function scorm_seq_flow_tree_traversal($activity, $direction, $childrenflag, $prevdirection, $seq, $userid, $skip = false)
{
$revdirection = false;
$parent = scorm_get_parent($activity);
if (!empty($parent)) {
$children = scorm_get_available_children($parent);
} else {
$children = array();
}
$childrensize = count($children);
if ($prevdirection != null && $prevdirection == 'backward' && $children[$childrensize - 1]->id == $activity->id) {
$direction = 'backward';
$activity = $children[0];
$revdirection = true;
}
if ($direction == 'forward') {
$ancestors = scorm_get_ancestors($activity);
$ancestorsroot = array_reverse($ancestors);
$preorder = array();
$preorder = scorm_get_preorder($preorder, $ancestorsroot[0]);
$preordersize = count($preorder);
if ($activity->id == $preorder[$preordersize - 1]->id || $activity->parent == '/' && !$childrenflag) {
// scorm_seq_terminate_descent($ancestorsroot, $userid); TODO: undefined
$seq->endsession = true;
$seq->nextactivity = null;
return $seq;
}
if (scorm_is_leaf($activity) || !$childrenflag) {
if ($children[$childrensize - 1]->id == $activity->id) {
$seq = scorm_seq_flow_tree_traversal($parent, $direction, false, null, $seq, $userid);
if ($seq->nextactivity->launch == null) {
$seq = scorm_seq_flow_tree_traversal($seq->nextactivity, $direction, true, null, $seq, $userid);
}
return $seq;
} else {
$position = 0;
foreach ($children as $sco) {
if ($sco->id == $activity->id) {
break;
}
$position++;
}
if ($position != $childrensize - 1) {
$seq->nextactivity = $children[$position + 1];
$seq->traversaldir = $direction;
return $seq;
} else {
$siblings = scorm_get_siblings($activity);
$children = scorm_get_children($siblings[0]);
$seq->nextactivity = $children[0];
return $seq;
}
}
} else {
$children = scorm_get_available_children($activity);
if (!empty($children)) {
$seq->traversaldir = $direction;
$seq->nextactivity = $children[0];
return $seq;
} else {
$seq->traversaldir = null;
$seq->nextactivity = null;
$seq->exception = 'SB.2.1-2';
return $seq;
}
}
} else {
if ($direction == 'backward') {
if ($activity->parent == '/') {
$seq->traversaldir = null;
$seq->nextactivity = null;
$seq->exception = 'SB.2.1-3';
return $seq;
}
if (scorm_is_leaf($activity) || !$childrenflag) {
if (!$revdirection) {
if (isset($parent->forwardonly) && ($parent->forwardonly == true && !$skip)) {
$seq->traversaldir = null;
$seq->nextactivity = null;
$seq->exception = 'SB.2.1-4';
return $seq;
}
}
if ($children[0]->id == $activity->id) {
$seq = scorm_seq_flow_tree_traversal($parent, 'backward', false, null, $seq, $userid);
return $seq;
} else {
$ancestors = scorm_get_ancestors($activity);
$ancestorsroot = array_reverse($ancestors);
$preorder = array();
$preorder = scorm_get_preorder($preorder, $ancestorsroot[0]);
$position = 0;
foreach ($preorder as $sco) {
if ($sco->id == $activity->id) {
break;
}
$position++;
}
if (isset($preorder[$position])) {
$seq->nextactivity = $preorder[$position - 1];
$seq->traversaldir = $direction;
}
return $seq;
}
} else {
$children = scorm_get_available_children($activity);
if (!empty($children)) {
if (isset($parent->flow) && $parent->flow == true) {
$seq->traversaldir = 'forward';
$seq->nextactivity = $children[0];
return $seq;
} else {
$seq->traversaldir = 'backward';
$seq->nextactivity = $children[count($children) - 1];
return $seq;
}
} else {
$seq->traversaldir = null;
$seq->nextactivity = null;
$seq->exception = 'SB.2.1-2';
return $seq;
}
}
}
}
}
function scorm_seq_choice_sequencing($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;
}
}