/****************************************************************************
**
** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
** Copyright (C) 2016 Paul Lemire
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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#include "framegraphvisitor_p.h"

#include "framegraphnode_p.h"
#include <Qt3DRender/private/renderer_p.h>
#include <Qt3DRender/private/managers_p.h>
#include <QThreadPool>

QT_BEGIN_NAMESPACE

using namespace Qt3DCore;

namespace Qt3DRender {
namespace Render {

FrameGraphVisitor::FrameGraphVisitor(const FrameGraphManager *manager)
    : m_manager(manager)
{
    m_leaves.reserve(8);
}

QVector<FrameGraphNode *> FrameGraphVisitor::traverse(FrameGraphNode *root)
{
    m_leaves.clear();

    Q_ASSERT_X(root, Q_FUNC_INFO, "The FrameGraphRoot is null");

    // Kick off the traversal
    Render::FrameGraphNode *node = root;
    if (node == nullptr)
        qCritical() << Q_FUNC_INFO << "FrameGraph is null";
    visit(node);
    return m_leaves;
}

void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
{
    // TO DO: check if node is a subtree selector
    // in which case, we only visit the subtrees returned
    // by the selector functor and not all the children
    // as we would otherwise do

    // Recurse to children (if we have any), otherwise if this is a leaf node,
    // initiate a rendering from the current camera
    const QVector<Qt3DCore::QNodeId> fgChildIds = node->childrenIds();

    for (const Qt3DCore::QNodeId fgChildId : fgChildIds)
        visit(m_manager->lookupNode(fgChildId));

    // Leaf node - create a RenderView ready to be populated
    // TODO: Pass in only framegraph config that has changed from previous
    // index RenderViewJob.
    if (fgChildIds.empty())
        m_leaves.push_back(node);
}

} // namespace Render
} // namespace Qt3DRender

QT_END_NAMESPACE
