#include "tidentifiable.h"
#include <set>

namespace
{

class IdentifierTable
{ // singleton

	unsigned long m_lastId;
	std::map<unsigned long, TIdentifiable *> m_table;
	std::set<TIdentifiable *> m_objects;

	IdentifierTable() : m_lastId(0) {}

public:
	static IdentifierTable *instance()
	{
		// NON DEVE MORIRE
		//static IdentifierTable _instance;
		//return &_instance;
		static IdentifierTable *_instance = 0;
		if (!_instance)
			_instance = new IdentifierTable;
		return _instance;
	}

	unsigned long getNextId()
	{
		return ++m_lastId;
	}

	void insert(TIdentifiable *o)
	{

		unsigned long id = o->getIdentifier();
		std::map<unsigned long, TIdentifiable *>::iterator it = m_table.find(id);
		if (it != m_table.end()) {
			if (it->second == o)
				return;
			m_objects.erase(it->second);
			it->second = o;
		} else {
			m_table[id] = o;
		}
		m_objects.insert(o);
	}

	void erase(TIdentifiable *o)
	{

		unsigned long id = o->getIdentifier();
		m_table.erase(id);
		m_objects.erase(o);
	}

	TIdentifiable *fetch(unsigned long id)
	{
		std::map<unsigned long, TIdentifiable *>::iterator it = m_table.find(id);
		return it == m_table.end() ? 0 : it->second;
	}
};

} // namespace

TIdentifiable::TIdentifiable()
	: m_id(0)
{
}

TIdentifiable::~TIdentifiable()
{
	if (m_id != 0)
		IdentifierTable::instance()->erase(this);
}

TIdentifiable::TIdentifiable(const TIdentifiable &src)
	: m_id(src.m_id)
{
}

const TIdentifiable &TIdentifiable::operator=(const TIdentifiable &src)
{
	if (src.m_id != m_id && m_id != 0)
		IdentifierTable::instance()->erase(this);
	m_id = src.m_id;
	return *this;
}

void TIdentifiable::setIdentifier(unsigned long id)
{
	bool wasStored = m_id > 0 && IdentifierTable::instance()->fetch(m_id) == this;
	if (m_id != id && m_id != 0)
		IdentifierTable::instance()->erase(this);
	m_id = id;
	if (wasStored)
		IdentifierTable::instance()->insert(this);
}

void TIdentifiable::setNewIdentifier()
{
	setIdentifier(IdentifierTable::instance()->getNextId());
}

void TIdentifiable::storeByIdentifier()
{
	assert(getIdentifier() >= 1);
	IdentifierTable::instance()->insert(this);
}

TIdentifiable *TIdentifiable::fetchByIdentifier(unsigned long id)
{
	return IdentifierTable::instance()->fetch(id);
}