package plist

type Iterator struct {
	pl  *PriorityList
	cur *Node
}

func (iter *Iterator) Value() interface{} {
	return iter.cur.Value
}

func (iter *Iterator) RingNext() bool {
	if iter.pl.size == 0 {
		return false
	}

	iter.cur = iter.cur.next
	if iter.cur == iter.pl.tail {
		iter.cur = iter.pl.head.next
	}

	return true
}

func (iter *Iterator) Next() bool {
	if iter.cur == iter.pl.tail {
		return false
	}
	if iter.cur.next == iter.pl.tail {
		iter.cur = iter.cur.next
		return false
	}
	iter.cur = iter.cur.next
	return true
}

func (iter *Iterator) RingPrev() bool {
	if iter.pl.size == 0 {
		return false
	}

	iter.cur = iter.cur.prev
	if iter.cur == iter.pl.head {
		iter.cur = iter.pl.tail.prev
	}

	return true
}

func (iter *Iterator) Prev() bool {

	if iter.cur == iter.pl.head {
		return false
	}
	if iter.cur.prev == iter.pl.head {
		iter.cur = iter.cur.prev
		return false
	}

	iter.cur = iter.cur.prev
	return true
}

func (iter *Iterator) MoveHead() {
	iter.cur = iter.pl.head
}

func (iter *Iterator) MoveTail() {
	iter.cur = iter.pl.tail
}