#include "quadtreenode.hpp"

#include <cassert>

#include <osgUtil/CullVisitor>

#include "defs.hpp"

namespace
{

    float distance(const osg::BoundingBox& box, const osg::Vec3f& v)
    {
        if (box.contains(v))
            return 0;
        else
        {
            osg::Vec3f maxDist(0,0,0);

            if (v.x() < box.xMin())
                maxDist.x() = box.xMin() - v.x();
            else if (v.x() > box.xMax())
                maxDist.x() = v.x() - box.xMax();

            if (v.y() < box.yMin())
                maxDist.y() = box.yMin() - v.y();
            else if (v.y() > box.yMax())
                maxDist.y() = v.y() - box.yMax();

            if (v.z() < box.zMin())
                maxDist.z() = box.zMin() - v.z();
            else if (v.z() > box.zMax())
                maxDist.z() = v.z() - box.zMax();

            return maxDist.length();
        }
    }

    int Log2( int n )
    {
        assert(n > 0);
        int targetlevel = 0;
        while (n >>= 1) ++targetlevel;
        return targetlevel;
    }

}

namespace Terrain
{

ChildDirection reflect(ChildDirection dir, Direction dir2)
{
    assert(dir != Root);
    const int lookupTable[4][4] =
    {
        // NW  NE  SW  SE
        {  SW, SE, NW, NE }, // N
        {  NE, NW, SE, SW }, // E
        {  SW, SE, NW, NE }, // S
        {  NE, NW, SE, SW }  // W
    };
    return (ChildDirection)lookupTable[dir2][dir];
}

bool adjacent(ChildDirection dir, Direction dir2)
{
    assert(dir != Root);
    const bool lookupTable[4][4] =
    {
        // NW    NE    SW     SE
        {  true, true, false, false }, // N
        {  false, true, false, true }, // E
        {  false, false, true, true }, // S
        {  true, false, true, false }  // W
    };
    return lookupTable[dir2][dir];
}

QuadTreeNode* searchNeighbour (QuadTreeNode* currentNode, Direction dir)
{
    if (currentNode->getDirection() == Root)
        return NULL; // Arrived at root node, the root node does not have neighbours

    QuadTreeNode* nextNode;
    if (adjacent(currentNode->getDirection(), dir))
        nextNode = searchNeighbour(currentNode->getParent(), dir);
    else
        nextNode = currentNode->getParent();

    if (nextNode && nextNode->getNumChildren())
        return nextNode->getChild(reflect(currentNode->getDirection(), dir));
    else
        return NULL;
}

QuadTreeNode::QuadTreeNode(QuadTreeNode* parent, ChildDirection direction, float size, const osg::Vec2f& center)
    : mParent(parent)
    , mDirection(direction)
    , mSize(size)
    , mCenter(center)
{
    for (unsigned int i=0; i<4; ++i)
        mNeighbours[i] = 0;
}

QuadTreeNode* QuadTreeNode::getParent()
{
    return mParent;
}

QuadTreeNode *QuadTreeNode::getChild(unsigned int i)
{
    return static_cast<QuadTreeNode*>(Group::getChild(i));
}

void QuadTreeNode::initNeighbours()
{
    for (int i=0; i<4; ++i)
        mNeighbours[i] = searchNeighbour(this, (Direction)i);

    for (unsigned int i=0; i<getNumChildren(); ++i)
        getChild(i)->initNeighbours();
}

void QuadTreeNode::traverse(osg::NodeVisitor &nv)
{
    if (nv.getVisitorType() != osg::NodeVisitor::CULL_VISITOR)
        return;

    osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>(&nv);

    // do another culling test against bounding box as its much more accurate than the bounding sphere.
    if (cv->isCulled(mBoundingBox))
        return;

    //float dist = distance(getBoundingBox(), nv.getEyePoint());

    osg::Group::traverse(nv);
}

void QuadTreeNode::setBoundingBox(const osg::BoundingBox &boundingBox)
{
    mBoundingBox = boundingBox;
    dirtyBound();
    getBound();
}

const osg::BoundingBox &QuadTreeNode::getBoundingBox() const
{
    return mBoundingBox;
}

osg::BoundingSphere QuadTreeNode::computeBound() const
{
    return osg::BoundingSphere(mBoundingBox);
}

float QuadTreeNode::getSize() const
{
    return mSize;
}

const osg::Vec2f &QuadTreeNode::getCenter() const
{
    return mCenter;
}

}