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