blog/lib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * Core global functions for Blog.
  20  *
  21  * @package    moodlecore
  22  * @subpackage blog
  23  * @copyright  2009 Nicolas Connault
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /**
  30  * Library of functions and constants for blog
  31  */
  32 require_once($CFG->dirroot .'/blog/rsslib.php');
  33 require_once($CFG->dirroot.'/tag/lib.php');
  34
  35 /**
  36  * User can edit a blog entry if this is their own blog entry and they have
  37  * the capability moodle/blog:create, or if they have the capability
  38  * moodle/blog:manageentries.
  39  *
  40  * This also applies to deleting of entries.
  41  */
  42 function blog_user_can_edit_entry($blogentry) {
  43     global $USER;
  44
  45     $sitecontext = get_context_instance(CONTEXT_SYSTEM);
  46
  47     if (has_capability('moodle/blog:manageentries', $sitecontext)) {
  48         return true; // can edit any blog entry
  49     }
  50
  51     if ($blogentry->userid == $USER->id && has_capability('moodle/blog:create', $sitecontext)) {
  52         return true; // can edit own when having blog:create capability
  53     }
  54
  55     return false;
  56 }
  57
  58
  59 /**
  60  * Checks to see if a user can view the blogs of another user.
  61  * Only blog level is checked here, the capabilities are enforced
  62  * in blog/index.php
  63  */
  64 function blog_user_can_view_user_entry($targetuserid, $blogentry=null) {
  65     global $CFG, $USER, $DB;
  66
  67     if (empty($CFG->bloglevel)) {
  68         return false; // blog system disabled
  69     }
  70
  71     if (isloggedin() && $USER->id == $targetuserid) {
  72         return true; // can view own entries in any case
  73     }
  74
  75     $sitecontext = get_context_instance(CONTEXT_SYSTEM);
  76     if (has_capability('moodle/blog:manageentries', $sitecontext)) {
  77         return true; // can manage all entries
  78     }
  79
  80     // coming for 1 entry, make sure it's not a draft
  81     if ($blogentry && $blogentry->publishstate == 'draft' && !has_capability('moodle/blog:viewdrafts', $sitecontext)) {
  82         return false;  // can not view draft of others
  83     }
  84
  85     // coming for 0 entry, make sure user is logged in, if not a public blog
  86     if ($blogentry && $blogentry->publishstate != 'public' && !isloggedin()) {
  87         return false;
  88     }
  89
  90     switch ($CFG->bloglevel) {
  91         case BLOG_GLOBAL_LEVEL:
  92             return true;
  93         break;
  94
  95         case BLOG_SITE_LEVEL:
  96             if (isloggedin()) { // not logged in viewers forbidden
  97                 return true;
  98             }
  99             return false;
 100         break;
 101
 102         case BLOG_USER_LEVEL:
 103         default:
 104             $personalcontext = get_context_instance(CONTEXT_USER, $targetuserid);
 105             return has_capability('moodle/user:readuserblogs', $personalcontext);
 106         break;
 107
 108     }
 109 }
 110
 111 /**
 112  * remove all associations for the blog entries of a particular user
 113  * @param int userid - id of user whose blog associations will be deleted
 114  */
 115 function blog_remove_associations_for_user($userid) {
 116     global $DB;
 117     throw new coding_exception('function blog_remove_associations_for_user() is not finished');
 118     /*
 119     $blogentries = blog_fetch_entries(array('user' => $userid), 'lasmodified DESC');
 120     foreach ($blogentries as $entry) {
 121         if (blog_user_can_edit_entry($entry)) {
 122             blog_remove_associations_for_entry($entry->id);
 123         }
 124     }
 125      */
 126 }
 127
 128 /**
 129  * remove all associations for the blog entries of a particular course
 130  * @param int courseid - id of user whose blog associations will be deleted
 131  */
 132 function blog_remove_associations_for_course($courseid) {
 133     global $DB;
 134     $context = get_context_instance(CONTEXT_COURSE, $courseid);
 135     $DB->delete_records('blog_association', array('contextid' => $context->id));
 136 }
 137
 138 /**
 139  * Given a record in the {blog_external} table, checks the blog's URL
 140  * for new entries not yet copied into Moodle.
 141  * Also attempts to identify and remove deleted blog entries
 142  *
 143  * @param object $externalblog
 144  * @return boolean False if the Feed is invalid
 145  */
 146 function blog_sync_external_entries($externalblog) {
 147     global $CFG, $DB;
 148     require_once($CFG->libdir . '/simplepie/moodle_simplepie.php');
 149
 150     $rssfile = new moodle_simplepie_file($externalblog->url);
 151     $filetest = new SimplePie_Locator($rssfile);
 152
 153     $textlib = textlib_get_instance(); // Going to use textlib services
 154
 155     if (!$filetest->is_feed($rssfile)) {
 156         $externalblog->failedlastsync = 1;
 157         $DB->update_record('blog_external', $externalblog);
 158         return false;
 159     } else if (!empty($externalblog->failedlastsync)) {
 160         $externalblog->failedlastsync = 0;
 161         $DB->update_record('blog_external', $externalblog);
 162     }
 163
 164     $rss = new moodle_simplepie($externalblog->url);
 165
 166     if (empty($rss->data)) {
 167         return null;
 168     }
 169     //used to identify blog posts that have been deleted from the source feed
 170     $oldesttimestamp = null;
 171     $uniquehashes = array();
 172
 173     foreach ($rss->get_items() as $entry) {
 174         // If filtertags are defined, use them to filter the entries by RSS category
 175         if (!empty($externalblog->filtertags)) {
 176             $containsfiltertag = false;
 177             $categories = $entry->get_categories();
 178             $filtertags = explode(',', $externalblog->filtertags);
 179             $filtertags = array_map('trim', $filtertags);
 180             $filtertags = array_map('strtolower', $filtertags);
 181
 182             foreach ($categories as $category) {
 183                 if (in_array(trim(strtolower($category->term)), $filtertags)) {
 184                     $containsfiltertag = true;
 185                 }
 186             }
 187
 188             if (!$containsfiltertag) {
 189                 continue;
 190             }
 191         }
 192
 193         $uniquehashes[] = $entry->get_permalink();
 194
 195         $newentry = new stdClass();
 196         $newentry->userid = $externalblog->userid;
 197         $newentry->module = 'blog_external';
 198         $newentry->content = $externalblog->id;
 199         $newentry->uniquehash = $entry->get_permalink();
 200         $newentry->publishstate = 'site';
 201         $newentry->format = FORMAT_HTML;
 202         // Clean subject of html, just in case
 203         $newentry->subject = clean_param($entry->get_title(), PARAM_TEXT);
 204         // Observe 128 max chars in DB
 205         // TODO: +1 to raise this to 255
 206         if ($textlib->strlen($newentry->subject) > 128) {
 207             $newentry->subject = $textlib->substr($newentry->subject, 0, 125) . '...';
 208         }
 209         $newentry->summary = $entry->get_description();
 210
 211         //used to decide whether to insert or update
 212         //uses enty permalink plus creation date if available
 213         $existingpostconditions = array('uniquehash' => $entry->get_permalink());
 214
 215         //our DB doesnt allow null creation or modified timestamps so check the external blog supplied one
 216         $entrydate = $entry->get_date('U');
 217         if (!empty($entrydate)) {
 218             $existingpostconditions['created'] = $entrydate;
 219         }
 220
 221         //the post ID or false if post not found in DB
 222         $postid = $DB->get_field('post', 'id', $existingpostconditions);
 223
 224         $timestamp = null;
 225         if (empty($entrydate)) {
 226             $timestamp = time();
 227         } else {
 228             $timestamp = $entrydate;
 229         }
 230
 231         //only set created if its a new post so we retain the original creation timestamp if the post is edited
 232         if ($postid === false) {
 233             $newentry->created = $timestamp;
 234         }
 235         $newentry->lastmodified = $timestamp;
 236
 237         if (empty($oldesttimestamp) || $timestamp < $oldesttimestamp) {
 238             //found an older post
 239             $oldesttimestamp = $timestamp;
 240         }
 241
 242         $textlib = textlib_get_instance();
 243         if ($textlib->strlen($newentry->uniquehash) > 255) {
 244             // The URL for this item is too long for the field. Rather than add
 245             // the entry without the link we will skip straight over it.
 246             // RSS spec says recommended length 500, we use 255.
 247             debugging('External blog entry skipped because of oversized URL', DEBUG_DEVELOPER);
 248             continue;
 249         }
 250
 251         if ($postid === false) {
 252             $id = $DB->insert_record('post', $newentry);
 253
 254             // Set tags
 255             if ($tags = tag_get_tags_array('blog_external', $externalblog->id)) {
 256                 tag_set('post', $id, $tags);
 257             }
 258         } else {
 259             $newentry->id = $postid;
 260             $DB->update_record('post', $newentry);
 261         }
 262     }
 263
 264     // Look at the posts we have in the database to check if any of them have been deleted from the feed.
 265     // Only checking posts within the time frame returned by the rss feed. Older items may have been deleted or
 266     // may just not be returned anymore. We can't tell the difference so we leave older posts alone.
 267     $sql = "SELECT id, uniquehash
 268               FROM {post}
 269              WHERE module = 'blog_external'
 270                    AND " . $DB->sql_compare_text('content') . " = " . $DB->sql_compare_text(':blogid') . "
 271                    AND created > :ts";
 272     $dbposts = $DB->get_records_sql($sql, array('blogid' => $externalblog->id, 'ts' => $oldesttimestamp));
 273
 274     $todelete = array();
 275     foreach($dbposts as $dbpost) {
 276         if ( !in_array($dbpost->uniquehash, $uniquehashes) ) {
 277             $todelete[] = $dbpost->id;
 278         }
 279     }
 280     $DB->delete_records_list('post', 'id', $todelete);
 281
 282     $DB->update_record('blog_external', array('id' => $externalblog->id, 'timefetched' => time()));
 283 }
 284
 285 /**
 286  * Given an external blog object, deletes all related blog entries from the post table.
 287  * NOTE: The external blog's id is saved as post.content, a field that is not oterhwise used by blog entries.
 288  * @param object $externablog
 289  */
 290 function blog_delete_external_entries($externalblog) {
 291     global $DB;
 292     require_capability('moodle/blog:manageexternal', get_context_instance(CONTEXT_SYSTEM));
 293     $DB->delete_records_select('post',
 294                                "module='blog_external' AND " . $DB->sql_compare_text('content') . " = ?",
 295                                array($externalblog->id));
 296 }
 297
 298 /**
 299  * Returns a URL based on the context of the current page.
 300  * This URL points to blog/index.php and includes filter parameters appropriate for the current page.
 301  *
 302  * @param stdclass $context
 303  * @return string
 304  */
 305 function blog_get_context_url($context=null) {
 306     global $CFG;
 307
 308     $viewblogentriesurl = new moodle_url('/blog/index.php');
 309
 310     if (empty($context)) {
 311         global $PAGE;
 312         $context = $PAGE->context;
 313     }
 314
 315     // Change contextlevel to SYSTEM if viewing the site course
 316     if ($context->contextlevel == CONTEXT_COURSE && $context->instanceid == SITEID) {
 317         $context->contextlevel = CONTEXT_SYSTEM;
 318     }
 319
 320     $filterparam = '';
 321     $strlevel = '';
 322
 323     switch ($context->contextlevel) {
 324         case CONTEXT_SYSTEM:
 325         case CONTEXT_BLOCK:
 326         case CONTEXT_COURSECAT:
 327             break;
 328         case CONTEXT_COURSE:
 329             $filterparam = 'courseid';
 330             $strlevel = get_string('course');
 331             break;
 332         case CONTEXT_MODULE:
 333             $filterparam = 'modid';
 334             $strlevel = print_context_name($context);
 335             break;
 336         case CONTEXT_USER:
 337             $filterparam = 'userid';
 338             $strlevel = get_string('user');
 339             break;
 340     }
 341
 342     if (!empty($filterparam)) {
 343         $viewblogentriesurl->param($filterparam, $context->instanceid);
 344     }
 345
 346     return $viewblogentriesurl;
 347 }
 348
 349 /**
 350  * This function checks that blogs are enabled, and that the user can see blogs at all
 351  * @return bool
 352  */
 353 function blog_is_enabled_for_user() {
 354     global $CFG;
 355     //return (!empty($CFG->bloglevel) && $CFG->bloglevel <= BLOG_GLOBAL_LEVEL && isloggedin() && !isguestuser());
 356     return (!empty($CFG->bloglevel) && (isloggedin() || ($CFG->bloglevel == BLOG_GLOBAL_LEVEL)));
 357 }
 358
 359 /**
 360  * This function gets all of the options available for the current user in respect
 361  * to blogs.
 362  *
 363  * It loads the following if applicable:
 364  * -  Module options {@see blog_get_options_for_module}
 365  * -  Course options {@see blog_get_options_for_course}
 366  * -  User specific options {@see blog_get_options_for_user}
 367  * -  General options (BLOG_LEVEL_GLOBAL)
 368  *
 369  * @param moodle_page $page The page to load for (normally $PAGE)
 370  * @param stdClass $userid Load for a specific user
 371  * @return array An array of options organised by type.
 372  */
 373 function blog_get_all_options(moodle_page $page, stdClass $userid = null) {
 374     global $CFG, $DB, $USER;
 375
 376     $options = array();
 377
 378     // If blogs are enabled and the user is logged in and not a guest
 379     if (blog_is_enabled_for_user()) {
 380         // If the context is the user then assume we want to load for the users context
 381         if (is_null($userid) && $page->context->contextlevel == CONTEXT_USER) {
 382             $userid = $page->context->instanceid;
 383         }
 384         // Check the userid var
 385         if (!is_null($userid) && $userid!==$USER->id) {
 386             // Load the user from the userid... it MUST EXIST throw a wobbly if it doesn't!
 387             $user = $DB->get_record('user', array('id'=>$userid), '*', MUST_EXIST);
 388         } else {
 389             $user = null;
 390         }
 391
 392         if ($CFG->useblogassociations && $page->cm !== null) {
 393             // Load for the module associated with the page
 394             $options[CONTEXT_MODULE] = blog_get_options_for_module($page->cm, $user);
 395         } else if ($CFG->useblogassociations && $page->course->id != SITEID) {
 396             // Load the options for the course associated with the page
 397             $options[CONTEXT_COURSE] = blog_get_options_for_course($page->course, $user);
 398         }
 399
 400         // Get the options for the user
 401         if ($user !== null and !isguestuser($user)) {
 402             // Load for the requested user
 403             $options[CONTEXT_USER+1] = blog_get_options_for_user($user);
 404         }
 405         // Load for the current user
 406         if (isloggedin() and !isguestuser()) {
 407             $options[CONTEXT_USER] = blog_get_options_for_user();
 408         }
 409     }
 410
 411     // If blog level is global then display a link to view all site entries
 412     if (!empty($CFG->bloglevel) && $CFG->bloglevel >= BLOG_GLOBAL_LEVEL && has_capability('moodle/blog:view', get_context_instance(CONTEXT_SYSTEM))) {
 413         $options[CONTEXT_SYSTEM] = array('viewsite' => array(
 414             'string' => get_string('viewsiteentries', 'blog'),
 415             'link' => new moodle_url('/blog/index.php')
 416         ));
 417     }
 418
 419     // Return the options
 420     return $options;
 421 }
 422
 423 /**
 424  * Get all of the blog options that relate to the passed user.
 425  *
 426  * If no user is passed the current user is assumed.
 427  *
 428  * @staticvar array $useroptions Cache so we don't have to regenerate multiple times
 429  * @param stdClass $user
 430  * @return array The array of options for the requested user
 431  */
 432 function blog_get_options_for_user(stdClass $user=null) {
 433     global $CFG, $USER;
 434     // Cache
 435     static $useroptions = array();
 436
 437     $options = array();
 438     // Blogs must be enabled and the user must be logged in
 439     if (!blog_is_enabled_for_user()) {
 440         return $options;
 441     }
 442
 443     // Sort out the user var
 444     if ($user === null || $user->id == $USER->id) {
 445         $user = $USER;
 446         $iscurrentuser = true;
 447     } else {
 448         $iscurrentuser = false;
 449     }
 450
 451     // If we've already generated serve from the cache
 452     if (array_key_exists($user->id, $useroptions)) {
 453         return $useroptions[$user->id];
 454     }
 455
 456     $sitecontext = get_context_instance(CONTEXT_SYSTEM);
 457     $canview = has_capability('moodle/blog:view', $sitecontext);
 458
 459     if (!$iscurrentuser && $canview && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {
 460         // Not the current user, but we can view and its blogs are enabled for SITE or GLOBAL
 461         $options['userentries'] = array(
 462             'string' => get_string('viewuserentries', 'blog', fullname($user)),
 463             'link' => new moodle_url('/blog/index.php', array('userid'=>$user->id))
 464         );
 465     } else {
 466         // It's the current user
 467         if ($canview) {
 468             // We can view our own blogs .... BIG surprise
 469             $options['view'] = array(
 470                 'string' => get_string('viewallmyentries', 'blog'),
 471                 'link' => new moodle_url('/blog/index.php', array('userid'=>$USER->id))
 472             );
 473         }
 474         if (has_capability('moodle/blog:create', $sitecontext)) {
 475             // We can add to our own blog
 476             $options['add'] = array(
 477                 'string' => get_string('addnewentry', 'blog'),
 478                 'link' => new moodle_url('/blog/edit.php', array('action'=>'add'))
 479             );
 480         }
 481     }
 482     if ($canview && $CFG->enablerssfeeds) {
 483         $options['rss'] = array(
 484             'string' => get_string('rssfeed', 'blog'),
 485             'link' => new moodle_url(rss_get_url($sitecontext->id, $USER->id, 'blog', 'user/'.$user->id))
 486         );
 487     }
 488
 489     // Cache the options
 490     $useroptions[$user->id] = $options;
 491     // Return the options
 492     return $options;
 493 }
 494
 495 /**
 496  * Get the blog options that relate to the given course for the given user.
 497  *
 498  * @staticvar array $courseoptions A cache so we can save regenerating multiple times
 499  * @param stdClass $course The course to load options for
 500  * @param stdClass $user The user to load options for null == current user
 501  * @return array The array of options
 502  */
 503 function blog_get_options_for_course(stdClass $course, stdClass $user=null) {
 504     global $CFG, $USER;
 505     // Cache
 506     static $courseoptions = array();
 507
 508     $options = array();
 509
 510     // User must be logged in and blogs must be enabled
 511     if (!blog_is_enabled_for_user()) {
 512         return $options;
 513     }
 514
 515     // Check that the user can associate with the course
 516     $sitecontext =      get_context_instance(CONTEXT_SYSTEM);
 517     if (!has_capability('moodle/blog:associatecourse', $sitecontext)) {
 518         return $options;
 519     }
 520     // Generate the cache key
 521     $key = $course->id.':';
 522     if (!empty($user)) {
 523         $key .= $user->id;
 524     } else {
 525         $key .= $USER->id;
 526     }
 527     // Serve from the cache if we've already generated for this course
 528     if (array_key_exists($key, $courseoptions)) {
 529         return $courseoptions[$key];
 530     }
 531
 532     if (has_capability('moodle/blog:view', get_context_instance(CONTEXT_COURSE, $course->id))) {
 533         // We can view!
 534         if ($CFG->bloglevel >= BLOG_SITE_LEVEL) {
 535             // View entries about this course
 536             $options['courseview'] = array(
 537                 'string' => get_string('viewcourseblogs', 'blog'),
 538                 'link' => new moodle_url('/blog/index.php', array('courseid'=>$course->id))
 539             );
 540         }
 541         // View MY entries about this course
 542         $options['courseviewmine'] = array(
 543             'string' => get_string('viewmyentriesaboutcourse', 'blog'),
 544             'link' => new moodle_url('/blog/index.php', array('courseid'=>$course->id, 'userid'=>$USER->id))
 545         );
 546         if (!empty($user) && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {
 547             // View the provided users entries about this course
 548             $options['courseviewuser'] = array(
 549                 'string' => get_string('viewentriesbyuseraboutcourse', 'blog', fullname($user)),
 550                 'link' => new moodle_url('/blog/index.php', array('courseid'=>$course->id, 'userid'=>$user->id))
 551             );
 552         }
 553     }
 554
 555     if (has_capability('moodle/blog:create', $sitecontext)) {
 556         // We can blog about this course
 557         $options['courseadd'] = array(
 558             'string' => get_string('blogaboutthiscourse', 'blog'),
 559             'link' => new moodle_url('/blog/edit.php', array('action'=>'add', 'courseid'=>$course->id))
 560         );
 561     }
 562
 563
 564     // Cache the options for this course
 565     $courseoptions[$key] = $options;
 566     // Return the options
 567     return $options;
 568 }
 569
 570 /**
 571  * Get the blog options relating to the given module for the given user
 572  *
 573  * @staticvar array $moduleoptions Cache
 574  * @param stdClass|cm_info $module The module to get options for
 575  * @param stdClass $user The user to get options for null == currentuser
 576  * @return array
 577  */
 578 function blog_get_options_for_module($module, $user=null) {
 579     global $CFG, $USER;
 580     // Cache
 581     static $moduleoptions = array();
 582
 583     $options = array();
 584     // User must be logged in, blogs must be enabled
 585     if (!blog_is_enabled_for_user()) {
 586         return $options;
 587     }
 588
 589     // Check the user can associate with the module
 590     $sitecontext =      get_context_instance(CONTEXT_SYSTEM);
 591     if (!has_capability('moodle/blog:associatemodule', $sitecontext)) {
 592         return $options;
 593     }
 594
 595     // Generate the cache key
 596     $key = $module->id.':';
 597     if (!empty($user)) {
 598         $key .= $user->id;
 599     } else {
 600         $key .= $USER->id;
 601     }
 602     if (array_key_exists($key, $moduleoptions)) {
 603         // Serve from the cache so we don't have to regenerate
 604         return $moduleoptions[$module->id];
 605     }
 606
 607     if (has_capability('moodle/blog:view', get_context_instance(CONTEXT_MODULE, $module->id))) {
 608         // We can view!
 609         if ($CFG->bloglevel >= BLOG_SITE_LEVEL) {
 610             // View all entries about this module
 611             $a = new stdClass;
 612             $a->type = $module->modname;
 613             $options['moduleview'] = array(
 614                 'string' => get_string('viewallmodentries', 'blog', $a),
 615                 'link' => new moodle_url('/blog/index.php', array('modid'=>$module->id))
 616             );
 617         }
 618         // View MY entries about this module
 619         $options['moduleviewmine'] = array(
 620             'string' => get_string('viewmyentriesaboutmodule', 'blog', $module->modname),
 621             'link' => new moodle_url('/blog/index.php', array('modid'=>$module->id, 'userid'=>$USER->id))
 622         );
 623         if (!empty($user) && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {
 624             // View the given users entries about this module
 625             $a = new stdClass;
 626             $a->mod = $module->modname;
 627             $a->user = fullname($user);
 628             $options['moduleviewuser'] = array(
 629                 'string' => get_string('blogentriesbyuseraboutmodule', 'blog', $a),
 630                 'link' => new moodle_url('/blog/index.php', array('modid'=>$module->id, 'userid'=>$user->id))
 631             );
 632         }
 633     }
 634
 635     if (has_capability('moodle/blog:create', $sitecontext)) {
 636         // The user can blog about this module
 637         $options['moduleadd'] = array(
 638             'string' => get_string('blogaboutthismodule', 'blog', $module->modname),
 639             'link' => new moodle_url('/blog/edit.php', array('action'=>'add', 'modid'=>$module->id))
 640         );
 641     }
 642     // Cache the options
 643     $moduleoptions[$key] = $options;
 644     // Return the options
 645     return $options;
 646 }
 647
 648 /**
 649  * This function encapsulates all the logic behind the complex
 650  * navigation, titles and headings of the blog listing page, depending
 651  * on URL params. It looks at URL params and at the current context level.
 652  * It builds and returns an array containing:
 653  *
 654  * 1. heading: The heading displayed above the blog entries
 655  * 2. stradd:  The text to be used as the "Add entry" link
 656  * 3. strview: The text to be used as the "View entries" link
 657  * 4. url:     The moodle_url object used as the base for add and view links
 658  * 5. filters: An array of parameters used to filter blog listings. Used by index.php and the Recent blogs block
 659  *
 660  * All other variables are set directly in $PAGE
 661  *
 662  * It uses the current URL to build these variables.
 663  * A number of mutually exclusive use cases are used to structure this function.
 664  *
 665  * @return array
 666  */
 667 function blog_get_headers($courseid=null, $groupid=null, $userid=null, $tagid=null) {
 668     global $CFG, $PAGE, $DB, $USER;
 669
 670     $id       = optional_param('id', null, PARAM_INT);
 671     $tag      = optional_param('tag', null, PARAM_NOTAGS);
 672     $tagid    = optional_param('tagid', $tagid, PARAM_INT);
 673     $userid   = optional_param('userid', $userid, PARAM_INT);
 674     $modid    = optional_param('modid', null, PARAM_INT);
 675     $entryid  = optional_param('entryid', null, PARAM_INT);
 676     $groupid  = optional_param('groupid', $groupid, PARAM_INT);
 677     $courseid = optional_param('courseid', $courseid, PARAM_INT);
 678     $search   = optional_param('search', null, PARAM_RAW);
 679     $action   = optional_param('action', null, PARAM_ALPHA);
 680     $confirm  = optional_param('confirm', false, PARAM_BOOL);
 681
 682     // Ignore userid when action == add
 683     if ($action == 'add' && $userid) {
 684         unset($userid);
 685         $PAGE->url->remove_params(array('userid'));
 686     } else if ($action == 'add' && $entryid) {
 687         unset($entryid);
 688         $PAGE->url->remove_params(array('entryid'));
 689     }
 690
 691     $headers = array('title' => '', 'heading' => '', 'cm' => null, 'filters' => array());
 692
 693     $blogurl = new moodle_url('/blog/index.php');
 694
 695     // If the title is not yet set, it's likely that the context isn't set either, so skip this part
 696     $pagetitle = $PAGE->title;
 697     if (!empty($pagetitle)) {
 698         $contexturl = blog_get_context_url();
 699
 700         // Look at the context URL, it may have additional params that are not in the current URL
 701         if (!$blogurl->compare($contexturl)) {
 702             $blogurl = $contexturl;
 703             if (empty($courseid)) {
 704                 $courseid = $blogurl->param('courseid');
 705             }
 706             if (empty($modid)) {
 707                 $modid = $blogurl->param('modid');
 708             }
 709         }
 710     }
 711
 712     $headers['stradd'] = get_string('addnewentry', 'blog');
 713     $headers['strview'] = null;
 714
 715     $site = $DB->get_record('course', array('id' => SITEID));
 716     $sitecontext = get_context_instance(CONTEXT_SYSTEM);
 717     // Common Lang strings
 718     $strparticipants = get_string("participants");
 719     $strblogentries  = get_string("blogentries", 'blog');
 720
 721     // Prepare record objects as needed
 722     if (!empty($courseid)) {
 723         $headers['filters']['course'] = $courseid;
 724         $course = $DB->get_record('course', array('id' => $courseid));
 725     }
 726
 727     if (!empty($userid)) {
 728         $headers['filters']['user'] = $userid;
 729         $user = $DB->get_record('user', array('id' => $userid));
 730     }
 731
 732     if (!empty($groupid)) { // groupid always overrides courseid
 733         $headers['filters']['group'] = $groupid;
 734         $group = $DB->get_record('groups', array('id' => $groupid));
 735         $course = $DB->get_record('course', array('id' => $group->courseid));
 736     }
 737
 738     $PAGE->set_pagelayout('standard');
 739
 740     if (!empty($modid) && $CFG->useblogassociations && has_capability('moodle/blog:associatemodule', $sitecontext)) { // modid always overrides courseid, so the $course object may be reset here
 741         $headers['filters']['module'] = $modid;
 742         // A groupid param may conflict with this coursemod's courseid. Ignore groupid in that case
 743         $courseid = $DB->get_field('course_modules', 'course', array('id'=>$modid));
 744         $course = $DB->get_record('course', array('id' => $courseid));
 745         $cm = $DB->get_record('course_modules', array('id' => $modid));
 746         $cm->modname = $DB->get_field('modules', 'name', array('id' => $cm->module));
 747         $cm->name = $DB->get_field($cm->modname, 'name', array('id' => $cm->instance));
 748         $a = new stdClass();
 749         $a->type = get_string('modulename', $cm->modname);
 750         $PAGE->set_cm($cm, $course);
 751         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 752         $headers['strview'] = get_string('viewallmodentries', 'blog', $a);
 753     }
 754
 755     // Case 1: No entry, mod, course or user params: all site entries to be shown (filtered by search and tag/tagid)
 756     // Note: if action is set to 'add' or 'edit', we do this at the end
 757     if (empty($entryid) && empty($modid) && empty($courseid) && empty($userid) && !in_array($action, array('edit', 'add'))) {
 758         $PAGE->navbar->add($strblogentries, $blogurl);
 759         $PAGE->set_title("$site->shortname: " . get_string('blog', 'blog'));
 760         $PAGE->set_heading("$site->shortname: " . get_string('blog', 'blog'));
 761         $headers['heading'] = get_string('siteblog', 'blog', $site->shortname);
 762         // $headers['strview'] = get_string('viewsiteentries', 'blog');
 763     }
 764
 765     // Case 2: only entryid is requested, ignore all other filters. courseid is used to give more contextual information
 766     if (!empty($entryid)) {
 767         $headers['filters']['entry'] = $entryid;
 768         $sql = 'SELECT u.* FROM {user} u, {post} p WHERE p.id = ? AND p.userid = u.id';
 769         $user = $DB->get_record_sql($sql, array($entryid));
 770         $entry = $DB->get_record('post', array('id' => $entryid));
 771
 772         $blogurl->param('userid', $user->id);
 773
 774         if (!empty($course)) {
 775             $mycourseid = $course->id;
 776             $blogurl->param('courseid', $mycourseid);
 777         } else {
 778             $mycourseid = $site->id;
 779         }
 780
 781         $PAGE->navbar->add($strblogentries, $blogurl);
 782
 783         $blogurl->remove_params('userid');
 784         $PAGE->navbar->add($entry->subject, $blogurl);
 785
 786         $PAGE->set_title("$site->shortname: " . fullname($user) . ": $entry->subject");
 787         $PAGE->set_heading("$site->shortname: " . fullname($user) . ": $entry->subject");
 788         $headers['heading'] = get_string('blogentrybyuser', 'blog', fullname($user));
 789
 790         // We ignore tag and search params
 791         if (empty($action) || !$CFG->useblogassociations) {
 792             $headers['url'] = $blogurl;
 793             return $headers;
 794         }
 795     }
 796
 797     // Case 3: A user's blog entries
 798     if (!empty($userid) && empty($entryid) && ((empty($courseid) && empty($modid)) || !$CFG->useblogassociations)) {
 799         $blogurl->param('userid', $userid);
 800         $PAGE->set_title("$site->shortname: " . fullname($user) . ": " . get_string('blog', 'blog'));
 801         $PAGE->set_heading("$site->shortname: " . fullname($user) . ": " . get_string('blog', 'blog'));
 802         $headers['heading'] = get_string('userblog', 'blog', fullname($user));
 803         $headers['strview'] = get_string('viewuserentries', 'blog', fullname($user));
 804
 805     } else
 806
 807     // Case 4: No blog associations, no userid
 808     if (!$CFG->useblogassociations && empty($userid) && !in_array($action, array('edit', 'add'))) {
 809         $PAGE->set_title("$site->shortname: " . get_string('blog', 'blog'));
 810         $PAGE->set_heading("$site->shortname: " . get_string('blog', 'blog'));
 811         $headers['heading'] = get_string('siteblog', 'blog', $site->shortname);
 812     } else
 813
 814     // Case 5: Blog entries associated with an activity by a specific user (courseid ignored)
 815     if (!empty($userid) && !empty($modid) && empty($entryid)) {
 816         $blogurl->param('userid', $userid);
 817         $blogurl->param('modid', $modid);
 818
 819         // Course module navigation is handled by build_navigation as the second param
 820         $headers['cm'] = $cm;
 821         $PAGE->navbar->add(fullname($user), "$CFG->wwwroot/user/view.php?id=$user->id");
 822         $PAGE->navbar->add($strblogentries, $blogurl);
 823
 824         $PAGE->set_title("$site->shortname: $cm->name: " . fullname($user) . ': ' . get_string('blogentries', 'blog'));
 825         $PAGE->set_heading("$site->shortname: $cm->name: " . fullname($user) . ': ' . get_string('blogentries', 'blog'));
 826
 827         $a = new stdClass();
 828         $a->user = fullname($user);
 829         $a->mod = $cm->name;
 830         $a->type = get_string('modulename', $cm->modname);
 831         $headers['heading'] = get_string('blogentriesbyuseraboutmodule', 'blog', $a);
 832         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 833         $headers['strview'] = get_string('viewallmodentries', 'blog', $a);
 834     } else
 835
 836     // Case 6: Blog entries associated with a course by a specific user
 837     if (!empty($userid) && !empty($courseid) && empty($modid) && empty($entryid)) {
 838         $blogurl->param('userid', $userid);
 839         $blogurl->param('courseid', $courseid);
 840
 841         $PAGE->navbar->add($strblogentries, $blogurl);
 842
 843         $PAGE->set_title("$site->shortname: $course->shortname: " . fullname($user) . ': ' . get_string('blogentries', 'blog'));
 844         $PAGE->set_heading("$site->shortname: $course->shortname: " . fullname($user) . ': ' . get_string('blogentries', 'blog'));
 845
 846         $a = new stdClass();
 847         $a->user = fullname($user);
 848         $a->course = $course->fullname;
 849         $a->type = get_string('course');
 850         $headers['heading'] = get_string('blogentriesbyuseraboutcourse', 'blog', $a);
 851         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 852         $headers['strview'] = get_string('viewblogentries', 'blog', $a);
 853
 854         // Remove the userid from the URL to inform the blog_menu block correctly
 855         $blogurl->remove_params(array('userid'));
 856     } else
 857
 858     // Case 7: Blog entries by members of a group, associated with that group's course
 859     if (!empty($groupid) && empty($modid) && empty($entryid)) {
 860         $blogurl->param('courseid', $course->id);
 861
 862         $PAGE->navbar->add($strblogentries, $blogurl);
 863         $blogurl->remove_params(array('courseid'));
 864         $blogurl->param('groupid', $groupid);
 865         $PAGE->navbar->add($group->name, $blogurl);
 866
 867         $PAGE->set_title("$site->shortname: $course->shortname: " . get_string('blogentries', 'blog') . ": $group->name");
 868         $PAGE->set_heading("$site->shortname: $course->shortname: " . get_string('blogentries', 'blog') . ": $group->name");
 869
 870         $a = new stdClass();
 871         $a->group = $group->name;
 872         $a->course = $course->fullname;
 873         $a->type = get_string('course');
 874         $headers['heading'] = get_string('blogentriesbygroupaboutcourse', 'blog', $a);
 875         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 876         $headers['strview'] = get_string('viewblogentries', 'blog', $a);
 877     } else
 878
 879     // Case 8: Blog entries by members of a group, associated with an activity in that course
 880     if (!empty($groupid) && !empty($modid) && empty($entryid)) {
 881         $headers['cm'] = $cm;
 882         $blogurl->param('modid', $modid);
 883         $PAGE->navbar->add($strblogentries, $blogurl);
 884
 885         $blogurl->param('groupid', $groupid);
 886         $PAGE->navbar->add($group->name, $blogurl);
 887
 888         $PAGE->set_title("$site->shortname: $course->shortname: $cm->name: " . get_string('blogentries', 'blog') . ": $group->name");
 889         $PAGE->set_heading("$site->shortname: $course->shortname: $cm->name: " . get_string('blogentries', 'blog') . ": $group->name");
 890
 891         $a = new stdClass();
 892         $a->group = $group->name;
 893         $a->mod = $cm->name;
 894         $a->type = get_string('modulename', $cm->modname);
 895         $headers['heading'] = get_string('blogentriesbygroupaboutmodule', 'blog', $a);
 896         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 897         $headers['strview'] = get_string('viewallmodentries', 'blog', $a);
 898
 899     } else
 900
 901     // Case 9: All blog entries associated with an activity
 902     if (!empty($modid) && empty($userid) && empty($groupid) && empty($entryid)) {
 903         $PAGE->set_cm($cm, $course);
 904         $blogurl->param('modid', $modid);
 905         $PAGE->navbar->add($strblogentries, $blogurl);
 906         $PAGE->set_title("$site->shortname: $course->shortname: $cm->name: " . get_string('blogentries', 'blog'));
 907         $PAGE->set_heading("$site->shortname: $course->shortname: $cm->name: " . get_string('blogentries', 'blog'));
 908         $headers['heading'] = get_string('blogentriesabout', 'blog', $cm->name);
 909         $a = new stdClass();
 910         $a->type = get_string('modulename', $cm->modname);
 911         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 912         $headers['strview'] = get_string('viewallmodentries', 'blog', $a);
 913     } else
 914
 915     // Case 10: All blog entries associated with a course
 916     if (!empty($courseid) && empty($userid) && empty($groupid) && empty($modid) && empty($entryid)) {
 917         $blogurl->param('courseid', $courseid);
 918         $PAGE->navbar->add($strblogentries, $blogurl);
 919         $PAGE->set_title("$site->shortname: $course->shortname: " . get_string('blogentries', 'blog'));
 920         $PAGE->set_heading("$site->shortname: $course->shortname: " . get_string('blogentries', 'blog'));
 921         $a = new stdClass();
 922         $a->type = get_string('course');
 923         $headers['heading'] = get_string('blogentriesabout', 'blog', $course->fullname);
 924         $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);
 925         $headers['strview'] = get_string('viewblogentries', 'blog', $a);
 926         $blogurl->remove_params(array('userid'));
 927     }
 928
 929     if (!in_array($action, array('edit', 'add'))) {
 930         // Append Tag info
 931         if (!empty($tagid)) {
 932             $headers['filters']['tag'] = $tagid;
 933             $blogurl->param('tagid', $tagid);
 934             $tagrec = $DB->get_record('tag', array('id'=>$tagid));
 935             $PAGE->navbar->add($tagrec->name, $blogurl);
 936         } elseif (!empty($tag)) {
 937             $blogurl->param('tag', $tag);
 938             $PAGE->navbar->add(get_string('tagparam', 'blog', $tag), $blogurl);
 939         }
 940
 941         // Append Search info
 942         if (!empty($search)) {
 943             $headers['filters']['search'] = $search;
 944             $blogurl->param('search', $search);
 945             $PAGE->navbar->add(get_string('searchterm', 'blog', $search), $blogurl->out());
 946         }
 947     }
 948
 949     // Append edit mode info
 950     if (!empty($action) && $action == 'add') {
 951
 952     } else if (!empty($action) && $action == 'edit') {
 953         $PAGE->navbar->add(get_string('editentry', 'blog'));
 954     }
 955
 956     if (empty($headers['url'])) {
 957         $headers['url'] = $blogurl;
 958     }
 959     return $headers;
 960 }
 961
 962 /**
 963  * Shortcut function for getting a count of blog entries associated with a course or a module
 964  * @param int $courseid The ID of the course
 965  * @param int $cmid The ID of the course_modules
 966  * @return string The number of associated entries
 967  */
 968 function blog_get_associated_count($courseid, $cmid=null) {
 969     global $DB;
 970     $context = get_context_instance(CONTEXT_COURSE, $courseid);
 971     if ($cmid) {
 972         $context = get_context_instance(CONTEXT_MODULE, $cmid);
 973     }
 974     return $DB->count_records('blog_association', array('contextid' => $context->id));
 975 }
 976
 977 /**
 978  * Running addtional permission check on plugin, for example, plugins
 979  * may have switch to turn on/off comments option, this callback will
 980  * affect UI display, not like pluginname_comment_validate only throw
 981  * exceptions.
 982  * Capability check has been done in comment->check_permissions(), we
 983  * don't need to do it again here.
 984  *
 985  * @param stdClass $comment_param {
 986  *              context  => context the context object
 987  *              courseid => int course id
 988  *              cm       => stdClass course module object
 989  *              commentarea => string comment area
 990  *              itemid      => int itemid
 991  * }
 992  * @return array
 993  */
 994 function blog_comment_permissions($comment_param) {
 995     return array('post'=>true, 'view'=>true);
 996 }
 997
 998 /**
 999  * Validate comment parameter before perform other comments actions
1000  *
1001  * @param stdClass $comment {
1002  *              context  => context the context object
1003  *              courseid => int course id
1004  *              cm       => stdClass course module object
1005  *              commentarea => string comment area
1006  *              itemid      => int itemid
1007  * }
1008  * @return boolean
1009  */
1010 function blog_comment_validate($comment_param) {
1011     global $DB;
1012     // validate comment itemid
1013     if (!$entry = $DB->get_record('post', array('id'=>$comment_param->itemid))) {
1014         throw new comment_exception('invalidcommentitemid');
1015     }
1016     // validate comment area
1017     if ($comment_param->commentarea != 'format_blog') {
1018         throw new comment_exception('invalidcommentarea');
1019     }
1020     // validation for comment deletion
1021     if (!empty($comment_param->commentid)) {
1022         if ($record = $DB->get_record('comments', array('id'=>$comment_param->commentid))) {
1023             if ($record->commentarea != 'format_blog') {
1024                 throw new comment_exception('invalidcommentarea');
1025             }
1026             if ($record->contextid != $comment_param->context->id) {
1027                 throw new comment_exception('invalidcontext');
1028             }
1029             if ($record->itemid != $comment_param->itemid) {
1030                 throw new comment_exception('invalidcommentitemid');
1031             }
1032         } else {
1033             throw new comment_exception('invalidcommentid');
1034         }
1035     }
1036     return true;
1037 }