#include "List.H"

List::List() 
	: _head(NULL), _current(NULL)
{
}

List::~List() 
{
	_destroyList(_head);
	delete _head;
	_current = _head = NULL;
}

void 
List::_destroyList(ListNode * l) 
{
	if (l == NULL)
		return;

	_destroyList(l->_next);
	delete l;
	
	return;
}


List::List(const List & rhs) 
{
	
}

List & 
List::operator =(const List &rhs) 
{
	return *this;
}

bool 
List::insert(int x) {

	if (isEmpty()) {
		_head = new ListNode(x, NULL);
		_current = _head;
		return true;
	}

	if (isPastEnd())
		return false;


	//  If we're inserting at the beginning of the list,
	//  there's no previous node.
	if (_current == _head) {
		_head = _current = new ListNode(x, _head);
		return true;
	} else {
		ListNode * previous = _findPrevious(_current);
		ListNode * tmp = new ListNode(x, _current);
		previous->_next = tmp;
		_current = tmp;
	}

	return true;
}


ListNode * 
List::_findPrevious(ListNode * l) 
{
	ListNode * previous;

	if (l == NULL)
		return NULL;

	for (previous = _head; 
	     previous != NULL; 
	     previous = previous->_next) {
			if (previous->_next == l)
				return previous;
	}

	return NULL;
}


void 
List::remove() 
{
	if (isEmpty() || isPastEnd())
		return;

	ListNode * previous = _findPrevious(_current);
	previous->_next = _current->_next;
	delete _current;
	_current = previous->_next;
}
	
void 
List::next() 
{
	if (!isPastEnd())
		_current = _current->_next;
	else
		_current = NULL;
}

void 
List::previous() 
{
	if (!isPastEnd())
		_current = _findPrevious(_current);
}
	
int  
List::current() 
{
	if (isPastEnd()) {
		cerr << "Uh oh" << endl;
		return -1;
	} else
		return _current->_data;
}

void 
List::reset() 
{
	_current = _head;
}

bool
List::isEmpty()
{
	return _head == NULL;
}

bool 
List::isPastEnd() 
{
	return _current == NULL;
}

ostream &
operator <<(ostream & os, List & l) 
{
	ListNode * old_current = l._current;

	if (l.isEmpty())
		return os << "()";

	os << "(";

	bool first_pass=true;
	for (l.reset() ; !l.isPastEnd(); l.next()) {
		if (first_pass) {
			os << l.current();
			first_pass = false;
		} else
			os << "," << l.current();
	}

	l._current = old_current;
	os << ")";
	
	return os;
}