Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Core global functions for Blog.

 *

 * @package    moodlecore

 * @subpackage blog

 * @copyright  2009 Nicolas Connault

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

/*

 * Library of functions and constants for blog

 */

require_once($CFG->dirroot .'/blog/rsslib.php');

/**

 * User can edit a blog entry if this is their own blog entry and they have

 * the capability moodle/blog:create, or if they have the capability

 * moodle/blog:manageentries.

 *

 * This also applies to deleting of entries.

 */

function blog_user_can_edit_entry($blogentry) {

    global $USER;

    $sitecontext = context_system::instance();

    if (has_capability('moodle/blog:manageentries', $sitecontext)) {

        return true; // Can edit any blog entry.

    }

    if ($blogentry->userid == $USER->id && has_capability('moodle/blog:create', $sitecontext)) {

        return true; // Can edit own when having blog:create capability.

    }

    return false;

}

/**

 * Checks to see if a user can view the blogs of another user.

 * Only blog level is checked here, the capabilities are enforced

 * in blog/index.php

 */

function blog_user_can_view_user_entry($targetuserid, $blogentry=null) {

    global $CFG, $USER, $DB;

    if (empty($CFG->enableblogs)) {

        return false; // Blog system disabled.

    }

    if (isloggedin() && $USER->id == $targetuserid) {

        return true; // Can view own entries in any case.

    }

    $sitecontext = context_system::instance();

    if (has_capability('moodle/blog:manageentries', $sitecontext)) {

        return true; // Can manage all entries.

    }

    // If blog is in draft state, then make sure user have proper capability.

    if ($blogentry && $blogentry->publishstate == 'draft' && !has_capability('moodle/blog:viewdrafts', $sitecontext)) {

        return false;  // Can not view draft of others.

    }

    // If blog entry is not public, make sure user is logged in.

    if ($blogentry && $blogentry->publishstate != 'public' && !isloggedin()) {

        return false;

    }

    // If blogentry is not passed or all above checks pass, then check capability based on system config.

    switch ($CFG->bloglevel) {

        case BLOG_GLOBAL_LEVEL:

            return true;

        break;

        case BLOG_SITE_LEVEL:

            if (isloggedin()) { // Not logged in viewers forbidden.

                return true;

            }

            return false;

        break;

        case BLOG_USER_LEVEL:

        default:

            // If user is viewing other user blog, then user should have user:readuserblogs capability.

            $personalcontext = context_user::instance($targetuserid);

            return has_capability('moodle/user:readuserblogs', $personalcontext);

        break;

    }

}

/**

 * remove all associations for the blog entries of a particular course

 * @param int courseid - id of user whose blog associations will be deleted

 */

function blog_remove_associations_for_course($courseid) {

    global $DB;

    $context = context_course::instance($courseid);

    $DB->delete_records('blog_association', array('contextid' => $context->id));

}

/**

 * Remove module associated blogs and blog tag instances.

 *

 * @param  int $modcontextid Module context ID.

 */

function blog_remove_associations_for_module($modcontextid) {

    global $DB;

    if (!empty($assocblogids = $DB->get_fieldset_select('blog_association', 'blogid',

        'contextid = :contextid', ['contextid' => $modcontextid]))) {

        list($sql, $params) = $DB->get_in_or_equal($assocblogids, SQL_PARAMS_NAMED);

        $DB->delete_records_select('tag_instance', "itemid $sql", $params);

        $DB->delete_records_select('post', "id $sql AND module = :module",

            array_merge($params, ['module' => 'blog']));

        $DB->delete_records('blog_association', ['contextid' => $modcontextid]);

    }

}

/**

 * Given a record in the {blog_external} table, checks the blog's URL

 * for new entries not yet copied into Moodle.

 * Also attempts to identify and remove deleted blog entries

 *

 * @param object $externalblog

 * @return boolean False if the Feed is invalid

 */

function blog_sync_external_entries($externalblog) {

    global $CFG, $DB;

    require_once($CFG->libdir . '/simplepie/moodle_simplepie.php');

    $rss = new moodle_simplepie();

    $rssfile = $rss->registry->create('File', array($externalblog->url));

    $filetest = $rss->registry->create('Locator', array($rssfile));

    if (!$filetest->is_feed($rssfile)) {

        $externalblog->failedlastsync = 1;

        $DB->update_record('blog_external', $externalblog);

        return false;

    } else if (!empty($externalblog->failedlastsync)) {

        $externalblog->failedlastsync = 0;

        $DB->update_record('blog_external', $externalblog);

    }

    $rss->set_feed_url($externalblog->url);

    $rss->init();

    if (empty($rss->data)) {

        return null;

    }

    // Used to identify blog posts that have been deleted from the source feed.

    $oldesttimestamp = null;

    $uniquehashes = array();

    foreach ($rss->get_items() as $entry) {

        // If filtertags are defined, use them to filter the entries by RSS category.

        if (!empty($externalblog->filtertags)) {

            $containsfiltertag = false;

            $categories = $entry->get_categories();

            $filtertags = explode(',', $externalblog->filtertags);

            $filtertags = array_map('trim', $filtertags);

            $filtertags = array_map('strtolower', $filtertags);

            if (!empty($categories)) {

                foreach ($categories as $category) {

                    if (in_array(trim(strtolower($category->term)), $filtertags)) {

                        $containsfiltertag = true;

                    }

                }

            }

            if (!$containsfiltertag) {

                continue;

            }

        }

        $uniquehashes[] = $entry->get_permalink();

        $newentry = new stdClass();

        $newentry->userid = $externalblog->userid;

        $newentry->module = 'blog_external';

        $newentry->content = $externalblog->id;

        $newentry->uniquehash = $entry->get_permalink();

        $newentry->publishstate = 'site';

        $newentry->format = FORMAT_HTML;

        // Clean subject of html, just in case.

        $newentry->subject = clean_param($entry->get_title(), PARAM_TEXT);

        // Observe 128 max chars in DB.

        // TODO: +1 to raise this to 255.

        if (core_text::strlen($newentry->subject) > 128) {

            $newentry->subject = core_text::substr($newentry->subject, 0, 125) . '...';

        }

        $newentry->summary = $entry->get_description();

        // Used to decide whether to insert or update.

        // Uses enty permalink plus creation date if available.

        $existingpostconditions = array('uniquehash' => $entry->get_permalink());

        // Our DB doesnt allow null creation or modified timestamps so check the external blog supplied one.

        $entrydate = $entry->get_date('U');

        if (!empty($entrydate)) {

            $existingpostconditions['created'] = $entrydate;

        }

        // The post ID or false if post not found in DB.

        $postid = $DB->get_field('post', 'id', $existingpostconditions);

        $timestamp = null;

        if (empty($entrydate)) {

            $timestamp = time();

        } else {

            $timestamp = $entrydate;

        }

        // Only set created if its a new post so we retain the original creation timestamp if the post is edited.

        if ($postid === false) {

            $newentry->created = $timestamp;

        }

        $newentry->lastmodified = $timestamp;

        if (empty($oldesttimestamp) || $timestamp < $oldesttimestamp) {

            // Found an older post.

            $oldesttimestamp = $timestamp;

        }

        if (core_text::strlen($newentry->uniquehash) > 255) {

            // The URL for this item is too long for the field. Rather than add

            // the entry without the link we will skip straight over it.

            // RSS spec says recommended length 500, we use 255.

            debugging('External blog entry skipped because of oversized URL', DEBUG_DEVELOPER);

            continue;

        }

        if ($postid === false) {

            $id = $DB->insert_record('post', $newentry);

            // Set tags.

            if ($tags = core_tag_tag::get_item_tags_array('core', 'blog_external', $externalblog->id)) {

                core_tag_tag::set_item_tags('core', 'post', $id, context_user::instance($externalblog->userid), $tags);

            }

        } else {

            $newentry->id = $postid;

            $DB->update_record('post', $newentry);

        }

    }

    // Look at the posts we have in the database to check if any of them have been deleted from the feed.

    // Only checking posts within the time frame returned by the rss feed. Older items may have been deleted or

    // may just not be returned anymore. We can't tell the difference so we leave older posts alone.

    $sql = "SELECT id, uniquehash

              FROM {post}

             WHERE module = 'blog_external'

                   AND " . $DB->sql_compare_text('content') . " = " . $DB->sql_compare_text(':blogid') . "

                   AND created > :ts";

    $dbposts = $DB->get_records_sql($sql, array('blogid' => $externalblog->id, 'ts' => $oldesttimestamp));

    $todelete = array();

    foreach ($dbposts as $dbpost) {

        if ( !in_array($dbpost->uniquehash, $uniquehashes) ) {

            $todelete[] = $dbpost->id;

        }

    }

    $DB->delete_records_list('post', 'id', $todelete);

    $DB->update_record('blog_external', array('id' => $externalblog->id, 'timefetched' => time()));

}

/**

 * Given an external blog object, deletes all related blog entries from the post table.

 * NOTE: The external blog's id is saved as post.content, a field that is not oterhwise used by blog entries.

 * @param object $externablog

 */

function blog_delete_external_entries($externalblog) {

    global $DB;

    require_capability('moodle/blog:manageexternal', context_system::instance());

    $DB->delete_records_select('post',

                               "module='blog_external' AND " . $DB->sql_compare_text('content') . " = ?",

                               array($externalblog->id));

}

/**

 * This function checks that blogs are enabled, and that the user can see blogs at all

 * @return bool

 */

function blog_is_enabled_for_user() {

    global $CFG;

    return (!empty($CFG->enableblogs) && (isloggedin() || ($CFG->bloglevel == BLOG_GLOBAL_LEVEL)));

}

/**

 * This function gets all of the options available for the current user in respect

 * to blogs.

 *

 * It loads the following if applicable:

 * -  Module options {@see blog_get_options_for_module}

 * -  Course options {@see blog_get_options_for_course}

 * -  User specific options {@see blog_get_options_for_user}

 * -  General options (BLOG_LEVEL_GLOBAL)

 *

 * @param moodle_page $page The page to load for (normally $PAGE)

 * @param stdClass $userid Load for a specific user

 * @return array An array of options organised by type.

 */

function blog_get_all_options(moodle_page $page, ?stdClass $userid = null) {

    global $CFG, $DB, $USER;

    $options = array();

    // If blogs are enabled and the user is logged in and not a guest.

    if (blog_is_enabled_for_user()) {

        // If the context is the user then assume we want to load for the users context.

        if (is_null($userid) && $page->context->contextlevel == CONTEXT_USER) {

            $userid = $page->context->instanceid;

        }

        // Check the userid var.

        if (!is_null($userid) && $userid !== $USER->id) {

            // Load the user from the userid... it MUST EXIST throw a wobbly if it doesn't!

            $user = $DB->get_record('user', array('id' => $userid), '*', MUST_EXIST);

        } else {

            $user = null;

        }

        if ($CFG->useblogassociations && $page->cm !== null) {

            // Load for the module associated with the page.

            $options[CONTEXT_MODULE] = blog_get_options_for_module($page->cm, $user);

        } else if ($CFG->useblogassociations && $page->course->id != SITEID) {

            // Load the options for the course associated with the page.

            $options[CONTEXT_COURSE] = blog_get_options_for_course($page->course, $user);

        }

        // Get the options for the user.

        if ($user !== null and !isguestuser($user)) {

            // Load for the requested user.

            $options[CONTEXT_USER + 1] = blog_get_options_for_user($user);

        }

        // Load for the current user.

        if (isloggedin() and !isguestuser()) {

            $options[CONTEXT_USER] = blog_get_options_for_user();

        }

    }

    // If blog level is global then display a link to view all site entries.

    if (!empty($CFG->enableblogs)

        && $CFG->bloglevel >= BLOG_GLOBAL_LEVEL

        && has_capability('moodle/blog:view', context_system::instance())) {

        $options[CONTEXT_SYSTEM] = array('viewsite' => array(

            'string' => get_string('viewsiteentries', 'blog'),

            'link' => new moodle_url('/blog/index.php')

        ));

    }

    // Return the options.

    return $options;

}

/**

 * Get all of the blog options that relate to the passed user.

 *

 * If no user is passed the current user is assumed.

 *

 * @staticvar array $useroptions Cache so we don't have to regenerate multiple times

 * @param stdClass $user

 * @return array The array of options for the requested user

 */

function blog_get_options_for_user(?stdClass $user=null) {

    global $CFG, $USER;

    // Cache.

    static $useroptions = array();

    $options = array();

    // Blogs must be enabled and the user must be logged in.

    if (!blog_is_enabled_for_user()) {

        return $options;

    }

    // Sort out the user var.

    if ($user === null || $user->id == $USER->id) {

        $user = $USER;

        $iscurrentuser = true;

    } else {

        $iscurrentuser = false;

    }

    // If we've already generated serve from the cache.

    if (array_key_exists($user->id, $useroptions)) {

        return $useroptions[$user->id];

    }

    $sitecontext = context_system::instance();

    $canview = has_capability('moodle/blog:view', $sitecontext);

    if (!$iscurrentuser && $canview && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {

        // Not the current user, but we can view and its blogs are enabled for SITE or GLOBAL.

        $options['userentries'] = array(

            'string' => get_string('viewuserentries', 'blog', fullname($user)),

            'link' => new moodle_url('/blog/index.php', array('userid' => $user->id))

        );

    } else {

        // It's the current user.

        if ($canview) {

            // We can view our own blogs .... BIG surprise.

            $options['view'] = array(

                'string' => get_string('blogentries', 'blog'),

                'link' => new moodle_url('/blog/index.php', array('userid' => $USER->id))

            );

        }

        if (has_capability('moodle/blog:create', $sitecontext)) {

            // We can add to our own blog.

            $options['add'] = array(

                'string' => get_string('addnewentry', 'blog'),

                'link' => new moodle_url('/blog/edit.php', array('action' => 'add'))

            );

        }

    }

    if ($canview && $CFG->enablerssfeeds) {

        $options['rss'] = array(

            'string' => get_string('rssfeed', 'blog'),

            'link' => new moodle_url(rss_get_url($sitecontext->id, $USER->id, 'blog', 'user/'.$user->id))

        );

    }

    // Cache the options.

    $useroptions[$user->id] = $options;

    // Return the options.

    return $options;

}

/**

 * Get the blog options that relate to the given course for the given user.

 *

 * @staticvar array $courseoptions A cache so we can save regenerating multiple times

 * @param stdClass $course The course to load options for

 * @param stdClass $user The user to load options for null == current user

 * @return array The array of options

 */

function blog_get_options_for_course(stdClass $course, ?stdClass $user=null) {

    global $CFG, $USER;

    // Cache.

    static $courseoptions = array();

    $options = array();

    // User must be logged in and blogs must be enabled.

    if (!blog_is_enabled_for_user()) {

        return $options;

    }

    // Check that the user can associate with the course.

    $sitecontext = context_system::instance();

    // Generate the cache key.

    $key = $course->id.':';

    if (!empty($user)) {

        $key .= $user->id;

    } else {

        $key .= $USER->id;

    }

    // Serve from the cache if we've already generated for this course.

    if (array_key_exists($key, $courseoptions)) {

        return $courseoptions[$key];

    }

    if (has_capability('moodle/blog:view', $sitecontext)) {

        // We can view!

        if ($CFG->bloglevel >= BLOG_SITE_LEVEL) {

            // View entries about this course.

            $options['courseview'] = array(

                'string' => get_string('viewcourseblogs', 'blog'),

                'link' => new moodle_url('/blog/index.php', array('courseid' => $course->id))

            );

        }

        // View MY entries about this course.

        $options['courseviewmine'] = array(

            'string' => get_string('viewmyentriesaboutcourse', 'blog'),

            'link' => new moodle_url('/blog/index.php', array('courseid' => $course->id, 'userid' => $USER->id))

        );

        if (!empty($user) && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {

            // View the provided users entries about this course.

            $options['courseviewuser'] = array(

                'string' => get_string('viewentriesbyuseraboutcourse', 'blog', fullname($user)),

                'link' => new moodle_url('/blog/index.php', array('courseid' => $course->id, 'userid' => $user->id))

            );

        }

    }

    if (has_capability('moodle/blog:create', $sitecontext)) {

        // We can blog about this course.

        $options['courseadd'] = array(

            'string' => get_string('blogaboutthiscourse', 'blog'),

            'link' => new moodle_url('/blog/edit.php', array('action' => 'add', 'courseid' => $course->id))

        );

    }

    // Cache the options for this course.

    $courseoptions[$key] = $options;

    // Return the options.

    return $options;

}

/**

 * Get the blog options relating to the given module for the given user

 *

 * @staticvar array $moduleoptions Cache

 * @param stdClass|cm_info $module The module to get options for

 * @param stdClass $user The user to get options for null == currentuser

 * @return array

 */

function blog_get_options_for_module($module, $user=null) {

    global $CFG, $USER;

    // Cache.

    static $moduleoptions = array();

    $options = array();

    // User must be logged in, blogs must be enabled.

    if (!blog_is_enabled_for_user()) {

        return $options;

    }

    $sitecontext = context_system::instance();

    // Generate the cache key.

    $key = $module->id.':';

    if (!empty($user)) {

        $key .= $user->id;

    } else {

        $key .= $USER->id;

    }

    if (array_key_exists($key, $moduleoptions)) {

        // Serve from the cache so we don't have to regenerate.

        return $moduleoptions[$key];

    }

    if (has_capability('moodle/blog:view', $sitecontext)) {

        // Save correct module name for later usage.

        $modulename = get_string('modulename', $module->modname);

        // We can view!

        if ($CFG->bloglevel >= BLOG_SITE_LEVEL) {

            // View all entries about this module.

            $a = new stdClass;

            $a->type = $modulename;

            $options['moduleview'] = array(

                'string' => get_string('viewallmodentries', 'blog', $a),

                'link' => new moodle_url('/blog/index.php', array('modid' => $module->id))

            );

        }

        // View MY entries about this module.

        $options['moduleviewmine'] = array(

            'string' => get_string('viewmyentriesaboutmodule', 'blog', $modulename),

            'link' => new moodle_url('/blog/index.php', array('modid' => $module->id, 'userid' => $USER->id))

        );

        if (!empty($user) && ($CFG->bloglevel >= BLOG_SITE_LEVEL)) {

            // View the given users entries about this module.

            $a = new stdClass;

            $a->mod = $modulename;

            $a->user = fullname($user);

            $options['moduleviewuser'] = array(

                'string' => get_string('blogentriesbyuseraboutmodule', 'blog', $a),

                'link' => new moodle_url('/blog/index.php', array('modid' => $module->id, 'userid' => $user->id))

            );

        }

    }

    if (has_capability('moodle/blog:create', $sitecontext)) {

        // The user can blog about this module.

        $options['moduleadd'] = array(

            'string' => get_string('blogaboutthismodule', 'blog', $modulename),

            'link' => new moodle_url('/blog/edit.php', array('action' => 'add', 'modid' => $module->id))

        );

    }

    // Cache the options.

    $moduleoptions[$key] = $options;

    // Return the options.

    return $options;

}

/**

 * This function encapsulates all the logic behind the complex

 * navigation, titles and headings of the blog listing page, depending

 * on URL params. It looks at URL params and at the current context level.

 * It builds and returns an array containing:

 *

 * 1. heading: The heading displayed above the blog entries

 * 2. stradd:  The text to be used as the "Add entry" link

 * 3. strview: The text to be used as the "View entries" link

 * 4. url:     The moodle_url object used as the base for add and view links

 * 5. filters: An array of parameters used to filter blog listings. Used by index.php and the Recent blogs block

 *

 * All other variables are set directly in $PAGE

 *

 * It uses the current URL to build these variables.

 * A number of mutually exclusive use cases are used to structure this function.

 *

 * @param  int $courseid   course id the the blog is associated to (can be null).

 * @param  int $groupid    group id to filter blogs I can see (can be null)

 * @param  int $userid     blog author id (can be null)

 * @param  int $tagid      tag id to filter (can be null)

 * @param  string $tag     tag name to filter (can be null)

 * @param  int $modid      module id the blog is associated to (can be null).

 * @param  int $entryid    blog entry id to filter(can be null)

 * @param  string $search  string to search (can be null)

 * @return array

 */

function blog_get_headers($courseid=null, $groupid=null, $userid=null, $tagid=null, $tag=null, $modid=null, $entryid=null,

        $search = null) {

    global $CFG, $PAGE, $DB, $USER;

    $id       = optional_param('id', null, PARAM_INT);

    $tag      = optional_param('tag', $tag, PARAM_NOTAGS);

    $tagid    = optional_param('tagid', $tagid, PARAM_INT);

    $userid   = optional_param('userid', $userid, PARAM_INT);

    $modid    = optional_param('modid', $modid, PARAM_INT);

    $entryid  = optional_param('entryid', $entryid, PARAM_INT);

    $groupid  = optional_param('groupid', $groupid, PARAM_INT);

    $courseid = optional_param('courseid', $courseid, PARAM_INT);

    $search   = optional_param('search', $search, PARAM_RAW);

    $action   = optional_param('action', null, PARAM_ALPHA);

    $confirm  = optional_param('confirm', false, PARAM_BOOL);

    // Ignore userid when action == add.

    if ($action == 'add' && $userid) {

        unset($userid);

        $PAGE->url->remove_params(array('userid'));

    } else if ($action == 'add' && $entryid) {

        unset($entryid);

        $PAGE->url->remove_params(array('entryid'));

    }

    $headers = array('title' => '', 'heading' => '', 'cm' => null, 'filters' => array());

    $blogurl = new moodle_url('/blog/index.php');

    $headers['stradd'] = get_string('addnewentry', 'blog');

    $headers['strview'] = null;

    $site = $DB->get_record('course', array('id' => SITEID));

    $sitecontext = context_system::instance();

    // Common Lang strings.

    $strparticipants = get_string("participants");

    $strblogentries  = get_string("blogentries", 'blog');

    // Prepare record objects as needed.

    if (!empty($courseid)) {

        $headers['filters']['course'] = $courseid;

        $course = $DB->get_record('course', array('id' => $courseid));

    }

    if (!empty($userid)) {

        $headers['filters']['user'] = $userid;

        $user = $DB->get_record('user', array('id' => $userid));

    }

    if (!empty($groupid)) { // The groupid always overrides courseid.

        $headers['filters']['group'] = $groupid;

        $group = $DB->get_record('groups', array('id' => $groupid));

        $course = $DB->get_record('course', array('id' => $group->courseid));

    }

    $PAGE->set_pagelayout('standard');

    // The modid always overrides courseid, so the $course object may be reset here.

    if (!empty($modid) && $CFG->useblogassociations) {

        $headers['filters']['module'] = $modid;

        // A groupid param may conflict with this coursemod's courseid. Ignore groupid in that case.

        $courseid = $DB->get_field('course_modules', 'course', array('id' => $modid));

        $course = $DB->get_record('course', array('id' => $courseid));

        $cm = $DB->get_record('course_modules', array('id' => $modid));

        $cm->modname = $DB->get_field('modules', 'name', array('id' => $cm->module));

        $cm->name = $DB->get_field($cm->modname, 'name', array('id' => $cm->instance));

        $a = new stdClass();

        $a->type = get_string('modulename', $cm->modname);

        $PAGE->set_cm($cm, $course);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewallmodentries', 'blog', $a);

    }

    // Case 1: No entry, mod, course or user params: all site entries to be shown (filtered by search and tag/tagid)

    // Note: if action is set to 'add' or 'edit', we do this at the end.

    if (empty($entryid) && empty($modid) && empty($courseid) && empty($userid) && !in_array($action, array('edit', 'add'))) {

        $PAGE->navbar->add($strblogentries, $blogurl);

        $strsiteblog = get_string('siteblogheading', 'blog');

        $PAGE->set_title($strsiteblog);

        $PAGE->set_heading($site->fullname);

        $headers['heading'] = $strsiteblog;

    }

    // Case 2: only entryid is requested, ignore all other filters. courseid is used to give more contextual information.

    if (!empty($entryid)) {

        $headers['filters']['entry'] = $entryid;

        $sql = 'SELECT u.* FROM {user} u, {post} p WHERE p.id = ? AND p.userid = u.id';

        $user = $DB->get_record_sql($sql, array($entryid));

        $entry = $DB->get_record('post', array('id' => $entryid));

        $blogurl->param('userid', $user->id);

        if (!empty($course)) {

            $mycourseid = $course->id;

            $blogurl->param('courseid', $mycourseid);

        } else {

            $mycourseid = $site->id;

        }

        $shortname = format_string($site->shortname, true, array('context' => context_course::instance(SITEID)));

        $PAGE->navbar->add($strblogentries, $blogurl);

        $blogurl->remove_params('userid');

        $PAGE->navbar->add($entry->subject, $blogurl);

        $blogentryby = get_string('blogentrybyuser', 'blog', fullname($user));

        $PAGE->set_title($entry->subject . moodle_page::TITLE_SEPARATOR . $blogentryby);

        $PAGE->set_heading("$shortname: " . fullname($user) . ": $entry->subject");

        $headers['heading'] = $blogentryby;

        // We ignore tag and search params.

        if (empty($action) || !$CFG->useblogassociations) {

            $headers['url'] = $blogurl;

            return $headers;

        }

    }

    if (!empty($userid) && empty($entryid) && ((empty($courseid) && empty($modid)) || !$CFG->useblogassociations)) {

        // Case 3: A user's blog entries.

        $shortname = format_string($site->shortname, true, array('context' => context_course::instance(SITEID)));

        $blogurl->param('userid', $userid);

        $PAGE->set_title(fullname($user) . ": " . get_string('blog', 'blog'));

        $PAGE->set_heading("$shortname: " . fullname($user) . ": " . get_string('blog', 'blog'));

        $headers['heading'] = get_string('userblog', 'blog', fullname($user));

        $headers['strview'] = get_string('viewuserentries', 'blog', fullname($user));

    } else if (!$CFG->useblogassociations && empty($userid) && !in_array($action, array('edit', 'add'))) {

        // Case 4: No blog associations, no userid.

        $strsiteblog = get_string('siteblogheading', 'blog');

        $PAGE->set_title($strsiteblog);

        $PAGE->set_heading($site->fullname);

        $headers['heading'] = $strsiteblog;

    } else if (!empty($userid) && !empty($modid) && empty($entryid)) {

        // Case 5: Blog entries associated with an activity by a specific user (courseid ignored).

        $shortname = format_string($site->shortname, true, array('context' => context_course::instance(SITEID)));

        $blogurl->param('userid', $userid);

        $blogurl->param('modid', $modid);

        // Course module navigation is handled by build_navigation as the second param.

        $headers['cm'] = $cm;

        $PAGE->navbar->add(fullname($user), "$CFG->wwwroot/user/view.php?id=$user->id");

        $PAGE->navbar->add($strblogentries, $blogurl);

        $PAGE->set_title(fullname($user) . ': ' . get_string('blogentries', 'blog') . moodle_page::TITLE_SEPARATOR . $cm->name);

        $PAGE->set_heading("$shortname: $cm->name: " . fullname($user) . ': ' . get_string('blogentries', 'blog'));

        $a = new stdClass();

        $a->user = fullname($user);

        $a->mod = $cm->name;

        $a->type = get_string('modulename', $cm->modname);

        $headers['heading'] = get_string('blogentriesbyuseraboutmodule', 'blog', $a);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewallmodentries', 'blog', $a);

    } else if (!empty($userid) && !empty($courseid) && empty($modid) && empty($entryid)) {

        // Case 6: Blog entries associated with a course by a specific user.

        $blogurl->param('userid', $userid);

        $blogurl->param('courseid', $courseid);

        $PAGE->set_title($course->fullname);

        $PAGE->set_heading($course->fullname);

        $a = new stdClass();

        $a->user = fullname($user);

        $a->course = format_string($course->fullname, true, array('context' => context_course::instance($course->id)));

        $a->type = get_string('course');

        $headers['heading'] = get_string('blogentriesbyuseraboutcourse', 'blog', $a);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewblogentries', 'blog', $a);

        // Remove the userid from the URL to inform the blog_menu block correctly.

        $blogurl->remove_params(array('userid'));

    } else if (!empty($groupid) && empty($modid) && empty($entryid)) {

        // Case 7: Blog entries by members of a group, associated with that group's course.

        $blogurl->param('courseid', $course->id);

        $PAGE->navbar->add($strblogentries, $blogurl);

        $blogurl->remove_params(array('courseid'));

        $blogurl->param('groupid', $groupid);

        $PAGE->navbar->add($group->name, $blogurl);

        $PAGE->set_title($course->fullname);

        $PAGE->set_heading($course->fullname);

        $a = new stdClass();

        $a->group = $group->name;

        $a->course = format_string($course->fullname, true, array('context' => context_course::instance($course->id)));

        $a->type = get_string('course');

        $headers['heading'] = get_string('blogentriesbygroupaboutcourse', 'blog', $a);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewblogentries', 'blog', $a);

    } else if (!empty($groupid) && !empty($modid) && empty($entryid)) {

        // Case 8: Blog entries by members of a group, associated with an activity in that course.

        $headers['cm'] = $cm;

        $blogurl->param('modid', $modid);

        $PAGE->navbar->add($strblogentries, $blogurl);

        $blogurl->param('groupid', $groupid);

        $PAGE->navbar->add($group->name, $blogurl);

        $PAGE->set_title($course->fullname);

        $PAGE->set_heading($course->fullname);

        $a = new stdClass();

        $a->group = $group->name;

        $a->mod = $cm->name;

        $a->type = get_string('modulename', $cm->modname);

        $headers['heading'] = get_string('blogentriesbygroupaboutmodule', 'blog', $a);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewallmodentries', 'blog', $a);

    } else if (!empty($modid) && empty($userid) && empty($groupid) && empty($entryid)) {

        // Case 9: All blog entries associated with an activity.

        $PAGE->set_cm($cm, $course);

        $blogurl->param('modid', $modid);

        $PAGE->navbar->add($strblogentries, $blogurl);

        $PAGE->set_title($course->fullname);

        $PAGE->set_heading($course->fullname);

        $headers['heading'] = get_string('blogentriesabout', 'blog', $cm->name);

        $a = new stdClass();

        $a->type = get_string('modulename', $cm->modname);

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewallmodentries', 'blog', $a);

    } else if (!empty($courseid) && empty($userid) && empty($groupid) && empty($modid) && empty($entryid)) {

        // Case 10: All blog entries associated with a course.

        $blogurl->param('courseid', $courseid);

        $PAGE->navbar->add($strblogentries, $blogurl);

        $PAGE->set_title($course->fullname);

        $PAGE->set_heading($course->fullname);

        $a = new stdClass();

        $a->type = get_string('course');

        $headers['heading'] = get_string('blogentriesabout',

                                         'blog',

                                         format_string($course->fullname,

                                                       true,

                                                       array('context' => context_course::instance($course->id))));

        $headers['stradd'] = get_string('blogaboutthis', 'blog', $a);

        $headers['strview'] = get_string('viewblogentries', 'blog', $a);

        $blogurl->remove_params(array('userid'));

    }

    if (!in_array($action, array('edit', 'add'))) {

        // Append Tag info.

        if (!empty($tagid)) {

            $headers['filters']['tag'] = $tagid;

            $blogurl->param('tagid', $tagid);

            $tagrec = $DB->get_record('tag', array('id' => $tagid));

            $PAGE->navbar->add($tagrec->name, $blogurl);

        } else if (!empty($tag)) {

            if ($tagrec = $DB->get_record('tag', array('name' => $tag))) {

                $tagid = $tagrec->id;

                $headers['filters']['tag'] = $tagid;

                $blogurl->param('tag', $tag);

                $PAGE->navbar->add(get_string('tagparam', 'blog', $tag), $blogurl);

            }

        }

        // Append Search info.

        if (!empty($search) && has_capability('moodle/blog:search', $sitecontext)) {

            $headers['filters']['search'] = $search;

            $blogurl->param('search', $search);

            $PAGE->navbar->add(get_string('searchterm', 'blog', s($search)), $blogurl->out());

        }

    }

    // Append edit mode info.

    if (!empty($action) && $action == 'add') {

    } else if (!empty($action) && $action == 'edit') {

        $PAGE->navbar->add(get_string('editentry', 'blog'));

    }

    if (empty($headers['url'])) {

        $headers['url'] = $blogurl;

    }

    return $headers;

}

/**

 * Shortcut function for getting a count of blog entries associated with a course or a module

 * @param int $courseid The ID of the course

 * @param int $cmid The ID of the course_modules

 * @return string The number of associated entries

 */

function blog_get_associated_count($courseid, $cmid=null) {

    global $DB;

    $context = context_course::instance($courseid);

    if ($cmid) {

        $context = context_module::instance($cmid);

    }

    return $DB->count_records('blog_association', array('contextid' => $context->id));

}

/**

 * Running addtional permission check on plugin, for example, plugins

 * may have switch to turn on/off comments option, this callback will

 * affect UI display, not like pluginname_comment_validate only throw

 * exceptions.

 * blog_comment_validate will be called before viewing/adding/deleting

 * comment, so don't repeat checks.

 * Capability check has been done in comment->check_permissions(), we

 * don't need to do it again here.

 *

 * @package  core_blog

 * @category comment

 *

 * @param stdClass $commentparam {

 *              context  => context the context object

 *              courseid => int course id

 *              cm       => stdClass course module object

 *              commentarea => string comment area

 *              itemid      => int itemid

 * }

 * @return array

 */

function blog_comment_permissions($commentparam) {

    global $DB;

    // If blog is public and current user is guest, then don't let him post comments.

    $blogentry = $DB->get_record('post', array('id' => $commentparam->itemid), 'publishstate', MUST_EXIST);

    if ($blogentry->publishstate != 'public') {

        if (!isloggedin() || isguestuser()) {

            return array('post' => false, 'view' => true);

        }

    }

    return array('post' => true, 'view' => true);

}

/**

 * Validate comment parameter before perform other comments actions

 *

 * @package  core_blog

 * @category comment

 *

 * @param stdClass $comment {

 *              context  => context the context object

 *              courseid => int course id

 *              cm       => stdClass course module object

 *              commentarea => string comment area

 *              itemid      => int itemid

 * }

 * @return boolean

 */

function blog_comment_validate($commentparam) {

    global $CFG, $DB, $USER;

    // Check if blogs are enabled user can comment.

    if (empty($CFG->enableblogs) || empty($CFG->blogusecomments)) {

        throw new comment_exception('nopermissiontocomment');

    }

    // Validate comment area.

    if ($commentparam->commentarea != 'format_blog') {

        throw new comment_exception('invalidcommentarea');

    }

    $blogentry = $DB->get_record('post', array('id' => $commentparam->itemid), '*', MUST_EXIST);

    // Validation for comment deletion.

    if (!empty($commentparam->commentid)) {

        if ($record = $DB->get_record('comments', array('id' => $commentparam->commentid))) {

            if ($record->commentarea != 'format_blog') {

                throw new comment_exception('invalidcommentarea');

            }

            if ($record->contextid != $commentparam->context->id) {

                throw new comment_exception('invalidcontext');

            }

            if ($record->itemid != $commentparam->itemid) {

                throw new comment_exception('invalidcommentitemid');

            }

        } else {

            throw new comment_exception('invalidcommentid');