
 477
 478                         // For boolean attributes, support [ 'foo' ] instead of
 479                         // requiring [ 'foo' => 'meaningless' ].
 480                         if ( is_int( $key ) && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 481                                 $key = $value;
 482                         }
 483
 484                         // Not technically required in HTML5 but we'd like consistency
 485                         // and better compression anyway.
 486                         $key = strtolower( $key );
 487
 488                         // Bug 23769: Blacklist all form validation attributes for now.  Current
 489                         // (June 2010) WebKit has no UI, so the form just refuses to submit
 490                         // without telling the user why, which is much worse than failing
 491                         // server-side validation.  Opera is the only other implementation at
 492                         // this time, and has ugly UI, so just kill the feature entirely until
 493                         // we have at least one good implementation.
 494
 495                         // As the default value of "1" for "step" rejects decimal
 496                         // numbers to be entered in 'type="number"' fields, allow
 497                         // the special case 'step="any"'.
 498
 499                         if ( in_array( $key, [ 'max', 'min', 'pattern', 'required' ] )
 500                                 || $key === 'step' && $value !== 'any' ) {
 501                                 continue;
 502                         }
 503
 504                         // https://www.w3.org/TR/html401/index/attributes.html ("space-separated")
 505                         // https://www.w3.org/TR/html5/index.html#attributes-1 ("space-separated")
 506                         $spaceSeparatedListAttributes = [
 507                                 'class', // html4, html5
 508                                 'accesskey', // as of html5, multiple space-separated values allowed
 509                                 // html4-spec doesn't document rel= as space-separated
 510                                 // but has been used like that and is now documented as such
 511                                 // in the html5-spec.
 512                                 'rel',
 513                         ];
 514
 515                         // Specific features for attributes that allow a list of space-separated values
 516                         if ( in_array( $key, $spaceSeparatedListAttributes ) ) {
 517                                 // Apply some normalization and remove duplicates
 518
 519                                 // Convert into correct array. Array can contain space-separated
 520                                 // values. Implode/explode to get those into the main array as well.
 521                                 if ( is_array( $value ) ) {
 522                                         // If input wasn't an array, we can skip this step
 523                                         $newValue = [];
 524                                         foreach ( $value as $k => $v ) {
 525                                                 if ( is_string( $v ) ) {
 526                                                         // String values should be normal `array( 'foo' )`
 527                                                         // Just append them
 528                                                         if ( !isset( $value[$v] ) ) {
 529                                                                 // As a special case don't set 'foo' if a
 530                                                                 // separate 'foo' => true/false exists in the array
 531                                                                 // keys should be authoritative
 532                                                                 $newValue[] = $v;
 533                                                         }
 534                                                 } elseif ( $v ) {
 535                                                         // If the value is truthy but not a string this is likely
 536                                                         // an [ 'foo' => true ], falsy values don't add strings
 537                                                         $newValue[] = $k;
 538                                                 }
 539                                         }
 540                                         $value = implode( ' ', $newValue );
 541                                 }
 542                                 $value = explode( ' ', $value );
 543
 544                                 // Normalize spacing by fixing up cases where people used
 545                                 // more than 1 space and/or a trailing/leading space
 546                                 $value = array_diff( $value, [ '', ' ' ] );
 547
 548                                 // Remove duplicates and create the string
 549                                 $value = implode( ' ', array_unique( $value ) );
 550                         } elseif ( is_array( $value ) ) {
 551                                 throw new MWException( "HTML attribute $key can not contain a list of values" );
 552                         }
 553
 554                         $quote = '"';
 555
 556                         if ( in_array( $key, self::$boolAttribs ) ) {
 557                                 $ret .= " $key=\"\"";
 558                         } else {
 559                                 // Apparently we need to entity-encode \n, \r, \t, although the
 560                                 // spec doesn't mention that.  Since we're doing strtr() anyway,
 561                                 // we may as well not call htmlspecialchars().
 562                                 // @todo FIXME: Verify that we actually need to
 563                                 // escape \n\r\t here, and explain why, exactly.
 564                                 // We could call Sanitizer::encodeAttribute() for this, but we
 565                                 // don't because we're stubborn and like our marginal savings on
 566                                 // byte size from not having to encode unnecessary quotes.
 567                                 // The only difference between this transform and the one by
 568                                 // Sanitizer::encodeAttribute() is ' is not encoded.
 569                                 $map = [
 570                                         '&' => '&amp;',
 571                                         '"' => '&quot;',
 572                                         '>' => '&gt;',
 573                                         // '<' allegedly allowed per spec
 574                                         // but breaks some tools if not escaped.
 575                                         "<" => '&lt;',
 576                                         "\n" => '&#10;',
 577                                         "\r" => '&#13;',
 578                                         "\t" => '&#9;'
 579                                 ];
 580                                 $ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
 581                         }
 582                 }
 583                 return $ret;
 584         }
 585
 586         /**
 587          * Output a "<script>" tag with the given contents.
 588          *
 589          * @todo do some useful escaping as well, like if $contents contains
 590          * literal "</script>" or (for XML) literal "]]>".
 591          *
 592          * @param string $contents JavaScript
 593          * @return string Raw HTML
 594          */
 595         public static function inlineScript( $contents ) {
 596                 $attrs = [];
 597
 598                 if ( preg_match( '/[<&]/', $contents ) ) {
 599                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 600                 }
 601
 602                 return self::rawElement( 'script', $attrs, $contents );
 603         }
 604
 605         /**
 606          * Output a "<script>" tag linking to the given URL, e.g.,
 607          * "<script src=foo.js></script>".
 608          *
 609          * @param string $url
 610          * @return string Raw HTML
 611          */
 612         public static function linkedScript( $url ) {
 613                 $attrs = [ 'src' => $url ];
 614
 615                 return self::element( 'script', $attrs );
 616         }
 617
 618         /**
 619          * Output a "<style>" tag with the given contents for the given media type
 620          * (if any).  TODO: do some useful escaping as well, like if $contents
 621          * contains literal "</style>" (admittedly unlikely).
 622          *
 623          * @param string $contents CSS
 624          * @param string $media A media type string, like 'screen'
 625          * @return string Raw HTML
 626          */
 627         public static function inlineStyle( $contents, $media = 'all' ) {
 628                 // Don't escape '>' since that is used
 629                 // as direct child selector.
 630                 // Remember, in css, there is no "x" for hexadecimal escapes, and
 631                 // the space immediately after an escape sequence is swallowed.
 632                 $contents = strtr( $contents, [
 633                         '<' => '\3C ',
 634                         // CDATA end tag for good measure, but the main security
 635                         // is from escaping the '<'.
 636                         ']]>' => '\5D\5D\3E '
 637                 ] );
 638
 639                 if ( preg_match( '/[<&]/', $contents ) ) {
 640                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 641                 }
 642
 643                 return self::rawElement( 'style', [
 644                         'media' => $media,
 645                 ], $contents );
 646         }
 647
 648         /**
 649          * Output a "<link rel=stylesheet>" linking to the given URL for the given
 650          * media type (if any).
 651          *
 652          * @param string $url
 653          * @param string $media A media type string, like 'screen'
 654          * @return string Raw HTML
 655          */
 656         public static function linkedStyle( $url, $media = 'all' ) {
 657                 return self::element( 'link', [
 658                         'rel' => 'stylesheet',
 659                         'href' => $url,
 660                         'media' => $media,
 661                 ] );
 662         }
 663
 664         /**
 665          * Convenience function to produce an "<input>" element.  This supports the
 666          * new HTML5 input types and attributes.
 667          *
 668          * @param string $name Name attribute
 669          * @param string $value Value attribute
 670          * @param string $type Type attribute
 671          * @param array $attribs Associative array of miscellaneous extra
 672          *   attributes, passed to Html::element()
 673          * @return string Raw HTML
 674          */
 675         public static function input( $name, $value = '', $type = 'text', array $attribs = [] ) {
 676                 $attribs['type'] = $type;
 677                 $attribs['value'] = $value;
 678                 $attribs['name'] = $name;
 679                 if ( in_array( $type, [ 'text', 'search', 'email', 'password', 'number' ] ) ) {
 680                         $attribs = self::getTextInputAttributes( $attribs );
 681                 }
 682                 if ( in_array( $type, [ 'button', 'reset', 'submit' ] ) ) {
 683                         $attribs = self::buttonAttributes( $attribs );
 684                 }
 685                 return self::element( 'input', $attribs );
 686         }
 687
 688         /**
 689          * Convenience function to produce a checkbox (input element with type=checkbox)
 690          *
 691          * @param string $name Name attribute
 692          * @param bool $checked Whether the checkbox is checked or not
 693          * @param array $attribs Array of additional attributes
 694          * @return string Raw HTML
 695          */
 696         public static function check( $name, $checked = false, array $attribs = [] ) {
 697                 if ( isset( $attribs['value'] ) ) {
 698                         $value = $attribs['value'];
 699                         unset( $attribs['value'] );
 700                 } else {
 701                         $value = 1;
 702                 }
 703
 704                 if ( $checked ) {
 705                         $attribs[] = 'checked';
 706                 }
 707
 708                 return self::input( $name, $value, 'checkbox', $attribs );
 709         }
 710
 711         /**
 712          * Convenience function to produce a radio button (input element with type=radio)
 713          *
 714          * @param string $name Name attribute
 715          * @param bool $checked Whether the radio button is checked or not
 716          * @param array $attribs Array of additional attributes
 717          * @return string Raw HTML
 718          */
 719         public static function radio( $name, $checked = false, array $attribs = [] ) {
 720                 if ( isset( $attribs['value'] ) ) {
 721                         $value = $attribs['value'];
 722                         unset( $attribs['value'] );
 723                 } else {
 724                         $value = 1;
 725                 }
 726
 727                 if ( $checked ) {
 728                         $attribs[] = 'checked';
 729                 }
 730
 731                 return self::input( $name, $value, 'radio', $attribs );
 732         }
 733
 734         /**
 735          * Convenience function for generating a label for inputs.
 736          *
 737          * @param string $label Contents of the label
 738          * @param string $id ID of the element being labeled
 739          * @param array $attribs Additional attributes
 740          * @return string Raw HTML
 741          */
 742         public static function label( $label, $id, array $attribs = [] ) {
 743                 $attribs += [
 744                         'for' => $id
 745                 ];
 746                 return self::element( 'label', $attribs, $label );
 747         }
 748
 749         /**
 750          * Convenience function to produce an input element with type=hidden
 751          *
 752          * @param string $name Name attribute
 753          * @param string $value Value attribute
 754          * @param array $attribs Associative array of miscellaneous extra
 755          *   attributes, passed to Html::element()
 756          * @return string Raw HTML
 757          */
 758         public static function hidden( $name, $value, array $attribs = [] ) {
 759                 return self::input( $name, $value, 'hidden', $attribs );
 760         }
 761
 762         /**
 763          * Convenience function to produce a <textarea> element.
 764          *
 765          * This supports leaving out the cols= and rows= which Xml requires and are
 766          * required by HTML4/XHTML but not required by HTML5.
 767          *
 768          * @param string $name Name attribute
 769          * @param string $value Value attribute
 770          * @param array $attribs Associative array of miscellaneous extra
 771          *   attributes, passed to Html::element()
 772          * @return string Raw HTML
 773          */
 774         public static function textarea( $name, $value = '', array $attribs = [] ) {
 775                 $attribs['name'] = $name;
 776
 777                 if ( substr( $value, 0, 1 ) == "\n" ) {
 778                         // Workaround for bug 12130: browsers eat the initial newline
 779                         // assuming that it's just for show, but they do keep the later
 780                         // newlines, which we may want to preserve during editing.
 781                         // Prepending a single newline
 782                         $spacedValue = "\n" . $value;
 783                 } else {
 784                         $spacedValue = $value;
 785                 }
 786                 return self::element( 'textarea', self::getTextInputAttributes( $attribs ), $spacedValue );
 787         }
 788
 789         /**
 790          * Helper for Html::namespaceSelector().
 791          * @param array $params See Html::namespaceSelector()
 792          * @return array
 793          */
 794         public static function namespaceSelectorOptions( array $params = [] ) {
 795                 global $wgContLang;
 796
 797                 $options = [];
 798
 799                 if ( !isset( $params['exclude'] ) || !is_array( $params['exclude'] ) ) {
 800                         $params['exclude'] = [];
 801                 }
 802
 803                 if ( isset( $params['all'] ) ) {
 804                         // add an option that would let the user select all namespaces.
 805                         // Value is provided by user, the name shown is localized for the user.
 806                         $options[$params['all']] = wfMessage( 'namespacesall' )->text();
 807                 }
 808                 // Add all namespaces as options (in the content language)
 809                 $options += $wgContLang->getFormattedNamespaces();
 810
 811                 $optionsOut = [];
 812                 // Filter out namespaces below 0 and massage labels
 813                 foreach ( $options as $nsId => $nsName ) {
 814                         if ( $nsId < NS_MAIN || in_array( $nsId, $params['exclude'] ) ) {
 815                                 continue;
 816                         }
 817                         if ( $nsId === NS_MAIN ) {
 818                                 // For other namespaces use the namespace prefix as label, but for
 819                                 // main we don't use "" but the user message describing it (e.g. "(Main)" or "(Article)")
 820                                 $nsName = wfMessage( 'blanknamespace' )->text();
 821                         } elseif ( is_int( $nsId ) ) {
 822                                 $nsName = $wgContLang->convertNamespace( $nsId );
 823                         }
 824                         $optionsOut[$nsId] = $nsName;
 825                 }
 826
 827                 return $optionsOut;
 828         }
 829
 830         /**
 831          * Build a drop-down box for selecting a namespace
 832          *
 833          * @param array $params Params to set.
 834          * - selected: [optional] Id of namespace which should be pre-selected
 835          * - all: [optional] Value of item for "all namespaces". If null or unset,
 836          *   no "<option>" is generated to select all namespaces.
 837          * - label: text for label to add before the field.
 838          * - exclude: [optional] Array of namespace ids to exclude.
 839          * - disable: [optional] Array of namespace ids for which the option should
 840          *   be disabled in the selector.
 841          * @param array $selectAttribs HTML attributes for the generated select element.
 842          * - id:   [optional], default: 'namespace'.
 843          * - name: [optional], default: 'namespace'.
 844          * @return string HTML code to select a namespace.
 845          */
 846         public static function namespaceSelector( array $params = [],
 847                 array $selectAttribs = []
 848         ) {
 849                 ksort( $selectAttribs );
 850
 851                 // Is a namespace selected?
 852                 if ( isset( $params['selected'] ) ) {
 853                         // If string only contains digits, convert to clean int. Selected could also
 854                         // be "all" or "" etc. which needs to be left untouched.
 855                         // PHP is_numeric() has issues with large strings, PHP ctype_digit has other issues
 856                         // and returns false for already clean ints. Use regex instead..
 857                         if ( preg_match( '/^\d+$/', $params['selected'] ) ) {
 858                                 $params['selected'] = intval( $params['selected'] );
 859                         }
 860                         // else: leaves it untouched for later processing
 861                 } else {
 862                         $params['selected'] = '';
 863                 }
 864
 865                 if ( !isset( $params['disable'] ) || !is_array( $params['disable'] ) ) {
 866                         $params['disable'] = [];
 867                 }
 868
 869                 // Associative array between option-values and option-labels
 870                 $options = self::namespaceSelectorOptions( $params );
 871
 872                 // Convert $options to HTML
 873                 $optionsHtml = [];
 874                 foreach ( $options as $nsId => $nsName ) {
 875                         $optionsHtml[] = self::element(
 876                                 'option', [
 877                                         'disabled' => in_array( $nsId, $params['disable'] ),
 878                                         'value' => $nsId,
 879                                         'selected' => $nsId === $params['selected'],
 880                                 ], $nsName
 881                         );
 882                 }
 883
 884                 if ( !array_key_exists( 'id', $selectAttribs ) ) {
 885                         $selectAttribs['id'] = 'namespace';
 886                 }
 887
 888                 if ( !array_key_exists( 'name', $selectAttribs ) ) {
 889                         $selectAttribs['name'] = 'namespace';
 890                 }
 891
 892                 $ret = '';
 893                 if ( isset( $params['label'] ) ) {
 894                         $ret .= self::element(
 895                                 'label', [
 896                                         'for' => isset( $selectAttribs['id'] ) ? $selectAttribs['id'] : null,
 897                                 ], $params['label']
 898                         ) . '&#160;';
 899                 }
 900
 901                 // Wrap options in a <select>
 902                 $ret .= self::openElement( 'select', $selectAttribs )
 903                         . "\n"
 904                         . implode( "\n", $optionsHtml )
 905                         . "\n"
 906                         . self::closeElement( 'select' );
 907
 908                 return $ret;
 909         }
 910
 911         /**
 912          * Constructs the opening html-tag with necessary doctypes depending on
 913          * global variables.
 914          *
 915          * @param array $attribs Associative array of miscellaneous extra
 916          *   attributes, passed to Html::element() of html tag.
 917          * @return string Raw HTML
 918          */
 919         public static function htmlHeader( array $attribs = [] ) {
 920                 $ret = '';
 921
 922                 global $wgHtml5Version, $wgMimeType, $wgXhtmlNamespaces;
 923
 924                 $isXHTML = self::isXmlMimeType( $wgMimeType );
 925
 926                 if ( $isXHTML ) { // XHTML5
 927                         // XML MIME-typed markup should have an xml header.
 928                         // However a DOCTYPE is not needed.
 929                         $ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?" . ">\n";
 930
 931                         // Add the standard xmlns
 932                         $attribs['xmlns'] = 'http://www.w3.org/1999/xhtml';
 933
 934                         // And support custom namespaces
 935                         foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
 936                                 $attribs["xmlns:$tag"] = $ns;
 937                         }
 938                 } else { // HTML5
 939                         // DOCTYPE
 940                         $ret .= "<!DOCTYPE html>\n";
 941                 }
 942
 943                 if ( $wgHtml5Version ) {
 944                         $attribs['version'] = $wgHtml5Version;
 945                 }
 946
 947                 $ret .= self::openElement( 'html', $attribs );
 948
 949                 return $ret;
 950         }
 951
 952         /**
 953          * Determines if the given MIME type is xml.
 954          *
 955          * @param string $mimetype MIME type
 956          * @return bool
 957          */
 958         public static function isXmlMimeType( $mimetype ) {
 959                 # https://html.spec.whatwg.org/multipage/infrastructure.html#xml-mime-type
 960                 # * text/xml
 961                 # * application/xml
 962                 # * Any MIME type with a subtype ending in +xml (this implicitly includes application/xhtml+xml)
 963                 return (bool)preg_match( '!^(text|application)/xml$|^.+/.+\+xml$!', $mimetype );
 964         }
 965
 966         /**
 967          * Get HTML for an info box with an icon.
 968          *
 969          * @param string $text Wikitext, get this with wfMessage()->plain()
 970          * @param string $icon Path to icon file (used as 'src' attribute)
 971          * @param string $alt Alternate text for the icon
 972          * @param string $class Additional class name to add to the wrapper div
 973          *
 974          * @return string
 975          */
 976         static function infoBox( $text, $icon, $alt, $class = '' ) {
 977                 $s = self::openElement( 'div', [ 'class' => "mw-infobox $class" ] );
 978
 979                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-left' ] ) .
 980                                 self::element( 'img',
 981                                         [
 982                                                 'src' => $icon,
 983                                                 'alt' => $alt,
 984                                         ]
 985                                 ) .
 986                                 self::closeElement( 'div' );
 987
 988                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-right' ] ) .
 989                                 $text .
 990                                 self::closeElement( 'div' );
 991                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
 992
 993                 $s .= self::closeElement( 'div' );
 994
 995                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
 996
 997                 return $s;
 998         }
 999
1000         /**
1001          * Generate a srcset attribute value.
1002          *
1003          * Generates a srcset attribute value from an array mapping pixel densities
1004          * to URLs. A trailing 'x' in pixel density values is optional.
1005          *
1006          * @note srcset width and height values are not supported.
1007          *
1008          * @see https://html.spec.whatwg.org/#attr-img-srcset
1009          *
1010          * @par Example:
1011          * @code
1012          *     Html::srcSet( [
1013          *         '1x'   => 'standard.jpeg',
1014          *         '1.5x' => 'large.jpeg',
1015          *         '3x'   => 'extra-large.jpeg',
1016          *     ] );
1017          *     // gives 'standard.jpeg 1x, large.jpeg 1.5x, extra-large.jpeg 2x'
1018          * @endcode
1019          *
1020          * @param string[] $urls
1021          * @return string
1022          */
1023         static function srcSet( array $urls ) {
1024                 $candidates = [];
1025                 foreach ( $urls as $density => $url ) {
1026                         // Cast density to float to strip 'x', then back to string to serve
1027                         // as array index.
1028                         $density = (string)(float)$density;
1029                         $candidates[$density] = $url;
1030                 }
1031
1032                 // Remove duplicates that are the same as a smaller value
1033                 ksort( $candidates, SORT_NUMERIC );
1034                 $candidates = array_unique( $candidates );
1035
1036                 // Append density info to the url
1037                 foreach ( $candidates as $density => $url ) {
1038                         $candidates[$density] = $url . ' ' . $density . 'x';
1039                 }
1040
1041                 return implode( ", ", $candidates );
1042         }
1043 }