#include "tundo.h"
#include <deque>

//-----------------------------------------------------------------------------

using std::for_each;

namespace
{

void deleteUndo(const TUndo *undo) { delete undo; }
void callUndo(const TUndo *undo) { undo->undo(); }
void callRedo(const TUndo *undo) { undo->redo(); }
// void callRepeat(const TUndo* undo) {undo->repeat(); }

class TUndoBlock : public TUndo
{
	std::vector<TUndo *> m_undos;
	typedef std::vector<TUndo *>::const_iterator Iterator;
	typedef std::vector<TUndo *>::const_reverse_iterator ReverseIterator;
	mutable bool m_deleted, m_undoing;

public:
	TUndoBlock() : m_deleted(false), m_undoing(false) {}
	~TUndoBlock()
	{
		assert(m_undoing == false);
		assert(m_deleted == false);
		m_deleted = true;
		for_each(m_undos.begin(), m_undos.end(), deleteUndo);
		m_undos.clear();
	}

	int getSize() const
	{
		int size = sizeof(*this);
		for (Iterator cit = m_undos.begin(); cit != m_undos.end(); ++cit)
			size += (*cit)->getSize();
		size += (m_undos.capacity() - m_undos.size()) * sizeof(TUndo *);
		return size;
	}
	int getUndoCount() const
	{
		return (int)m_undos.size();
	}
	void setLast()
	{
		for (UINT i = 1; i < m_undos.size(); i++)
			m_undos[i]->m_isLastInBlock = false;
		m_undos[0]->m_isLastInBlock = true;
	}

	void undo() const
	{
		assert(!m_deleted);
		assert(!m_undoing);
		m_undoing = true;
		//VERSIONE CORRETTA
		for_each(m_undos.rbegin(), m_undos.rend(), callUndo);
		//VERSIONE SBAGLIATA
		//for_each(m_undos.begin(), m_undos.end(), callUndo);
		m_undoing = false;
	}
	void redo() const
	{
		assert(!m_deleted);
		//VERSIONE CORRETTA
		for_each(m_undos.begin(), m_undos.end(), callRedo);
		//VERSIONE SBAGLIATA
		//for_each(m_undos.rbegin(), m_undos.rend(), callRedo);
	}

	//void repeat() const {
	//  for_each(m_undos.begin(), m_undos.end(), callRepeat);
	//}
	void onAdd() {}
	void add(TUndo *undo)
	{
		undo->m_isLastInBlock = true;
		m_undos.push_back(undo);
	}

	void popUndo(int n)
	{
		if (n == -1)
			n = m_undos.size();
		if (m_undos.empty() || n <= 0)
			return;
		while (n > 0 && !m_undos.empty()) {
			TUndo *undo = m_undos.back();
			m_undos.pop_back();
			delete undo;
			n--;
		}
	}

	virtual QString getHistoryString()
	{
		if (m_undos.empty())
			return TUndo::getHistoryString();
		else if ((int)m_undos.size() == 1)
			return m_undos.back()->getHistoryString();
		else {
			return QString("%1  etc..").arg(m_undos.back()->getHistoryString());
		}
	}

	virtual int getHistoryType()
	{
		if (m_undos.empty())
			return TUndo::getHistoryType();
		else
			return m_undos.back()->getHistoryType();
	}
};
}

typedef std::deque<TUndo *> UndoList;
typedef UndoList::iterator UndoListIterator;
typedef UndoList::const_iterator UndoListConstIterator;

//-----------------------------------------------------------------------------

struct TUndoManager::TUndoManagerImp {
	UndoList m_undoList;
	UndoListIterator m_current;
	bool m_skipped;
	int m_undoMemorySize; // in bytes

	std::vector<TUndoBlock *> m_blockStack;

public:
	TUndoManagerImp() : m_skipped(false), m_undoMemorySize(0) { m_current = m_undoList.end(); }
	~TUndoManagerImp() {}

	void add(TUndo *undo);

public:
	static struct ManagerPtr {
		TUndoManager *m_ptr;

	public:
		ManagerPtr() : m_ptr(0) {}
		~ManagerPtr()
		{
			if (m_ptr)
				delete m_ptr;
			m_ptr = 0;
		}

	} theManager;

private:
	void doAdd(TUndo *undo);
};

//=============================================================================

TUndoManager::TUndoManagerImp::ManagerPtr TUndoManager::TUndoManagerImp::theManager;

//-----------------------------------------------------------------------------

TUndoManager *TUndoManager::manager()
{
	if (!TUndoManagerImp::theManager.m_ptr)
		TUndoManagerImp::theManager.m_ptr = new TUndoManager;
	return TUndoManagerImp::theManager.m_ptr;
}

//=============================================================================

TUndoManager::TUndoManager()
	: m_imp(new TUndoManagerImp)
{
}

//-----------------------------------------------------------------------------

TUndoManager::~TUndoManager()
{
	//cout << "Distrutto undo manager" << endl;
	assert(m_imp->m_blockStack.empty());
	reset();
}

//-----------------------------------------------------------------------------

void TUndoManager::TUndoManagerImp::add(TUndo *undo)
{
	assert(undo);

	if (!m_blockStack.empty()) {
		assert(m_current == m_undoList.end());
		m_blockStack.back()->add(undo);
	} else
		doAdd(undo);
}

//-----------------------------------------------------------------------------

void TUndoManager::TUndoManagerImp::doAdd(TUndo *undo)
{
	if (m_current != m_undoList.end()) {
		for_each(m_current, m_undoList.end(), deleteUndo);
		m_undoList.erase(m_current, m_undoList.end());
	}

	int i, memorySize = 0, count = m_undoList.size();
	for (i = 0; i < count; i++)
		memorySize += m_undoList[i]->getSize();

	while (count > 100 || (count != 0 && memorySize + undo->getSize() > m_undoMemorySize)) //20MB
	{
		--count;
		TUndo *undo = m_undoList.front();
		m_undoList.pop_front();
		memorySize -= undo->getSize();
		delete undo;
	}

	undo->m_isLastInBlock = true;
	m_undoList.push_back(undo);
	m_current = m_undoList.end();
}

//-----------------------------------------------------------------------------

void TUndoManager::beginBlock()
{
	if (m_imp->m_current != m_imp->m_undoList.end()) {
		for_each(m_imp->m_current, m_imp->m_undoList.end(), deleteUndo);
		m_imp->m_undoList.erase(m_imp->m_current, m_imp->m_undoList.end());
	}

	TUndoBlock *undoBlock = new TUndoBlock;
	m_imp->m_blockStack.push_back(undoBlock);
	m_imp->m_current = m_imp->m_undoList.end();
}

//-----------------------------------------------------------------------------

void TUndoManager::endBlock()
{
	//vogliamo fare anche resize del vector ???
	assert(m_imp->m_blockStack.empty() == false);
	TUndoBlock *undoBlock = m_imp->m_blockStack.back();
	m_imp->m_blockStack.pop_back();
	if (undoBlock->getUndoCount() > 0) {
		undoBlock->setLast();
		m_imp->add(undoBlock);
		emit historyChanged();
	} else {
		delete undoBlock;
		m_imp->m_current = m_imp->m_undoList.end();
	}
}

//-----------------------------------------------------------------------------

bool TUndoManager::undo()
{
	assert(m_imp->m_blockStack.empty());
	UndoListIterator &it = m_imp->m_current;
	if (it != m_imp->m_undoList.begin()) {
		m_imp->m_skipped = false;
		--it;
		(*it)->undo();
		emit historyChanged();
		if (m_imp->m_skipped) {
			m_imp->m_skipped = false;
			return undo();
		}
		return true;
	} else
		return false;
}

//-----------------------------------------------------------------------------

bool TUndoManager::redo()
{
	assert(m_imp->m_blockStack.empty());
	UndoListIterator &it = m_imp->m_current;
	if (it != m_imp->m_undoList.end()) {
		m_imp->m_skipped = false;
		(*it)->redo();
		++it;
		emit historyChanged();
		if (m_imp->m_skipped) {
			m_imp->m_skipped = false;
			return redo();
		}
		return true;
	} else
		return false;
}

//-----------------------------------------------------------------------------
//repeat e' come redo ma non sposta il puntatore al corrente
/*
void TUndoManager::repeat()
{
  assert(m_imp->m_blockStack.empty());
  UndoListIterator &it = m_imp->m_current;
  if (it != m_imp->m_undoList.end())
  {
    (*it)->repeat();
  }
}
*/

//-----------------------------------------------------------------------------

void TUndoManager::skip()
{
	m_imp->m_skipped = true;
}

//-----------------------------------------------------------------------------

void TUndoManager::setUndoMemorySize(int memorySyze)
{
	m_imp->m_undoMemorySize = 1048576 * memorySyze;
}

//-----------------------------------------------------------------------------

void TUndoManager::add(TUndo *undo)
{
	assert(undo);
	if (!undo)
		return;

	m_imp->add(undo);
	Q_EMIT historyChanged();

	undo->onAdd();
	Q_EMIT somethingChanged();
}

//-----------------------------------------------------------------------------

void TUndoManager::reset()
{
	assert(m_imp->m_blockStack.empty());
	m_imp->m_blockStack.clear();
	UndoList &lst = m_imp->m_undoList;
	for_each(lst.begin(), lst.end(), deleteUndo);
	lst.clear();
	m_imp->m_current = m_imp->m_undoList.end();
	Q_EMIT historyChanged();
}

//-----------------------------------------------------------------------------

void TUndoManager::popUndo(int n, bool forward)
{
	if (!forward) {
		if (m_imp->m_blockStack.empty()) {
			if (n == -1) {
				UndoListIterator start = m_imp->m_undoList.begin();
				n = 0;
				while (start != m_imp->m_current)
					++n;
			}
			if (m_imp->m_undoList.empty() || n <= 0)
				return;
			if (m_imp->m_current == m_imp->m_undoList.end()) {
				int i;
				for (i = 0; i < n && m_imp->m_current != m_imp->m_undoList.begin(); i++) {
					m_imp->m_current--;
					delete (*m_imp->m_current);
					m_imp->m_undoList.erase(m_imp->m_current);
					m_imp->m_current = m_imp->m_undoList.end();
				}
			} else {
				TUndo *undo = *m_imp->m_current;
				UndoListIterator start, end = m_imp->m_current;
				if (end == m_imp->m_undoList.begin())
					return;

				int i;
				for (i = 0; i < n && m_imp->m_current != m_imp->m_undoList.begin(); i++)
					m_imp->m_current--;

				start = m_imp->m_current;
				UndoListIterator _end = end;
				while (_end != start) {
					_end--;
					delete (*_end);
				}
				m_imp->m_undoList.erase(start, end);

				m_imp->m_current = m_imp->m_undoList.begin();
				while (*m_imp->m_current != undo)
					m_imp->m_current++;
			}
		} else
			m_imp->m_blockStack.back()->popUndo(n);
		return;
	}

	if (m_imp->m_current == m_imp->m_undoList.end())
		return;
	if (m_imp->m_blockStack.empty()) {
		UndoListIterator end, start = m_imp->m_current++;
		if (n == -1)
			end = m_imp->m_undoList.end();
		else {
			UndoListIterator it = start;
			end = it;
			int i = 0;
			while (i != n && end != m_imp->m_undoList.end()) {
				++end;
				i++;
			}
		}
		for_each(start, end, deleteUndo);
		m_imp->m_undoList.erase(start, end);
		m_imp->m_current = m_imp->m_undoList.end();
	} else
		m_imp->m_blockStack.back()->popUndo(n);
}

//-----------------------------------------------------------------------------

int TUndoManager::getHistoryCount()
{
	return (int)m_imp->m_undoList.size();
}

//-----------------------------------------------------------------------------

int TUndoManager::getCurrentHistoryIndex()
{
	int index = 0;
	UndoListIterator it = m_imp->m_undoList.begin();
	while (1) {
		if (it == m_imp->m_current)
			return index;

		if (it == m_imp->m_undoList.end())
			break;

		index++;
		it++;
	}
	return 0;
}

//-----------------------------------------------------------------------------

TUndo *TUndoManager::getUndoItem(int index)
{
	if (index > (int)m_imp->m_undoList.size() || index <= 0)
		return 0;

	return m_imp->m_undoList.at(index - 1);
}