tag/lib.php

   1 <?php // $Id$
   2
   3 /**
   4  * Moodle tag library
   5  *
   6  * Tag strings : you can use any character in tags, except the comma (which is
   7  * the separator) and the '\' (backslash).  Note that many spaces (or other
   8  * blank characters) will get "compressed" into one. A tag string is always a
   9  * rawurlencode'd string. This is the same behavior as http://del.icio.us.
  10  *
  11  * A "record" is a php array (note that an object will work too) that contains
  12  * the following variables :
  13  *  - type: the table containing the record that we are tagging (eg: for a
  14  *    blog, this is table 'post', and for a user it is 'user')
  15  *  - id: the id of the record
  16  *
  17  * TODO: turn this into a full-fledged categorization system. This could start
  18  * by modifying (removing, probably) the 'tag type' to use another table
  19  * describing the relationship between tags (parents, sibling, etc.), which
  20  * could then be merged with the 'course categorization' system...
  21  *
  22  * BASIC INSTRUCTIONS :
  23  *  - to "tag a blog post" (for example):
  24  *        tag_set('post', $blog_post->id, $array_of_tags);
  25  *
  26  *  - to "remove all the tags on a blog post":
  27  *        tag_set('post', $blog_post->id, array());
  28  *
  29  * Tag set will create tags that need to be created.
  30  *
  31  * @version: $Id$
  32  * @licence http://www.gnu.org/copyleft/gpl.html GNU Public License
  33  * @package moodlecore
  34  * @subpackage tag
  35  * @see http://www.php.net/manual/en/function.urlencode.php
  36  */
  37
  38 define('TAG_RETURN_ARRAY', 0);
  39 define('TAG_RETURN_OBJECT', 1);
  40 define('TAG_RETURN_TEXT', 2);
  41 define('TAG_RETURN_HTML', 3);
  42
  43 define('TAG_CASE_LOWER', 0);
  44 define('TAG_CASE_ORIGINAL', 1);
  45
  46 define('TAG_RELATED_ALL', 0);
  47 define('TAG_RELATED_MANUAL', 1);
  48 define('TAG_RELATED_CORRELATED', 2);
  49
  50
  51 require_once($CFG->dirroot .'/tag/locallib.php');
  52
  53 ///////////////////////////////////////////////////////
  54 /////////////////// PUBLIC TAG API ////////////////////
  55
  56 /// Functions for settings tags  //////////////////////
  57
  58 /**
  59  * Set the tags assigned to a record.  This overwrites the current tags.
  60  *
  61  * This function is meant to be fed the string coming up from the user
  62  * interface, which contains all tags assigned to a record.
  63  *
  64  * @param string $record_type the type of record to tag ('post' for blogs,
  65  *     'user' for users, 'tag' for tags, etc.
  66  * @param int $record_id the id of the record to tag
  67  * @param array $tags the array of tags to set on the record. If
  68  *     given an empty array, all tags will be removed.
  69  * @return void
  70  */
  71 function tag_set($record_type, $record_id, $tags) {
  72
  73     static $in_recursion_semaphore = false; // this is to prevent loops when tagging a tag
  74     if ( $record_type == 'tag' && !$in_recursion_semaphore) {
  75         $current_tagged_tag_name = tag_get_name($record_id);
  76     }
  77
  78     $tags_ids = tag_get_id($tags, TAG_RETURN_ARRAY); // force an array, even if we only have one tag.
  79     $cleaned_tags = tag_normalize($tags);
  80     //echo 'tags-in-tag_set'; var_dump($tags); var_dump($tags_ids); var_dump($cleaned_tags);
  81
  82     $current_ids = tag_get_tags_ids($record_type, $record_id);
  83     //var_dump($current_ids);
  84
  85     // for data coherence reasons, it's better to remove deleted tags
  86     // before adding new data: ordering could be duplicated.
  87     foreach($current_ids as $current_id) {
  88         if (!in_array($current_id, $tags_ids)) {
  89             tag_delete_instance($record_type, $record_id, $current_id);
  90             if ( $record_type == 'tag' && !$in_recursion_semaphore) {
  91                 // if we are removing a tag-on-a-tag (manually related tag),
  92                 // we need to remove the opposite relationship as well.
  93                 tag_delete_instance('tag', $current_id, $record_id);
  94             }
  95         }
  96     }
  97
  98     foreach($tags as $ordering => $tag) {
  99         $tag = trim($tag);
 100         if (!$tag) {
 101             continue;
 102         }
 103
 104         $clean_tag = $cleaned_tags[$tag];
 105         $tag_current_id = $tags_ids[$clean_tag];
 106
 107         if ( is_null($tag_current_id) ) {
 108             // create new tags
 109             //echo "call to add tag $tag\n";
 110             $new_tag = tag_add($tag);
 111             $tag_current_id = $new_tag[$clean_tag];
 112         }
 113
 114         tag_assign($record_type, $record_id, $tag_current_id, $ordering);
 115
 116         // if we are tagging a tag (adding a manually-assigned related tag), we
 117         // need to create the opposite relationship as well.
 118         if ( $record_type == 'tag' && !$in_recursion_semaphore) {
 119             $in_recursion_semaphore = true;
 120             tag_set_add('tag', $tag_current_id, $current_tagged_tag_name);
 121             $in_recursion_semaphore = false;
 122         }
 123     }
 124 }
 125
 126 /**
 127  * Adds a tag to a record, without overwriting the current tags.
 128  *
 129  * @param string $record_type the type of record to tag ('post' for blogs,
 130  *     'user' for users, etc.
 131  * @param int $record_id the id of the record to tag
 132  * @param string $tag the tag to add
 133  * @return void
 134  */
 135 function tag_set_add($record_type, $record_id, $tag) {
 136
 137     $new_tags = array();
 138     foreach( tag_get_tags($record_type, $record_id) as $current_tag ) {
 139         $new_tags[] = $current_tag->rawname;
 140     }
 141     $new_tags[] = $tag;
 142
 143     return tag_set($record_type, $record_id, $new_tags);
 144 }
 145
 146 /**
 147  * Removes a tag from a record, without overwriting other current tags.
 148  *
 149  * @param string $record_type the type of record to tag ('post' for blogs,
 150  *     'user' for users, etc.
 151  * @param int $record_id the id of the record to tag
 152  * @param string $tag the tag to delete
 153  * @return void
 154  */
 155 function tag_set_delete($record_type, $record_id, $tag) {
 156
 157     $new_tags = array();
 158     foreach( tag_get_tags($record_type, $record_id) as $current_tag ) {
 159         if ($current_tag->name != $tag) {  // Keep all tags but the one specified
 160             $new_tags[] = $current_tag->name;
 161         }
 162     }
 163
 164     return tag_set($record_type, $record_id, $new_tags);
 165 }
 166
 167 /**
 168  * Set the type of a tag.  At this time (version 1.9) the possible values
 169  * are 'default' or 'official'.  Official tags will be displayed separately "at
 170  * tagging time" (while selecting the tags to apply to a record).
 171  *
 172  * @param string $tagid tagid to modify
 173  * @param string $type either 'default' or 'official'
 174  * @return true on success, false otherwise
 175  */
 176 function tag_type_set($tagid, $type) {
 177     if ($tag = get_record('tag', 'id', $tagid, '', '', '', '', 'id')) {
 178         $tag->tagtype = addslashes($type);
 179         $tag->timemodified = time();
 180         return update_record('tag', $tag);
 181     }
 182     return false;
 183 }
 184
 185
 186 /**
 187  * Set the description of a tag
 188  *
 189  * @param int $tagid the id of the tag
 190  * @param string $description the description
 191  * @param int $descriptionformat the moodle text format of the description
 192  * @return true on success, false otherwise
 193  */
 194 function tag_description_set($tagid, $description, $descriptionformat) {
 195     if ($tag = get_record('tag', 'id', $tagid, '', '', '', '', 'id')) {
 196         $tag->description = addslashes($description);
 197         $tag->descriptionformat = addslashes($descriptionformat);
 198         $tag->timemodified = time();
 199         return update_record('tag', $tag);
 200     }
 201     return false;
 202 }
 203
 204
 205
 206
 207
 208
 209 /// Functions for getting information about tags //////
 210
 211 /**
 212  * Simple function to just return a single tag object when you know the name or something
 213  *
 214  * @param string $field which field do we use to identify the tag: id, name or rawname
 215  * @param string $value the required value of the aforementioned field
 216  * @param string $returnfields which fields do we want returned?
 217  * @return tag object
 218  *
 219  **/
 220 function tag_get($field, $value, $returnfields='id, name, rawname') {
 221     if ($field == 'name') {
 222         $value = addslashes(moodle_strtolower($value));   // To cope with input that might just be wrong case
 223     }
 224     return get_record('tag', $field, $value, '', '', '', '', $returnfields);
 225 }
 226
 227
 228 /**
 229  * Get the array of db record of tags associated to a record (instances).  Use
 230  * tag_get_tags_csv to get the same information in a comma-separated string.
 231  *
 232  * @param string $record_type the record type for which we want to get the tags
 233  * @param int $record_id the record id for which we want to get the tags
 234  * @param string $type the tag type (either 'default' or 'official'). By default,
 235  *     all tags are returned.
 236  * @return array the array of tags
 237  */
 238 function tag_get_tags($record_type, $record_id, $type=null) {
 239
 240     global $CFG;
 241
 242     if ($type) {
 243         $type = "AND tg.tagtype = '$type'";
 244     }
 245
 246     // if the fields in this query are changed, you need to do the same changes in tag_get_correlated_tags
 247     $tags = get_records_sql("SELECT tg.id, tg.tagtype, tg.name, tg.rawname, tg.flag, ti.ordering ".
 248         "FROM {$CFG->prefix}tag_instance ti INNER JOIN {$CFG->prefix}tag tg ON tg.id = ti.tagid ".
 249         "WHERE ti.itemtype = '{$record_type}' AND ti.itemid = '{$record_id}' {$type} ".
 250         "ORDER BY ti.ordering ASC");
 251     // This version of the query, reversing the ON clause, "correctly" returns
 252     // a row with NULL values for instances that are still in the DB even though
 253     // the tag has been deleted.  This shouldn't happen, but if it did, using
 254     // this query could help "clean it up".  This causes bugs at this time.
 255     //$tags = get_records_sql("SELECT ti.tagid, tg.tagtype, tg.name, tg.rawname, tg.flag, ti.ordering ".
 256     //    "FROM {$CFG->prefix}tag_instance ti LEFT JOIN {$CFG->prefix}tag tg ON ti.tagid = tg.id ".
 257     //    "WHERE ti.itemtype = '{$record_type}' AND ti.itemid = '{$record_id}' {$type} ".
 258     //    "ORDER BY ti.ordering ASC");
 259
 260     if (!$tags) {
 261         return array();
 262     } else {
 263         return $tags;
 264     }
 265 }
 266
 267 /**
 268  * Get the array of tags display names, indexed by id.
 269  *
 270  * @param string $record_type the record type for which we want to get the tags
 271  * @param int $record_id the record id for which we want to get the tags
 272  * @param string $type the tag type (either 'default' or 'official'). By default,
 273  *     all tags are returned.
 274  * @return array the array of tags (with the value returned by tag_display_name), indexed by id
 275  */
 276 function tag_get_tags_array($record_type, $record_id, $type=null) {
 277     $tags = array();
 278     foreach(tag_get_tags($record_type, $record_id, $type) as $tag) {
 279         $tags[$tag->id] = tag_display_name($tag);
 280     }
 281     return $tags;
 282 }
 283
 284 /**
 285  * Get a comma-separated string of tags associated to a record.  Use tag_get_tags
 286  * to get the same information in an array.
 287  *
 288  * @param string $record_type the record type for which we want to get the tags
 289  * @param int $record_id the record id for which we want to get the tags
 290  * @param int $html either TAG_RETURN_HTML or TAG_RETURN_TEXT, depending
 291  *     on the type of output desired
 292  * @param string $type either 'official' or 'default', if null, all tags are
 293  *     returned
 294  * @return string the comma-separated list of tags.
 295  */
 296 function tag_get_tags_csv($record_type, $record_id, $html=TAG_RETURN_HTML, $type=null) {
 297     global $CFG;
 298
 299     $tags_names = array();
 300     foreach(tag_get_tags($record_type, $record_id, $type) as $tag) {
 301         if ($html == TAG_RETURN_TEXT) {
 302             $tags_names[] = tag_display_name($tag);
 303         } else { // TAG_RETURN_HTML
 304             $tags_names[] = '<a href="'. $CFG->wwwroot .'/tag/index.php?tag='. rawurlencode($tag->name) .'">'. tag_display_name($tag) .'</a>';
 305         }
 306     }
 307     return implode(', ', $tags_names);
 308 }
 309
 310 /**
 311  * Get an array of tag ids associated to a record.
 312  *
 313  * @param string $record_type the record type for which we want to get the tags
 314  * @param int $record_id the record id for which we want to get the tags
 315  * @return array of tag ids, indexed and sorted by 'ordering'
 316  */
 317 function tag_get_tags_ids($record_type, $record_id) {
 318
 319     $tag_ids = array();
 320     foreach (tag_get_tags($record_type, $record_id) as $tag) {
 321         if ( array_key_exists($tag->ordering, $tag_ids) ) {
 322             // until we can add a unique constraint, in table tag_instance,
 323             // on (itemtype, itemid, ordering), this is needed to prevent a bug
 324             // TODO : modify database in 2.0
 325             $tag->ordering++;
 326         }
 327         $tag_ids[$tag->ordering] = $tag->id;
 328     }
 329     ksort($tag_ids);
 330     return $tag_ids;
 331 }
 332
 333 /**
 334  * Returns the database ID of a set of tags.
 335  *
 336  * @param mixed $tags one tag, or array of tags, to look for.
 337  * @param bool $return_value specify the type of the returned value. Either
 338  *     TAG_RETURN_OBJECT, or TAG_RETURN_ARRAY (default). If TAG_RETURN_ARRAY
 339  *     is specified, an array will be returned even if only one tag was
 340  *     passed in $tags.
 341  * @return mixed tag-indexed array of ids (or objects, if second parameter is
 342  *     TAG_RETURN_OBJECT), or only an int, if only one tag is given *and* the
 343  *     second parameter is null. No value for a key means the tag wasn't found.
 344  */
 345 function tag_get_id($tags, $return_value=null) {
 346     global $CFG;
 347     static $tag_id_cache = array();
 348
 349     $return_an_int = false;
 350     if (!is_array($tags)) {
 351         if(is_null($return_value) || $return_value == TAG_RETURN_OBJECT) {
 352             $return_an_int = true;
 353         }
 354         $tags = array($tags);
 355     }
 356
 357     $result = array();
 358
 359     //TODO: test this and see if it helps performance without breaking anything
 360     //foreach($tags as $key => $tag) {
 361     //    $clean_tag = moodle_strtolower($tag);
 362     //    if ( array_key_exists($clean_tag), $tag_id_cache) ) {
 363     //        $result[$clean_tag] = $tag_id_cache[$clean_tag];
 364     //        $tags[$key] = ''; // prevent further processing for this one.
 365     //    }
 366     //}
 367
 368     $tags = array_values(tag_normalize($tags));
 369     foreach($tags as $key => $tag) {
 370         $tags[$key] = addslashes(moodle_strtolower($tag));
 371         $result[moodle_strtolower($tag)] = null; // key must exists : no value for a key means the tag wasn't found.
 372     }
 373     $tag_string = "'". implode("', '", $tags) ."'";
 374
 375     if ($rs = get_recordset_sql("SELECT * FROM {$CFG->prefix}tag WHERE name in ({$tag_string}) order by name")) {
 376         while ($record = rs_fetch_next_record($rs)) {
 377             if ($return_value == TAG_RETURN_OBJECT) {
 378                 $result[$record->name] = $record;
 379             } else { // TAG_RETURN_ARRAY
 380                 $result[$record->name] = $record->id;
 381             }
 382         }
 383     }
 384
 385     if ($return_an_int) {
 386         return array_pop($result);
 387     }
 388
 389     return $result;
 390 }
 391
 392
 393 /**
 394  * Returns tags related to a tag
 395  *
 396  * Related tags of a tag come from two sources:
 397  *   - manually added related tags, which are tag_instance entries for that tag
 398  *   - correlated tags, which are a calculated
 399  *
 400  * @param string $tag_name_or_id is a single **normalized** tag name or the id
 401  *     of a tag
 402  * @param int $type the function will return either manually
 403  *     (TAG_RELATED_MANUAL) related tags or correlated (TAG_RELATED_CORRELATED)
 404  *     tags. Default is TAG_RELATED_ALL, which returns everything.
 405  * @param int $limitnum return a subset comprising this many records (optional,
 406  *     default is 10)
 407  * @return array an array of tag objects
 408  */
 409 function tag_get_related_tags($tagid, $type=TAG_RELATED_ALL, $limitnum=10) {
 410
 411     $related_tags = array();
 412
 413     if ( $type == TAG_RELATED_ALL || $type == TAG_RELATED_MANUAL) {
 414         //gets the manually added related tags
 415         $related_tags = tag_get_tags('tag', $tagid);
 416     }
 417
 418     if ( $type == TAG_RELATED_ALL || $type == TAG_RELATED_CORRELATED ) {
 419         //gets the correlated tags
 420         $automatic_related_tags = tag_get_correlated($tagid, $limitnum);
 421         if (is_array($automatic_related_tags)) {
 422             $related_tags = array_merge($related_tags, $automatic_related_tags);
 423         }
 424     }
 425
 426     return array_slice(object_array_unique($related_tags), 0 , $limitnum);
 427 }
 428
 429 /**
 430  * Get a comma-separated list of tags related to another tag.
 431  *
 432  * @param array $related_tags the array returned by tag_get_related_tags
 433  * @param int $html either TAG_RETURN_HTML (default) or TAG_RETURN_TEXT : return html links, or just text.
 434  * @return string comma-separated list
 435  */
 436 function tag_get_related_tags_csv($related_tags, $html=TAG_RETURN_HTML) {
 437     global $CFG;
 438
 439     $tags_names = array();
 440     foreach($related_tags as $tag) {
 441         if ( $html == TAG_RETURN_TEXT) {
 442             $tags_names[] = tag_display_name($tag);
 443         } else {
 444             // TAG_RETURN_HTML
 445             $tags_names[] = '<a href="'. $CFG->wwwroot .'/tag/index.php?tag='. rawurlencode($tag->name) .'">'. tag_display_name($tag) .'</a>';
 446         }
 447     }
 448
 449     return implode(', ', $tags_names);
 450 }
 451
 452 /**
 453  * Change the "value" of a tag, and update the associated 'name'.
 454  *
 455  * @param int $tagid the id of the tag to modify
 456  * @param string $newtag the new rawname
 457  * @return bool true on success, false otherwise
 458  */
 459 function tag_rename($tagid, $newrawname) {
 460
 461     if (! $newrawname_clean = array_shift(tag_normalize($newrawname, TAG_CASE_ORIGINAL)) ) {
 462         return false;
 463     }
 464
 465     if (! $newname_clean = moodle_strtolower($newrawname_clean)) {
 466         return false;
 467     }
 468
 469     // Prevent the rename if a tag with that name already exists
 470     if ($existing = tag_get('name', $newname_clean, 'id, name, rawname')) {
 471         if ($existing->id != $tagid) {  // Another tag already exists with this name
 472             return false;
 473         }
 474     }
 475
 476     if ($tag = tag_get('id', $tagid, 'id, name, rawname')) {
 477         $tag->rawname = addslashes($newrawname_clean);
 478         $tag->name = addslashes($newname_clean);
 479         $tag->timemodified = time();
 480         return update_record('tag', $tag);
 481     }
 482     return false;
 483 }
 484
 485
 486 /**
 487  * Delete one or more tag, and all their instances if there are any left.
 488  *
 489  * @param mixed $tagids one tagid (int), or one array of tagids to delete
 490  * @return bool true on success, false otherwise
 491  */
 492 function tag_delete($tagids) {
 493
 494     if (!is_array($tagids)) {
 495         $tagids = array($tagids);
 496     }
 497
 498     $success = true;
 499     foreach( $tagids as $tagid ) {
 500         if (is_null($tagid)) { // can happen if tag doesn't exists
 501             continue;
 502         }
 503         // only delete the main entry if there were no problems deleting all the
 504         // instances - that (and the fact we won't often delete lots of tags)
 505         // is the reason for not using delete_records_select()
 506         if ( delete_records('tag_instance', 'tagid', $tagid) ) {
 507             $success &= (bool) delete_records('tag', 'id', $tagid);
 508         }
 509     }
 510
 511     return $success;
 512 }
 513
 514 /**
 515  * Delete one instance of a tag.  If the last instance was deleted, it will
 516  * also delete the tag, unless it's type is 'official'.
 517  *
 518  * @param string $record_type the type of the record for which to remove the instance
 519  * @param int $record_id the id of the record for which to remove the instance
 520  * @param int $tagid the tagid that needs to be removed
 521  * @return bool true on success, false otherwise
 522  */
 523 function tag_delete_instance($record_type, $record_id, $tagid) {
 524     global $CFG;
 525
 526     if ( delete_records('tag_instance', 'tagid', $tagid, 'itemtype', $record_type, 'itemid', $record_id) ) {
 527         if ( !record_exists_sql("SELECT * FROM {$CFG->prefix}tag tg, {$CFG->prefix}tag_instance ti ".
 528                 "WHERE (tg.id = ti.tagid AND ti.tagid = {$tagid} ) OR ".
 529                 "(tg.id = {$tagid} AND tg.tagtype = 'official')") ) {
 530             return tag_delete($tagid);
 531         }
 532     } else {
 533         return false;
 534     }
 535
 536     return true;
 537 }
 538
 539
 540 /**
 541  * Function that returns the name that should be displayed for a specific tag
 542  *
 543  * @param object $tag_object a line out of tag table, as returned by the adobd functions
 544  * @return string
 545  */
 546 function tag_display_name($tag_object) {
 547
 548     global $CFG;
 549
 550     if(!isset($tag_object->name)) {
 551         return '';
 552     }
 553
 554     if (empty($CFG->keeptagnamecase)) {
 555         //this is the normalized tag name
 556         $textlib = textlib_get_instance();
 557         return htmlspecialchars($textlib->strtotitle($tag_object->name));
 558     } else {
 559         //original casing of the tag name
 560         return htmlspecialchars($tag_object->rawname);
 561     }
 562 }
 563
 564 /**
 565  * Find all records tagged with a tag of a given type ('post', 'user', etc.)
 566  *
 567  * @param string $tag tag to look for
 568  * @param string $type type to restrict search to.  If null, every matching
 569  *     record will be returned
 570  * @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
 571  * @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
 572  * @return array of matching objects, indexed by record id, from the table containing the type requested
 573  */
 574 function tag_find_records($tag, $type, $limitfrom='', $limitnum='') {
 575
 576     global $CFG;
 577
 578     if (!$tag || !$type) {
 579         return array();
 580     }
 581
 582     $tagid = tag_get_id($tag);
 583
 584     $query = "SELECT it.* ".
 585         "FROM {$CFG->prefix}{$type} it INNER JOIN {$CFG->prefix}tag_instance tt ON it.id = tt.itemid ".
 586         "WHERE tt.itemtype = '{$type}' AND tt.tagid = '{$tagid}'";
 587
 588     return get_records_sql($query, $limitfrom, $limitnum);
 589 }
 590
 591
 592
 593
 594 ///////////////////////////////////////////////////////
 595 /////////////////// PRIVATE TAG API ///////////////////
 596
 597 /**
 598  * Adds one or more tag in the database.  This function should not be called
 599  * directly : you should use tag_set.
 600  *
 601  * @param mixed $tags one tag, or an array of tags, to be created
 602  * @param string $type type of tag to be created ("default" is the default
 603  *     value and "official" is the only other supported value at this time). An
 604  *     official tag is kept even if there are no records tagged with it.
 605  * @return an array of tags ids, indexed by their lowercase normalized names.
 606  *     Any boolean false in the array indicates an error while adding the tag.
 607  */
 608 function tag_add($tags, $type="default") {
 609     global $USER;
 610
 611     require_capability('moodle/tag:create', get_context_instance(CONTEXT_SYSTEM));
 612
 613     if (!is_array($tags)) {
 614         $tags = array($tags);
 615     }
 616
 617     $tag_object = new StdClass;
 618     $tag_object->tagtype = $type;
 619     $tag_object->userid = $USER->id;
 620     $tag_object->timemodified   = time();
 621
 622     $clean_tags = tag_normalize($tags, TAG_CASE_ORIGINAL);
 623
 624     $tags_ids = array();
 625     foreach($clean_tags as $tag) {
 626         $tag = trim($tag);
 627         if (!$tag) {
 628             $tags_ids[$tag] = false;
 629         } else {
 630             // note that the difference between rawname and name is only
 631             // capitalization : the rawname is NOT the same at the rawtag.
 632             $tag_object->rawname = addslashes($tag);
 633             $tag_name_lc = moodle_strtolower($tag);
 634             $tag_object->name = addslashes($tag_name_lc);
 635             //var_dump($tag_object);
 636             $tags_ids[$tag_name_lc] = insert_record('tag', $tag_object);
 637         }
 638     }
 639
 640     return $tags_ids;
 641 }
 642
 643 /**
 644  * Assigns a tag to a record: if the record already exists, the time and
 645  * ordering will be updated.
 646  *
 647  * @param string $record_type the type of the record that will be tagged
 648  * @param int $record_id the id of the record that will be tagged
 649  * @param string $tagid the tag id to set on the record.
 650  * @param int $ordering the order of the instance for this record
 651  * @return bool true on success, false otherwise
 652  */
 653 function tag_assign($record_type, $record_id, $tagid, $ordering) {
 654
 655     require_capability('moodle/tag:create', get_context_instance(CONTEXT_SYSTEM));
 656
 657     if ( $tag_instance_object = get_record('tag_instance', 'tagid', $tagid, 'itemtype', $record_type, 'itemid', $record_id, 'id') ) {
 658         $tag_instance_object->ordering = $ordering;
 659         $tag_instance_object->timemodified = time();
 660         return update_record('tag_instance', $tag_instance_object);
 661     } else {
 662         $tag_instance_object = new StdClass;
 663         $tag_instance_object->tagid = $tagid;
 664         $tag_instance_object->itemid = $record_id;
 665         $tag_instance_object->itemtype = $record_type;
 666         $tag_instance_object->ordering = $ordering;
 667         $tag_instance_object->timemodified = time();
 668         return insert_record('tag_instance', $tag_instance_object);
 669     }
 670 }
 671
 672 /**
 673  * Function that returns tags that start with some text, for use by the autocomplete feature
 674  *
 675  * @param string $text string that the tag names will be matched against
 676  * @return mixed an array of objects, or false if no records were found or an error occured.
 677  */
 678 function tag_autocomplete($text) {
 679     global $CFG;
 680     return get_records_sql("SELECT tg.id, tg.name, tg.rawname FROM {$CFG->prefix}tag tg WHERE tg.name LIKE '". moodle_strtolower($text) ."%'");
 681 }
 682
 683 /**
 684  * Clean up the tag tables, making sure all tagged object still exists.
 685  *
 686  * This should normally not be necessary, but in case related tags are not deleted
 687  * when the tagged record is removed, this should be done once in a while, perhaps on
 688  * an occasional cron run.  On a site with lots of tags, this could become an expensive
 689  * function to call: don't run at peak time.
 690  */
 691 function tag_cleanup() {
 692     global $CFG;
 693
 694     $instances = get_recordset('tag_instance');
 695
 696     // cleanup tag instances
 697     while ($instance = rs_fetch_next_record($instances)) {
 698         $delete = false;
 699
 700         if (!record_exists('tag', 'id', $instance->tagid)) {
 701             // if the tag has been removed, instance should be deleted.
 702             $delete = true;
 703         } else {
 704             switch ($instance->itemtype) {
 705                 case 'user': // users are marked as deleted, but not actually deleted
 706                     if (record_exists('user', 'id', $instance->itemid, 'deleted', 1)) {
 707                         $delete = true;
 708                     }
 709                     break;
 710                 default: // anything else, if the instance is not there, delete.
 711                     if (!record_exists($instance->itemtype, 'id', $instance->itemid)) {
 712                         $delete = true;
 713                     }
 714                     break;
 715             }
 716         }
 717         if ($delete) {
 718             tag_delete_instance($instance->itemtype, $instance->itemid, $instance->tagid);
 719             //debugging('deleting tag_instance #'. $instance->id .', linked to tag id #'. $instance->tagid, DEBUG_DEVELOPER);
 720         }
 721     }
 722     rs_close($instances);
 723
 724     // TODO: this will only clean tags of type 'default'.  This is good as
 725     // it won't delete 'official' tags, but the day we get more than two
 726     // types, we need to fix this.
 727     $unused_tags = get_recordset_sql("SELECT tg.id FROM {$CFG->prefix}tag tg WHERE tg.tagtype = 'default' AND NOT EXISTS (".
 728         "SELECT 'x' FROM {$CFG->prefix}tag_instance ti WHERE ti.tagid = tg.id)");
 729
 730     // cleanup tags
 731     while ($unused_tag = rs_fetch_next_record($unused_tags)) {
 732         tag_delete($unused_tag->id);
 733         //debugging('deleting unused tag #'. $unused_tag->id,  DEBUG_DEVELOPER);
 734     }
 735     rs_close($unused_tags);
 736 }
 737
 738 /**
 739  * Calculates and stores the correlated tags of all tags.
 740  * The correlations are stored in the 'tag_correlation' table.
 741  *
 742  * Two tags are correlated if they appear together a lot.
 743  * Ex.: Users tagged with "computers" will probably also be tagged with "algorithms".
 744  *
 745  * The rationale for the 'tag_correlation' table is performance.
 746  * It works as a cache for a potentially heavy load query done at the 'tag_instance' table.
 747  * So, the 'tag_correlation' table stores redundant information derived from the 'tag_instance' table.
 748  *
 749  * @param number $min_correlation cutoff percentage (optional, default is 2)
 750  */
 751 function tag_compute_correlations($min_correlation=2) {
 752
 753     global $CFG;
 754
 755     if (!$all_tags = get_records_list('tag')) {
 756         return;
 757     }
 758
 759     $tag_correlation_obj = new object();
 760     foreach($all_tags as $tag) {
 761
 762         // query that counts how many times any tag appears together in items
 763         // with the tag passed as argument ($tag_id)
 764         $query = "SELECT tb.tagid , COUNT(*) AS nr ".
 765             "FROM {$CFG->prefix}tag_instance ta INNER JOIN {$CFG->prefix}tag_instance tb ON ta.itemid = tb.itemid ".
 766             "WHERE ta.tagid = {$tag->id} AND tb.tagid != {$tag->id} ".
 767             "GROUP BY tb.tagid ".
 768             "HAVING nr > $min_correlation ".
 769             "ORDER BY nr DESC";
 770
 771         $correlated = array();
 772
 773         // Correlated tags happen when they appear together in more occasions
 774         // than $min_correlation.
 775         if ($tag_correlations = get_records_sql($query)) {
 776             foreach($tag_correlations as $correlation) {
 777             // commented out - now done in query. kept here in case it breaks on some db
 778             // if($correlation->nr >= $min_correlation){
 779                     $correlated[] = $correlation->tagid;
 780             // }
 781             }
 782         }
 783
 784         if (empty($correlated)) {
 785             continue;
 786         }
 787
 788         $correlated = implode(',', $correlated);
 789         //var_dump($correlated);
 790
 791         //saves correlation info in the caching table
 792         if ($tag_correlation_obj = get_record('tag_correlation', 'tagid', $tag->id, '', '', '', '', 'tagid')) {
 793             $tag_correlation_obj->correlatedtags = $correlated;
 794             update_record('tag_correlation', $tag_correlation_obj);
 795         } else {
 796             $tag_correlation_obj->tagid          = $tag->id;
 797             $tag_correlation_obj->correlatedtags = $correlated;
 798             insert_record('tag_correlation', $tag_correlation_obj);
 799         }
 800     }
 801 }
 802
 803 /**
 804  * Tasks that should be performed at cron time
 805  */
 806 function tag_cron() {
 807     tag_compute_correlations();
 808     tag_cleanup();
 809 }
 810
 811 /**
 812  * Search for tags with names that match some text
 813  *
 814  * @param string $text escaped string that the tag names will be matched against
 815  * @param boolean $ordered If true, tags are ordered by their popularity. If false, no ordering.
 816  * @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
 817  * @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
 818  * @return mixed an array of objects, or false if no records were found or an error occured.
 819  */
 820 function tag_find_tags($text, $ordered=true, $limitfrom='', $limitnum='') {
 821
 822     global $CFG;
 823
 824     $text = array_shift(tag_normalize($text, TAG_CASE_LOWER));
 825
 826     if ($ordered) {
 827         $query = "SELECT tg.id, tg.name, tg.rawname, COUNT(ti.id) AS count ".
 828             "FROM {$CFG->prefix}tag tg LEFT JOIN {$CFG->prefix}tag_instance ti ON tg.id = ti.tagid ".
 829             "WHERE tg.name LIKE '%{$text}%' ".
 830             "GROUP BY tg.id, tg.name, tg.rawname ".
 831             "ORDER BY count DESC";
 832     } else {
 833         $query = "SELECT tg.id, tg.name, tg.rawname ".
 834             "FROM {$CFG->prefix}tag tg ".
 835             "WHERE tg.name LIKE '%{$text}%'";
 836     }
 837     return get_records_sql($query, $limitfrom , $limitnum);
 838 }
 839
 840 /**
 841  * Get the name of a tag
 842  *
 843  * @param mixed $tagids the id of the tag, or an array of ids
 844  * @return mixed string name of one tag, or id-indexed array of strings
 845  */
 846 function tag_get_name($tagids) {
 847
 848     $return_a_string = false;
 849     if ( !is_array($tagids) ) {
 850         $return_a_string = true;
 851         $tagids = array($tagids);
 852     }
 853
 854     $tag_names = array();
 855     foreach(get_records_list('tag', 'id', implode(',', $tagids)) as $tag) {
 856         $tag_names[$tag->id] = $tag->name;
 857     }
 858
 859     if ($return_a_string) {
 860         return array_pop($tag_names);
 861     }
 862
 863     return $tag_names;
 864 }
 865
 866 /**
 867  * Returns the correlated tags of a tag, retrieved from the tag_correlation
 868  * table.  Make sure cron runs, otherwise the table will be empty and this
 869  * function won't return anything.
 870  *
 871  * @param int $tag_id is a single tag id
 872  * @return array an array of tag objects, empty if no correlated tags are found
 873  */
 874 function tag_get_correlated($tag_id, $limitnum=null) {
 875     global $CFG;
 876
 877     $tag_correlation = get_record('tag_correlation', 'tagid', $tag_id);
 878
 879     if (!$tag_correlation || empty($tag_correlation->correlatedtags)) {
 880         return array();
 881     }
 882
 883     // this is (and has to) return the same fields as the query in tag_get_tags
 884     if ( !$result = get_records_sql("SELECT tg.id, tg.tagtype, tg.name, tg.rawname, tg.flag, ti.ordering ".
 885         "FROM {$CFG->prefix}tag tg INNER JOIN {$CFG->prefix}tag_instance ti ON tg.id = ti.tagid ".
 886         "WHERE tg.id IN ({$tag_correlation->correlatedtags})") ) {
 887         return array();
 888     }
 889
 890     return $result;
 891 }
 892
 893 /**
 894  * Function that normalizes a list of tag names.
 895  *
 896  * @param mixed $tags array of tags, or a single tag.
 897  * @param int $case case to use for returned value (default: lower case).
 898  *     Either TAG_CASE_LOWER (default) or TAG_CASE_ORIGINAL
 899  * @return array of lowercased normalized tags, indexed by the normalized tag,
 900  *     in the same order as the original array. (Eg: 'Banana' => 'banana').
 901  */
 902 function tag_normalize($rawtags, $case = TAG_CASE_LOWER) {
 903
 904     // cache normalized tags, to prevent costly repeated calls to clean_param
 905     static $cleaned_tags_lc = array(); // lower case - use for comparison
 906     static $cleaned_tags_mc = array(); // mixed case - use for saving to database
 907
 908     if ( !is_array($rawtags) ) {
 909         $rawtags = array($rawtags);
 910     }
 911
 912     $result = array();
 913     foreach($rawtags as $rawtag) {
 914         $rawtag = trim($rawtag);
 915         if (!$rawtag) {
 916             continue;
 917         }
 918         if ( !array_key_exists($rawtag, $cleaned_tags_lc) ) {
 919             $cleaned_tags_lc[$rawtag] = moodle_strtolower( clean_param($rawtag, PARAM_TAG) );
 920             $cleaned_tags_mc[$rawtag] = clean_param($rawtag, PARAM_TAG);
 921         }
 922         if ( $case == TAG_CASE_LOWER ) {
 923             $result[$rawtag] = $cleaned_tags_lc[$rawtag];
 924         } else { // TAG_CASE_ORIGINAL
 925             $result[$rawtag] = $cleaned_tags_mc[$rawtag];
 926         }
 927     }
 928
 929     return $result;
 930 }
 931
 932 /**
 933  * Count how many records are tagged with a specific tag,
 934  *
 935  * @param string $record record to look for ('post', 'user', etc.)
 936  * @param int $tag is a single tag id
 937  * @return int number of mathing tags.
 938  */
 939 function tag_record_count($record_type, $tagid) {
 940     return count_records('tag_instance', 'itemtype', $record_type, 'tagid', $tagid);
 941 }
 942
 943 /**
 944  * Determine if a record is tagged with a specific tag
 945  *
 946  * @param string $record_type the record type to look for
 947  * @param int $record_id the record id to look for
 948  * @param string $tag a tag name
 949  * @return bool true if it is tagged, false otherwise
 950  */
 951 function tag_record_tagged_with($record_type, $record_id, $tag) {
 952     if ($tagid = tag_get_id($tag)) {
 953         return count_records('tag_instance', 'itemtype', $record_type, 'itemid', $record_id, 'tagid', $tagid);
 954     } else {
 955         return 0; // tag doesn't exist
 956     }
 957 }
 958
 959 /**
 960  * Flag a tag as inapropriate
 961  *
 962  * @param mixed $tagids one (int) tagid, or an array of tagids
 963  * @return void
 964  */
 965 function tag_set_flag($tagids) {
 966     if ( !is_array($tagids) ) {
 967         $tagids = array($tagids);
 968     }
 969     foreach ($tagids as $tagid) {
 970         $tag = get_record('tag', 'id', $tagid, '', '', '', '', 'id, flag');
 971         $tag->flag++;
 972         $tag->timemodified = time();
 973         update_record('tag', $tag);
 974     }
 975 }
 976
 977 /**
 978  * Remove the inapropriate flag on a tag
 979  *
 980  * @param mixed $tagids one (int) tagid, or an array of tagids
 981  * @return bool true if function succeeds, false otherwise
 982  */
 983 function tag_unset_flag($tagids) {
 984     global $CFG;
 985
 986     require_capability('moodle/tag:manage', get_context_instance(CONTEXT_SYSTEM));
 987
 988     if ( is_array($tagids) ) {
 989         $tagids = implode(',', $tagids);
 990     }
 991     $timemodified = time();
 992     return execute_sql("UPDATE {$CFG->prefix}tag tg SET tg.flag = 0, tg.timemodified = $timemodified WHERE tg.id IN ($tagids)", false);
 993 }
 994
 995 ?>