Search moodle.org's
Developer Documentation

See Release Notes

  • Bug fixes for general core bugs in 4.3.x will end 7 October 2024 (12 months).
  • Bug fixes for security issues in 4.3.x will end 21 April 2025 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.2.x is supported too.
/lib/ -> filterlib.php (source)

Differences Between: [Versions 310 and 403] [Versions 311 and 403] [Versions 39 and 403] [Versions 400 and 403] [Versions 401 and 403]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Library functions for managing text filter plugins.
  19   *
  20   * @package   core
  21   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
  22   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  defined('MOODLE_INTERNAL') || die();
  26  
  27  /** The states a filter can be in, stored in the filter_active table. */
  28  define('TEXTFILTER_ON', 1);
  29  /** The states a filter can be in, stored in the filter_active table. */
  30  define('TEXTFILTER_INHERIT', 0);
  31  /** The states a filter can be in, stored in the filter_active table. */
  32  define('TEXTFILTER_OFF', -1);
  33  /** The states a filter can be in, stored in the filter_active table. */
  34  define('TEXTFILTER_DISABLED', -9999);
  35  
  36  /**
  37   * Define one exclusive separator that we'll use in the temp saved tags
  38   *  keys. It must be something rare enough to avoid having matches with
  39   *  filterobjects. MDL-18165
  40   */
  41  define('TEXTFILTER_EXCL_SEPARATOR', chr(0x1F) . '%' . chr(0x1F));
  42  
  43  
  44  /**
  45   * Class to manage the filtering of strings. It is intended that this class is
  46   * only used by weblib.php. Client code should probably be using the
  47   * format_text and format_string functions.
  48   *
  49   * This class is a singleton.
  50   *
  51   * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  52   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  53   */
  54  class filter_manager {
  55      /**
  56       * @var moodle_text_filter[][] This list of active filters, by context, for filtering content.
  57       * An array contextid => ordered array of filter name => filter objects.
  58       */
  59      protected $textfilters = array();
  60  
  61      /**
  62       * @var moodle_text_filter[][] This list of active filters, by context, for filtering strings.
  63       * An array contextid => ordered array of filter name => filter objects.
  64       */
  65      protected $stringfilters = array();
  66  
  67      /** @var array Exploded version of $CFG->stringfilters. */
  68      protected $stringfilternames = array();
  69  
  70      /** @var filter_manager Holds the singleton instance. */
  71      protected static $singletoninstance;
  72  
  73      /**
  74       * Constructor. Protected. Use {@link instance()} instead.
  75       */
  76      protected function __construct() {
  77          $this->stringfilternames = filter_get_string_filters();
  78      }
  79  
  80      /**
  81       * Factory method. Use this to get the filter manager.
  82       *
  83       * @return filter_manager the singleton instance.
  84       */
  85      public static function instance() {
  86          global $CFG;
  87          if (is_null(self::$singletoninstance)) {
  88              if (!empty($CFG->perfdebug) and $CFG->perfdebug > 7) {
  89                  self::$singletoninstance = new performance_measuring_filter_manager();
  90              } else {
  91                  self::$singletoninstance = new self();
  92              }
  93          }
  94          return self::$singletoninstance;
  95      }
  96  
  97      /**
  98       * Resets the caches, usually to be called between unit tests
  99       */
 100      public static function reset_caches() {
 101          if (self::$singletoninstance) {
 102              self::$singletoninstance->unload_all_filters();
 103          }
 104          self::$singletoninstance = null;
 105      }
 106  
 107      /**
 108       * Unloads all filters and other cached information
 109       */
 110      protected function unload_all_filters() {
 111          $this->textfilters = array();
 112          $this->stringfilters = array();
 113          $this->stringfilternames = array();
 114      }
 115  
 116      /**
 117       * Load all the filters required by this context.
 118       *
 119       * @param context $context the context.
 120       */
 121      protected function load_filters($context) {
 122          $filters = filter_get_active_in_context($context);
 123          $this->textfilters[$context->id] = array();
 124          $this->stringfilters[$context->id] = array();
 125          foreach ($filters as $filtername => $localconfig) {
 126              $filter = $this->make_filter_object($filtername, $context, $localconfig);
 127              if (is_null($filter)) {
 128                  continue;
 129              }
 130              $this->textfilters[$context->id][$filtername] = $filter;
 131              if (in_array($filtername, $this->stringfilternames)) {
 132                  $this->stringfilters[$context->id][$filtername] = $filter;
 133              }
 134          }
 135      }
 136  
 137      /**
 138       * Factory method for creating a filter.
 139       *
 140       * @param string $filtername The filter name, for example 'tex'.
 141       * @param context $context context object.
 142       * @param array $localconfig array of local configuration variables for this filter.
 143       * @return moodle_text_filter The filter, or null, if this type of filter is
 144       *      not recognised or could not be created.
 145       */
 146      protected function make_filter_object($filtername, $context, $localconfig) {
 147          global $CFG;
 148          $path = $CFG->dirroot .'/filter/'. $filtername .'/filter.php';
 149          if (!is_readable($path)) {
 150              return null;
 151          }
 152          include_once($path);
 153  
 154          $filterclassname = 'filter_' . $filtername;
 155          if (class_exists($filterclassname)) {
 156              return new $filterclassname($context, $localconfig);
 157          }
 158  
 159          return null;
 160      }
 161  
 162      /**
 163       * Apply a list of filters to some content.
 164       * @param string $text
 165       * @param moodle_text_filter[] $filterchain array filter name => filter object.
 166       * @param array $options options passed to the filters.
 167       * @param array $skipfilters of filter names. Any filters that should not be applied to this text.
 168       * @return string $text
 169       */
 170      protected function apply_filter_chain($text, $filterchain, array $options = array(),
 171              array $skipfilters = null) {
 172          if (!isset($options['stage'])) {
 173              $filtermethod = 'filter';
 174          } else if (in_array($options['stage'], ['pre_format', 'pre_clean', 'post_clean', 'string'], true)) {
 175              $filtermethod = 'filter_stage_' . $options['stage'];
 176          } else {
 177              $filtermethod = 'filter';
 178              debugging('Invalid filter stage specified in options: ' . $options['stage'], DEBUG_DEVELOPER);
 179          }
 180          if ($text === null || $text === '') {
 181              // Nothing to filter.
 182              return '';
 183          }
 184          foreach ($filterchain as $filtername => $filter) {
 185              if ($skipfilters !== null && in_array($filtername, $skipfilters)) {
 186                  continue;
 187              }
 188              $text = $filter->$filtermethod($text, $options);
 189          }
 190          return $text;
 191      }
 192  
 193      /**
 194       * Get all the filters that apply to a given context for calls to format_text.
 195       *
 196       * @param context $context
 197       * @return moodle_text_filter[] A text filter
 198       */
 199      protected function get_text_filters($context) {
 200          if (!isset($this->textfilters[$context->id])) {
 201              $this->load_filters($context);
 202          }
 203          return $this->textfilters[$context->id];
 204      }
 205  
 206      /**
 207       * Get all the filters that apply to a given context for calls to format_string.
 208       *
 209       * @param context $context the context.
 210       * @return moodle_text_filter[] A text filter
 211       */
 212      protected function get_string_filters($context) {
 213          if (!isset($this->stringfilters[$context->id])) {
 214              $this->load_filters($context);
 215          }
 216          return $this->stringfilters[$context->id];
 217      }
 218  
 219      /**
 220       * Filter some text
 221       *
 222       * @param string $text The text to filter
 223       * @param context $context the context.
 224       * @param array $options options passed to the filters
 225       * @param array $skipfilters of filter names. Any filters that should not be applied to this text.
 226       * @return string resulting text
 227       */
 228      public function filter_text($text, $context, array $options = array(),
 229              array $skipfilters = null) {
 230          $text = $this->apply_filter_chain($text, $this->get_text_filters($context), $options, $skipfilters);
 231          if (!isset($options['stage']) || $options['stage'] === 'post_clean') {
 232              // Remove <nolink> tags for XHTML compatibility after the last filtering stage.
 233              $text = str_replace(array('<nolink>', '</nolink>'), '', $text);
 234          }
 235          return $text;
 236      }
 237  
 238      /**
 239       * Filter a piece of string
 240       *
 241       * @param string $string The text to filter
 242       * @param context $context the context.
 243       * @return string resulting string
 244       */
 245      public function filter_string($string, $context) {
 246          return $this->apply_filter_chain($string, $this->get_string_filters($context), ['stage' => 'string']);
 247      }
 248  
 249      /**
 250       * @deprecated Since Moodle 3.0 MDL-50491. This was used by the old text filtering system, but no more.
 251       */
 252      public function text_filtering_hash() {
 253          throw new coding_exception('filter_manager::text_filtering_hash() can not be used any more');
 254      }
 255  
 256      /**
 257       * Setup page with filters requirements and other prepare stuff.
 258       *
 259       * This method is used by {@see format_text()} and {@see format_string()}
 260       * in order to allow filters to setup any page requirement (js, css...)
 261       * or perform any action needed to get them prepared before filtering itself
 262       * happens by calling to each every active setup() method.
 263       *
 264       * Note it's executed for each piece of text filtered, so filter implementations
 265       * are responsible of controlling the cardinality of the executions that may
 266       * be different depending of the stuff to prepare.
 267       *
 268       * @param moodle_page $page the page we are going to add requirements to.
 269       * @param context $context the context which contents are going to be filtered.
 270       * @since Moodle 2.3
 271       */
 272      public function setup_page_for_filters($page, $context) {
 273          $filters = $this->get_text_filters($context);
 274          foreach ($filters as $filter) {
 275              $filter->setup($page, $context);
 276          }
 277      }
 278  
 279      /**
 280       * Setup the page for globally available filters.
 281       *
 282       * This helps setting up the page for filters which may be applied to
 283       * the page, even if they do not belong to the current context, or are
 284       * not yet visible because the content is lazily added (ajax). This method
 285       * always uses to the system context which determines the globally
 286       * available filters.
 287       *
 288       * This should only ever be called once per request.
 289       *
 290       * @param moodle_page $page The page.
 291       * @since Moodle 3.2
 292       */
 293      public function setup_page_for_globally_available_filters($page) {
 294          $context = context_system::instance();
 295          $filterdata = filter_get_globally_enabled_filters_with_config();
 296          foreach ($filterdata as $name => $config) {
 297              if (isset($this->textfilters[$context->id][$name])) {
 298                  $filter = $this->textfilters[$context->id][$name];
 299              } else {
 300                  $filter = $this->make_filter_object($name, $context, $config);
 301                  if (is_null($filter)) {
 302                      continue;
 303                  }
 304              }
 305              $filter->setup($page, $context);
 306          }
 307      }
 308  }
 309  
 310  
 311  /**
 312   * Filter manager subclass that does nothing. Having this simplifies the logic
 313   * of format_text, etc.
 314   *
 315   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 316   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 317   */
 318  class null_filter_manager {
 319      /**
 320       * As for the equivalent {@link filter_manager} method.
 321       *
 322       * @param string $text The text to filter
 323       * @param context $context not used.
 324       * @param array $options not used
 325       * @param array $skipfilters not used
 326       * @return string resulting text.
 327       */
 328      public function filter_text($text, $context, array $options = array(),
 329              array $skipfilters = null) {
 330          return $text;
 331      }
 332  
 333      /**
 334       * As for the equivalent {@link filter_manager} method.
 335       *
 336       * @param string $string The text to filter
 337       * @param context $context not used.
 338       * @return string resulting string
 339       */
 340      public function filter_string($string, $context) {
 341          return $string;
 342      }
 343  
 344      /**
 345       * As for the equivalent {@link filter_manager} method.
 346       *
 347       * @deprecated Since Moodle 3.0 MDL-50491.
 348       */
 349      public function text_filtering_hash() {
 350          throw new coding_exception('filter_manager::text_filtering_hash() can not be used any more');
 351      }
 352  }
 353  
 354  
 355  /**
 356   * Filter manager subclass that tracks how much work it does.
 357   *
 358   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 359   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 360   */
 361  class performance_measuring_filter_manager extends filter_manager {
 362      /** @var int number of filter objects created. */
 363      protected $filterscreated = 0;
 364  
 365      /** @var int number of calls to filter_text. */
 366      protected $textsfiltered = 0;
 367  
 368      /** @var int number of calls to filter_string. */
 369      protected $stringsfiltered = 0;
 370  
 371      protected function unload_all_filters() {
 372          parent::unload_all_filters();
 373          $this->filterscreated = 0;
 374          $this->textsfiltered = 0;
 375          $this->stringsfiltered = 0;
 376      }
 377  
 378      protected function make_filter_object($filtername, $context, $localconfig) {
 379          $this->filterscreated++;
 380          return parent::make_filter_object($filtername, $context, $localconfig);
 381      }
 382  
 383      public function filter_text($text, $context, array $options = array(),
 384              array $skipfilters = null) {
 385          if (!isset($options['stage']) || $options['stage'] === 'post_clean') {
 386              $this->textsfiltered++;
 387          }
 388          return parent::filter_text($text, $context, $options, $skipfilters);
 389      }
 390  
 391      public function filter_string($string, $context) {
 392          $this->stringsfiltered++;
 393          return parent::filter_string($string, $context);
 394      }
 395  
 396      /**
 397       * Return performance information, in the form required by {@link get_performance_info()}.
 398       * @return array the performance info.
 399       */
 400      public function get_performance_summary() {
 401          return array(array(
 402              'contextswithfilters' => count($this->textfilters),
 403              'filterscreated' => $this->filterscreated,
 404              'textsfiltered' => $this->textsfiltered,
 405              'stringsfiltered' => $this->stringsfiltered,
 406          ), array(
 407              'contextswithfilters' => 'Contexts for which filters were loaded',
 408              'filterscreated' => 'Filters created',
 409              'textsfiltered' => 'Pieces of content filtered',
 410              'stringsfiltered' => 'Strings filtered',
 411          ));
 412      }
 413  }
 414  
 415  
 416  /**
 417   * Base class for text filters. You just need to override this class and
 418   * implement the filter method.
 419   *
 420   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 421   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 422   */
 423  abstract class moodle_text_filter {
 424      /** @var context The context we are in. */
 425      protected $context;
 426  
 427      /** @var array Any local configuration for this filter in this context. */
 428      protected $localconfig;
 429  
 430      /**
 431       * Set any context-specific configuration for this filter.
 432       *
 433       * @param context $context The current context.
 434       * @param array $localconfig Any context-specific configuration for this filter.
 435       */
 436      public function __construct($context, array $localconfig) {
 437          $this->context = $context;
 438          $this->localconfig = $localconfig;
 439      }
 440  
 441      /**
 442       * @deprecated Since Moodle 3.0 MDL-50491. This was used by the old text filtering system, but no more.
 443       */
 444      public function hash() {
 445          throw new coding_exception('moodle_text_filter::hash() can not be used any more');
 446      }
 447  
 448      /**
 449       * Setup page with filter requirements and other prepare stuff.
 450       *
 451       * Override this method if the filter needs to setup page
 452       * requirements or needs other stuff to be executed.
 453       *
 454       * Note this method is invoked from {@see setup_page_for_filters()}
 455       * for each piece of text being filtered, so it is responsible
 456       * for controlling its own execution cardinality.
 457       *
 458       * @param moodle_page $page the page we are going to add requirements to.
 459       * @param context $context the context which contents are going to be filtered.
 460       * @since Moodle 2.3
 461       */
 462      public function setup($page, $context) {
 463          // Override me, if needed.
 464      }
 465  
 466      /**
 467       * Override this function to actually implement the filtering.
 468       *
 469       * Filter developers must make sure that filtering done after text cleaning
 470       * does not introduce security vulnerabilities.
 471       *
 472       * @param string $text some HTML content to process.
 473       * @param array $options options passed to the filters
 474       * @return string the HTML content after the filtering has been applied.
 475       */
 476      public abstract function filter($text, array $options = array());
 477  
 478      /**
 479       * Filter text before changing format to HTML.
 480       *
 481       * @param string $text
 482       * @param array $options
 483       * @return string
 484       */
 485      public function filter_stage_pre_format(string $text, array $options): string {
 486          // NOTE: override if necessary.
 487          return $text;
 488      }
 489  
 490      /**
 491       * Filter HTML text before sanitising text.
 492       *
 493       * NOTE: this is called even if $options['noclean'] is true and text is not cleaned.
 494       *
 495       * @param string $text
 496       * @param array $options
 497       * @return string
 498       */
 499      public function filter_stage_pre_clean(string $text, array $options): string {
 500          // NOTE: override if necessary.
 501          return $text;
 502      }
 503  
 504      /**
 505       * Filter HTML text at the very end after text is sanitised.
 506       *
 507       * NOTE: this is called even if $options['noclean'] is true and text is not cleaned.
 508       *
 509       * @param string $text
 510       * @param array $options
 511       * @return string
 512       */
 513      public function filter_stage_post_clean(string $text, array $options): string {
 514          // NOTE: override if necessary.
 515          return $this->filter($text, $options);
 516      }
 517  
 518      /**
 519       * Filter simple text coming from format_string().
 520       *
 521       * Note that unless $CFG->formatstringstriptags is disabled
 522       * HTML tags are not expected in returned value.
 523       *
 524       * @param string $text
 525       * @param array $options
 526       * @return string
 527       */
 528      public function filter_stage_string(string $text, array $options): string {
 529          // NOTE: override if necessary.
 530          return $this->filter($text, $options);
 531      }
 532  }
 533  
 534  
 535  /**
 536   * This is just a little object to define a phrase and some instructions
 537   * for how to process it.  Filters can create an array of these to pass
 538   * to the @{link filter_phrases()} function below.
 539   *
 540   * Note that although the fields here are public, you almost certainly should
 541   * never use that. All that is supported is contructing new instances of this
 542   * class, and then passing an array of them to filter_phrases.
 543   *
 544   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 545   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 546   */
 547  class filterobject {
 548      /** @var string this is the phrase that should be matched. */
 549      public $phrase;
 550  
 551      /** @var bool whether to match complete words. If true, 'T' won't be matched in 'Tim'. */
 552      public $fullmatch;
 553  
 554      /** @var bool whether the match needs to be case sensitive. */
 555      public $casesensitive;
 556  
 557      /** @var string HTML to insert before any match. */
 558      public $hreftagbegin;
 559      /** @var string HTML to insert after any match. */
 560      public $hreftagend;
 561  
 562      /** @var null|string replacement text to go inside begin and end. If not set,
 563       * the body of the replacement will be the original phrase.
 564       */
 565      public $replacementphrase;
 566  
 567      /** @var null|string once initialised, holds the regexp for matching this phrase. */
 568      public $workregexp = null;
 569  
 570      /** @var null|string once initialised, holds the mangled HTML to replace the regexp with. */
 571      public $workreplacementphrase = null;
 572  
 573      /** @var null|callable hold a replacement function to be called. */
 574      public $replacementcallback;
 575  
 576      /** @var null|array data to be passed to $replacementcallback. */
 577      public $replacementcallbackdata;
 578  
 579      /**
 580       * Constructor.
 581       *
 582       * @param string $phrase this is the phrase that should be matched.
 583       * @param string $hreftagbegin HTML to insert before any match. Default '<span class="highlight">'.
 584       * @param string $hreftagend HTML to insert after any match. Default '</span>'.
 585       * @param bool $casesensitive whether the match needs to be case sensitive
 586       * @param bool $fullmatch whether to match complete words. If true, 'T' won't be matched in 'Tim'.
 587       * @param mixed $replacementphrase replacement text to go inside begin and end. If not set,
 588       * the body of the replacement will be the original phrase.
 589       * @param callback $replacementcallback if set, then this will be called just before
 590       * $hreftagbegin, $hreftagend and $replacementphrase are needed, so they can be computed only if required.
 591       * The call made is
 592       * list($linkobject->hreftagbegin, $linkobject->hreftagend, $linkobject->replacementphrase) =
 593       *         call_user_func_array($linkobject->replacementcallback, $linkobject->replacementcallbackdata);
 594       * so the return should be an array [$hreftagbegin, $hreftagend, $replacementphrase], the last of which may be null.
 595       * @param array $replacementcallbackdata data to be passed to $replacementcallback (optional).
 596       */
 597      public function __construct($phrase, $hreftagbegin = '<span class="highlight">',
 598              $hreftagend = '</span>',
 599              $casesensitive = false,
 600              $fullmatch = false,
 601              $replacementphrase = null,
 602              $replacementcallback = null,
 603              array $replacementcallbackdata = null) {
 604  
 605          $this->phrase                  = $phrase;
 606          $this->hreftagbegin            = $hreftagbegin;
 607          $this->hreftagend              = $hreftagend;
 608          $this->casesensitive           = !empty($casesensitive);
 609          $this->fullmatch               = !empty($fullmatch);
 610          $this->replacementphrase       = $replacementphrase;
 611          $this->replacementcallback     = $replacementcallback;
 612          $this->replacementcallbackdata = $replacementcallbackdata;
 613      }
 614  }
 615  
 616  /**
 617   * Look up the name of this filter
 618   *
 619   * @param string $filter the filter name
 620   * @return string the human-readable name for this filter.
 621   */
 622  function filter_get_name($filter) {
 623      if (strpos($filter, 'filter/') === 0) {
 624          debugging("Old '$filter'' parameter used in filter_get_name()");
 625          $filter = substr($filter, 7);
 626      } else if (strpos($filter, '/') !== false) {
 627          throw new coding_exception('Unknown filter type ' . $filter);
 628      }
 629  
 630      if (get_string_manager()->string_exists('filtername', 'filter_' . $filter)) {
 631          return get_string('filtername', 'filter_' . $filter);
 632      } else {
 633          return $filter;
 634      }
 635  }
 636  
 637  /**
 638   * Get the names of all the filters installed in this Moodle.
 639   *
 640   * @return array path => filter name from the appropriate lang file. e.g.
 641   * array('tex' => 'TeX Notation');
 642   * sorted in alphabetical order of name.
 643   */
 644  function filter_get_all_installed() {
 645      $filternames = array();
 646      foreach (core_component::get_plugin_list('filter') as $filter => $fulldir) {
 647          if (is_readable("$fulldir/filter.php")) {
 648              $filternames[$filter] = filter_get_name($filter);
 649          }
 650      }
 651      core_collator::asort($filternames);
 652      return $filternames;
 653  }
 654  
 655  /**
 656   * Set the global activated state for a text filter.
 657   *
 658   * @param string $filtername The filter name, for example 'tex'.
 659   * @param int $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.
 660   * @param int $move -1 means up, 0 means the same, 1 means down
 661   */
 662  function filter_set_global_state($filtername, $state, $move = 0) {
 663      global $DB;
 664  
 665      // Check requested state is valid.
 666      if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_DISABLED))) {
 667          throw new coding_exception("Illegal option '$state' passed to filter_set_global_state. " .
 668                  "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_DISABLED.");
 669      }
 670  
 671      if ($move > 0) {
 672          $move = 1;
 673      } else if ($move < 0) {
 674          $move = -1;
 675      }
 676  
 677      if (strpos($filtername, 'filter/') === 0) {
 678          $filtername = substr($filtername, 7);
 679      } else if (strpos($filtername, '/') !== false) {
 680          throw new coding_exception("Invalid filter name '$filtername' used in filter_set_global_state()");
 681      }
 682  
 683      $transaction = $DB->start_delegated_transaction();
 684  
 685      $syscontext = context_system::instance();
 686      $filters = $DB->get_records('filter_active', array('contextid' => $syscontext->id), 'sortorder ASC');
 687  
 688      $on = array();
 689      $off = array();
 690  
 691      foreach ($filters as $f) {
 692          if ($f->active == TEXTFILTER_DISABLED) {
 693              $off[$f->filter] = $f;
 694          } else {
 695              $on[$f->filter] = $f;
 696          }
 697      }
 698  
 699      // Update the state or add new record.
 700      if (isset($on[$filtername])) {
 701          $filter = $on[$filtername];
 702          if ($filter->active != $state) {
 703              add_to_config_log('filter_active', $filter->active, $state, $filtername);
 704  
 705              $filter->active = $state;
 706              $DB->update_record('filter_active', $filter);
 707              if ($filter->active == TEXTFILTER_DISABLED) {
 708                  unset($on[$filtername]);
 709                  $off = array($filter->filter => $filter) + $off;
 710              }
 711  
 712          }
 713  
 714      } else if (isset($off[$filtername])) {
 715          $filter = $off[$filtername];
 716          if ($filter->active != $state) {
 717              add_to_config_log('filter_active', $filter->active, $state, $filtername);
 718  
 719              $filter->active = $state;
 720              $DB->update_record('filter_active', $filter);
 721              if ($filter->active != TEXTFILTER_DISABLED) {
 722                  unset($off[$filtername]);
 723                  $on[$filter->filter] = $filter;
 724              }
 725          }
 726  
 727      } else {
 728          add_to_config_log('filter_active', '', $state, $filtername);
 729  
 730          $filter = new stdClass();
 731          $filter->filter    = $filtername;
 732          $filter->contextid = $syscontext->id;
 733          $filter->active    = $state;
 734          $filter->sortorder = 99999;
 735          $filter->id = $DB->insert_record('filter_active', $filter);
 736  
 737          $filters[$filter->id] = $filter;
 738          if ($state == TEXTFILTER_DISABLED) {
 739              $off[$filter->filter] = $filter;
 740          } else {
 741              $on[$filter->filter] = $filter;
 742          }
 743      }
 744  
 745      // Move only active.
 746      if ($move != 0 and isset($on[$filter->filter])) {
 747          // Capture the old order for logging.
 748          $oldorder = implode(', ', array_map(
 749                  function($f) {
 750                      return $f->filter;
 751                  }, $on));
 752  
 753          // Work out the new order.
 754          $i = 1;
 755          foreach ($on as $f) {
 756              $f->newsortorder = $i;
 757              $i++;
 758          }
 759  
 760          $filter->newsortorder = $filter->newsortorder + $move;
 761  
 762          foreach ($on as $f) {
 763              if ($f->id == $filter->id) {
 764                  continue;
 765              }
 766              if ($f->newsortorder == $filter->newsortorder) {
 767                  if ($move == 1) {
 768                      $f->newsortorder = $f->newsortorder - 1;
 769                  } else {
 770                      $f->newsortorder = $f->newsortorder + 1;
 771                  }
 772              }
 773          }
 774  
 775          core_collator::asort_objects_by_property($on, 'newsortorder', core_collator::SORT_NUMERIC);
 776  
 777          // Log in config_log.
 778          $neworder = implode(', ', array_map(
 779                  function($f) {
 780                      return $f->filter;
 781                  }, $on));
 782          add_to_config_log('order', $oldorder, $neworder, 'core_filter');
 783      }
 784  
 785      // Inactive are sorted by filter name.
 786      core_collator::asort_objects_by_property($off, 'filter', core_collator::SORT_NATURAL);
 787  
 788      // Update records if necessary.
 789      $i = 1;
 790      foreach ($on as $f) {
 791          if ($f->sortorder != $i) {
 792              $DB->set_field('filter_active', 'sortorder', $i, array('id' => $f->id));
 793          }
 794          $i++;
 795      }
 796      foreach ($off as $f) {
 797          if ($f->sortorder != $i) {
 798              $DB->set_field('filter_active', 'sortorder', $i, array('id' => $f->id));
 799          }
 800          $i++;
 801      }
 802  
 803      $transaction->allow_commit();
 804  }
 805  
 806  /**
 807   * Returns the active state for a filter in the given context.
 808   *
 809   * @param string $filtername The filter name, for example 'tex'.
 810   * @param integer $contextid The id of the context to get the data for.
 811   * @return int value of active field for the given filter.
 812   */
 813  function filter_get_active_state(string $filtername, $contextid = null): int {
 814      global $DB;
 815  
 816      if ($contextid === null) {
 817          $contextid = context_system::instance()->id;
 818      }
 819      if (is_object($contextid)) {
 820          $contextid = $contextid->id;
 821      }
 822  
 823      if (strpos($filtername, 'filter/') === 0) {
 824          $filtername = substr($filtername, 7);
 825      } else if (strpos($filtername, '/') !== false) {
 826          throw new coding_exception("Invalid filter name '$filtername' used in filter_is_enabled()");
 827      }
 828      if ($active = $DB->get_field('filter_active', 'active', array('filter' => $filtername, 'contextid' => $contextid))) {
 829          return $active;
 830      }
 831  
 832      return TEXTFILTER_DISABLED;
 833  }
 834  
 835  /**
 836   * @param string $filtername The filter name, for example 'tex'.
 837   * @return boolean is this filter allowed to be used on this site. That is, the
 838   *      admin has set the global 'active' setting to On, or Off, but available.
 839   */
 840  function filter_is_enabled($filtername) {
 841      if (strpos($filtername, 'filter/') === 0) {
 842          $filtername = substr($filtername, 7);
 843      } else if (strpos($filtername, '/') !== false) {
 844          throw new coding_exception("Invalid filter name '$filtername' used in filter_is_enabled()");
 845      }
 846      return array_key_exists($filtername, filter_get_globally_enabled());
 847  }
 848  
 849  /**
 850   * Return a list of all the filters that may be in use somewhere.
 851   *
 852   * @return array where the keys and values are both the filter name, like 'tex'.
 853   */
 854  function filter_get_globally_enabled() {
 855      $cache = \cache::make_from_params(\cache_store::MODE_REQUEST, 'core_filter', 'global_filters');
 856      $enabledfilters = $cache->get('enabled');
 857      if ($enabledfilters !== false) {
 858          return $enabledfilters;
 859      }
 860  
 861      $filters = filter_get_global_states();
 862      $enabledfilters = array();
 863      foreach ($filters as $filter => $filerinfo) {
 864          if ($filerinfo->active != TEXTFILTER_DISABLED) {
 865              $enabledfilters[$filter] = $filter;
 866          }
 867      }
 868  
 869      $cache->set('enabled', $enabledfilters);
 870      return $enabledfilters;
 871  }
 872  
 873  /**
 874   * Get the globally enabled filters.
 875   *
 876   * This returns the filters which could be used in any context. Essentially
 877   * the filters which are not disabled for the entire site.
 878   *
 879   * @return array Keys are filter names, and values the config.
 880   */
 881  function filter_get_globally_enabled_filters_with_config() {
 882      global $DB;
 883  
 884      $sql = "SELECT f.filter, fc.name, fc.value
 885                FROM {filter_active} f
 886           LEFT JOIN {filter_config} fc
 887                  ON fc.filter = f.filter
 888                 AND fc.contextid = f.contextid
 889               WHERE f.contextid = :contextid
 890                 AND f.active != :disabled
 891            ORDER BY f.sortorder";
 892  
 893      $rs = $DB->get_recordset_sql($sql, [
 894          'contextid' => context_system::instance()->id,
 895          'disabled' => TEXTFILTER_DISABLED
 896      ]);
 897  
 898      // Massage the data into the specified format to return.
 899      $filters = array();
 900      foreach ($rs as $row) {
 901          if (!isset($filters[$row->filter])) {
 902              $filters[$row->filter] = array();
 903          }
 904          if ($row->name !== null) {
 905              $filters[$row->filter][$row->name] = $row->value;
 906          }
 907      }
 908      $rs->close();
 909  
 910      return $filters;
 911  }
 912  
 913  /**
 914   * Return the names of the filters that should also be applied to strings
 915   * (when they are enabled).
 916   *
 917   * @return array where the keys and values are both the filter name, like 'tex'.
 918   */
 919  function filter_get_string_filters() {
 920      global $CFG;
 921      $stringfilters = array();
 922      if (!empty($CFG->filterall) && !empty($CFG->stringfilters)) {
 923          $stringfilters = explode(',', $CFG->stringfilters);
 924          $stringfilters = array_combine($stringfilters, $stringfilters);
 925      }
 926      return $stringfilters;
 927  }
 928  
 929  /**
 930   * Sets whether a particular active filter should be applied to all strings by
 931   * format_string, or just used by format_text.
 932   *
 933   * @param string $filter The filter name, for example 'tex'.
 934   * @param boolean $applytostrings if true, this filter will apply to format_string
 935   *      and format_text, when it is enabled.
 936   */
 937  function filter_set_applies_to_strings($filter, $applytostrings) {
 938      $stringfilters = filter_get_string_filters();
 939      $prevfilters = $stringfilters;
 940      $allfilters = core_component::get_plugin_list('filter');
 941  
 942      if ($applytostrings) {
 943          $stringfilters[$filter] = $filter;
 944      } else {
 945          unset($stringfilters[$filter]);
 946      }
 947  
 948      // Remove missing filters.
 949      foreach ($stringfilters as $filter) {
 950          if (!isset($allfilters[$filter])) {
 951              unset($stringfilters[$filter]);
 952          }
 953      }
 954  
 955      if ($prevfilters != $stringfilters) {
 956          set_config('stringfilters', implode(',', $stringfilters));
 957          set_config('filterall', !empty($stringfilters));
 958      }
 959  }
 960  
 961  /**
 962   * Set the local activated state for a text filter.
 963   *
 964   * @param string $filter The filter name, for example 'tex'.
 965   * @param integer $contextid The id of the context to get the local config for.
 966   * @param integer $state One of the values TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.
 967   * @return void
 968   */
 969  function filter_set_local_state($filter, $contextid, $state) {
 970      global $DB;
 971  
 972      // Check requested state is valid.
 973      if (!in_array($state, array(TEXTFILTER_ON, TEXTFILTER_OFF, TEXTFILTER_INHERIT))) {
 974          throw new coding_exception("Illegal option '$state' passed to filter_set_local_state. " .
 975                  "Must be one of TEXTFILTER_ON, TEXTFILTER_OFF or TEXTFILTER_INHERIT.");
 976      }
 977  
 978      if ($contextid == context_system::instance()->id) {
 979          throw new coding_exception('You cannot use filter_set_local_state ' .
 980                  'with $contextid equal to the system context id.');
 981      }
 982  
 983      if ($state == TEXTFILTER_INHERIT) {
 984          $DB->delete_records('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 985          return;
 986      }
 987  
 988      $rec = $DB->get_record('filter_active', array('filter' => $filter, 'contextid' => $contextid));
 989      $insert = false;
 990      if (empty($rec)) {
 991          $insert = true;
 992          $rec = new stdClass;
 993          $rec->filter = $filter;
 994          $rec->contextid = $contextid;
 995      }
 996  
 997      $rec->active = $state;
 998  
 999      if ($insert) {
1000          $DB->insert_record('filter_active', $rec);
1001      } else {
1002          $DB->update_record('filter_active', $rec);
1003      }
1004  }
1005  
1006  /**
1007   * Set a particular local config variable for a filter in a context.
1008   *
1009   * @param string $filter The filter name, for example 'tex'.
1010   * @param integer $contextid The id of the context to get the local config for.
1011   * @param string $name the setting name.
1012   * @param string $value the corresponding value.
1013   */
1014  function filter_set_local_config($filter, $contextid, $name, $value) {
1015      global $DB;
1016      $rec = $DB->get_record('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
1017      $insert = false;
1018      if (empty($rec)) {
1019          $insert = true;
1020          $rec = new stdClass;
1021          $rec->filter = $filter;
1022          $rec->contextid = $contextid;
1023          $rec->name = $name;
1024      }
1025  
1026      $rec->value = $value;
1027  
1028      if ($insert) {
1029          $DB->insert_record('filter_config', $rec);
1030      } else {
1031          $DB->update_record('filter_config', $rec);
1032      }
1033  }
1034  
1035  /**
1036   * Remove a particular local config variable for a filter in a context.
1037   *
1038   * @param string $filter The filter name, for example 'tex'.
1039   * @param integer $contextid The id of the context to get the local config for.
1040   * @param string $name the setting name.
1041   */
1042  function filter_unset_local_config($filter, $contextid, $name) {
1043      global $DB;
1044      $DB->delete_records('filter_config', array('filter' => $filter, 'contextid' => $contextid, 'name' => $name));
1045  }
1046  
1047  /**
1048   * Get local config variables for a filter in a context. Normally (when your
1049   * filter is running) you don't need to call this, becuase the config is fetched
1050   * for you automatically. You only need this, for example, when you are getting
1051   * the config so you can show the user an editing from.
1052   *
1053   * @param string $filter The filter name, for example 'tex'.
1054   * @param integer $contextid The ID of the context to get the local config for.
1055   * @return array of name => value pairs.
1056   */
1057  function filter_get_local_config($filter, $contextid) {
1058      global $DB;
1059      return $DB->get_records_menu('filter_config', array('filter' => $filter, 'contextid' => $contextid), '', 'name,value');
1060  }
1061  
1062  /**
1063   * This function is for use by backup. Gets all the filter information specific
1064   * to one context.
1065   *
1066   * @param int $contextid
1067   * @return array Array with two elements. The first element is an array of objects with
1068   *      fields filter and active. These come from the filter_active table. The
1069   *      second element is an array of objects with fields filter, name and value
1070   *      from the filter_config table.
1071   */
1072  function filter_get_all_local_settings($contextid) {
1073      global $DB;
1074      return array(
1075          $DB->get_records('filter_active', array('contextid' => $contextid), 'filter', 'filter,active'),
1076          $DB->get_records('filter_config', array('contextid' => $contextid), 'filter,name', 'filter,name,value'),
1077      );
1078  }
1079  
1080  /**
1081   * Get the list of active filters, in the order that they should be used
1082   * for a particular context, along with any local configuration variables.
1083   *
1084   * @param context $context a context
1085   * @return array an array where the keys are the filter names, for example
1086   *      'tex' and the values are any local
1087   *      configuration for that filter, as an array of name => value pairs
1088   *      from the filter_config table. In a lot of cases, this will be an
1089   *      empty array. So, an example return value for this function might be
1090   *      array(tex' => array())
1091   */
1092  function filter_get_active_in_context($context) {
1093      global $DB, $FILTERLIB_PRIVATE;
1094  
1095      if (!isset($FILTERLIB_PRIVATE)) {
1096          $FILTERLIB_PRIVATE = new stdClass();
1097      }
1098  
1099      // Use cache (this is a within-request cache only) if available. See
1100      // function filter_preload_activities.
1101      if (isset($FILTERLIB_PRIVATE->active) &&
1102              array_key_exists($context->id, $FILTERLIB_PRIVATE->active)) {
1103          return $FILTERLIB_PRIVATE->active[$context->id];
1104      }
1105  
1106      $contextids = str_replace('/', ',', trim($context->path, '/'));
1107  
1108      // The following SQL is tricky. It is explained on
1109      // http://docs.moodle.org/dev/Filter_enable/disable_by_context.
1110      $sql = "SELECT active.filter, fc.name, fc.value
1111           FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder
1112               FROM {filter_active} f
1113               JOIN {context} ctx ON f.contextid = ctx.id
1114               WHERE ctx.id IN ($contextids)
1115               GROUP BY filter
1116               HAVING MAX(f.active * ctx.depth) > -MIN(f.active * ctx.depth)
1117           ) active
1118           LEFT JOIN {filter_config} fc ON fc.filter = active.filter AND fc.contextid = $context->id
1119           ORDER BY active.sortorder";
1120      $rs = $DB->get_recordset_sql($sql);
1121  
1122      // Massage the data into the specified format to return.
1123      $filters = array();
1124      foreach ($rs as $row) {
1125          if (!isset($filters[$row->filter])) {
1126              $filters[$row->filter] = array();
1127          }
1128          if (!is_null($row->name)) {
1129              $filters[$row->filter][$row->name] = $row->value;
1130          }
1131      }
1132  
1133      $rs->close();
1134  
1135      return $filters;
1136  }
1137  
1138  /**
1139   * Preloads the list of active filters for all activities (modules) on the course
1140   * using two database queries.
1141   *
1142   * @param course_modinfo $modinfo Course object from get_fast_modinfo
1143   */
1144  function filter_preload_activities(course_modinfo $modinfo) {
1145      global $DB, $FILTERLIB_PRIVATE;
1146  
1147      if (!isset($FILTERLIB_PRIVATE)) {
1148          $FILTERLIB_PRIVATE = new stdClass();
1149      }
1150  
1151      // Don't repeat preload.
1152      if (!isset($FILTERLIB_PRIVATE->preloaded)) {
1153          $FILTERLIB_PRIVATE->preloaded = array();
1154      }
1155      if (!empty($FILTERLIB_PRIVATE->preloaded[$modinfo->get_course_id()])) {
1156          return;
1157      }
1158      $FILTERLIB_PRIVATE->preloaded[$modinfo->get_course_id()] = true;
1159  
1160      // Get contexts for all CMs.
1161      $cmcontexts = array();
1162      $cmcontextids = array();
1163      foreach ($modinfo->get_cms() as $cm) {
1164          $modulecontext = context_module::instance($cm->id);
1165          $cmcontextids[] = $modulecontext->id;
1166          $cmcontexts[] = $modulecontext;
1167      }
1168  
1169      // Get course context and all other parents.
1170      $coursecontext = context_course::instance($modinfo->get_course_id());
1171      $parentcontextids = explode('/', substr($coursecontext->path, 1));
1172      $allcontextids = array_merge($cmcontextids, $parentcontextids);
1173  
1174      // Get all filter_active rows relating to all these contexts.
1175      list ($sql, $params) = $DB->get_in_or_equal($allcontextids);
1176      $filteractives = $DB->get_records_select('filter_active', "contextid $sql", $params, 'sortorder');
1177  
1178      // Get all filter_config only for the cm contexts.
1179      list ($sql, $params) = $DB->get_in_or_equal($cmcontextids);
1180      $filterconfigs = $DB->get_records_select('filter_config', "contextid $sql", $params);
1181  
1182      // Note: I was a bit surprised that filter_config only works for the
1183      // most specific context (i.e. it does not need to be checked for course
1184      // context if we only care about CMs) however basede on code in
1185      // filter_get_active_in_context, this does seem to be correct.
1186  
1187      // Build course default active list. Initially this will be an array of
1188      // filter name => active score (where an active score >0 means it's active).
1189      $courseactive = array();
1190  
1191      // Also build list of filter_active rows below course level, by contextid.
1192      $remainingactives = array();
1193  
1194      // Array lists filters that are banned at top level.
1195      $banned = array();
1196  
1197      // Add any active filters in parent contexts to the array.
1198      foreach ($filteractives as $row) {
1199          $depth = array_search($row->contextid, $parentcontextids);
1200          if ($depth !== false) {
1201              // Find entry.
1202              if (!array_key_exists($row->filter, $courseactive)) {
1203                  $courseactive[$row->filter] = 0;
1204              }
1205              // This maths copes with reading rows in any order. Turning on/off
1206              // at site level counts 1, at next level down 4, at next level 9,
1207              // then 16, etc. This means the deepest level always wins, except
1208              // against the -9999 at top level.
1209              $courseactive[$row->filter] +=
1210                  ($depth + 1) * ($depth + 1) * $row->active;
1211  
1212              if ($row->active == TEXTFILTER_DISABLED) {
1213                  $banned[$row->filter] = true;
1214              }
1215          } else {
1216              // Build list of other rows indexed by contextid.
1217              if (!array_key_exists($row->contextid, $remainingactives)) {
1218                  $remainingactives[$row->contextid] = array();
1219              }
1220              $remainingactives[$row->contextid][] = $row;
1221          }
1222      }
1223  
1224      // Chuck away the ones that aren't active.
1225      foreach ($courseactive as $filter => $score) {
1226          if ($score <= 0) {
1227              unset($courseactive[$filter]);
1228          } else {
1229              $courseactive[$filter] = array();
1230          }
1231      }
1232  
1233      // Loop through the contexts to reconstruct filter_active lists for each
1234      // cm on the course.
1235      if (!isset($FILTERLIB_PRIVATE->active)) {
1236          $FILTERLIB_PRIVATE->active = array();
1237      }
1238      foreach ($cmcontextids as $contextid) {
1239          // Copy course list.
1240          $FILTERLIB_PRIVATE->active[$contextid] = $courseactive;
1241  
1242          // Are there any changes to the active list?
1243          if (array_key_exists($contextid, $remainingactives)) {
1244              foreach ($remainingactives[$contextid] as $row) {
1245                  if ($row->active > 0 && empty($banned[$row->filter])) {
1246                      // If it's marked active for specific context, add entry
1247                      // (doesn't matter if one exists already).
1248                      $FILTERLIB_PRIVATE->active[$contextid][$row->filter] = array();
1249                  } else {
1250                      // If it's marked inactive, remove entry (doesn't matter
1251                      // if it doesn't exist).
1252                      unset($FILTERLIB_PRIVATE->active[$contextid][$row->filter]);
1253                  }
1254              }
1255          }
1256      }
1257  
1258      // Process all config rows to add config data to these entries.
1259      foreach ($filterconfigs as $row) {
1260          if (isset($FILTERLIB_PRIVATE->active[$row->contextid][$row->filter])) {
1261              $FILTERLIB_PRIVATE->active[$row->contextid][$row->filter][$row->name] = $row->value;
1262          }
1263      }
1264  }
1265  
1266  /**
1267   * List all of the filters that are available in this context, and what the
1268   * local and inherited states of that filter are.
1269   *
1270   * @param context $context a context that is not the system context.
1271   * @return array an array with filter names, for example 'tex'
1272   *      as keys. and and the values are objects with fields:
1273   *      ->filter filter name, same as the key.
1274   *      ->localstate TEXTFILTER_ON/OFF/INHERIT
1275   *      ->inheritedstate TEXTFILTER_ON/OFF - the state that will be used if localstate is set to TEXTFILTER_INHERIT.
1276   */
1277  function filter_get_available_in_context($context) {
1278      global $DB;
1279  
1280      // The complex logic is working out the active state in the parent context,
1281      // so strip the current context from the list.
1282      $contextids = explode('/', trim($context->path, '/'));
1283      array_pop($contextids);
1284      $contextids = implode(',', $contextids);
1285      if (empty($contextids)) {
1286          throw new coding_exception('filter_get_available_in_context cannot be called with the system context.');
1287      }
1288  
1289      // The following SQL is tricky, in the same way at the SQL in filter_get_active_in_context.
1290      $sql = "SELECT parent_states.filter,
1291                  CASE WHEN fa.active IS NULL THEN " . TEXTFILTER_INHERIT . "
1292                  ELSE fa.active END AS localstate,
1293               parent_states.inheritedstate
1294           FROM (SELECT f.filter, MAX(f.sortorder) AS sortorder,
1295                      CASE WHEN MAX(f.active * ctx.depth) > -MIN(f.active * ctx.depth) THEN " . TEXTFILTER_ON . "
1296                      ELSE " . TEXTFILTER_OFF . " END AS inheritedstate
1297               FROM {filter_active} f
1298               JOIN {context} ctx ON f.contextid = ctx.id
1299               WHERE ctx.id IN ($contextids)
1300               GROUP BY f.filter
1301               HAVING MIN(f.active) > " . TEXTFILTER_DISABLED . "
1302           ) parent_states
1303           LEFT JOIN {filter_active} fa ON fa.filter = parent_states.filter AND fa.contextid = $context->id
1304           ORDER BY parent_states.sortorder";
1305      return $DB->get_records_sql($sql);
1306  }
1307  
1308  /**
1309   * This function is for use by the filter administration page.
1310   *
1311   * @return array 'filtername' => object with fields 'filter' (=filtername), 'active' and 'sortorder'
1312   */
1313  function filter_get_global_states() {
1314      global $DB;
1315      $context = context_system::instance();
1316      return $DB->get_records('filter_active', array('contextid' => $context->id), 'sortorder', 'filter,active,sortorder');
1317  }
1318  
1319  /**
1320   * Delete all the data in the database relating to a filter, prior to deleting it.
1321   *
1322   * @param string $filter The filter name, for example 'tex'.
1323   */
1324  function filter_delete_all_for_filter($filter) {
1325      global $DB;
1326  
1327      unset_all_config_for_plugin('filter_' . $filter);
1328      $DB->delete_records('filter_active', array('filter' => $filter));
1329      $DB->delete_records('filter_config', array('filter' => $filter));
1330  }
1331  
1332  /**
1333   * Delete all the data in the database relating to a context, used when contexts are deleted.
1334   *
1335   * @param integer $contextid The id of the context being deleted.
1336   */
1337  function filter_delete_all_for_context($contextid) {
1338      global $DB;
1339      $DB->delete_records('filter_active', array('contextid' => $contextid));
1340      $DB->delete_records('filter_config', array('contextid' => $contextid));
1341  }
1342  
1343  /**
1344   * Does this filter have a global settings page in the admin tree?
1345   * (The settings page for a filter must be called, for example, filtersettingfiltertex.)
1346   *
1347   * @param string $filter The filter name, for example 'tex'.
1348   * @return boolean Whether there should be a 'Settings' link on the config page.
1349   */
1350  function filter_has_global_settings($filter) {
1351      global $CFG;
1352      $settingspath = $CFG->dirroot . '/filter/' . $filter . '/settings.php';
1353      if (is_readable($settingspath)) {
1354          return true;
1355      }
1356      $settingspath = $CFG->dirroot . '/filter/' . $filter . '/filtersettings.php';
1357      return is_readable($settingspath);
1358  }
1359  
1360  /**
1361   * Does this filter have local (per-context) settings?
1362   *
1363   * @param string $filter The filter name, for example 'tex'.
1364   * @return boolean Whether there should be a 'Settings' link on the manage filters in context page.
1365   */
1366  function filter_has_local_settings($filter) {
1367      global $CFG;
1368      $settingspath = $CFG->dirroot . '/filter/' . $filter . '/filterlocalsettings.php';
1369      return is_readable($settingspath);
1370  }
1371  
1372  /**
1373   * Certain types of context (block and user) may not have local filter settings.
1374   * the function checks a context to see whether it may have local config.
1375   *
1376   * @param object $context a context.
1377   * @return boolean whether this context may have local filter settings.
1378   */
1379  function filter_context_may_have_filter_settings($context) {
1380      return $context->contextlevel != CONTEXT_BLOCK && $context->contextlevel != CONTEXT_USER;
1381  }
1382  
1383  /**
1384   * Process phrases intelligently found within a HTML text (such as adding links).
1385   *
1386   * @param string $text            the text that we are filtering
1387   * @param filterobject[] $linkarray an array of filterobjects
1388   * @param array $ignoretagsopen   an array of opening tags that we should ignore while filtering
1389   * @param array $ignoretagsclose  an array of corresponding closing tags
1390   * @param bool $overridedefaultignore True to only use tags provided by arguments
1391   * @param bool $linkarrayalreadyprepared True to say that filter_prepare_phrases_for_filtering
1392   *      has already been called for $linkarray. Default false.
1393   * @return string
1394   */
1395  function filter_phrases($text, $linkarray, $ignoretagsopen = null, $ignoretagsclose = null,
1396          $overridedefaultignore = false, $linkarrayalreadyprepared = false) {
1397  
1398      global $CFG;
1399  
1400      // Used if $CFG->filtermatchoneperpage is on. Array with keys being the workregexp
1401      // for things that have already been matched on this page.
1402      static $usedphrases = [];
1403  
1404      $ignoretags = array();  // To store all the enclosing tags to be completely ignored.
1405      $tags = array();        // To store all the simple tags to be ignored.
1406  
1407      if (!$linkarrayalreadyprepared) {
1408          $linkarray = filter_prepare_phrases_for_filtering($linkarray);
1409      }
1410  
1411      if (!$overridedefaultignore) {
1412          // A list of open/close tags that we should not replace within.
1413          // Extended to include <script>, <textarea>, <select> and <a> tags.
1414          // Regular expression allows tags with or without attributes.
1415          $filterignoretagsopen  = array('<head>', '<nolink>', '<span(\s[^>]*?)?class="nolink"(\s[^>]*?)?>',
1416                  '<script(\s[^>]*?)?>', '<textarea(\s[^>]*?)?>',
1417                  '<select(\s[^>]*?)?>', '<a(\s[^>]*?)?>');
1418          $filterignoretagsclose = array('</head>', '</nolink>', '</span>',
1419                   '</script>', '</textarea>', '</select>', '</a>');
1420      } else {
1421          // Set an empty default list.
1422          $filterignoretagsopen = array();
1423          $filterignoretagsclose = array();
1424      }
1425  
1426      // Add the user defined ignore tags to the default list.
1427      if ( is_array($ignoretagsopen) ) {
1428          foreach ($ignoretagsopen as $open) {
1429              $filterignoretagsopen[] = $open;
1430          }
1431          foreach ($ignoretagsclose as $close) {
1432              $filterignoretagsclose[] = $close;
1433          }
1434      }
1435  
1436      // Double up some magic chars to avoid "accidental matches".
1437      $text = preg_replace('/([#*%])/', '\1\1', $text);
1438  
1439      // Remove everything enclosed by the ignore tags from $text.
1440      filter_save_ignore_tags($text, $filterignoretagsopen, $filterignoretagsclose, $ignoretags);
1441  
1442      // Remove tags from $text.
1443      filter_save_tags($text, $tags);
1444  
1445      // Prepare the limit for preg_match calls.
1446      if (!empty($CFG->filtermatchonepertext) || !empty($CFG->filtermatchoneperpage)) {
1447          $pregreplacelimit = 1;
1448      } else {
1449          $pregreplacelimit = -1; // No limit.
1450      }
1451  
1452      // Time to cycle through each phrase to be linked.
1453      foreach ($linkarray as $key => $linkobject) {
1454          if ($linkobject->workregexp === null) {
1455              // This is the case if, when preparing the phrases for filtering,
1456              // we decided that this was not a suitable phrase to match.
1457              continue;
1458          }
1459  
1460          // If $CFG->filtermatchoneperpage, avoid previously matched linked phrases.
1461          if (!empty($CFG->filtermatchoneperpage) && isset($usedphrases[$linkobject->workregexp])) {
1462              continue;
1463          }
1464  
1465          // Do our highlighting.
1466          $resulttext = preg_replace_callback($linkobject->workregexp,
1467                  function ($matches) use ($linkobject) {
1468                      if ($linkobject->workreplacementphrase === null) {
1469                          filter_prepare_phrase_for_replacement($linkobject);
1470                      }
1471  
1472                      return str_replace('$1', $matches[1], $linkobject->workreplacementphrase);
1473                  }, $text, $pregreplacelimit);
1474  
1475          // If the text has changed we have to look for links again.
1476          if ($resulttext != $text) {
1477              $text = $resulttext;
1478              // Remove everything enclosed by the ignore tags from $text.
1479              filter_save_ignore_tags($text, $filterignoretagsopen, $filterignoretagsclose, $ignoretags);
1480              // Remove tags from $text.
1481              filter_save_tags($text, $tags);
1482              // If $CFG->filtermatchoneperpage, save linked phrases to request.
1483              if (!empty($CFG->filtermatchoneperpage)) {
1484                  $usedphrases[$linkobject->workregexp] = 1;
1485              }
1486          }
1487      }
1488  
1489      // Rebuild the text with all the excluded areas.
1490      if (!empty($tags)) {
1491          $text = str_replace(array_keys($tags), $tags, $text);
1492      }
1493  
1494      if (!empty($ignoretags)) {
1495          $ignoretags = array_reverse($ignoretags);     // Reversed so "progressive" str_replace() will solve some nesting problems.
1496          $text = str_replace(array_keys($ignoretags), $ignoretags, $text);
1497      }
1498  
1499      // Remove the protective doubleups.
1500      $text = preg_replace('/([#*%])(\1)/', '\1', $text);
1501  
1502      // Add missing javascript for popus.
1503      $text = filter_add_javascript($text);
1504  
1505      return $text;
1506  }
1507  
1508  /**
1509   * Prepare a list of link for processing with {@link filter_phrases()}.
1510   *
1511   * @param filterobject[] $linkarray the links that will be passed to filter_phrases().
1512   * @return filterobject[] the updated list of links with necessary pre-processing done.
1513   */
1514  function filter_prepare_phrases_for_filtering(array $linkarray) {
1515      // Time to cycle through each phrase to be linked.
1516      foreach ($linkarray as $linkobject) {
1517  
1518          // Set some defaults if certain properties are missing.
1519          // Properties may be missing if the filterobject class has not been used to construct the object.
1520          if (empty($linkobject->phrase)) {
1521              continue;
1522          }
1523  
1524          // Avoid integers < 1000 to be linked. See bug 1446.
1525          $intcurrent = intval($linkobject->phrase);
1526          if (!empty($intcurrent) && strval($intcurrent) == $linkobject->phrase && $intcurrent < 1000) {
1527              continue;
1528          }
1529  
1530          // Strip tags out of the phrase.
1531          $linkobject->workregexp = strip_tags($linkobject->phrase);
1532  
1533          if (!$linkobject->casesensitive) {
1534              $linkobject->workregexp = core_text::strtolower($linkobject->workregexp);
1535          }
1536  
1537          // Double up chars that might cause a false match -- the duplicates will
1538          // be cleared up before returning to the user.
1539          $linkobject->workregexp = preg_replace('/([#*%])/', '\1\1', $linkobject->workregexp);
1540  
1541          // Quote any regular expression characters and the delimiter in the work phrase to be searched.
1542          $linkobject->workregexp = preg_quote($linkobject->workregexp, '/');
1543  
1544          // If we ony want to match entire words then add \b assertions. However, only
1545          // do this if the first or last thing in the phrase to match is a word character.
1546          if ($linkobject->fullmatch) {
1547              if (preg_match('~^\w~', $linkobject->workregexp)) {
1548                  $linkobject->workregexp = '\b' . $linkobject->workregexp;
1549              }
1550              if (preg_match('~\w$~', $linkobject->workregexp)) {
1551                  $linkobject->workregexp = $linkobject->workregexp . '\b';
1552              }
1553          }
1554  
1555          $linkobject->workregexp = '/(' . $linkobject->workregexp . ')/s';
1556  
1557          if (!$linkobject->casesensitive) {
1558              $linkobject->workregexp .= 'iu';
1559          }
1560      }
1561  
1562      return $linkarray;
1563  }
1564  
1565  /**
1566   * Fill in the remaining ->work... fields, that would be needed to replace the phrase.
1567   *
1568   * @param filterobject $linkobject the link object on which to set additional fields.
1569   */
1570  function filter_prepare_phrase_for_replacement(filterobject $linkobject) {
1571      if ($linkobject->replacementcallback !== null) {
1572          list($linkobject->hreftagbegin, $linkobject->hreftagend, $linkobject->replacementphrase) =
1573                  call_user_func_array($linkobject->replacementcallback, $linkobject->replacementcallbackdata);
1574      }
1575  
1576      if (!isset($linkobject->hreftagbegin) or !isset($linkobject->hreftagend)) {
1577          $linkobject->hreftagbegin = '<span class="highlight"';
1578          $linkobject->hreftagend   = '</span>';
1579      }
1580  
1581      // Double up chars to protect true duplicates
1582      // be cleared up before returning to the user.
1583      $hreftagbeginmangled = preg_replace('/([#*%])/', '\1\1', $linkobject->hreftagbegin);
1584  
1585      // Set the replacement phrase properly.
1586      if ($linkobject->replacementphrase) {    // We have specified a replacement phrase.
1587          $linkobject->workreplacementphrase = strip_tags($linkobject->replacementphrase);
1588      } else {                                 // The replacement is the original phrase as matched below.
1589          $linkobject->workreplacementphrase = '$1';
1590      }
1591  
1592      $linkobject->workreplacementphrase = $hreftagbeginmangled .
1593              $linkobject->workreplacementphrase . $linkobject->hreftagend;
1594  }
1595  
1596  /**
1597   * Remove duplicate from a list of {@link filterobject}.
1598   *
1599   * @param filterobject[] $linkarray a list of filterobject.
1600   * @return filterobject[] the same list, but with dupicates removed.
1601   */
1602  function filter_remove_duplicates($linkarray) {
1603  
1604      $concepts  = array(); // Keep a record of concepts as we cycle through.
1605      $lconcepts = array(); // A lower case version for case insensitive.
1606  
1607      $cleanlinks = array();
1608  
1609      foreach ($linkarray as $key => $filterobject) {
1610          if ($filterobject->casesensitive) {
1611              $exists = in_array($filterobject->phrase, $concepts);
1612          } else {
1613              $exists = in_array(core_text::strtolower($filterobject->phrase), $lconcepts);
1614          }
1615  
1616          if (!$exists) {
1617              $cleanlinks[] = $filterobject;
1618              $concepts[] = $filterobject->phrase;
1619              $lconcepts[] = core_text::strtolower($filterobject->phrase);
1620          }
1621      }
1622  
1623      return $cleanlinks;
1624  }
1625  
1626  /**
1627   * Extract open/lose tags and their contents to avoid being processed by filters.
1628   * Useful to extract pieces of code like <a>...</a> tags. It returns the text
1629   * converted with some <#xTEXTFILTER_EXCL_SEPARATORx#> codes replacing the extracted text. Such extracted
1630   * texts are returned in the ignoretags array (as values), with codes as keys.
1631   *
1632   * @param string $text                  the text that we are filtering (in/out)
1633   * @param array $filterignoretagsopen  an array of open tags to start searching
1634   * @param array $filterignoretagsclose an array of close tags to end searching
1635   * @param array $ignoretags            an array of saved strings useful to rebuild the original text (in/out)
1636   **/
1637  function filter_save_ignore_tags(&$text, $filterignoretagsopen, $filterignoretagsclose, &$ignoretags) {
1638  
1639      // Remove everything enclosed by the ignore tags from $text.
1640      foreach ($filterignoretagsopen as $ikey => $opentag) {
1641          $closetag = $filterignoretagsclose[$ikey];
1642          // Form regular expression.
1643          $opentag  = str_replace('/', '\/', $opentag); // Delimit forward slashes.
1644          $closetag = str_replace('/', '\/', $closetag); // Delimit forward slashes.
1645          $pregexp = '/'.$opentag.'(.*?)'.$closetag.'/is';
1646  
1647          preg_match_all($pregexp, $text, $listofignores);
1648          foreach (array_unique($listofignores[0]) as $key => $value) {
1649              $prefix = (string) (count($ignoretags) + 1);
1650              $ignoretags['<#'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$key.'#>'] = $value;
1651          }
1652          if (!empty($ignoretags)) {
1653              $text = str_replace($ignoretags, array_keys($ignoretags), $text);
1654          }
1655      }
1656  }
1657  
1658  /**
1659   * Extract tags (any text enclosed by < and > to avoid being processed by filters.
1660   * It returns the text converted with some <%xTEXTFILTER_EXCL_SEPARATORx%> codes replacing the extracted text. Such extracted
1661   * texts are returned in the tags array (as values), with codes as keys.
1662   *
1663   * @param string $text   the text that we are filtering (in/out)
1664   * @param array $tags   an array of saved strings useful to rebuild the original text (in/out)
1665   **/
1666  function filter_save_tags(&$text, &$tags) {
1667  
1668      preg_match_all('/<([^#%*].*?)>/is', $text, $listofnewtags);
1669      foreach (array_unique($listofnewtags[0]) as $ntkey => $value) {
1670          $prefix = (string)(count($tags) + 1);
1671          $tags['<%'.$prefix.TEXTFILTER_EXCL_SEPARATOR.$ntkey.'%>'] = $value;
1672      }
1673      if (!empty($tags)) {
1674          $text = str_replace($tags, array_keys($tags), $text);
1675      }
1676  }
1677  
1678  /**
1679   * Add missing openpopup javascript to HTML files.
1680   *
1681   * @param string $text
1682   * @return string
1683   */
1684  function filter_add_javascript($text) {
1685      global $CFG;
1686  
1687      if (stripos($text, '</html>') === false) {
1688          return $text; // This is not a html file.
1689      }
1690      if (strpos($text, 'onclick="return openpopup') === false) {
1691          return $text; // No popup - no need to add javascript.
1692      }
1693      $js = "
1694      <script type=\"text/javascript\">
1695      <!--
1696          function openpopup(url,name,options,fullscreen) {
1697            fullurl = \"".$CFG->wwwroot."\" + url;
1698            windowobj = window.open(fullurl,name,options);
1699            if (fullscreen) {
1700              windowobj.moveTo(0,0);
1701              windowobj.resizeTo(screen.availWidth,screen.availHeight);
1702            }
1703            windowobj.focus();
1704            return false;
1705          }
1706      // -->
1707      </script>";
1708      if (stripos($text, '</head>') !== false) {
1709          // Try to add it into the head element.
1710          $text = str_ireplace('</head>', $js.'</head>', $text);
1711          return $text;
1712      }
1713  
1714      // Last chance - try adding head element.
1715      return preg_replace("/<html.*?>/is", "\\0<head>".$js.'</head>', $text);
1716  }