/**********************************************************************

 *

 * GEOS - Geometry Engine Open Source

 * http://geos.osgeo.org

 *

 * Copyright (C) 2006 Refractions Research Inc.

 * Copyright (C) 2023 Martin Davis <mtnclimb@gmail.com>

 * Copyright (C) 2023 Paul Ramsey <pramsey@cleverelephant.ca>

 *

 * This is free software; you can redistribute and/or modify it under

 * the terms of the GNU Lesser General Licence as published

 * by the Free Software Foundation.

 * See the COPYING file for more information.

 *

 **********************************************************************/

#include <geos/simplify/ComponentJumpChecker.h>

#include <geos/simplify/TaggedLineString.h>

#include <geos/algorithm/RayCrossingCounter.h>

#include <geos/geom/Coordinate.h>

#include <geos/geom/CoordinateSequence.h>

#include <geos/geom/Envelope.h>

#include <geos/geom/LineSegment.h>

#include <geos/util.h>

using geos::algorithm::RayCrossingCounter;

using geos::geom::Coordinate;

using geos::geom::CoordinateSequence;

using geos::geom::Envelope;

using geos::geom::LineSegment;

namespace geos {

namespace simplify { // geos::simplify

/**

* Checks if a line section jumps a component if flattened.

*

* Assumes start <= end.

*

* @param line the line containing the section being flattened

* @param start start index of the section

* @param end end index of the section

* @param seg the flattening segment

* @return true if the flattened section jumps a component

*/

/*public*/

bool

ComponentJumpChecker::hasJump(

    const TaggedLineString* line,

    std::size_t start, std::size_t end,

    const LineSegment& seg) const

{

    Envelope sectionEnv = computeEnvelope(line, start, end);

    for (TaggedLineString* comp : components) {

      //-- don't test component against itself

        if (comp == line)

            continue;

        const Coordinate& compPt = comp->getComponentPoint();

        if (sectionEnv.intersects(compPt)) {

            if (hasJumpAtComponent(compPt, line, start, end, seg)) {

                return true;

            }

        }

    }

    return false;

}

/**

* Checks if two consecutive segments jumps a component if flattened.

* The segments are assumed to be consecutive.

* (so the seg1.p1 = seg2.p0).

* The flattening segment must be the segment between seg1.p0 and seg2.p1.

*

* @param line the line containing the section being flattened

* @param seg1 the first replaced segment

* @param seg2 the next replaced segment

* @param seg the flattening segment

* @return true if the flattened segment jumps a component

*/

/* public */

bool

ComponentJumpChecker::hasJump(

    const TaggedLineString* line,

    const LineSegment* seg1,

    const LineSegment* seg2,

    const LineSegment& seg) const

{

    Envelope sectionEnv = computeEnvelope(seg1, seg2);

    for (TaggedLineString* comp : components) {

        //-- don't test component against itself

        if (comp == line)

            continue;

        const Coordinate& compPt = comp->getComponentPoint();

        if (sectionEnv.intersects(compPt)) {

            if (hasJumpAtComponent(compPt, seg1, seg2, seg)) {

                return true;

            }

        }

    }

    return false;

}

/*private static*/

bool

ComponentJumpChecker::hasJumpAtComponent(

    const Coordinate& compPt,

    const TaggedLineString* line,

    std::size_t start, std::size_t end,

    const LineSegment& seg)

{

    std::size_t sectionCount = crossingCount(compPt, line, start, end);

    std::size_t segCount = crossingCount(compPt, seg);

    bool hasJump = sectionCount % 2 != segCount % 2;

    return hasJump;

}

/*private static*/

bool

ComponentJumpChecker::hasJumpAtComponent(

    const Coordinate& compPt,

    const LineSegment* seg1, const LineSegment* seg2,

    const LineSegment& seg)

{

    std::size_t sectionCount = crossingCount(compPt, seg1, seg2);

    std::size_t segCount = crossingCount(compPt, seg);

    bool hasJump = sectionCount % 2 != segCount % 2;

    return hasJump;

}

/*private static*/

std::size_t

ComponentJumpChecker::crossingCount(

    const Coordinate& compPt,

    const LineSegment& seg)

{

    RayCrossingCounter rcc(compPt);

    rcc.countSegment(seg.p0,  seg.p1);

    return rcc.getCount();

}

/*private static*/

std::size_t

ComponentJumpChecker::crossingCount(

    const Coordinate& compPt,

    const LineSegment* seg1, const LineSegment* seg2)

{

    RayCrossingCounter rcc(compPt);

    rcc.countSegment(seg1->p0,  seg1->p1);

    rcc.countSegment(seg2->p0,  seg2->p1);

    return rcc.getCount();

}

/*private static*/

std::size_t

ComponentJumpChecker::crossingCount(

    const Coordinate& compPt,

    const TaggedLineString* line,

    std::size_t start, std::size_t end)

{

    RayCrossingCounter rcc(compPt);

    for (std::size_t i = start; i < end; i++) {

        rcc.countSegment(line->getCoordinate(i), line->getCoordinate(i + 1));

    }

    return rcc.getCount();

}

/*private static*/

Envelope

ComponentJumpChecker::computeEnvelope(

    const LineSegment* seg1, const LineSegment* seg2)

{

    Envelope env;

    env.expandToInclude(seg1->p0);

    env.expandToInclude(seg1->p1);

    env.expandToInclude(seg2->p0);

    env.expandToInclude(seg2->p1);

    return env;

}

/*private static*/

Envelope

ComponentJumpChecker::computeEnvelope(

    const TaggedLineString* line,

    std::size_t start, std::size_t end)

{

    Envelope env;

    for (std::size_t i = start; i <= end; i++) {

        env.expandToInclude(line->getCoordinate(i));

    }

    return env;

}

} // namespace geos::simplify

} // namespace geos