function scorm_seq_choice_sequencing($sco, $userid, $seq)
{
$avchildren = array();
$comancestor = null;
$traverse = null;
if ($sco == null) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-1';
return $seq;
}
$ancestors = scorm_get_ancestors($sco);
$arrpath = array_reverse($ancestors);
array_push($arrpath, $sco);
//path from the root to the target
foreach ($arrpath as $activity) {
if ($activity->parent != '/') {
$avchildren = scorm_get_available_children(scorm_get_parent($activity));
$position = array_search($avchildren, $activity);
if ($position !== false) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-2';
return $seq;
}
}
if (scorm_seq_rules_check($activity, 'hidefromchoice' != null)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-3';
return $seq;
}
}
if ($sco->parent != '/') {
$parent = scorm_sco_get_parent($sco);
if (isset($parent->choice) && $parent->choice == false) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-4';
return $seq;
}
}
if ($seq->currentactivity != null) {
$commonpos = scorm_find_common_ancestor($ancestors, $seq->currentactivity);
$comancestor = $arrpath[$commonpos];
} else {
$comancestor = $arrpath[0];
}
if ($seq->currentactivity === $sco) {
break;
}
$sib = scorm_get_siblings($seq->currentactivity);
$pos = array_search($sib, $sco);
if ($pos !== false) {
$siblings = array_slice($sib, 0, $pos - 1);
if (empty($siblings)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-5';
return $seq;
}
$children = scorm_get_children(scorm_get_parent($sco));
$pos1 = array_search($children, $sco);
$pos2 = array_search($seq->currentactivity, $sco);
if ($pos1 > $pos2) {
$traverse = 'forward';
} else {
$traverse = 'backward';
}
foreach ($siblings as $sibling) {
$seq = scorm_seq_choice_activity_traversal($sibling, $userid, $seq, $traverse);
if (!$seq->reachable) {
$seq->delivery = null;
return $seq;
}
}
break;
}
if ($seq->currentactivity == null || $seq->currentactivity == $comancestor) {
$commonpos = scorm_find_common_ancestor($ancestors, $seq->currentactivity);
$comtarget = array_slice($ancestors, 1, $commonpos - 1);
//path from the common ancestor to the target activity
$comtarget = array_reverse($comtarget);
if (empty($comtarget)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-5';
return $seq;
}
foreach ($comtarget as $act) {
$seq = scorm_seq_choice_activity_traversal($act, $userid, $seq, 'forward');
if (!$seq->reachable) {
$seq->delivery = null;
return $seq;
}
$act = scorm_get_sco($acti->id);
if (scorm_seq_is('active', $act->id, $userid) && ($act->id != $comancestor->id && $act->preventactivation)) {
//adlseq:can i write it like another property for the $seq object?
$seq->delivery = null;
$seq->exception = 'SB.2.9-6';
return $seq;
}
}
break;
}
if ($comancestor->id == $sco->id) {
$ancestorscurrent = scorm_get_ancestors($seq->currentactivity);
$possco = array_search($ancestorscurrent, $sco);
$curtarget = array_slice($ancestorscurrent, 0, $possco);
//path from the current activity to the target
if (empty($curtarget)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-5';
return $seq;
}
$i = 0;
foreach ($curtarget as $activ) {
$i++;
if ($i != sizeof($curtarget)) {
if (isset($activ->choiceexit) && $activ->choiceexit == false) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-7';
return $seq;
}
}
}
break;
}
if (array_search($ancestors, $comancestor) !== false) {
$ancestorscurrent = scorm_get_ancestors($seq->currentactivity);
$commonpos = scorm_find_common_ancestor($ancestors, $sco);
$curcommon = array_slice($ancestorscurrent, 0, $commonpos - 1);
if (empty($curcommon)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-5';
return $seq;
}
$constrained = null;
foreach ($curcommon as $acti) {
$acti = scorm_get_sco($acti->id);
if (isset($acti->choiceexit) && $acti->choiceexit == false) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-7';
return $seq;
}
if ($constrained == null) {
if ($acti->constrainchoice == true) {
$constrained = $acti;
}
}
}
if ($constrained != null) {
$fwdir = scorm_get_preorder($constrained);
if (array_search($fwdir, $sco) !== false) {
$traverse = 'forward';
} else {
$traverse = 'backward';
}
$seq = scorm_seq_choice_flow($constrained, $traverse, $seq);
$actconsider = $seq->identifiedactivity;
$avdescendents = array();
$avdescendents = scorm_get_available_descendents($actconsider);
if (array_search($avdescendents, $sco) !== false && $sco->id != $actconsider->id && $constrained->id != $sco->id) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-8';
return $seq;
}
//CONTINUE 11.5.5
}
$commonpos = scorm_find_common_ancestor($ancestors, $seq->currentactivity);
$comtarget = array_slice($ancestors, 1, $commonpos - 1);
//path from the common ancestor to the target activity
$comtarget = array_reverse($comtarget);
if (empty($comtarget)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-5';
return $seq;
}
$fwdir = scorm_get_preorder($seq->currentactivity);
if (array_search($fwdir, $sco) !== false) {
foreach ($comtarget as $act) {
$seq = scorm_seq_choice_activity_traversal($act, $userid, $seq, 'forward');
if (!$seq->reachable) {
$seq->delivery = null;
return $seq;
}
$act = scorm_get_sco($act->id);
if (scorm_seq_is('active', $act->id, $userid) && ($act->id != $comancestor->id && $act->preventactivation == true)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-6';
return $seq;
}
}
} else {
foreach ($comtarget as $act) {
$act = scorm_get_sco($act->id);
if (scorm_seq_is('active', $act->id, $userid) && ($act->id != $comancestor->id && $act->preventactivation == true)) {
$seq->delivery = null;
$seq->exception = 'SB.2.9-6';
return $seq;
}
}
}
break;
}
if (scorm_is_leaf($sco)) {
$seq->delivery = $sco;
$seq->exception = 'SB.2.9-6';
return $seq;
}
$seq = scorm_seq_flow($sco, 'forward', $seq, true, $userid);
if ($seq->deliverable == false) {
scorm_terminate_descendent_attempts($comancestor, $userid, $seq);
scorm_seq_end_attempt($comancestor, $userid, $seq->attempt);
$seq->currentactivity = $sco;
$seq->delivery = null;
$seq->exception = 'SB.2.9-9';
return $seq;
} else {
return $seq;
}
}
$scorm = $DB->get_record("scorm", array("id" => $cm->instance), '*', MUST_EXIST);
} else {
if (!empty($a)) {
$scorm = $DB->get_record("scorm", array("id" => $a), '*', MUST_EXIST);
$course = $DB->get_record("course", array("id" => $scorm->course), '*', MUST_EXIST);
$cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id, false, MUST_EXIST);
} else {
print_error('missingparameter');
}
}
$PAGE->set_url('/mod/scorm/datamodels/sequencinghandler.php', array('scoid' => $scoid, 'attempt' => $attempt, 'id' => $cm->id, 'function' => $function, 'request' => $request));
require_login($course, false, $cm);
if (!empty($scoid) && !empty($function)) {
require_once $CFG->dirroot . '/mod/scorm/datamodels/scorm_13lib.php';
if (has_capability('mod/scorm:savetrack', context_module::instance($cm->id))) {
$result = null;
switch ($function) {
case 'scorm_seq_flow':
if ($request == 'forward' || $request == 'backward') {
$seq = scorm_seq_navigation($scoid, $USER->id, $request . '_', $attempt);
$sco = scorm_get_sco($scoid);
$seq = scorm_seq_flow($sco, $request, $seq, true, $USER->id);
if (!empty($seq->nextactivity)) {
scorm_seq_end_attempt($sco, $USER->id, $seq);
}
}
echo json_encode($seq);
break;
}
}
}