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 Name of the element, e.g., 'a'
 224          * @param array $attribs Associative array of attributes, e.g., [
 225          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 226          *   further documentation.
 227          * @param string $contents
 228          *
 229          * @return string
 230          */
 231         public static function element( $element, $attribs = [], $contents = '' ) {
 232                 return self::rawElement( $element, $attribs, strtr( $contents, [
 233                         // There's no point in escaping quotes, >, etc. in the contents of
 234                         // elements.
 235                         '&' => '&amp;',
 236                         '<' => '&lt;'
 237                 ] ) );
 238         }
 239
 240         /**
 241          * Identical to rawElement(), but has no third parameter and omits the end
 242          * tag (and the self-closing '/' in XML mode for empty elements).
 243          *
 244          * @param string $element Name of the element, e.g., 'a'
 245          * @param array $attribs Associative array of attributes, e.g., [
 246          *   'href' => 'https://www.mediawiki.org/' ]. See expandAttributes() for
 247          *   further documentation.
 248          *
 249          * @return string
 250          */
 251         public static function openElement( $element, $attribs = [] ) {
 252                 $attribs = (array)$attribs;
 253                 // This is not required in HTML5, but let's do it anyway, for
 254                 // consistency and better compression.
 255                 $element = strtolower( $element );
 256
 257                 // Remove invalid input types
 258                 if ( $element == 'input' ) {
 259                         $validTypes = [
 260                                 'hidden',
 261                                 'text',
 262                                 'password',
 263                                 'checkbox',
 264                                 'radio',
 265                                 'file',
 266                                 'submit',
 267                                 'image',
 268                                 'reset',
 269                                 'button',
 270
 271                                 // HTML input types
 272                                 'datetime',
 273                                 'datetime-local',
 274                                 'date',
 275                                 'month',
 276                                 'time',
 277                                 'week',
 278                                 'number',
 279                                 'range',
 280                                 'email',
 281                                 'url',
 282                                 'search',
 283                                 'tel',
 284                                 'color',
 285                         ];
 286                         if ( isset( $attribs['type'] ) && !in_array( $attribs['type'], $validTypes ) ) {
 287                                 unset( $attribs['type'] );
 288                         }
 289                 }
 290
 291                 // According to standard the default type for <button> elements is "submit".
 292                 // Depending on compatibility mode IE might use "button", instead.
 293                 // We enforce the standard "submit".
 294                 if ( $element == 'button' && !isset( $attribs['type'] ) ) {
 295                         $attribs['type'] = 'submit';
 296                 }
 297
 298                 return "<$element" . self::expandAttributes(
 299                         self::dropDefaults( $element, $attribs ) ) . '>';
 300         }
 301
 302         /**
 303          * Returns "</$element>"
 304          *
 305          * @since 1.17
 306          * @param string $element Name of the element, e.g., 'a'
 307          * @return string A closing tag
 308          */
 309         public static function closeElement( $element ) {
 310                 $element = strtolower( $element );
 311
 312                 return "</$element>";
 313         }
 314
 315         /**
 316          * Given an element name and an associative array of element attributes,
 317          * return an array that is functionally identical to the input array, but
 318          * possibly smaller.  In particular, attributes might be stripped if they
 319          * are given their default values.
 320          *
 321          * This method is not guaranteed to remove all redundant attributes, only
 322          * some common ones and some others selected arbitrarily at random.  It
 323          * only guarantees that the output array should be functionally identical
 324          * to the input array (currently per the HTML 5 draft as of 2009-09-06).
 325          *
 326          * @param string $element Name of the element, e.g., 'a'
 327          * @param array $attribs Associative array of attributes, e.g., [
 328          *   'href' => 'https://www.mediawiki.org/' ].  See expandAttributes() for
 329          *   further documentation.
 330          * @return array An array of attributes functionally identical to $attribs
 331          */
 332         private static function dropDefaults( $element, array $attribs ) {
 333                 // Whenever altering this array, please provide a covering test case
 334                 // in HtmlTest::provideElementsWithAttributesHavingDefaultValues
 335                 static $attribDefaults = [
 336                         'area' => [ 'shape' => 'rect' ],
 337                         'button' => [
 338                                 'formaction' => 'GET',
 339                                 'formenctype' => 'application/x-www-form-urlencoded',
 340                         ],
 341                         'canvas' => [
 342                                 'height' => '150',
 343                                 'width' => '300',
 344                         ],
 345                         'form' => [
 346                                 'action' => 'GET',
 347                                 'autocomplete' => 'on',
 348                                 'enctype' => 'application/x-www-form-urlencoded',
 349                         ],
 350                         'input' => [
 351                                 'formaction' => 'GET',
 352                                 'type' => 'text',
 353                         ],
 354                         'keygen' => [ 'keytype' => 'rsa' ],
 355                         'link' => [ 'media' => 'all' ],
 356                         'menu' => [ 'type' => 'list' ],
 357                         'script' => [ 'type' => 'text/javascript' ],
 358                         'style' => [
 359                                 'media' => 'all',
 360                                 'type' => 'text/css',
 361                         ],
 362                         'textarea' => [ 'wrap' => 'soft' ],
 363                 ];
 364
 365                 $element = strtolower( $element );
 366
 367                 foreach ( $attribs as $attrib => $value ) {
 368                         $lcattrib = strtolower( $attrib );
 369                         if ( is_array( $value ) ) {
 370                                 $value = implode( ' ', $value );
 371                         } else {
 372                                 $value = strval( $value );
 373                         }
 374
 375                         // Simple checks using $attribDefaults
 376                         if ( isset( $attribDefaults[$element][$lcattrib] )
 377                                 && $attribDefaults[$element][$lcattrib] == $value
 378                         ) {
 379                                 unset( $attribs[$attrib] );
 380                         }
 381
 382                         if ( $lcattrib == 'class' && $value == '' ) {
 383                                 unset( $attribs[$attrib] );
 384                         }
 385                 }
 386
 387                 // More subtle checks
 388                 if ( $element === 'link'
 389                         && isset( $attribs['type'] ) && strval( $attribs['type'] ) == 'text/css'
 390                 ) {
 391                         unset( $attribs['type'] );
 392                 }
 393                 if ( $element === 'input' ) {
 394                         $type = isset( $attribs['type'] ) ? $attribs['type'] : null;
 395                         $value = isset( $attribs['value'] ) ? $attribs['value'] : null;
 396                         if ( $type === 'checkbox' || $type === 'radio' ) {
 397                                 // The default value for checkboxes and radio buttons is 'on'
 398                                 // not ''. By stripping value="" we break radio boxes that
 399                                 // actually wants empty values.
 400                                 if ( $value === 'on' ) {
 401                                         unset( $attribs['value'] );
 402                                 }
 403                         } elseif ( $type === 'submit' ) {
 404                                 // The default value for submit appears to be "Submit" but
 405                                 // let's not bother stripping out localized text that matches
 406                                 // that.
 407                         } else {
 408                                 // The default value for nearly every other field type is ''
 409                                 // The 'range' and 'color' types use different defaults but
 410                                 // stripping a value="" does not hurt them.
 411                                 if ( $value === '' ) {
 412                                         unset( $attribs['value'] );
 413                                 }
 414                         }
 415                 }
 416                 if ( $element === 'select' && isset( $attribs['size'] ) ) {
 417                         if ( in_array( 'multiple', $attribs )
 418                                 || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
 419                         ) {
 420                                 // A multi-select
 421                                 if ( strval( $attribs['size'] ) == '4' ) {
 422                                         unset( $attribs['size'] );
 423                                 }
 424                         } else {
 425                                 // Single select
 426                                 if ( strval( $attribs['size'] ) == '1' ) {
 427                                         unset( $attribs['size'] );
 428                                 }
 429                         }
 430                 }
 431
 432                 return $attribs;
 433         }
 434
 435         /**
 436          * Given an associative array of element attributes, generate a string
 437          * to stick after the element name in HTML output.  Like [ 'href' =>
 438          * 'https://www.mediawiki.org/' ] becomes something like
 439          * ' href="https://www.mediawiki.org"'.  Again, this is like
 440          * Xml::expandAttributes(), but it implements some HTML-specific logic.
 441          *
 442          * Attributes that can contain space-separated lists ('class', 'accesskey' and 'rel') array
 443          * values are allowed as well, which will automagically be normalized
 444          * and converted to a space-separated string. In addition to a numerical
 445          * array, the attribute value may also be an associative array. See the
 446          * example below for how that works.
 447          *
 448          * @par Numerical array
 449          * @code
 450          *     Html::element( 'em', [
 451          *         'class' => [ 'foo', 'bar' ]
 452          *     ] );
 453          *     // gives '<em class="foo bar"></em>'
 454          * @endcode
 455          *
 456          * @par Associative array
 457          * @code
 458          *     Html::element( 'em', [
 459          *         'class' => [ 'foo', 'bar', 'foo' => false, 'quux' => true ]
 460          *     ] );
 461          *     // gives '<em class="bar quux"></em>'
 462          * @endcode
 463          *
 464          * @param array $attribs Associative array of attributes, e.g., [
 465          *   'href' => 'https://www.mediawiki.org/' ].  Values will be HTML-escaped.
 466          *   A value of false or null means to omit the attribute.  For boolean attributes,
 467          *   you can omit the key, e.g., [ 'checked' ] instead of
 468          *   [ 'checked' => 'checked' ] or such.
 469          *
 470          * @throws MWException If an attribute that doesn't allow lists is set to an array
 471          * @return string HTML fragment that goes between element name and '>'
 472          *   (starting with a space if at least one attribute is output)
 473          */
 474         public static function expandAttributes( array $attribs ) {
 475                 $ret = '';
 476                 foreach ( $attribs as $key => $value ) {
 477                         // Support intuitive [ 'checked' => true/false ] form
 478                         if ( $value === false || is_null( $value ) ) {
 479                                 continue;
 480                         }
 481
 482                         // For boolean attributes, support [ 'foo' ] instead of
 483                         // requiring [ 'foo' => 'meaningless' ].
 484                         if ( is_int( $key ) && in_array( strtolower( $value ), self::$boolAttribs ) ) {
 485                                 $key = $value;
 486                         }
 487
 488                         // Not technically required in HTML5 but we'd like consistency
 489                         // and better compression anyway.
 490                         $key = strtolower( $key );
 491
 492                         // https://www.w3.org/TR/html401/index/attributes.html ("space-separated")
 493                         // https://www.w3.org/TR/html5/index.html#attributes-1 ("space-separated")
 494                         $spaceSeparatedListAttributes = [
 495                                 'class', // html4, html5
 496                                 'accesskey', // as of html5, multiple space-separated values allowed
 497                                 // html4-spec doesn't document rel= as space-separated
 498                                 // but has been used like that and is now documented as such
 499                                 // in the html5-spec.
 500                                 'rel',
 501                         ];
 502
 503                         // Specific features for attributes that allow a list of space-separated values
 504                         if ( in_array( $key, $spaceSeparatedListAttributes ) ) {
 505                                 // Apply some normalization and remove duplicates
 506
 507                                 // Convert into correct array. Array can contain space-separated
 508                                 // values. Implode/explode to get those into the main array as well.
 509                                 if ( is_array( $value ) ) {
 510                                         // If input wasn't an array, we can skip this step
 511                                         $newValue = [];
 512                                         foreach ( $value as $k => $v ) {
 513                                                 if ( is_string( $v ) ) {
 514                                                         // String values should be normal `array( 'foo' )`
 515                                                         // Just append them
 516                                                         if ( !isset( $value[$v] ) ) {
 517                                                                 // As a special case don't set 'foo' if a
 518                                                                 // separate 'foo' => true/false exists in the array
 519                                                                 // keys should be authoritative
 520                                                                 $newValue[] = $v;
 521                                                         }
 522                                                 } elseif ( $v ) {
 523                                                         // If the value is truthy but not a string this is likely
 524                                                         // an [ 'foo' => true ], falsy values don't add strings
 525                                                         $newValue[] = $k;
 526                                                 }
 527                                         }
 528                                         $value = implode( ' ', $newValue );
 529                                 }
 530                                 $value = explode( ' ', $value );
 531
 532                                 // Normalize spacing by fixing up cases where people used
 533                                 // more than 1 space and/or a trailing/leading space
 534                                 $value = array_diff( $value, [ '', ' ' ] );
 535
 536                                 // Remove duplicates and create the string
 537                                 $value = implode( ' ', array_unique( $value ) );
 538                         } elseif ( is_array( $value ) ) {
 539                                 throw new MWException( "HTML attribute $key can not contain a list of values" );
 540                         }
 541
 542                         $quote = '"';
 543
 544                         if ( in_array( $key, self::$boolAttribs ) ) {
 545                                 $ret .= " $key=\"\"";
 546                         } else {
 547                                 // Apparently we need to entity-encode \n, \r, \t, although the
 548                                 // spec doesn't mention that.  Since we're doing strtr() anyway,
 549                                 // we may as well not call htmlspecialchars().
 550                                 // @todo FIXME: Verify that we actually need to
 551                                 // escape \n\r\t here, and explain why, exactly.
 552                                 // We could call Sanitizer::encodeAttribute() for this, but we
 553                                 // don't because we're stubborn and like our marginal savings on
 554                                 // byte size from not having to encode unnecessary quotes.
 555                                 // The only difference between this transform and the one by
 556                                 // Sanitizer::encodeAttribute() is ' is not encoded.
 557                                 $map = [
 558                                         '&' => '&amp;',
 559                                         '"' => '&quot;',
 560                                         '>' => '&gt;',
 561                                         // '<' allegedly allowed per spec
 562                                         // but breaks some tools if not escaped.
 563                                         "<" => '&lt;',
 564                                         "\n" => '&#10;',
 565                                         "\r" => '&#13;',
 566                                         "\t" => '&#9;'
 567                                 ];
 568                                 $ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
 569                         }
 570                 }
 571                 return $ret;
 572         }
 573
 574         /**
 575          * Output a "<script>" tag with the given contents.
 576          *
 577          * @todo do some useful escaping as well, like if $contents contains
 578          * literal "</script>" or (for XML) literal "]]>".
 579          *
 580          * @param string $contents JavaScript
 581          * @return string Raw HTML
 582          */
 583         public static function inlineScript( $contents ) {
 584                 $attrs = [];
 585
 586                 if ( preg_match( '/[<&]/', $contents ) ) {
 587                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 588                 }
 589
 590                 return self::rawElement( 'script', $attrs, $contents );
 591         }
 592
 593         /**
 594          * Output a "<script>" tag linking to the given URL, e.g.,
 595          * "<script src=foo.js></script>".
 596          *
 597          * @param string $url
 598          * @return string Raw HTML
 599          */
 600         public static function linkedScript( $url ) {
 601                 $attrs = [ 'src' => $url ];
 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          * @return string Raw HTML
 614          */
 615         public static function inlineStyle( $contents, $media = 'all' ) {
 616                 // Don't escape '>' since that is used
 617                 // as direct child selector.
 618                 // Remember, in css, there is no "x" for hexadecimal escapes, and
 619                 // the space immediately after an escape sequence is swallowed.
 620                 $contents = strtr( $contents, [
 621                         '<' => '\3C ',
 622                         // CDATA end tag for good measure, but the main security
 623                         // is from escaping the '<'.
 624                         ']]>' => '\5D\5D\3E '
 625                 ] );
 626
 627                 if ( preg_match( '/[<&]/', $contents ) ) {
 628                         $contents = "/*<![CDATA[*/$contents/*]]>*/";
 629                 }
 630
 631                 return self::rawElement( 'style', [
 632                         'media' => $media,
 633                 ], $contents );
 634         }
 635
 636         /**
 637          * Output a "<link rel=stylesheet>" linking to the given URL for the given
 638          * media type (if any).
 639          *
 640          * @param string $url
 641          * @param string $media A media type string, like 'screen'
 642          * @return string Raw HTML
 643          */
 644         public static function linkedStyle( $url, $media = 'all' ) {
 645                 return self::element( 'link', [
 646                         'rel' => 'stylesheet',
 647                         'href' => $url,
 648                         'media' => $media,
 649                 ] );
 650         }
 651
 652         /**
 653          * Convenience function to produce an "<input>" element.  This supports the
 654          * new HTML5 input types and attributes.
 655          *
 656          * @param string $name Name attribute
 657          * @param string $value Value attribute
 658          * @param string $type Type attribute
 659          * @param array $attribs Associative array of miscellaneous extra
 660          *   attributes, passed to Html::element()
 661          * @return string Raw HTML
 662          */
 663         public static function input( $name, $value = '', $type = 'text', array $attribs = [] ) {
 664                 $attribs['type'] = $type;
 665                 $attribs['value'] = $value;
 666                 $attribs['name'] = $name;
 667                 if ( in_array( $type, [ 'text', 'search', 'email', 'password', 'number' ] ) ) {
 668                         $attribs = self::getTextInputAttributes( $attribs );
 669                 }
 670                 if ( in_array( $type, [ 'button', 'reset', 'submit' ] ) ) {
 671                         $attribs = self::buttonAttributes( $attribs );
 672                 }
 673                 return self::element( 'input', $attribs );
 674         }
 675
 676         /**
 677          * Convenience function to produce a checkbox (input element with type=checkbox)
 678          *
 679          * @param string $name Name attribute
 680          * @param bool $checked Whether the checkbox is checked or not
 681          * @param array $attribs Array of additional attributes
 682          * @return string Raw HTML
 683          */
 684         public static function check( $name, $checked = false, array $attribs = [] ) {
 685                 if ( isset( $attribs['value'] ) ) {
 686                         $value = $attribs['value'];
 687                         unset( $attribs['value'] );
 688                 } else {
 689                         $value = 1;
 690                 }
 691
 692                 if ( $checked ) {
 693                         $attribs[] = 'checked';
 694                 }
 695
 696                 return self::input( $name, $value, 'checkbox', $attribs );
 697         }
 698
 699         /**
 700          * Convenience function to produce a radio button (input element with type=radio)
 701          *
 702          * @param string $name Name attribute
 703          * @param bool $checked Whether the radio button is checked or not
 704          * @param array $attribs Array of additional attributes
 705          * @return string Raw HTML
 706          */
 707         public static function radio( $name, $checked = false, array $attribs = [] ) {
 708                 if ( isset( $attribs['value'] ) ) {
 709                         $value = $attribs['value'];
 710                         unset( $attribs['value'] );
 711                 } else {
 712                         $value = 1;
 713                 }
 714
 715                 if ( $checked ) {
 716                         $attribs[] = 'checked';
 717                 }
 718
 719                 return self::input( $name, $value, 'radio', $attribs );
 720         }
 721
 722         /**
 723          * Convenience function for generating a label for inputs.
 724          *
 725          * @param string $label Contents of the label
 726          * @param string $id ID of the element being labeled
 727          * @param array $attribs Additional attributes
 728          * @return string Raw HTML
 729          */
 730         public static function label( $label, $id, array $attribs = [] ) {
 731                 $attribs += [
 732                         'for' => $id
 733                 ];
 734                 return self::element( 'label', $attribs, $label );
 735         }
 736
 737         /**
 738          * Convenience function to produce an input element with type=hidden
 739          *
 740          * @param string $name Name attribute
 741          * @param string $value Value attribute
 742          * @param array $attribs Associative array of miscellaneous extra
 743          *   attributes, passed to Html::element()
 744          * @return string Raw HTML
 745          */
 746         public static function hidden( $name, $value, array $attribs = [] ) {
 747                 return self::input( $name, $value, 'hidden', $attribs );
 748         }
 749
 750         /**
 751          * Convenience function to produce a <textarea> element.
 752          *
 753          * This supports leaving out the cols= and rows= which Xml requires and are
 754          * required by HTML4/XHTML but not required by HTML5.
 755          *
 756          * @param string $name Name attribute
 757          * @param string $value Value attribute
 758          * @param array $attribs Associative array of miscellaneous extra
 759          *   attributes, passed to Html::element()
 760          * @return string Raw HTML
 761          */
 762         public static function textarea( $name, $value = '', array $attribs = [] ) {
 763                 $attribs['name'] = $name;
 764
 765                 if ( substr( $value, 0, 1 ) == "\n" ) {
 766                         // Workaround for T14130: browsers eat the initial newline
 767                         // assuming that it's just for show, but they do keep the later
 768                         // newlines, which we may want to preserve during editing.
 769                         // Prepending a single newline
 770                         $spacedValue = "\n" . $value;
 771                 } else {
 772                         $spacedValue = $value;
 773                 }
 774                 return self::element( 'textarea', self::getTextInputAttributes( $attribs ), $spacedValue );
 775         }
 776
 777         /**
 778          * Helper for Html::namespaceSelector().
 779          * @param array $params See Html::namespaceSelector()
 780          * @return array
 781          */
 782         public static function namespaceSelectorOptions( array $params = [] ) {
 783                 global $wgContLang;
 784
 785                 $options = [];
 786
 787                 if ( !isset( $params['exclude'] ) || !is_array( $params['exclude'] ) ) {
 788                         $params['exclude'] = [];
 789                 }
 790
 791                 if ( isset( $params['all'] ) ) {
 792                         // add an option that would let the user select all namespaces.
 793                         // Value is provided by user, the name shown is localized for the user.
 794                         $options[$params['all']] = wfMessage( 'namespacesall' )->text();
 795                 }
 796                 // Add all namespaces as options (in the content language)
 797                 $options += $wgContLang->getFormattedNamespaces();
 798
 799                 $optionsOut = [];
 800                 // Filter out namespaces below 0 and massage labels
 801                 foreach ( $options as $nsId => $nsName ) {
 802                         if ( $nsId < NS_MAIN || in_array( $nsId, $params['exclude'] ) ) {
 803                                 continue;
 804                         }
 805                         if ( $nsId === NS_MAIN ) {
 806                                 // For other namespaces use the namespace prefix as label, but for
 807                                 // main we don't use "" but the user message describing it (e.g. "(Main)" or "(Article)")
 808                                 $nsName = wfMessage( 'blanknamespace' )->text();
 809                         } elseif ( is_int( $nsId ) ) {
 810                                 $nsName = $wgContLang->convertNamespace( $nsId );
 811                         }
 812                         $optionsOut[$nsId] = $nsName;
 813                 }
 814
 815                 return $optionsOut;
 816         }
 817
 818         /**
 819          * Build a drop-down box for selecting a namespace
 820          *
 821          * @param array $params Params to set.
 822          * - selected: [optional] Id of namespace which should be pre-selected
 823          * - all: [optional] Value of item for "all namespaces". If null or unset,
 824          *   no "<option>" is generated to select all namespaces.
 825          * - label: text for label to add before the field.
 826          * - exclude: [optional] Array of namespace ids to exclude.
 827          * - disable: [optional] Array of namespace ids for which the option should
 828          *   be disabled in the selector.
 829          * @param array $selectAttribs HTML attributes for the generated select element.
 830          * - id:   [optional], default: 'namespace'.
 831          * - name: [optional], default: 'namespace'.
 832          * @return string HTML code to select a namespace.
 833          */
 834         public static function namespaceSelector( array $params = [],
 835                 array $selectAttribs = []
 836         ) {
 837                 ksort( $selectAttribs );
 838
 839                 // Is a namespace selected?
 840                 if ( isset( $params['selected'] ) ) {
 841                         // If string only contains digits, convert to clean int. Selected could also
 842                         // be "all" or "" etc. which needs to be left untouched.
 843                         // PHP is_numeric() has issues with large strings, PHP ctype_digit has other issues
 844                         // and returns false for already clean ints. Use regex instead..
 845                         if ( preg_match( '/^\d+$/', $params['selected'] ) ) {
 846                                 $params['selected'] = intval( $params['selected'] );
 847                         }
 848                         // else: leaves it untouched for later processing
 849                 } else {
 850                         $params['selected'] = '';
 851                 }
 852
 853                 if ( !isset( $params['disable'] ) || !is_array( $params['disable'] ) ) {
 854                         $params['disable'] = [];
 855                 }
 856
 857                 // Associative array between option-values and option-labels
 858                 $options = self::namespaceSelectorOptions( $params );
 859
 860                 // Convert $options to HTML
 861                 $optionsHtml = [];
 862                 foreach ( $options as $nsId => $nsName ) {
 863                         $optionsHtml[] = self::element(
 864                                 'option', [
 865                                         'disabled' => in_array( $nsId, $params['disable'] ),
 866                                         'value' => $nsId,
 867                                         'selected' => $nsId === $params['selected'],
 868                                 ], $nsName
 869                         );
 870                 }
 871
 872                 if ( !array_key_exists( 'id', $selectAttribs ) ) {
 873                         $selectAttribs['id'] = 'namespace';
 874                 }
 875
 876                 if ( !array_key_exists( 'name', $selectAttribs ) ) {
 877                         $selectAttribs['name'] = 'namespace';
 878                 }
 879
 880                 $ret = '';
 881                 if ( isset( $params['label'] ) ) {
 882                         $ret .= self::element(
 883                                 'label', [
 884                                         'for' => isset( $selectAttribs['id'] ) ? $selectAttribs['id'] : null,
 885                                 ], $params['label']
 886                         ) . '&#160;';
 887                 }
 888
 889                 // Wrap options in a <select>
 890                 $ret .= self::openElement( 'select', $selectAttribs )
 891                         . "\n"
 892                         . implode( "\n", $optionsHtml )
 893                         . "\n"
 894                         . self::closeElement( 'select' );
 895
 896                 return $ret;
 897         }
 898
 899         /**
 900          * Constructs the opening html-tag with necessary doctypes depending on
 901          * global variables.
 902          *
 903          * @param array $attribs Associative array of miscellaneous extra
 904          *   attributes, passed to Html::element() of html tag.
 905          * @return string Raw HTML
 906          */
 907         public static function htmlHeader( array $attribs = [] ) {
 908                 $ret = '';
 909
 910                 global $wgHtml5Version, $wgMimeType, $wgXhtmlNamespaces;
 911
 912                 $isXHTML = self::isXmlMimeType( $wgMimeType );
 913
 914                 if ( $isXHTML ) { // XHTML5
 915                         // XML MIME-typed markup should have an xml header.
 916                         // However a DOCTYPE is not needed.
 917                         $ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?" . ">\n";
 918
 919                         // Add the standard xmlns
 920                         $attribs['xmlns'] = 'http://www.w3.org/1999/xhtml';
 921
 922                         // And support custom namespaces
 923                         foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
 924                                 $attribs["xmlns:$tag"] = $ns;
 925                         }
 926                 } else { // HTML5
 927                         // DOCTYPE
 928                         $ret .= "<!DOCTYPE html>\n";
 929                 }
 930
 931                 if ( $wgHtml5Version ) {
 932                         $attribs['version'] = $wgHtml5Version;
 933                 }
 934
 935                 $ret .= self::openElement( 'html', $attribs );
 936
 937                 return $ret;
 938         }
 939
 940         /**
 941          * Determines if the given MIME type is xml.
 942          *
 943          * @param string $mimetype MIME type
 944          * @return bool
 945          */
 946         public static function isXmlMimeType( $mimetype ) {
 947                 # https://html.spec.whatwg.org/multipage/infrastructure.html#xml-mime-type
 948                 # * text/xml
 949                 # * application/xml
 950                 # * Any MIME type with a subtype ending in +xml (this implicitly includes application/xhtml+xml)
 951                 return (bool)preg_match( '!^(text|application)/xml$|^.+/.+\+xml$!', $mimetype );
 952         }
 953
 954         /**
 955          * Get HTML for an info box with an icon.
 956          *
 957          * @param string $text Wikitext, get this with wfMessage()->plain()
 958          * @param string $icon Path to icon file (used as 'src' attribute)
 959          * @param string $alt Alternate text for the icon
 960          * @param string $class Additional class name to add to the wrapper div
 961          *
 962          * @return string
 963          */
 964         static function infoBox( $text, $icon, $alt, $class = '' ) {
 965                 $s = self::openElement( 'div', [ 'class' => "mw-infobox $class" ] );
 966
 967                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-left' ] ) .
 968                                 self::element( 'img',
 969                                         [
 970                                                 'src' => $icon,
 971                                                 'alt' => $alt,
 972                                         ]
 973                                 ) .
 974                                 self::closeElement( 'div' );
 975
 976                 $s .= self::openElement( 'div', [ 'class' => 'mw-infobox-right' ] ) .
 977                                 $text .
 978                                 self::closeElement( 'div' );
 979                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
 980
 981                 $s .= self::closeElement( 'div' );
 982
 983                 $s .= self::element( 'div', [ 'style' => 'clear: left;' ], ' ' );
 984
 985                 return $s;
 986         }
 987
 988         /**
 989          * Generate a srcset attribute value.
 990          *
 991          * Generates a srcset attribute value from an array mapping pixel densities
 992          * to URLs. A trailing 'x' in pixel density values is optional.
 993          *
 994          * @note srcset width and height values are not supported.
 995          *
 996          * @see https://html.spec.whatwg.org/#attr-img-srcset
 997          *
 998          * @par Example:
 999          * @code
1000          *     Html::srcSet( [
1001          *         '1x'   => 'standard.jpeg',
1002          *         '1.5x' => 'large.jpeg',
1003          *         '3x'   => 'extra-large.jpeg',
1004          *     ] );
1005          *     // gives 'standard.jpeg 1x, large.jpeg 1.5x, extra-large.jpeg 2x'
1006          * @endcode
1007          *
1008          * @param string[] $urls
1009          * @return string
1010          */
1011         static function srcSet( array $urls ) {
1012                 $candidates = [];
1013                 foreach ( $urls as $density => $url ) {
1014                         // Cast density to float to strip 'x', then back to string to serve
1015                         // as array index.
1016                         $density = (string)(float)$density;
1017                         $candidates[$density] = $url;
1018                 }
1019
1020                 // Remove duplicates that are the same as a smaller value
1021                 ksort( $candidates, SORT_NUMERIC );
1022                 $candidates = array_unique( $candidates );
1023
1024                 // Append density info to the url
1025                 foreach ( $candidates as $density => $url ) {
1026                         $candidates[$density] = $url . ' ' . $density . 'x';
1027                 }
1028
1029                 return implode( ", ", $candidates );
1030         }
1031 }