(bug 33321. Sort of) Adding a line to MediaWiki:Sidebar that contains a pipe, but...

[mediawiki.git] / includes / Html.php

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

/**
 * This class is a collection of static functions that serve two purposes:
 *
 * 1) Implement any algorithms specified by HTML5, or other HTML
 * specifications, in a convenient and self-contained way.
 *
 * 2) Allow HTML elements to be conveniently and safely generated, like the
 * current Xml class but a) less confused (Xml supports HTML-specific things,
 * but only sometimes!) and b) not necessarily confined to XML-compatible
 * output.
 *
 * There are two important configuration options this class uses:
 *
 * $wgHtml5: If this is set to false, then all output should be valid XHTML 1.0
 *     Transitional.
 * $wgWellFormedXml: If this is set to true, then all output should be
 *     well-formed XML (quotes on attributes, self-closing tags, etc.).
 *
 * This class is meant to be confined to utility functions that are called from
 * trusted code paths.  It does not do enforcement of policy like not allowing
 * <a> elements.
 *
 * @since 1.16
 */
class Html {
        # List of void elements from HTML5, section 8.1.2 as of 2011-08-12
        private static $voidElements = array(
                'area',
                'base',
                'br',
                'col',
                'command',
                'embed',
                'hr',
                'img',
                'input',
                'keygen',
                'link',
                'meta',
                'param',
                'source',
                'track',
                'wbr',
        );

        # Boolean attributes, which may have the value omitted entirely.  Manually
        # collected from the HTML5 spec as of 2011-08-12.
        private static $boolAttribs = array(
                'async',
                'autofocus',
                'autoplay',
                'checked',
                'controls',
                'default',
                'defer',
                'disabled',
                'formnovalidate',
                'hidden',
                'ismap',
                'itemscope',
                'loop',
                'multiple',
                'muted',
                'novalidate',
                'open',
                'pubdate',
                'readonly',
                'required',
                'reversed',
                'scoped',
                'seamless',
                'selected',
                'truespeed',
                'typemustmatch',
                # HTML5 Microdata
                'itemscope',
        );

        private static $HTMLFiveOnlyAttribs = array(
                'autocomplete',
                'autofocus',
                'max',
                'min',
                'multiple',
                'pattern',
                'placeholder',
                'required',
                'step',
                'spellcheck',
        );

        /**
         * Returns an HTML element in a string.  The major advantage here over
         * manually typing out the HTML is that it will escape all attribute
         * values.  If you're hardcoding all the attributes, or there are none, you
         * should probably just type out the html element yourself.
         *
         * This is quite similar to Xml::tags(), but it implements some useful
         * HTML-specific logic.  For instance, there is no $allowShortTag
         * parameter: the closing tag is magically omitted if $element has an empty
         * content model.  If $wgWellFormedXml is false, then a few bytes will be
         * shaved off the HTML output as well.
         *
         * @param $element string The element's name, e.g., 'a'
         * @param $attribs array  Associative array of attributes, e.g., array(
         *   'href' => 'http://www.mediawiki.org/' ). See expandAttributes() for
         *   further documentation.
         * @param $contents string The raw HTML contents of the element: *not*
         *   escaped!
         * @return string Raw HTML
         */
        public static function rawElement( $element, $attribs = array(), $contents = '' ) {
                global $wgWellFormedXml;
                $start = self::openElement( $element, $attribs );
                if ( in_array( $element, self::$voidElements ) ) {
                        if ( $wgWellFormedXml ) {
                                # Silly XML.
                                return substr( $start, 0, -1 ) . ' />';
                        }
                        return $start;
                } else {
                        return "$start$contents" . self::closeElement( $element );
                }
        }

        /**
         * Identical to rawElement(), but HTML-escapes $contents (like
         * Xml::element()).
         *
         * @param $element string
         * @param $attribs array
         * @param $contents string
         *
         * @return string
         */
        public static function element( $element, $attribs = array(), $contents = '' ) {
                return self::rawElement( $element, $attribs, strtr( $contents, array(
                        # There's no point in escaping quotes, >, etc. in the contents of
                        # elements.
                        '&' => '&amp;',
                        '<' => '&lt;'
                ) ) );
        }

        /**
         * Identical to rawElement(), but has no third parameter and omits the end
         * tag (and the self-closing '/' in XML mode for empty elements).
         *
         * @param $element string
         * @param $attribs array
         *
         * @return string
         */
        public static function openElement( $element, $attribs = array() ) {
                global $wgHtml5, $wgWellFormedXml;
                $attribs = (array)$attribs;
                # This is not required in HTML5, but let's do it anyway, for
                # consistency and better compression.
                $element = strtolower( $element );

                # In text/html, initial <html> and <head> tags can be omitted under
                # pretty much any sane circumstances, if they have no attributes.  See:
                # <http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#optional-tags>
                if ( !$wgWellFormedXml && !$attribs
                && in_array( $element, array( 'html', 'head' ) ) ) {
                        return '';
                }

                # Remove HTML5-only attributes if we aren't doing HTML5, and disable
                # form validation regardless (see bug 23769 and the more detailed
                # comment in expandAttributes())
                if ( $element == 'input' ) {
                        # Whitelist of types that don't cause validation.  All except
                        # 'search' are valid in XHTML1.
                        $validTypes = array(
                                'hidden',
                                'text',
                                'password',
                                'checkbox',
                                'radio',
                                'file',
                                'submit',
                                'image',
                                'reset',
                                'button',
                                'search',
                        );

                        if ( isset( $attribs['type'] )
                        && !in_array( $attribs['type'], $validTypes ) ) {
                                unset( $attribs['type'] );
                        }

                        if ( isset( $attribs['type'] ) && $attribs['type'] == 'search'
                        && !$wgHtml5 ) {
                                unset( $attribs['type'] );
                        }
                }

                if ( !$wgHtml5 && $element == 'textarea' && isset( $attribs['maxlength'] ) ) {
                        unset( $attribs['maxlength'] );
                }

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

        /**
         * Returns "</$element>", except if $wgWellFormedXml is off, in which case
         * it returns the empty string when that's guaranteed to be safe.
         *
         * @since 1.17
         * @param $element string Name of the element, e.g., 'a'
         * @return string A closing tag, if required
         */
        public static function closeElement( $element ) {
                global $wgWellFormedXml;

                $element = strtolower( $element );

                # Reference:
                # http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#optional-tags
                if ( !$wgWellFormedXml && in_array( $element, array(
                        'html',
                        'head',
                        'body',
                        'li',
                        'dt',
                        'dd',
                        'tr',
                        'td',
                        'th',
                ) ) ) {
                        return '';
                }
                return "</$element>";
        }

        /**
         * Given an element name and an associative array of element attributes,
         * return an array that is functionally identical to the input array, but
         * possibly smaller.  In particular, attributes might be stripped if they
         * are given their default values.
         *
         * This method is not guaranteed to remove all redundant attributes, only
         * some common ones and some others selected arbitrarily at random.  It
         * only guarantees that the output array should be functionally identical
         * to the input array (currently per the HTML 5 draft as of 2009-09-06).
         *
         * @param $element string Name of the element, e.g., 'a'
         * @param $attribs array  Associative array of attributes, e.g., array(
         *   'href' => 'http://www.mediawiki.org/' ).  See expandAttributes() for
         *   further documentation.
         * @return array An array of attributes functionally identical to $attribs
         */
        private static function dropDefaults( $element, $attribs ) {
                # Don't bother doing anything if we aren't outputting HTML5; it's too
                # much of a pain to maintain two sets of defaults.
                global $wgHtml5;
                if ( !$wgHtml5 ) {
                        return $attribs;
                }

                static $attribDefaults = array(
                        'area' => array( 'shape' => 'rect' ),
                        'button' => array(
                                'formaction' => 'GET',
                                'formenctype' => 'application/x-www-form-urlencoded',
                                'type' => 'submit',
                        ),
                        'canvas' => array(
                                'height' => '150',
                                'width' => '300',
                        ),
                        'command' => array( 'type' => 'command' ),
                        'form' => array(
                                'action' => 'GET',
                                'autocomplete' => 'on',
                                'enctype' => 'application/x-www-form-urlencoded',
                        ),
                        'input' => array(
                                'formaction' => 'GET',
                                'type' => 'text',
                                'value' => '',
                        ),
                        'keygen' => array( 'keytype' => 'rsa' ),
                        'link' => array( 'media' => 'all' ),
                        'menu' => array( 'type' => 'list' ),
                        # Note: the use of text/javascript here instead of other JavaScript
                        # MIME types follows the HTML5 spec.
                        'script' => array( 'type' => 'text/javascript' ),
                        'style' => array(
                                'media' => 'all',
                                'type' => 'text/css',
                        ),
                        'textarea' => array( 'wrap' => 'soft' ),
                );

                $element = strtolower( $element );

                foreach ( $attribs as $attrib => $value ) {
                        $lcattrib = strtolower( $attrib );
                        $value = strval( $value );

                        # Simple checks using $attribDefaults
                        if ( isset( $attribDefaults[$element][$lcattrib] ) &&
                        $attribDefaults[$element][$lcattrib] == $value ) {
                                unset( $attribs[$attrib] );
                        }

                        if ( $lcattrib == 'class' && $value == '' ) {
                                unset( $attribs[$attrib] );
                        }
                }

                # More subtle checks
                if ( $element === 'link' && isset( $attribs['type'] )
                && strval( $attribs['type'] ) == 'text/css' ) {
                        unset( $attribs['type'] );
                }
                if ( $element === 'select' && isset( $attribs['size'] ) ) {
                        if ( in_array( 'multiple', $attribs )
                                || ( isset( $attribs['multiple'] ) && $attribs['multiple'] !== false )
                        ) {
                                # A multi-select
                                if ( strval( $attribs['size'] ) == '4' ) {
                                        unset( $attribs['size'] );
                                }
                        } else {
                                # Single select
                                if ( strval( $attribs['size'] ) == '1' ) {
                                        unset( $attribs['size'] );
                                }
                        }
                }

                return $attribs;
        }

        /**
         * Given an associative array of element attributes, generate a string
         * to stick after the element name in HTML output.  Like array( 'href' =>
         * 'http://www.mediawiki.org/' ) becomes something like
         * ' href="http://www.mediawiki.org"'.  Again, this is like
         * Xml::expandAttributes(), but it implements some HTML-specific logic.
         * For instance, it will omit quotation marks if $wgWellFormedXml is false,
         * and will treat boolean attributes specially.
         *
         * Attributes that should contain space-separated lists (such as 'class') array
         * values are allowed as well, which will automagically be normalized
         * and converted to a space-separated string. In addition to a numerical
         * array, the attribute value may also be an associative array. See the
         * example below for how that works.
         * @example Numerical array
         * <code>
         *     Html::element( 'em', array(
         *         'class' => array( 'foo', 'bar' )
         *     ) );
         *     // gives '<em class="foo bar"></em>'
         * </code>
         * @example Associative array
         * <code>
         *     Html::element( 'em', array(
         *         'class' => array( 'foo', 'bar', 'foo' => false, 'quux' => true )
         *     ) );
         *     // gives '<em class="bar quux"></em>'
         * </code>
         *
         * @param $attribs array Associative array of attributes, e.g., array(
         *   'href' => 'http://www.mediawiki.org/' ).  Values will be HTML-escaped.
         *   A value of false means to omit the attribute.  For boolean attributes,
         *   you can omit the key, e.g., array( 'checked' ) instead of
         *   array( 'checked' => 'checked' ) or such.
         * @return string HTML fragment that goes between element name and '>'
         *   (starting with a space if at least one attribute is output)
         */
        public static function expandAttributes( $attribs ) {
                global $wgHtml5, $wgWellFormedXml;

                $ret = '';
                $attribs = (array)$attribs;
                foreach ( $attribs as $key => $value ) {
                        if ( $value === false || is_null( $value ) ) {
                                continue;
                        }

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

                        # Not technically required in HTML5, but required in XHTML 1.0,
                        # and we'd like consistency and better compression anyway.
                        $key = strtolower( $key );

                        # Here we're blacklisting some HTML5-only attributes...
                        if ( !$wgHtml5 && in_array( $key, self::$HTMLFiveOnlyAttribs )
                         ) {
                                continue;
                        }

                        # Bug 23769: Blacklist all form validation attributes for now.  Current
                        # (June 2010) WebKit has no UI, so the form just refuses to submit
                        # without telling the user why, which is much worse than failing
                        # server-side validation.  Opera is the only other implementation at
                        # this time, and has ugly UI, so just kill the feature entirely until
                        # we have at least one good implementation.
                        if ( in_array( $key, array( 'max', 'min', 'pattern', 'required', 'step' ) ) ) {
                                continue;
                        }

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

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

                                // Convert into correct array. Array can contain space-seperated
                                // values. Implode/explode to get those into the main array as well.
                                if ( is_array( $value ) ) {
                                        // If input wasn't an array, we can skip this step
                                        
                                        $newValue = array();
                                        foreach ( $value as $k => $v ) {
                                                if ( is_string( $v ) ) {
                                                        // String values should be normal `array( 'foo' )`
                                                        // Just append them
                                                        if ( !isset( $value[$v] ) ) {
                                                                // As a special case don't set 'foo' if a
                                                                // separate 'foo' => true/false exists in the array
                                                                // keys should be authoritive
                                                                $newValue[] = $v;
                                                        }
                                                } elseif ( $v ) {
                                                        // If the value is truthy but not a string this is likely
                                                        // an array( 'foo' => true ), falsy values don't add strings
                                                        $newValue[] = $k;
                                                }
                                        }
                                        $value = implode( ' ', $newValue );
                                }
                                $value = explode( ' ', $value );

                                // Normalize spacing by fixing up cases where people used
                                // more than 1 space and/or a trailing/leading space
                                $value = array_diff( $value, array( '', ' ' ) );

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

                        # See the "Attributes" section in the HTML syntax part of HTML5,
                        # 9.1.2.3 as of 2009-08-10.  Most attributes can have quotation
                        # marks omitted, but not all.  (Although a literal " is not
                        # permitted, we don't check for that, since it will be escaped
                        # anyway.)
                        #
                        # See also research done on further characters that need to be
                        # escaped: http://code.google.com/p/html5lib/issues/detail?id=93
                        $badChars = "\\x00- '=<>`/\x{00a0}\x{1680}\x{180e}\x{180F}\x{2000}\x{2001}"
                                . "\x{2002}\x{2003}\x{2004}\x{2005}\x{2006}\x{2007}\x{2008}\x{2009}"
                                . "\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}";
                        if ( $wgWellFormedXml || $value === ''
                        || preg_match( "![$badChars]!u", $value ) ) {
                                $quote = '"';
                        } else {
                                $quote = '';
                        }

                        if ( in_array( $key, self::$boolAttribs ) ) {
                                # In XHTML 1.0 Transitional, the value needs to be equal to the
                                # key.  In HTML5, we can leave the value empty instead.  If we
                                # don't need well-formed XML, we can omit the = entirely.
                                if ( !$wgWellFormedXml ) {
                                        $ret .= " $key";
                                } elseif ( $wgHtml5 ) {
                                        $ret .= " $key=\"\"";
                                } else {
                                        $ret .= " $key=\"$key\"";
                                }
                        } else {
                                # Apparently we need to entity-encode \n, \r, \t, although the
                                # spec doesn't mention that.  Since we're doing strtr() anyway,
                                # and we don't need <> escaped here, we may as well not call
                                # htmlspecialchars().
                                # @todo FIXME: Verify that we actually need to
                                # escape \n\r\t here, and explain why, exactly.
                                #
                                # We could call Sanitizer::encodeAttribute() for this, but we
                                # don't because we're stubborn and like our marginal savings on
                                # byte size from not having to encode unnecessary quotes.
                                $map = array(
                                        '&' => '&amp;',
                                        '"' => '&quot;',
                                        "\n" => '&#10;',
                                        "\r" => '&#13;',
                                        "\t" => '&#9;'
                                );
                                if ( $wgWellFormedXml ) {
                                        # This is allowed per spec: <http://www.w3.org/TR/xml/#NT-AttValue>
                                        # But reportedly it breaks some XML tools?
                                        # @todo FIXME: Is this really true?
                                        $map['<'] = '&lt;';
                                }
                                
                                $ret .= " $key=$quote" . strtr( $value, $map ) . $quote;
                        }
                }
                return $ret;
        }

        /**
         * Output a <script> tag with the given contents.  TODO: do some useful
         * escaping as well, like if $contents contains literal '</script>' or (for
         * XML) literal "]]>".
         *
         * @param $contents string JavaScript
         * @return string Raw HTML
         */
        public static function inlineScript( $contents ) {
                global $wgHtml5, $wgJsMimeType, $wgWellFormedXml;

                $attrs = array();

                if ( !$wgHtml5 ) {
                        $attrs['type'] = $wgJsMimeType;
                }

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

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

        /**
         * Output a <script> tag linking to the given URL, e.g.,
         * <script src=foo.js></script>.
         *
         * @param $url string
         * @return string Raw HTML
         */
        public static function linkedScript( $url ) {
                global $wgHtml5, $wgJsMimeType;

                $attrs = array( 'src' => $url );

                if ( !$wgHtml5 ) {
                        $attrs['type'] = $wgJsMimeType;
                }

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

        /**
         * Output a <style> tag with the given contents for the given media type
         * (if any).  TODO: do some useful escaping as well, like if $contents
         * contains literal '</style>' (admittedly unlikely).
         *
         * @param $contents string CSS
         * @param $media mixed A media type string, like 'screen'
         * @return string Raw HTML
         */
        public static function inlineStyle( $contents, $media = 'all' ) {
                global $wgWellFormedXml;

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

                return self::rawElement( 'style', array(
                        'type' => 'text/css',
                        'media' => $media,
                ), $contents );
        }

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

        /**
         * Convenience function to produce an <input> element.  This supports the
         * new HTML5 input types and attributes, and will silently strip them if
         * $wgHtml5 is false.
         *
         * @param $name    string name attribute
         * @param $value   mixed  value attribute
         * @param $type    string type attribute
         * @param $attribs array  Associative array of miscellaneous extra
         *   attributes, passed to Html::element()
         * @return string Raw HTML
         */
        public static function input( $name, $value = '', $type = 'text', $attribs = array() ) {
                $attribs['type'] = $type;
                $attribs['value'] = $value;
                $attribs['name'] = $name;

                return self::element( 'input', $attribs );
        }

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

        /**
         * Convenience function to produce an <input> element.  This supports leaving
         * out the cols= and rows= which Xml requires and are required by HTML4/XHTML
         * but not required by HTML5 and will silently set cols="" and rows="" if
         * $wgHtml5 is false and cols and rows are omitted (HTML4 validates present
         * but empty cols="" and rows="" as valid).
         *
         * @param $name    string name attribute
         * @param $value   string value attribute
         * @param $attribs array  Associative array of miscellaneous extra
         *   attributes, passed to Html::element()
         * @return string Raw HTML
         */
        public static function textarea( $name, $value = '', $attribs = array() ) {
                global $wgHtml5;

                $attribs['name'] = $name;

                if ( !$wgHtml5 ) {
                        if ( !isset( $attribs['cols'] ) ) {
                                $attribs['cols'] = "";
                        }

                        if ( !isset( $attribs['rows'] ) ) {
                                $attribs['rows'] = "";
                        }
                }

                if (substr($value, 0, 1) == "\n") {
                        // Workaround for bug 12130: browsers eat the initial newline
                        // assuming that it's just for show, but they do keep the later
                        // newlines, which we may want to preserve during editing.
                        // Prepending a single newline
                        $spacedValue = "\n" . $value;
                } else {
                        $spacedValue = $value;
                }
                return self::element( 'textarea', $attribs, $spacedValue );
        }

        /**
         * Constructs the opening html-tag with necessary doctypes depending on
         * global variables.
         *
         * @param $attribs array  Associative array of miscellaneous extra
         *   attributes, passed to Html::element() of html tag.
         * @return string  Raw HTML
         */
        public static function htmlHeader( $attribs = array() ) {
                $ret = '';

                global $wgMimeType;

                if ( self::isXmlMimeType( $wgMimeType ) ) {
                        $ret .= "<?xml version=\"1.0\" encoding=\"UTF-8\" ?" . ">\n";
                }

                global $wgHtml5, $wgHtml5Version, $wgDocType, $wgDTD;
                global $wgXhtmlNamespaces, $wgXhtmlDefaultNamespace;

                if ( $wgHtml5 ) {
                        $ret .= "<!DOCTYPE html>\n";

                        if ( $wgHtml5Version ) {
                                $attribs['version'] = $wgHtml5Version;
                        }
                } else {
                        $ret .= "<!DOCTYPE html PUBLIC \"$wgDocType\" \"$wgDTD\">\n";
                        $attribs['xmlns'] = $wgXhtmlDefaultNamespace;

                        foreach ( $wgXhtmlNamespaces as $tag => $ns ) {
                                $attribs["xmlns:$tag"] = $ns;
                        }
                }

                $html = Html::openElement( 'html', $attribs );

                if ( $html ) {
                        $html .= "\n";
                }

                $ret .= $html;

                return $ret;
        }

        /**
         * Determines if the given mime type is xml.
         *
         * @param $mimetype    string MimeType
         * @return Boolean
         */
        public static function isXmlMimeType( $mimetype ) {
                switch ( $mimetype ) {
                        case 'text/xml':
                        case 'application/xhtml+xml':
                        case 'application/xml':
                                return true;
                        default:
                                return false;
                }
        }

        /**
         * Get HTML for an info box with an icon.
         *
         * @param $text String: wikitext, get this with wfMsgNoTrans()
         * @param $icon String: icon name, file in skins/common/images
         * @param $alt String: alternate text for the icon
         * @param $class String: additional class name to add to the wrapper div
         * @param $useStylePath
         *
         * @return string
         */
        static function infoBox( $text, $icon, $alt, $class = false, $useStylePath = true ) {
                global $wgStylePath;

                if ( $useStylePath ) {
                        $icon = $wgStylePath.'/common/images/'.$icon;
                }

                $s  = Html::openElement( 'div', array( 'class' => "mw-infobox $class") );

                $s .= Html::openElement( 'div', array( 'class' => 'mw-infobox-left' ) ).
                                Html::element( 'img',
                                        array(
                                                'src' => $icon,
                                                'alt' => $alt,
                                        )
                                ).
                                Html::closeElement( 'div' );

                $s .= Html::openElement( 'div', array( 'class' => 'mw-infobox-right' ) ).
                                $text.
                                Html::closeElement( 'div' );
                $s .= Html::element( 'div', array( 'style' => 'clear: left;' ), ' ' );

                $s .= Html::closeElement( 'div' );

                $s .= Html::element( 'div', array( 'style' => 'clear: left;' ), ' ' );

                return $s;
        }
}