/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2020 Paul Ramsey <pramsey@cleverelephant.ca>
 *
 * 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: algorithm/construct/MaximumInscribedCircle.java
 * https://github.com/locationtech/jts/commit/98274a7ea9b40651e9de6323dc10fb2cac17a245
 *
 **********************************************************************/

#pragma once

#include <geos/geom/Coordinate.h>
#include <geos/geom/Point.h>
#include <geos/geom/Envelope.h>
#include <geos/algorithm/locate/IndexedPointInAreaLocator.h>
#include <geos/operation/distance/IndexedFacetDistance.h>

#include <memory>
#include <queue>



namespace geos {
namespace geom {
class Coordinate;
class Envelope;
class Geometry;
class GeometryFactory;
class LineString;
class Point;
}
}

namespace geos {
namespace algorithm { // geos::algorithm
namespace construct { // geos::algorithm::construct

/**
 * Computes the Euclidean distance (L2 metric) from a Point to a Geometry.
 *
 * Also computes two points which are separated by the distance.
 */
class GEOS_DLL MaximumInscribedCircle {
    using IndexedPointInAreaLocator = geos::algorithm::locate::IndexedPointInAreaLocator;
    using IndexedFacetDistance = geos::operation::distance::IndexedFacetDistance;

public:

    MaximumInscribedCircle(const geom::Geometry* polygonal, double tolerance);
    ~MaximumInscribedCircle() = default;

    /**
    * Gets the center point of the maximum inscribed circle
    * (up to the tolerance distance).
    *
    * @return the center point of the maximum inscribed circle
    */
    std::unique_ptr<geom::Point> getCenter();

    /**
    * Gets a point defining the radius of the Maximum Inscribed Circle.
    * This is a point on the boundary which is
    * nearest to the computed center of the Maximum Inscribed Circle.
    * The line segment from the center to this point
    * is a radius of the constructed circle, and this point
    * lies on the boundary of the circle.
    *
    * @return a point defining the radius of the Maximum Inscribed Circle
    */
    std::unique_ptr<geom::Point> getRadiusPoint();

    /**
    * Gets a line representing a radius of the Largest Empty Circle.
    *
    * @return a line from the center of the circle to a point on the edge
    */
    std::unique_ptr<geom::LineString> getRadiusLine();

    /**
    * Computes the center point of the Maximum Inscribed Circle
    * of a polygonal geometry, up to a given tolerance distance.
    *
    * @param polygonal a polygonal geometry
    * @param tolerance the distance tolerance for computing the center point
    * @return the center point of the maximum inscribed circle
    */
    static std::unique_ptr<geom::Point> getCenter(const geom::Geometry* polygonal, double tolerance);

    /**
    * Computes a radius line of the Maximum Inscribed Circle
    * of a polygonal geometry, up to a given tolerance distance.
    *
    * @param polygonal a polygonal geometry
    * @param tolerance the distance tolerance for computing the center point
    * @return a line from the center to a point on the circle
    */
    static std::unique_ptr<geom::LineString> getRadiusLine(const geom::Geometry* polygonal, double tolerance);

    /**
     * Computes the maximum number of iterations allowed.
     * Uses a heuristic based on the area of the input geometry
     * and the tolerance distance.
     * The number of tolerance-sized cells that cover the input geometry area
     * is computed, times a safety factor.
     * This prevents massive numbers of iterations and created cells
     * for casees where the input geometry has extremely small area
     * (e.g. is very thin).
     *
     * @param geom the input geometry
     * @param toleranceDist the tolerance distance
     * @return the maximum number of iterations allowed
     */
    static std::size_t computeMaximumIterations(const geom::Geometry* geom, double toleranceDist);

private:

    /* private members */
    const geom::Geometry* inputGeom;
    std::unique_ptr<geom::Geometry> inputGeomBoundary;
    double tolerance;
    IndexedFacetDistance indexedDistance;
    IndexedPointInAreaLocator ptLocator;
    const geom::GeometryFactory* factory;
    bool done;
    geom::CoordinateXY centerPt;
    geom::CoordinateXY radiusPt;

    /* private methods */
    double distanceToBoundary(const geom::Coordinate& c);
    double distanceToBoundary(double x, double y);
    void compute();

    /* private class */
    class Cell {
    private:
        static constexpr double SQRT2 = 1.4142135623730951;
        double x;
        double y;
        double hSize;
        double distance;
        double maxDist;

    public:
        Cell(double p_x, double p_y, double p_hSize, double p_distanceToBoundary)
            : x(p_x)
            , y(p_y)
            , hSize(p_hSize)
            , distance(p_distanceToBoundary)
            , maxDist(p_distanceToBoundary+(p_hSize*SQRT2))
        {};

        geom::Envelope getEnvelope() const
        {
            geom::Envelope env(x-hSize, x+hSize, y-hSize, y+hSize);
            return env;
        }

        double getMaxDistance() const
        {
            return maxDist;
        }
        double getDistance() const
        {
            return distance;
        }
        double getHSize() const
        {
            return hSize;
        }
        double getX() const
        {
            return x;
        }
        double getY() const
        {
            return y;
        }

        bool operator< (const Cell& rhs) const
        {
            return maxDist <  rhs.maxDist;
        }

        bool operator> (const Cell& rhs) const
        {
            return maxDist >  rhs.maxDist;
        }

        bool operator==(const Cell& rhs) const
        {
            return maxDist == rhs.maxDist;
        }

        /**
         * The Cell priority queue is sorted by the natural order of maxDistance.
         * std::priority_queue sorts with largest first,
         * which is what is needed for this algorithm.
         */
        using CellQueue = std::priority_queue<Cell>;
    };

    void createInitialGrid(const geom::Envelope* env, Cell::CellQueue& cellQueue);
    Cell createInteriorPointCell(const geom::Geometry* geom);

};


} // geos::algorithm::construct
} // geos::algorithm
} // geos
