/**************************************************************************
**
** This file is part of Qt Creator
**
** Copyright (c) 2012 Nokia Corporation and/or its subsidiary(-ies).
**
** Contact: Nokia Corporation (qt-info@nokia.com)
**
**
** GNU Lesser General Public License Usage
**
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this file.
** Please review the following information to ensure the GNU Lesser General
** Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** Other Usage
**
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**************************************************************************/

#include "callgrindcycledetection.h"

#include "callgrindfunction.h"
#include "callgrindfunctioncall.h"
#include "callgrindparsedata.h"
#include "callgrindfunctioncycle.h"

#include <utils/qtcassert.h>

#include <QDebug>

namespace Valgrind {
namespace Callgrind {
namespace Internal {

CycleDetection::CycleDetection(ParseData *data)
    : m_data(data)
    , m_depth(0)
    , m_cycle(0)
{
}

QVector<const Function *> CycleDetection::run(const QVector<const Function *> &input)
{
    foreach (const Function *function, input) {
        Node *node = new Node;
        node->function = function;
        node->dfs = -1;
        node->lowlink = -1;
        m_nodes.insert(function, node);
    }
    foreach (Node *node, m_nodes) {
        if (node->dfs == -1)
            tarjan(node);
    }
    qDeleteAll(m_nodes);
    return m_ret;
}

void CycleDetection::tarjan(Node *node)
{
    QTC_ASSERT(node->dfs == -1, return);
    node->dfs = m_depth;
    node->lowlink = m_depth;

    m_depth++;
    m_stack.push(node);

    foreach (const FunctionCall *call, node->function->outgoingCalls())
        tarjanForChildNode(node, m_nodes.value(call->callee()));

    if (node->dfs == node->lowlink) {
        QVector<const Function *> functions;
        Node *n;
        do {
            n = m_stack.pop();
            functions << n->function;
        } while (n != node);

        if (functions.size() == 1) {
            // not a real cycle
            m_ret.append(node->function);
        } else {
            // actual cycle
            FunctionCycle *cycle = new FunctionCycle(m_data);
            cycle->setFile(node->function->fileId());
            m_cycle++;
            qint64 id = -1;
            m_data->addCompressedFunction(QString("cycle %1").arg(m_cycle), id);
            cycle->setName(id);
            cycle->setObject(node->function->objectId());
            cycle->setFunctions(functions);
            m_ret.append(cycle);
        }
    }
}

void CycleDetection::tarjanForChildNode(Node *node, Node *childNode)
{
    if (childNode->dfs == -1) {
        tarjan(childNode);
        if (childNode->lowlink < node->lowlink)
            node->lowlink = childNode->lowlink;
    } else if (childNode->dfs < node->lowlink && m_stack.contains(childNode)) {
        node->lowlink = childNode->dfs;
    }
}

} // namespace Internal
} // namespace Callgrind
} // namespace Valgrind