Fix session course redirection

Checking the visibility and visibility priority:

SESSION_AVAILABLE,
SESSION_VISIBLE
SESSION_VISIBLE_READ_ONLY

If the user is subscribed in different sessions with the same course

See BT#12083 BT#15106

main/inc/local.inc.php

@@ -1358,10 +1358,40 @@ if ((isset($uidReset) && $uidReset) || $cidReset) {
                     $_course['real_id']
                 );
 
-                if (!empty($courseSession) && isset($courseSession[0])) {
-                    $courseSessionItem = $courseSession[0];
+
+                $priorityList = [];
+                if (!empty($courseSession)) {
+                    foreach ($courseSession as $courseSessionItem) {
                         if (isset($courseSessionItem['session_id'])) {
                             $customSessionId = $courseSessionItem['session_id'];
+                            $visibility = api_get_session_visibility($customSessionId, $_course['real_id']);
+
+                            if ($visibility == SESSION_INVISIBLE) {
+                                continue;
+                            }
+
+                            switch ($visibility) {
+                                case SESSION_AVAILABLE:
+                                    $priorityList[1][] = $customSessionId;
+                                    break;
+                                case SESSION_VISIBLE:
+                                    $priorityList[2][] = $customSessionId;
+                                    break;
+                                case SESSION_VISIBLE_READ_ONLY:
+                                    $priorityList[3][] = $customSessionId;
+                                    break;
+                            }
+                        }
+                    }
+                }
+
+                if (!empty($priorityList)) {
+                    ksort($priorityList);
+                    foreach ($priorityList as $sessionList) {
+                        if (empty($sessionList)) {
+                            continue;
+                        }
+                        foreach ($sessionList as $customSessionId) {
                             $currentUrl = htmlentities($_SERVER['REQUEST_URI']);
                             $currentUrl = str_replace('id_session=0', '', $currentUrl);
                             $currentUrl = str_replace('&', '&', $currentUrl);
@@ -1385,6 +1415,7 @@ if ((isset($uidReset) && $uidReset) || $cidReset) {
                     }
                 }
             }
+        }
     } else { // keys missing => not anymore in the course - user relation
         // course
         $is_courseMember = false;