MDL-27508 introducing workshop::get_participants() and workshop::is_participant()

Note how the participant is defined: it is a user that (1) can submit or
assess or both and (2) is actively enrolled in the course. This means
that usually admins or managers won't be considered as workshop
participants, for example.

mod/workshop/locallib.php

@@ -431,6 +431,66 @@ class workshop {
         return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
     }
 
+    /**
+     * Fetches all enrolled users that are authors or reviewers (or both) in the current workshop
+     *
+     * The returned objects contain properties required by user_picture and are ordered by lastname, firstname.
+     * Only users with the active enrolment are returned.
+     *
+     * @see self::get_potential_authors()
+     * @see self::get_potential_reviewers()
+     * @param bool $musthavesubmission if true, return only users who have already submitted
+     * @param int $groupid 0 means ignore groups, any other value limits the result by group id
+     * @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set)
+     * @param int $limitnum return a subset containing this number of records (optional, required if $limitfrom is set)
+     * @return array array[userid] => stdClass
+     */
+    public function get_participants($musthavesubmission=false, $groupid=0, $limitfrom=0, $limitnum=0) {
+        global $DB;
+
+        list($sql, $params) = $this->get_participants_sql($musthavesubmission, $groupid);
+
+        if (empty($sql)) {
+            return array();
+        }
+
+        $sql .= " ORDER BY lastname ASC, firstname ASC, id ASC";
+
+        return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
+    }
+
+    /**
+     * Checks if the given user is an actively enrolled participant in the workshop
+     *
+     * @param int $userid, defaults to the current $USER
+     * @return boolean
+     */
+    public function is_participant($userid=null) {
+        global $USER, $DB;
+
+        if (is_null($userid)) {
+            $userid = $USER->id;
+        }
+
+        list($sql, $params) = $this->get_participants_sql();
+
+        if (empty($sql)) {
+            return false;
+        }
+
+        $sql = "SELECT COUNT(*)
+                  FROM {user} uxx
+                  JOIN ({$sql}) pxx ON uxx.id = pxx.id
+                 WHERE uxx.id = :uxxid";
+        $params['uxxid'] = $userid;
+
+        if ($DB->count_records_sql($sql, $params)) {
+            return true;
+        }
+
+        return false;
+    }
+
     /**
      * Groups the given users by the group membership
      *
@@ -1491,7 +1551,7 @@ class workshop {
         global $DB;
 
         $canviewall     = has_capability('mod/workshop:viewallassessments', $this->context, $userid);
-        $isparticipant  = has_any_capability(array('mod/workshop:submit', 'mod/workshop:peerassess'), $this->context, $userid);
+        $isparticipant  = $this->is_participant($userid);
 
         if (!$canviewall and !$isparticipant) {
             // who the hell is this?
@@ -2156,7 +2216,7 @@ class workshop {
      * @return array of (string)sql, (array)params
      */
     protected function get_users_with_capability_sql($capability, $musthavesubmission, $groupid) {
-        global $DB, $CFG;
+        global $CFG;
         /** @var int static counter used to generate unique parameter holders */
         static $inc = 0;
         $inc++;
@@ -2195,6 +2255,36 @@ class workshop {
         return array($sql, $params);
     }
 
+    /**
+     * Returns SQL statement that can be used to fetch all actively enrolled participants in the workshop
+     *
+     * @param bool $musthavesubmission if true, return only users who have already submitted
+     * @param int $groupid 0 means ignore groups, any other value limits the result by group id
+     * @return array of (string)sql, (array)params
+     */
+    protected function get_participants_sql($musthavesubmission=false, $groupid=0) {
+
+        list($sql1, $params1) = $this->get_users_with_capability_sql('mod/workshop:submit', $musthavesubmission, $groupid);
+        list($sql2, $params2) = $this->get_users_with_capability_sql('mod/workshop:peerassess', $musthavesubmission, $groupid);
+
+        if (empty($sql1) or empty($sql2)) {
+            if (empty($sql1) and empty($sql2)) {
+                return array('', array());
+            } else if (empty($sql1)) {
+                $sql = $sql2;
+                $params = $params2;
+            } else {
+                $sql = $sql1;
+                $params = $params1;
+            }
+        } else {
+            $sql = $sql1.PHP_EOL." UNION ".PHP_EOL.$sql2;
+            $params = array_merge($params1, $params2);
+        }
+
+        return array($sql, $params);
+    }
+
     /**
      * @return array of available workshop phases
      */