public function pack()
{
$this->_sort();
$items = $this->items;
while (!empty($items)) {
$level = new Level(count($this->levels), $this->maxLength);
foreach ($items as $i => $item) {
if ($level->getRemainFloorLength() >= $item->getLength()) {
$level->addFloor(new LevelItem($item));
unset($items[$i]);
}
}
foreach ($items as $i => $item) {
if ($level->isItemCeilPlaced($item)) {
$level->addCeil(new LevelItem($item));
unset($items[$i]);
}
}
$this->levels[] = $level;
}
return $this;
}
