/**********************************************************************
 * $Id: MonotoneChain.cpp 2479 2009-05-06 17:42:58Z strk $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * Copyright (C) 2006 Refractions Research Inc.
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation. 
 * See the COPYING file for more information.
 *
 **********************************************************************
 *
 * Last port: index/chain/MonotoneChain.java rev. 1.15 (JTS-1.10)
 *
 **********************************************************************/

#include <geos/index/chain/MonotoneChain.h>
#include <geos/index/chain/MonotoneChainSelectAction.h>
#include <geos/index/chain/MonotoneChainOverlapAction.h>
#include <geos/geom/CoordinateSequence.h>
#include <geos/geom/LineSegment.h>
#include <geos/geom/Envelope.h>

using namespace geos::geom;

namespace geos {
namespace index { // geos.index
namespace chain { // geos.index.chain

MonotoneChain::MonotoneChain(const geom::CoordinateSequence& newPts,
                             size_t nstart, size_t nend, void* nContext)
	:
	pts(newPts),
	env(0),
	context(nContext),
	start(nstart),
	end(nend),
	id(-1)
{
}

MonotoneChain::~MonotoneChain()
{ 
    delete env;
}

const Envelope&
MonotoneChain::getEnvelope() const
{
    if (0 == env)
    {
        const Coordinate& p0 = pts[start];
        const Coordinate& p1 = pts[end];
        env = new Envelope(p0, p1);
    }
    return *env;
}

void
MonotoneChain::getLineSegment(size_t index, LineSegment& ls) const
{
    ls.p0 = pts[index];
    ls.p1 = pts[index+1];
}

std::auto_ptr<CoordinateSequence>
MonotoneChain::getCoordinates() const
{
    return std::auto_ptr<CoordinateSequence>(pts.clone());
}

void
MonotoneChain::select(const Envelope& searchEnv, MonotoneChainSelectAction& mcs)
{
    computeSelect(searchEnv, start, end, mcs);
}

void
MonotoneChain::computeSelect(const Envelope& searchEnv,
                             size_t start0, size_t end0,
                             MonotoneChainSelectAction& mcs )
{
    const Coordinate& p0=pts[start0];
    const Coordinate& p1=pts[end0];
    mcs.tempEnv1.init(p0,p1);

    //Debug.println("trying:"+p0+p1+" [ "+start0+","+end0+" ]");
    // terminating condition for the recursion
    if(end0-start0==1)
    {
        //Debug.println("computeSelect:"+p0+p1);
        mcs.select(*this,start0);
        return;
    }
    // nothing to do if the envelopes don't overlap
    if (!searchEnv.intersects(mcs.tempEnv1))
        return;
    // the chains overlap,so split each in half and iterate (binary search)
    unsigned int mid=(start0+end0)/2;

    // Assert: mid != start or end (since we checked above for end-start <= 1)
    // check terminating conditions before recursing
    if (start0 < mid)
    {
        computeSelect(searchEnv,start0,mid,mcs);
    }
    
    if (mid < end0)
    {
        computeSelect(searchEnv,mid,end0,mcs);
    }
}

/* public */
void
MonotoneChain::computeOverlaps(MonotoneChain *mc,
                               MonotoneChainOverlapAction *mco)
{
    computeOverlaps(start, end, *mc, mc->start, mc->end, *mco);
}

/*private*/
void
MonotoneChain::computeOverlaps(size_t start0, size_t end0,
                               MonotoneChain& mc,
                               size_t start1, size_t end1,
                               MonotoneChainOverlapAction& mco)
{
    //Debug.println("computeIntersectsForChain:"+p00+p01+p10+p11);
    // terminating condition for the recursion
    if (end0-start0==1 && end1-start1==1)
    {
        mco.overlap(*this, start0, mc, start1);
        return;
    }

    const Coordinate& p00 = pts[start0];
    const Coordinate& p01 = pts[end0];
    const Coordinate& p10 = mc.pts[start1];
    const Coordinate& p11 = mc.pts[end1];

    // nothing to do if the envelopes of these chains don't overlap
    mco.tempEnv1.init(p00, p01);
    mco.tempEnv2.init(p10, p11);
    if (!mco.tempEnv1.intersects(mco.tempEnv2)) return;

    // the chains overlap,so split each in half and iterate (binary search)
    size_t mid0=(start0+end0)/2;
    size_t mid1=(start1+end1)/2;

    // Assert: mid != start or end (since we checked above for
    // end-start <= 1)
    // check terminating conditions before recursing
    if (start0<mid0)
    {
        if (start1<mid1)
            computeOverlaps(start0, mid0, mc, start1, mid1, mco);
        if (mid1<end1)
            computeOverlaps(start0, mid0, mc, mid1, end1, mco);
    }
    
    if (mid0<end0)
    {
        if (start1<mid1)
            computeOverlaps(mid0, end0, mc, start1, mid1, mco);
        if (mid1<end1)
            computeOverlaps(mid0, end0, mc, mid1, end1, mco);
    }
}

} // namespace geos.index.chain
} // namespace geos.index
} // namespace geos

/**********************************************************************
 * $Log$
 * Revision 1.1  2006/03/22 18:12:32  strk
 * indexChain.h header split.
 *
 **********************************************************************/

