lib/filterlib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * Library functions for managing text filter plugins.
  20  *
  21  * @package    core
  22  * @subpackage filter
  23  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /** The states a filter can be in, stored in the filter_active table. */
  30 define('TEXTFILTER_ON', 1);
  31 /** The states a filter can be in, stored in the filter_active table. */
  32 define('TEXTFILTER_INHERIT', 0);
  33 /** The states a filter can be in, stored in the filter_active table. */
  34 define('TEXTFILTER_OFF', -1);
  35 /** The states a filter can be in, stored in the filter_active table. */
  36 define('TEXTFILTER_DISABLED', -9999);
  37
  38 /**
  39  * Define one exclusive separator that we'll use in the temp saved tags
  40  *  keys. It must be something rare enough to avoid having matches with
  41  *  filterobjects. MDL-18165
  42  */
  43 define('TEXTFILTER_EXCL_SEPARATOR', '-%-');
  44
  45
  46 /**
  47  * Class to manage the filtering of strings. It is intended that this class is
  48  * only used by weblib.php. Client code should probably be using the
  49  * format_text and format_string functions.
  50  *
  51  * This class is a singleton.
  52  *
  53  * @package    core
  54  * @subpackage filter
  55  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  56  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  57  */
  58 class filter_manager {
  59     /**
  60      * @var array This list of active filters, by context, for filtering content.
  61      * An array contextid => array of filter objects.
  62      */
  63     protected $textfilters = array();
  64
  65     /**
  66      * @var array This list of active filters, by context, for filtering strings.
  67      * An array contextid => array of filter objects.
  68      */
  69     protected $stringfilters = array();
  70
  71     /** @var array Exploded version of $CFG->stringfilters. */
  72     protected $stringfilternames = array();
  73
  74     /** @var object Holds the singleton instance. */
  75     protected static $singletoninstance;
  76
  77     protected function __construct() {
  78         $this->stringfilternames = filter_get_string_filters();
  79     }
  80
  81     /**
  82      * @return filter_manager the singleton instance.
  83      */
  84     public static function instance() {
  85         global $CFG;
  86         if (is_null(self::$singletoninstance)) {
  87             if (!empty($CFG->perfdebug)) {
  88                 self::$singletoninstance = new performance_measuring_filter_manager();
  89             } else {
  90                 self::$singletoninstance = new self();
  91             }
  92         }
  93         return self::$singletoninstance;
  94     }
  95
  96     /**
  97      * Load all the filters required by this context.
  98      *
  99      * @param object $context
 100      */
 101     protected function load_filters($context) {
 102         $filters = filter_get_active_in_context($context);
 103         $this->textfilters[$context->id] = array();
 104         $this->stringfilters[$context->id] = array();
 105         foreach ($filters as $filtername => $localconfig) {
 106             $filter = $this->make_filter_object($filtername, $context, $localconfig);
 107             if (is_null($filter)) {
 108                 continue;
 109             }
 110             $this->textfilters[$context->id][] = $filter;
 111             if (in_array($filtername, $this->stringfilternames)) {
 112                 $this->stringfilters[$context->id][] = $filter;
 113             }
 114         }
 115     }
 116
 117     /**
 118      * Factory method for creating a filter
 119      *
 120      * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 121      * @param object $context context object.
 122      * @param array $localconfig array of local configuration variables for this filter.
 123      * @return object moodle_text_filter The filter, or null, if this type of filter is
 124      *      not recognised or could not be created.
 125      */
 126     protected function make_filter_object($filtername, $context, $localconfig) {
 127         global $CFG;
 128         $path = $CFG->dirroot .'/'. $filtername .'/filter.php';
 129         if (!is_readable($path)) {
 130             return null;
 131         }
 132         include_once($path);
 133
 134         $filterclassname = 'filter_' . basename($filtername);
 135         if (class_exists($filterclassname)) {
 136             return new $filterclassname($context, $localconfig);
 137         }
 138
 139         $legacyfunctionname = basename($filtername) . '_filter';
 140         if (function_exists($legacyfunctionname)) {
 141             return new legacy_filter($legacyfunctionname, $context, $localconfig);
 142         }
 143
 144         return null;
 145     }
 146
 147     /**
 148      * @todo Document this function
 149      * @param string $text
 150      * @param array $filterchain
 151      * @param array $options options passed to the filters
 152      * @return string $text
 153      */
 154     protected function apply_filter_chain($text, $filterchain, array $options = array()) {
 155         foreach ($filterchain as $filter) {
 156             $text = $filter->filter($text, $options);
 157         }
 158         return $text;
 159     }
 160
 161     /**
 162      * @todo Document this function
 163      * @param object $context
 164      * @return object A text filter
 165      */
 166     protected function get_text_filters($context) {
 167         if (!isset($this->textfilters[$context->id])) {
 168             $this->load_filters($context);
 169         }
 170         return $this->textfilters[$context->id];
 171     }
 172
 173     /**
 174      * @todo Document this function
 175      * @param object $context
 176      * @return object A string filter
 177      */
 178     protected function get_string_filters($context) {
 179         if (!isset($this->stringfilters[$context->id])) {
 180             $this->load_filters($context);
 181         }
 182         return $this->stringfilters[$context->id];
 183     }
 184
 185     /**
 186      * Filter some text
 187      *
 188      * @param string $text The text to filter
 189      * @param object $context
 190      * @param array $options options passed to the filters
 191      * @return string resulting text
 192      */
 193     public function filter_text($text, $context, array $options = array()) {
 194         $text = $this->apply_filter_chain($text, $this->get_text_filters($context), $options);
 195         /// <nolink> tags removed for XHTML compatibility
 196         $text = str_replace(array('<nolink>', '</nolink>'), '', $text);
 197         return $text;
 198     }
 199
 200     /**
 201      * Filter a piece of string
 202      *
 203      * @param string $string The text to filter
 204      * @param object $context
 205      * @return string resulting string
 206      */
 207     public function filter_string($string, $context) {
 208         return $this->apply_filter_chain($string, $this->get_string_filters($context));
 209     }
 210
 211     /**
 212      * @todo Document this function
 213      * @param object $context
 214      * @return object A string filter
 215      */
 216     public function text_filtering_hash($context) {
 217         $filters = $this->get_text_filters($context);
 218         $hashes = array();
 219         foreach ($filters as $filter) {
 220             $hashes[] = $filter->hash();
 221         }
 222         return implode('-', $hashes);
 223     }
 224 }
 225
 226 /**
 227  * Filter manager subclass that does nothing. Having this simplifies the logic
 228  * of format_text, etc.
 229  *
 230  * @todo Document this class
 231  *
 232  * @package    core
 233  * @subpackage filter
 234  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 235  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 236  */
 237 class null_filter_manager {
 238     /**
 239      * @return string
 240      */
 241     public function filter_text($text, $context, $options) {
 242         return $text;
 243     }
 244
 245     /**
 246      * @return string
 247      */
 248     public function filter_string($string, $context) {
 249         return $string;
 250     }
 251
 252     /**
 253      * @return string
 254      */
 255     public function text_filtering_hash() {
 256         return '';
 257     }
 258 }
 259
 260 /**
 261  * Filter manager subclass that tacks how much work it does.
 262  *
 263  * @todo Document this class
 264  *
 265  * @package    core
 266  * @subpackage filter
 267  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 268  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 269  */
 270 class performance_measuring_filter_manager extends filter_manager {
 271     /** @var int */
 272     protected $filterscreated = 0;
 273     protected $textsfiltered = 0;
 274     protected $stringsfiltered = 0;
 275
 276     /**
 277      * @param string $filtername
 278      * @param object $context
 279      * @param mixed $localconfig
 280      * @return mixed
 281      */
 282     protected function make_filter_object($filtername, $context, $localconfig) {
 283         $this->filterscreated++;
 284         return parent::make_filter_object($filtername, $context, $localconfig);
 285     }
 286
 287     /**
 288      * @param string $text
 289      * @param object $context
 290      * @param array $options options passed to the filters
 291      * @return mixed
 292      */
 293     public function filter_text($text, $context, array $options = array()) {
 294         $this->textsfiltered++;
 295         return parent::filter_text($text, $context, $options);
 296     }
 297
 298     /**
 299      * @param string $string
 300      * @param object $context
 301      * @return mixed
 302      */
 303     public function filter_string($string, $context) {
 304         $this->stringsfiltered++;
 305         return parent::filter_string($string, $context);
 306     }
 307
 308     /**
 309      * @return array
 310      */
 311     public function get_performance_summary() {
 312         return array(array(
 313             'contextswithfilters' => count($this->textfilters),
 314             'filterscreated' => $this->filterscreated,
 315             'textsfiltered' => $this->textsfiltered,
 316             'stringsfiltered' => $this->stringsfiltered,
 317         ), array(
 318             'contextswithfilters' => 'Contexts for which filters were loaded',
 319             'filterscreated' => 'Filters created',
 320             'textsfiltered' => 'Pieces of content filtered',
 321             'stringsfiltered' => 'Strings filtered',
 322         ));
 323     }
 324 }
 325
 326 /**
 327  * Base class for text filters. You just need to override this class and
 328  * implement the filter method.
 329  *
 330  * @package    core
 331  * @subpackage filter
 332  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 333  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 334  */
 335 abstract class moodle_text_filter {
 336     /** @var object The context we are in. */
 337     protected $context;
 338     /** @var array Any local configuration for this filter in this context. */
 339     protected $localconfig;
 340
 341     /**
 342      * Set any context-specific configuration for this filter.
 343      * @param object $context The current course id.
 344      * @param object $context The current context.
 345      * @param array $config Any context-specific configuration for this filter.
 346      */
 347     public function __construct($context, array $localconfig) {
 348         $this->context = $context;
 349         $this->localconfig = $localconfig;
 350     }
 351
 352     /**
 353      * @return string The class name of the current class
 354      */
 355     public function hash() {
 356         return __CLASS__;
 357     }
 358
 359     /**
 360      * Override this function to actually implement the filtering.
 361      *
 362      * @param $text some HTML content.
 363      * @param array $options options passed to the filters
 364      * @return the HTML content after the filtering has been applied.
 365      */
 366     public abstract function filter($text, array $options = array());
 367 }
 368
 369 /**
 370  * moodle_text_filter implementation that encapsulates an old-style filter that
 371  * only defines a function, not a class.
 372  *
 373  * @package    core
 374  * @subpackage filter
 375  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 376  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 377  */
 378 class legacy_filter extends moodle_text_filter {
 379     /** @var string */
 380     protected $filterfunction;
 381     protected $courseid;
 382
 383     /**
 384      * Set any context-specific configuration for this filter.
 385      *
 386      * @param string $filterfunction
 387      * @param object $context The current context.
 388      * @param array $config Any context-specific configuration for this filter.
 389      */
 390     public function __construct($filterfunction, $context, array $localconfig) {
 391         parent::__construct($context, $localconfig);
 392         $this->filterfunction = $filterfunction;
 393         $this->courseid = get_courseid_from_context($this->context);
 394     }
 395
 396     /**
 397      * @param string $text
 398      * @param array $options options - not supported for legacy filters
 399      * @return mixed
 400      */
 401     public function filter($text, array $options = array()) {
 402         if ($this->courseid) {
 403             // old filters are called only when inside courses
 404             return call_user_func($this->filterfunction, $this->courseid, $text);
 405         } else {
 406             return $text;
 407         }
 408     }
 409 }
 410
 411 /**
 412  * This is just a little object to define a phrase and some instructions
 413  * for how to process it.  Filters can create an array of these to pass
 414  * to the filter_phrases function below.
 415  *
 416  * @package    core
 417  * @subpackage filter
 418  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 419  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 420  **/
 421 class filterobject {
 422     /** @var string */
 423     var $phrase;
 424     var $hreftagbegin;
 425     var $hreftagend;
 426     /** @var bool */
 427     var $casesensitive;
 428     var $fullmatch;
 429     /** @var mixed */
 430     var $replacementphrase;
 431     var $work_phrase;
 432     var $work_hreftagbegin;
 433     var $work_hreftagend;
 434     var $work_casesensitive;
 435     var $work_fullmatch;
 436     var $work_replacementphrase;
 437     /** @var bool */
 438     var $work_calculated;
 439
 440     /**
 441      * A constructor just because I like constructing
 442      *
 443      * @param string $phrase
 444      * @param string $hreftagbegin
 445      * @param string $hreftagend
 446      * @param bool $casesensitive
 447      * @param bool $fullmatch
 448      * @param mixed $replacementphrase
 449      */
 450     function filterobject($phrase, $hreftagbegin = '<span class="highlight">',
 451                                    $hreftagend = '</span>',
 452                                    $casesensitive = false,
 453                                    $fullmatch = false,
 454                                    $replacementphrase = NULL) {
 455
 456         $this->phrase           = $phrase;
 457         $this->hreftagbegin     = $hreftagbegin;
 458         $this->hreftagend       = $hreftagend;
 459         $this->casesensitive    = $casesensitive;
 460         $this->fullmatch        = $fullmatch;
 461         $this->replacementphrase= $replacementphrase;
 462         $this->work_calculated  = false;
 463
 464     }
 465 }
 466
 467 /**
 468  * Look up the name of this filter in the most appropriate location.
 469  * If $filterlocation = 'mod' then does get_string('filtername', $filter);
 470  * else if $filterlocation = 'filter' then does get_string('filtername', 'filter_' . $filter);
 471  * with a fallback to get_string('filtername', $filter) for backwards compatibility.
 472  * These are the only two options supported at the moment.
 473  *
 474  * @param string $filter the folder name where the filter lives.
 475  * @return string the human-readable name for this filter.
 476  */
 477 function filter_get_name($filter) {
 478     list($type, $filter) = explode('/', $filter);
 479     switch ($type) {
 480         case 'filter':
 481             $strfiltername = get_string('filtername', 'filter_' . $filter);
 482             if (substr($strfiltername, 0, 2) != '[[') {
 483                 // found a valid string.
 484                 return $strfiltername;
 485             }
 486             // Fall through to try the legacy location.
 487
 488         case 'mod':
 489             $strfiltername = get_string('filtername', $filter);
 490             if (substr($strfiltername, 0, 2) == '[[') {
 491                 $strfiltername .= ' (' . $type . '/' . $filter . ')';
 492             }
 493             return $strfiltername;
 494
 495         default:
 496             throw new coding_exception('Unknown filter type ' . $type);
 497     }
 498 }
 499
 500 /**
 501  * Get the names of all the filters installed in this Moodle.
 502  *
 503  * @global object
 504  * @return array path => filter name from the appropriate lang file. e.g.
 505  * array('mod/glossary' => 'Glossary Auto-linking', 'filter/tex' => 'TeX Notation');
 506  * sorted in alphabetical order of name.
 507  */
 508 function filter_get_all_installed() {
 509     global $CFG;
 510     $filternames = array();
 511     $filterlocations = array('mod', 'filter');
 512     foreach ($filterlocations as $filterlocation) {
 513         $filters = get_list_of_plugins($filterlocation);
 514         foreach ($filters as $filter) {
 515             $path = $filterlocation . '/' . $filter;
 516             if (is_readable($CFG->dirroot . '/' . $path . '/filter.php')) {
 517                 $strfiltername = filter_get_name($path);
 518                 $filternames[$path] = $strfiltername;
 519             }
 520         }
 521     }
 522     textlib_get_instance()->asort($filternames);
 523     return $filternames;
 524 }
 525
 526 /**
 527  * Set the global activated state for a text filter.
 528  *
 529  * @global object
 530  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 531  * @param integer $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.
 532  * @param integer $sortorder (optional) a position in the sortorder to place this filter.
 533  *      If not given defaults to:
 534  *      No change in order if we are updating an existing record, and not changing to or from TEXTFILTER_DISABLED.
 535  *      Just after the last currently active filter when adding an unknown filter
 536  *          in state TEXTFILTER_ON or TEXTFILTER_OFF, or enabling/disabling an existing filter.
 537  *      Just after the very last filter when adding an unknown filter in state TEXTFILTER_DISABLED
 538  */
 539 function filter_set_global_state($filter, $state, $sortorder = false) {
 540     global $DB;
 541
 542     // Check requested state is valid.
 543     if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_DISABLED))) {
 544         throw new coding_exception("Illegal option '$state' passed to filter_set_global_state. " .
 545                 "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.");
 546     }
 547
 548     // Check sortorder is valid.
 549     if ($sortorder !== false) {
 550         if ($sortorder < 1 || $sortorder > $DB->get_field('filter_active', 'MAX(sortorder)', array()) + 1) {
 551             throw new coding_exception("Invalid sort order passed to filter_set_global_state.");
 552         }
 553     }
 554
 555     // See if there is an existing record.
 556     $syscontext = get_context_instance(CONTEXT_SYSTEM);
 557     $rec = $DB->get_record('filter_active', array('filter' => $filter, 'contextid' => $syscontext->id));
 558     if (empty($rec)) {
 559         $insert = true;
 560         $rec = new stdClass;
 561         $rec->filter = $filter;
 562         $rec->contextid = $syscontext->id;
 563     } else {
 564         $insert = false;
 565         if ($sortorder === false && !($rec->active == TEXTFILTER_DISABLED xor $state == TEXTFILTER_DISABLED)) {
 566             $sortorder = $rec->sortorder;
 567         }
 568     }
 569
 570     // Automatic sort order.
 571     if ($sortorder === false) {
 572         if ($state == TEXTFILTER_DISABLED && $insert) {
 573             $prevmaxsortorder = $DB->get_field('filter_active', 'MAX(sortorder)', array());
 574         } else {
 575             $prevmaxsortorder = $DB->get_field_select('filter_active', 'MAX(sortorder)', 'active <> ?', array(TEXTFILTER_DISABLED));
 576         }
 577         if (empty($prevmaxsortorder)) {
 578             $sortorder = 1;
 579         } else {
 580             $sortorder = $prevmaxsortorder + 1;
 581             if (!$insert && $state == TEXTFILTER_DISABLED) {
 582                 $sortorder = $prevmaxsortorder;
 583             }
 584         }
 585     }
 586
 587     // Move any existing records out of the way of the sortorder.
 588     if ($insert) {
 589         $DB->execute('UPDATE {filter_active} SET sortorder = sortorder + 1 WHERE sortorder >= ?', array($sortorder));
 590     } else if ($sortorder != $rec->sortorder) {
 591         $sparesortorder = $DB->get_field('filter_active', 'MIN(sortorder)', array()) - 1;
 592         $DB->set_field('filter_active', 'sortorder', $sparesortorder, array('filter' => $filter, 'contextid' => $syscontext->id));
 593         if ($sortorder < $rec->sortorder) {
 594             $DB->execute('UPDATE {filter_active} SET sortorder = sortorder + 1 WHERE sortorder >= ? AND sortorder < ?',
 595                     array($sortorder, $rec->sortorder));
 596         } else if ($sortorder > $rec->sortorder) {
 597             $DB->execute('UPDATE {filter_active} SET sortorder = sortorder - 1 WHERE sortorder <= ? AND sortorder > ?',
 598                     array($sortorder, $rec->sortorder));
 599         }
 600     }
 601
 602     // Insert/update the new record.
 603     $rec->active = $state;
 604     $rec->sortorder = $sortorder;
 605     if ($insert) {
 606         $DB->insert_record('filter_active', $rec);
 607     } else {
 608         $DB->update_record('filter_active', $rec);
 609     }
 610 }
 611
 612 /**
 613  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 614  * @return boolean is this filter allowed to be used on this site. That is, the
 615  *      admin has set the global 'active' setting to On, or Off, but available.
 616  */
 617 function filter_is_enabled($filter) {
 618     return array_key_exists($filter, filter_get_globally_enabled());
 619 }
 620
 621 /**
 622  * Return a list of all the filters that may be in use somewhere.
 623  *
 624  * @staticvar array $enabledfilters
 625  * @return array where the keys and values are both the filter name, like 'filter/tex'.
 626  */
 627 function filter_get_globally_enabled() {
 628     static $enabledfilters = null;
 629     if (is_null($enabledfilters)) {
 630         $filters = filter_get_global_states();
 631         $enabledfilters = array();
 632         foreach ($filters as $filter => $filerinfo) {
 633             if ($filerinfo->active != TEXTFILTER_DISABLED) {
 634                 $enabledfilters[$filter] = $filter;
 635             }
 636         }
 637     }
 638     return $enabledfilters;
 639 }
 640
 641 /**
 642  * Return the names of the filters that should also be applied to strings
 643  * (when they are enabled).
 644  *
 645  * @global object
 646  * @return array where the keys and values are both the filter name, like 'filter/tex'.
 647  */
 648 function filter_get_string_filters() {
 649     global $CFG;
 650     $stringfilters = array();
 651     if (!empty($CFG->filterall) && !empty($CFG->stringfilters)) {
 652         $stringfilters = explode(',', $CFG->stringfilters);
 653         $stringfilters = array_combine($stringfilters, $stringfilters);
 654     }
 655     return $stringfilters;
 656 }
 657
 658 /**
 659  * Sets whether a particular active filter should be applied to all strings by
 660  * format_string, or just used by format_text.
 661  *
 662  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 663  * @param boolean $applytostrings if true, this filter will apply to format_string
 664  *      and format_text, when it is enabled.
 665  */
 666 function filter_set_applies_to_strings($filter, $applytostrings) {
 667     $stringfilters = filter_get_string_filters();
 668     $numstringfilters = count($stringfilters);
 669     if ($applytostrings) {
 670         $stringfilters[$filter] = $filter;
 671     } else {
 672         unset($stringfilters[$filter]);
 673     }
 674     if (count($stringfilters) != $numstringfilters) {
 675         set_config('stringfilters', implode(',', $stringfilters));
 676         set_config('filterall', !empty($stringfilters));
 677     }
 678 }
 679
 680 /**
 681  * Set the local activated state for a text filter.
 682  *
 683  * @global object
 684  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 685  * @param integer $contextid The id of the context to get the local config for.
 686  * @param integer $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.
 687  * @return void
 688  */
 689 function filter_set_local_state($filter, $contextid, $state) {
 690     global $DB;
 691
 692     // Check requested state is valid.
 693     if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_INHERIT))) {
 694         throw new coding_exception("Illegal option '$state' passed to filter_set_local_state. " .
 695                 "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.");
 696     }
 697
 698     if ($contextid == get_context_instance(CONTEXT_SYSTEM)->id) {
 699         throw new coding_exception('You cannot use filter_set_local_state ' .
 700                 'with $contextid equal to the system context id.');
 701     }
 702
 703     if ($state == TEXTFILTER_INHERIT) {
 704         $DB->delete_records('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 705         return;
 706     }
 707
 708     $rec = $DB->get_record('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 709     $insert = false;
 710     if (empty($rec)) {
 711         $insert = true;
 712         $rec = new stdClass;
 713         $rec->filter = $filter;
 714         $rec->contextid = $contextid;
 715     }
 716
 717     $rec->active = $state;
 718
 719     if ($insert) {
 720         $DB->insert_record('filter_active', $rec);
 721     } else {
 722         $DB->update_record('filter_active', $rec);
 723     }
 724 }
 725
 726 /**
 727  * Set a particular local config variable for a filter in a context.
 728  *
 729  * @global object
 730  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 731  * @param integer $contextid The id of the context to get the local config for.
 732  * @param string $name the setting name.
 733  * @param string $value the corresponding value.
 734  */
 735 function filter_set_local_config($filter, $contextid, $name, $value) {
 736     global $DB;
 737     $rec = $DB->get_record('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
 738     $insert = false;
 739     if (empty($rec)) {
 740         $insert = true;
 741         $rec = new stdClass;
 742         $rec->filter = $filter;
 743         $rec->contextid = $contextid;
 744         $rec->name = $name;
 745     }
 746
 747     $rec->value = $value;
 748
 749     if ($insert) {
 750         $DB->insert_record('filter_config', $rec);
 751     } else {
 752         $DB->update_record('filter_config', $rec);
 753     }
 754 }
 755
 756 /**
 757  * Remove a particular local config variable for a filter in a context.
 758  *
 759  * @global object
 760  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 761  * @param integer $contextid The id of the context to get the local config for.
 762  * @param string $name the setting name.
 763  */
 764 function filter_unset_local_config($filter, $contextid, $name) {
 765     global $DB;
 766     $DB->delete_records('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
 767 }
 768
 769 /**
 770  * Get local config variables for a filter in a context. Normally (when your
 771  * filter is running) you don't need to call this, becuase the config is fetched
 772  * for you automatically. You only need this, for example, when you are getting
 773  * the config so you can show the user an editing from.
 774  *
 775  * @global object
 776  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 777  * @param integer $contextid The ID of the context to get the local config for.
 778  * @return array of name => value pairs.
 779  */
 780 function filter_get_local_config($filter, $contextid) {
 781     global $DB;
 782     return $DB->get_records_menu('filter_config', array('filter' => $filter, 'contextid' => $contextid), '', 'name,value');
 783 }
 784
 785 /**
 786  * This function is for use by backup. Gets all the filter information specific
 787  * to one context.
 788  *
 789  * @global object
 790  * @param int $contextid
 791  * @return array Array with two elements. The first element is an array of objects with
 792  *      fields filter and active. These come from the filter_active table. The
 793  *      second element is an array of objects with fields filter, name and value
 794  *      from the filter_config table.
 795  */
 796 function filter_get_all_local_settings($contextid) {
 797     global $DB;
 798     $context = get_context_instance(CONTEXT_SYSTEM);
 799     return array(
 800         $DB->get_records('filter_active', array('contextid' => $contextid), 'filter', 'filter,active'),
 801         $DB->get_records('filter_config', array('contextid' => $contextid), 'filter,name', 'filter,name,value'),
 802     );
 803 }
 804
 805 /**
 806  * Get the list of active filters, in the order that they should be used
 807  * for a particular context, along with any local configuration variables.
 808  *
 809  * @global object
 810  * @param object $context a context
 811  * @return array an array where the keys are the filter names, for example
 812  *      'filter/tex' or 'mod/glossary' and the values are any local
 813  *      configuration for that filter, as an array of name => value pairs
 814  *      from the filter_config table. In a lot of cases, this will be an
 815  *      empty array. So, an example return value for this function might be
 816  *      array('filter/tex' => array(), 'mod/glossary' => array('glossaryid', 123))
 817  */
 818 function filter_get_active_in_context($context) {
 819     global $DB;
 820     $contextids = str_replace('/', ',', trim($context->path, '/'));
 821
 822     // The following SQL is tricky. It is explained on
 823     // http://docs.moodle.org/en/Development:Filter_enable/disable_by_context
 824     $sql = "SELECT active.filter, fc.name, fc.value
 825          FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder
 826              FROM {filter_active} f
 827              JOIN {context} ctx ON f.contextid = ctx.id
 828              WHERE ctx.id IN ($contextids)
 829              GROUP BY filter
 830              HAVING MAX(f.active * " . $DB->sql_cast_2signed('ctx.depth') .
 831                     ") > -MIN(f.active * " . $DB->sql_cast_2signed('ctx.depth') . ")
 832          ) active
 833          LEFT JOIN {filter_config} fc ON fc.filter = active.filter AND fc.contextid = $context->id
 834          ORDER BY active.sortorder";
 835     $rs = $DB->get_recordset_sql($sql);
 836
 837     // Masssage the data into the specified format to return.
 838     $filters = array();
 839     foreach ($rs as $row) {
 840         if (!isset($filters[$row->filter])) {
 841             $filters[$row->filter] = array();
 842         }
 843         if (!is_null($row->name)) {
 844             $filters[$row->filter][$row->name] = $row->value;
 845         }
 846     }
 847
 848     $rs->close();
 849
 850     return $filters;
 851 }
 852
 853 /**
 854  * List all of the filters that are available in this context, and what the
 855  * local and inherited states of that filter are.
 856  *
 857  * @global object
 858  * @param object $context a context that is not the system context.
 859  * @return array an array with filter names, for example 'filter/tex' or
 860  *      'mod/glossary' as keys. and and the values are objects with fields:
 861  *      ->filter filter name, same as the key.
 862  *      ->localstate TEXTFILTER_ON/OFF/INHERIT
 863  *      ->inheritedstate TEXTFILTER_ON/OFF - the state that will be used if localstate is set to TEXTFILTER_INHERIT.
 864  */
 865 function filter_get_available_in_context($context) {
 866     global $DB;
 867
 868     // The complex logic is working out the active state in the parent context,
 869     // so strip the current context from the list.
 870     $contextids = explode('/', trim($context->path, '/'));
 871     array_pop($contextids);
 872     $contextids = implode(',', $contextids);
 873     if (empty($contextids)) {
 874         throw new coding_exception('filter_get_available_in_context cannot be called with the system context.');
 875     }
 876
 877     // The following SQL is tricky, in the same way at the SQL in filter_get_active_in_context.
 878     $sql = "SELECT parent_states.filter,
 879                 CASE WHEN fa.active IS NULL THEN " . TEXTFILTER_INHERIT . "
 880                 ELSE fa.active END AS localstate,
 881              parent_states.inheritedstate
 882          FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder,
 883                     CASE WHEN MAX(f.active * " . $DB->sql_cast_2signed('ctx.depth') .
 884                             ") > -MIN(f.active * " . $DB->sql_cast_2signed('ctx.depth') . ") THEN " . TEXTFILTER_ON . "
 885                     ELSE " . TEXTFILTER_OFF . " END AS inheritedstate
 886              FROM {filter_active} f
 887              JOIN {context} ctx ON f.contextid = ctx.id
 888              WHERE ctx.id IN ($contextids)
 889              GROUP BY f.filter
 890              HAVING MIN(f.active) > " . TEXTFILTER_DISABLED . "
 891          ) parent_states
 892          LEFT JOIN {filter_active} fa ON fa.filter = parent_states.filter AND fa.contextid = $context->id
 893          ORDER BY parent_states.sortorder";
 894     return $DB->get_records_sql($sql);
 895 }
 896
 897 /**
 898  * This function is for use by the filter administration page.
 899  *
 900  * @global object
 901  * @return array 'filtername' => object with fields 'filter' (=filtername), 'active' and 'sortorder'
 902  */
 903 function filter_get_global_states() {
 904     global $DB;
 905     $context = get_context_instance(CONTEXT_SYSTEM);
 906     return $DB->get_records('filter_active', array('contextid' => $context->id), 'sortorder', 'filter,active,sortorder');
 907 }
 908
 909 /**
 910  * Delete all the data in the database relating to a filter, prior to deleting it.
 911  *
 912  * @global object
 913  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 914  */
 915 function filter_delete_all_for_filter($filter) {
 916     global $DB;
 917     if (substr($filter, 0, 7) == 'filter/') {
 918         unset_all_config_for_plugin('filter_' . basename($filter));
 919     }
 920     $DB->delete_records('filter_active', array('filter' => $filter));
 921     $DB->delete_records('filter_config', array('filter' => $filter));
 922 }
 923
 924 /**
 925  * Delete all the data in the database relating to a context, used when contexts are deleted.
 926  *
 927  * @param integer $contextid The id of the context being deleted.
 928  */
 929 function filter_delete_all_for_context($contextid) {
 930     global $DB;
 931     $DB->delete_records('filter_active', array('contextid' => $contextid));
 932     $DB->delete_records('filter_config', array('contextid' => $contextid));
 933 }
 934
 935 /**
 936  * Does this filter have a global settings page in the admin tree?
 937  * (The settings page for a filter must be called, for example,
 938  * filtersettingfiltertex or filtersettingmodglossay.)
 939  *
 940  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 941  * @return boolean Whether there should be a 'Settings' link on the config page.
 942  */
 943 function filter_has_global_settings($filter) {
 944     global $CFG;
 945     $settingspath = $CFG->dirroot . '/' . $filter . '/filtersettings.php';
 946     return is_readable($settingspath);
 947 }
 948
 949 /**
 950  * Does this filter have local (per-context) settings?
 951  *
 952  * @param string $filter The filter name, for example 'filter/tex' or 'mod/glossary'.
 953  * @return boolean Whether there should be a 'Settings' link on the manage filters in context page.
 954  */
 955 function filter_has_local_settings($filter) {
 956     global $CFG;
 957     $settingspath = $CFG->dirroot . '/' . $filter . '/filterlocalsettings.php';
 958     return is_readable($settingspath);
 959 }
 960
 961 /**
 962  * Certain types of context (block and user) may not have local filter settings.
 963  * the function checks a context to see whether it may have local config.
 964  *
 965  * @param object $context a context.
 966  * @return boolean whether this context may have local filter settings.
 967  */
 968 function filter_context_may_have_filter_settings($context) {
 969     return $context->contextlevel != CONTEXT_BLOCK && $context->contextlevel != CONTEXT_USER;
 970 }
 971
 972 /**
 973  * Process phrases intelligently found within a HTML text (such as adding links)
 974  *
 975  * @staticvar array $usedpharses
 976  * @param string $text             the text that we are filtering
 977  * @param array $link_array       an array of filterobjects
 978  * @param array $ignoretagsopen   an array of opening tags that we should ignore while filtering
 979  * @param array $ignoretagsclose  an array of corresponding closing tags
 980  * @return string
 981  **/
 982 function filter_phrases($text, &$link_array, $ignoretagsopen=NULL, $ignoretagsclose=NULL) {
 983
 984     global $CFG;
 985
 986     static $usedphrases;
 987
 988     $ignoretags = array();  //To store all the enclosig tags to be completely ignored
 989     $tags = array();        //To store all the simple tags to be ignored
 990
 991 /// A list of open/close tags that we should not replace within
 992 /// No reason why you can't put full preg expressions in here too
 993 /// eg '<script(.+?)>' to match any type of script tag
 994     $filterignoretagsopen  = array('<head>' , '<nolink>' , '<span class="nolink">');
 995     $filterignoretagsclose = array('</head>', '</nolink>', '</span>');
 996
 997 /// Invalid prefixes and suffixes for the fullmatch searches
 998 /// Every "word" character, but the underscore, is a invalid suffix or prefix.
 999 /// (nice to use this because it includes national characters (accents...) as word characters.
1000     $filterinvalidprefixes = '([^\W_])';
1001     $filterinvalidsuffixes = '([^\W_])';
1002
1003 /// Add the user defined ignore tags to the default list
1004 /// Unless specified otherwise, we will not replace within <a></a> tags
1005     if ( $ignoretagsopen === NULL ) {
1006         //$ignoretagsopen  = array('<a(.+?)>');
1007         $ignoretagsopen  = array('<a\s[^>]+?>');
1008         $ignoretagsclose = array('</a>');
1009     }
1010
1011     if ( is_array($ignoretagsopen) ) {
1012         foreach ($ignoretagsopen as $open) $filterignoretagsopen[] = $open;
1013         foreach ($ignoretagsclose as $close) $filterignoretagsclose[] = $close;
1014     }
1015
1016     //// Double up some magic chars to avoid "accidental matches"
1017     $text = preg_replace('/([#*%])/','\1\1',$text);
1018
1019
1020 ////Remove everything enclosed by the ignore tags from $text
1021     filter_save_ignore_tags($text,$filterignoretagsopen,$filterignoretagsclose,$ignoretags);
1022
1023 /// Remove tags from $text
1024     filter_save_tags($text,$tags);
1025
1026 /// Time to cycle through each phrase to be linked
1027     $size = sizeof($link_array);
1028     for ($n=0; $n < $size; $n++) {
1029         $linkobject =& $link_array[$n];
1030
1031     /// Set some defaults if certain properties are missing
1032     /// Properties may be missing if the filterobject class has not been used to construct the object
1033         if (empty($linkobject->phrase)) {
1034             continue;
1035         }
1036
1037     /// Avoid integers < 1000 to be linked. See bug 1446.
1038         $intcurrent = intval($linkobject->phrase);
1039         if (!empty($intcurrent) && strval($intcurrent) == $linkobject->phrase && $intcurrent < 1000) {
1040             continue;
1041         }
1042
1043     /// All this work has to be done ONLY it it hasn't been done before
1044     if (!$linkobject->work_calculated) {
1045             if (!isset($linkobject->hreftagbegin) or !isset($linkobject->hreftagend)) {
1046                 $linkobject->work_hreftagbegin = '<span class="highlight"';
1047                 $linkobject->work_hreftagend   = '</span>';
1048             } else {
1049                 $linkobject->work_hreftagbegin = $linkobject->hreftagbegin;
1050                 $linkobject->work_hreftagend   = $linkobject->hreftagend;
1051             }
1052
1053         /// Double up chars to protect true duplicates
1054         /// be cleared up before returning to the user.
1055             $linkobject->work_hreftagbegin = preg_replace('/([#*%])/','\1\1',$linkobject->work_hreftagbegin);
1056
1057             if (empty($linkobject->casesensitive)) {
1058                 $linkobject->work_casesensitive = false;
1059             } else {
1060                 $linkobject->work_casesensitive = true;
1061             }
1062             if (empty($linkobject->fullmatch)) {
1063                 $linkobject->work_fullmatch = false;
1064             } else {
1065                 $linkobject->work_fullmatch = true;
1066             }
1067
1068         /// Strip tags out of the phrase
1069             $linkobject->work_phrase = strip_tags($linkobject->phrase);
1070
1071         /// Double up chars that might cause a false match -- the duplicates will
1072         /// be cleared up before returning to the user.
1073             $linkobject->work_phrase = preg_replace('/([#*%])/','\1\1',$linkobject->work_phrase);
1074
1075         /// Set the replacement phrase properly
1076             if ($linkobject->replacementphrase) {    //We have specified a replacement phrase
1077             /// Strip tags
1078                 $linkobject->work_replacementphrase = strip_tags($linkobject->replacementphrase);
1079             } else {                                 //The replacement is the original phrase as matched below
1080                 $linkobject->work_replacementphrase = '$1';
1081             }
1082
1083         /// Quote any regular expression characters and the delimiter in the work phrase to be searched
1084             $linkobject->work_phrase = preg_quote($linkobject->work_phrase, '/');
1085
1086         /// Work calculated
1087             $linkobject->work_calculated = true;
1088
1089         }
1090
1091     /// If $CFG->filtermatchoneperpage, avoid previously (request) linked phrases
1092         if (!empty($CFG->filtermatchoneperpage)) {
1093             if (!empty($usedphrases) && in_array($linkobject->work_phrase,$usedphrases)) {
1094                 continue;
1095             }
1096         }
1097
1098     /// Regular expression modifiers
1099         $modifiers = ($linkobject->work_casesensitive) ? 's' : 'isu'; // works in unicode mode!
1100
1101     /// Do we need to do a fullmatch?
1102     /// If yes then go through and remove any non full matching entries
1103         if ($linkobject->work_fullmatch) {
1104             $notfullmatches = array();
1105             $regexp = '/'.$filterinvalidprefixes.'('.$linkobject->work_phrase.')|('.$linkobject->work_phrase.')'.$filterinvalidsuffixes.'/'.$modifiers;
1106
1107             preg_match_all($regexp,$text,$list_of_notfullmatches);
1108
1109             if ($list_of_notfullmatches) {
1110                 foreach (array_unique($list_of_notfullmatches[0]) as $key=>$value) {
1111                     $notfullmatches['<*'.$key.'*>'] = $value;
1112                 }
1113                 if (!empty($notfullmatches)) {
1114                     $text = str_replace($notfullmatches,array_keys($notfullmatches),$text);
1115                 }
1116             }
1117         }
1118
1119     /// Finally we do our highlighting
1120         if (!empty($CFG->filtermatchonepertext) || !empty($CFG->filtermatchoneperpage)) {
1121             $resulttext = preg_replace('/('.$linkobject->work_phrase.')/'.$modifiers,
1122                                       $linkobject->work_hreftagbegin.
1123                                       $linkobject->work_replacementphrase.
1124                                       $linkobject->work_hreftagend, $text, 1);
1125         } else {
1126             $resulttext = preg_replace('/('.$linkobject->work_phrase.')/'.$modifiers,
1127                                       $linkobject->work_hreftagbegin.
1128                                       $linkobject->work_replacementphrase.
1129                                       $linkobject->work_hreftagend, $text);
1130         }
1131
1132
1133     /// If the text has changed we have to look for links again
1134         if ($resulttext != $text) {
1135         /// Set $text to $resulttext
1136             $text = $resulttext;
1137         /// Remove everything enclosed by the ignore tags from $text
1138             filter_save_ignore_tags($text,$filterignoretagsopen,$filterignoretagsclose,$ignoretags);
1139         /// Remove tags from $text
1140             filter_save_tags($text,$tags);
1141         /// If $CFG->filtermatchoneperpage, save linked phrases to request
1142             if (!empty($CFG->filtermatchoneperpage)) {
1143                 $usedphrases[] = $linkobject->work_phrase;
1144             }
1145         }
1146
1147
1148     /// Replace the not full matches before cycling to next link object
1149         if (!empty($notfullmatches)) {
1150             $text = str_replace(array_keys($notfullmatches),$notfullmatches,$text);
1151             unset($notfullmatches);
1152         }
1153     }
1154
1155 /// Rebuild the text with all the excluded areas
1156
1157     if (!empty($tags)) {
1158         $text = str_replace(array_keys($tags), $tags, $text);
1159     }
1160
1161     if (!empty($ignoretags)) {
1162         $ignoretags = array_reverse($ignoretags); /// Reversed so "progressive" str_replace() will solve some nesting problems.
1163         $text = str_replace(array_keys($ignoretags),$ignoretags,$text);
1164     }
1165
1166     //// Remove the protective doubleups
1167     $text =  preg_replace('/([#*%])(\1)/','\1',$text);
1168
1169 /// Add missing javascript for popus
1170     $text = filter_add_javascript($text);
1171
1172
1173     return $text;
1174 }
1175
1176 /**
1177  * @todo Document this function
1178  * @param array $linkarray
1179  * @return array
1180  */
1181 function filter_remove_duplicates($linkarray) {
1182
1183     $concepts  = array(); // keep a record of concepts as we cycle through
1184     $lconcepts = array(); // a lower case version for case insensitive
1185
1186     $cleanlinks = array();
1187
1188     foreach ($linkarray as $key=>$filterobject) {
1189         if ($filterobject->casesensitive) {
1190             $exists = in_array($filterobject->phrase, $concepts);
1191         } else {
1192             $exists = in_array(moodle_strtolower($filterobject->phrase), $lconcepts);
1193         }
1194
1195         if (!$exists) {
1196             $cleanlinks[] = $filterobject;
1197             $concepts[] = $filterobject->phrase;
1198             $lconcepts[] = moodle_strtolower($filterobject->phrase);
1199         }
1200     }
1201
1202     return $cleanlinks;
1203 }
1204
1205 /**
1206  * Extract open/lose tags and their contents to avoid being processed by filters.
1207  * Useful to extract pieces of code like <a>...</a> tags. It returns the text
1208  * converted with some <#xTEXTFILTER_EXCL_SEPARATORx#> codes replacing the extracted text. Such extracted
1209  * texts are returned in the ignoretags array (as values), with codes as keys.
1210  *
1211  * @param string $text                  the text that we are filtering (in/out)
1212  * @param array $filterignoretagsopen  an array of open tags to start searching
1213  * @param array $filterignoretagsclose an array of close tags to end searching
1214  * @param array $ignoretags            an array of saved strings useful to rebuild the original text (in/out)
1215  **/
1216 function filter_save_ignore_tags(&$text, $filterignoretagsopen, $filterignoretagsclose, &$ignoretags) {
1217
1218 /// Remove everything enclosed by the ignore tags from $text
1219     foreach ($filterignoretagsopen as $ikey=>$opentag) {
1220         $closetag = $filterignoretagsclose[$ikey];
1221     /// form regular expression
1222         $opentag  = str_replace('/','\/',$opentag); // delimit forward slashes
1223         $closetag = str_replace('/','\/',$closetag); // delimit forward slashes
1224         $pregexp = '/'.$opentag.'(.*?)'.$closetag.'/is';
1225
1226         preg_match_all($pregexp, $text, $list_of_ignores);
1227         foreach (array_unique($list_of_ignores[0]) as $key=>$value) {
1228             $prefix = (string)(count($ignoretags) + 1);
1229             $ignoretags['<#'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$key.'#>'] = $value;
1230         }
1231         if (!empty($ignoretags)) {
1232             $text = str_replace($ignoretags,array_keys($ignoretags),$text);
1233         }
1234     }
1235 }
1236
1237 /**
1238  * Extract tags (any text enclosed by < and > to avoid being processed by filters.
1239  * It returns the text converted with some <%xTEXTFILTER_EXCL_SEPARATORx%> codes replacing the extracted text. Such extracted
1240  * texts are returned in the tags array (as values), with codes as keys.
1241  *
1242  * @param string $text   the text that we are filtering (in/out)
1243  * @param array $tags   an array of saved strings useful to rebuild the original text (in/out)
1244  **/
1245 function filter_save_tags(&$text, &$tags) {
1246
1247     preg_match_all('/<([^#%*].*?)>/is',$text,$list_of_newtags);
1248     foreach (array_unique($list_of_newtags[0]) as $ntkey=>$value) {
1249         $prefix = (string)(count($tags) + 1);
1250         $tags['<%'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$ntkey.'%>'] = $value;
1251     }
1252     if (!empty($tags)) {
1253         $text = str_replace($tags,array_keys($tags),$text);
1254     }
1255 }
1256
1257 /**
1258  * Add missing openpopup javascript to HTML files.
1259  *
1260  * @param string $text
1261  * @return string
1262  */
1263 function filter_add_javascript($text) {
1264     global $CFG;
1265
1266     if (stripos($text, '</html>') === FALSE) {
1267         return $text; // this is not a html file
1268     }
1269     if (strpos($text, 'onclick="return openpopup') === FALSE) {
1270         return $text; // no popup - no need to add javascript
1271     }
1272     $js ="
1273     <script type=\"text/javascript\">
1274     <!--
1275         function openpopup(url,name,options,fullscreen) {
1276           fullurl = \"".$CFG->httpswwwroot."\" + url;
1277           windowobj = window.open(fullurl,name,options);
1278           if (fullscreen) {
1279             windowobj.moveTo(0,0);
1280             windowobj.resizeTo(screen.availWidth,screen.availHeight);
1281           }
1282           windowobj.focus();
1283           return false;
1284         }
1285     // -->
1286     </script>";
1287     if (stripos($text, '</head>') !== FALSE) {
1288         //try to add it into the head element
1289         $text = str_ireplace('</head>', $js.'</head>', $text);
1290         return $text;
1291     }
1292
1293     //last chance - try adding head element
1294     return preg_replace("/<html.*?>/is", "\\0<head>".$js.'</head>', $text);
1295 }