#if !defined ( INCLUDED_TRAVERSELIB_H )
#define INCLUDED_TRAVERSELIB_H

#include "debugging/debugging.h"

#include "scenelib.h"
#include "undolib.h"
#include "container/container.h"

#include <list>
#include <vector>
#include <algorithm>

class TraversableObserverInsertOutputIterator
{
protected:
scene::Traversable::Observer* m_observer;
public:
typedef std::output_iterator_tag iterator_category;
typedef void difference_type;
typedef void value_type;
typedef void pointer;
typedef void reference;

TraversableObserverInsertOutputIterator( scene::Traversable::Observer* observer )
	: m_observer( observer ){
}
TraversableObserverInsertOutputIterator& operator=( const NodeReference& node ){
	m_observer->insert( node );
	return *this;
}
TraversableObserverInsertOutputIterator& operator*() { return *this; }
TraversableObserverInsertOutputIterator& operator++() { return *this; }
TraversableObserverInsertOutputIterator& operator++( int ) { return *this; }
};

class TraversableObserverEraseOutputIterator
{
protected:
scene::Traversable::Observer* m_observer;
public:
typedef std::output_iterator_tag iterator_category;
typedef void difference_type;
typedef void value_type;
typedef void pointer;
typedef void reference;

TraversableObserverEraseOutputIterator( scene::Traversable::Observer* observer )
	: m_observer( observer ){
}
TraversableObserverEraseOutputIterator& operator=( const NodeReference& node ){
	m_observer->erase( node );
	return *this;
}
TraversableObserverEraseOutputIterator& operator*() { return *this; }
TraversableObserverEraseOutputIterator& operator++() { return *this; }
TraversableObserverEraseOutputIterator& operator++( int ) { return *this; }
};

typedef UnsortedSet<NodeSmartReference> UnsortedNodeSet;

/// \brief Calls \p observer->\c insert for each node that exists only in \p other and \p observer->\c erase for each node that exists only in \p self
inline void nodeset_diff( const UnsortedNodeSet& self, const UnsortedNodeSet& other, scene::Traversable::Observer* observer ){
	std::vector<NodeReference> sorted( self.begin(), self.end() );
	std::vector<NodeReference> other_sorted( other.begin(), other.end() );

	std::sort( sorted.begin(), sorted.end() );
	std::sort( other_sorted.begin(), other_sorted.end() );

	std::set_difference( sorted.begin(), sorted.end(), other_sorted.begin(), other_sorted.end(), TraversableObserverEraseOutputIterator( observer ) );
	std::set_difference( other_sorted.begin(), other_sorted.end(), sorted.begin(), sorted.end(), TraversableObserverInsertOutputIterator( observer ) );
}

/// \brief A sequence of node references which notifies an observer of inserts and deletions, and uses the global undo system to provide undo for modifications.
class TraversableNodeSet : public scene::Traversable
{
UnsortedNodeSet m_children;
UndoableObject<TraversableNodeSet> m_undo;
Observer* m_observer;

void copy( const TraversableNodeSet& other ){
	m_children = other.m_children;
}
void notifyInsertAll(){
	if ( m_observer ) {
		for ( UnsortedNodeSet::iterator i = m_children.begin(); i != m_children.end(); ++i )
		{
			m_observer->insert( *i );
		}
	}
}
void notifyEraseAll(){
	if ( m_observer ) {
		for ( UnsortedNodeSet::iterator i = m_children.begin(); i != m_children.end(); ++i )
		{
			m_observer->erase( *i );
		}
	}
}
public:
TraversableNodeSet()
	: m_undo( *this ), m_observer( 0 ){
}
TraversableNodeSet( const TraversableNodeSet& other )
	: scene::Traversable( other ), m_undo( *this ), m_observer( 0 ){
	copy( other );
	notifyInsertAll();
}
~TraversableNodeSet(){
	notifyEraseAll();
}
TraversableNodeSet& operator=( const TraversableNodeSet& other ){
#if 1 // optimised change-tracking using diff algorithm
	if ( m_observer ) {
		nodeset_diff( m_children, other.m_children, m_observer );
	}
	copy( other );
#else
	TraversableNodeSet tmp( other );
	tmp.swap( *this );
#endif
	return *this;
}
void swap( TraversableNodeSet& other ){
	std::swap( m_children, other.m_children );
	std::swap( m_observer, other.m_observer );
}

void attach( Observer* observer ){
	ASSERT_MESSAGE( m_observer == 0, "TraversableNodeSet::attach: observer cannot be attached" );
	m_observer = observer;
	notifyInsertAll();
}
void detach( Observer* observer ){
	ASSERT_MESSAGE( m_observer == observer, "TraversableNodeSet::detach: observer cannot be detached" );
	notifyEraseAll();
	m_observer = 0;
}
/// \brief \copydoc scene::Traversable::insert()
void insert( scene::Node& node ){
	ASSERT_MESSAGE( &node != 0, "TraversableNodeSet::insert: sanity check failed" );
	m_undo.save();

	ASSERT_MESSAGE( m_children.find( NodeSmartReference( node ) ) == m_children.end(), "TraversableNodeSet::insert - element already exists" );

	m_children.insert( NodeSmartReference( node ) );

	if ( m_observer ) {
		m_observer->insert( node );
	}
}
/// \brief \copydoc scene::Traversable::erase()
void erase( scene::Node& node ){
	ASSERT_MESSAGE( &node != 0, "TraversableNodeSet::erase: sanity check failed" );
	m_undo.save();

	ASSERT_MESSAGE( m_children.find( NodeSmartReference( node ) ) != m_children.end(), "TraversableNodeSet::erase - failed to find element" );

	if ( m_observer ) {
		m_observer->erase( node );
	}

	m_children.erase( NodeSmartReference( node ) );
}
/// \brief \copydoc scene::Traversable::traverse()
void traverse( const Walker& walker ){
	UnsortedNodeSet::iterator i = m_children.begin();
	while ( i != m_children.end() )
	{
		// post-increment the iterator
		Node_traverseSubgraph( *i++, walker );
		// the Walker can safely remove the current node from
		// this container without invalidating the iterator
	}
}
/// \brief \copydoc scene::Traversable::empty()
bool empty() const {
	return m_children.empty();
}

void instanceAttach( MapFile* map ){
	m_undo.instanceAttach( map );
}
void instanceDetach( MapFile* map ){
	m_undo.instanceDetach( map );
}
};

namespace std
{
/// \brief Swaps the values of \p self and \p other.
/// Overloads std::swap.
inline void swap( TraversableNodeSet& self, TraversableNodeSet& other ){
	self.swap( other );
}
}


class TraversableNode : public scene::Traversable
{
public:
TraversableNode() : m_node( 0 ), m_observer( 0 ){
}

// traverse
void attach( Observer* observer ){
	ASSERT_MESSAGE( m_observer == 0, "TraversableNode::attach - cannot attach observer" );
	m_observer = observer;
	if ( m_node != 0 ) {
		m_observer->insert( *m_node );
	}
}
void detach( Observer* observer ){
	ASSERT_MESSAGE( m_observer == observer, "TraversableNode::detach - cannot detach observer" );
	if ( m_node != 0 ) {
		m_observer->erase( *m_node );
	}
	m_observer = 0;
}
void insert( scene::Node& node ){
	ASSERT_MESSAGE( m_node == 0, "TraversableNode::insert - element already exists" );

	m_node = &node;
	node.IncRef();

	if ( m_observer != 0 ) {
		m_observer->insert( node );
	}
}
void erase( scene::Node& node ){
	ASSERT_MESSAGE( m_node == &node, "TraversableNode::erase - failed to find element" );

	if ( m_observer != 0 ) {
		m_observer->erase( node );
	}

	m_node = 0;
	node.DecRef();
}
void traverse( const scene::Traversable::Walker& walker ){
	if ( m_node != 0 ) {
		Node_traverseSubgraph( *m_node, walker );
	}
}
bool empty() const {
	return m_node != 0;
}

scene::Node& get(){
	return *m_node;
}

private:
scene::Node* m_node;
Observer* m_observer;
};


class TraversableObserverPairRelay : public scene::Traversable::Observer
{
scene::Traversable::Observer* m_first;
scene::Traversable::Observer* m_second;
public:
TraversableObserverPairRelay() : m_first( 0 ), m_second( 0 ){
}
void attach( scene::Traversable::Observer* observer ){
	ASSERT_MESSAGE( m_first == 0 || m_second == 0, "TraversableObserverPair::attach: cannot attach observer" );
	if ( m_first == 0 ) {
		m_first = observer;
	}
	else if ( m_second == 0 ) {
		m_second = observer;
	}
}
void detach( scene::Traversable::Observer* observer ){
	ASSERT_MESSAGE( m_first == observer || m_second == observer, "TraversableObserverPair::detach: cannot detach observer" );
	if ( m_first == observer ) {
		m_first = 0;
	}
	else if ( m_second == observer ) {
		m_second = 0;
	}
}
void insert( scene::Node& node ){
	if ( m_first != 0 ) {
		m_first->insert( node );
	}
	if ( m_second != 0 ) {
		m_second->insert( node );
	}
}
void erase( scene::Node& node ){
	if ( m_second != 0 ) {
		m_second->erase( node );
	}
	if ( m_first != 0 ) {
		m_first->erase( node );
	}
}
};


#endif