/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2016 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */
#include <osgEarthSymbology/GeometryFactory>
#include <osgEarth/GeoMath>

#define LC "[GeometryFactory] "

using namespace osgEarth;
using namespace osgEarth::Symbology;

GeometryFactory::GeometryFactory( const SpatialReference* srs ) :
_srs( srs )
{
    //nop
}

Geometry*
GeometryFactory::createCircle(const osg::Vec3d& center,
                              const Distance&   radius,
                              unsigned          numSegments,
                              Geometry*         geomToUse) const
{
    Geometry* geom = geomToUse ? geomToUse : new Polygon();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double segLen = radius.as(Units::METERS) / 8.0;
        double circumference = 2*osg::PI*radius.as(Units::METERS);
        numSegments = (unsigned)::ceil(circumference / segLen);
    }
    
    double segAngle = (2.0*osg::PI)/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double rM  = radius.as(Units::METERS);

        for( int i=numSegments-1; i >= 0; --i )
        {
            double angle = segAngle * (double)i;
            double clat, clon;
            GeoMath::destination( lat, lon, angle, rM, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }

    else
    {
        double rM = radius.as(Units::METERS);

        for( int i=numSegments-1; i >= 0; --i )
        {
            double angle = segAngle * (double)i;
            double x, y;
            x = center.x() + sin(angle)*rM;
            y = center.y() + cos(angle)*rM;
            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    return geom;
}

Geometry*
GeometryFactory::createArc(const osg::Vec3d& center,
                           const Distance&   radius,
                           const Angle&      start,
                           const Angle&      end,
                           unsigned          numSegments,
                           Geometry*         geomToUse,
                           bool              pie) const
{
    Geometry* geom = geomToUse? geomToUse : new LineString();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double segLen = radius.as(Units::METERS) / 8.0;
        double circumference = 2*osg::PI*radius.as(Units::METERS);
        numSegments = (unsigned)::ceil(circumference / segLen);
    }

    double startRad = std::min( start.as(Units::RADIANS), end.as(Units::RADIANS) );
    double endRad   = std::max( start.as(Units::RADIANS), end.as(Units::RADIANS) );

    if ( endRad == startRad )
        endRad += 2*osg::PI;

    double span     = endRad - startRad;    
    double step     = span/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double rM  = radius.as(Units::METERS);

        for( int i=numSegments; i >= 0; --i )
        {
            double angle = startRad + step*(double)i;
            double clat, clon;
            GeoMath::destination( lat, lon, angle, rM, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }

    else
    {
        double rM = radius.as(Units::METERS);

        for( int i=numSegments; i >= 0; --i )
        {
            double angle = startRad + step*(double)i;
            double x, y;
            x = center.x() + sin(angle)*rM;
            y = center.y() + cos(angle)*rM;
            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    if (pie && (geom->getTotalPointCount() > 0) && ((startRad + 2*osg::PI) != endRad))
    {
        geom->push_back(center);
        geom->push_back(geom->at(0));
    }
    geom->rewind(Geometry::ORIENTATION_CCW);

    return geom;
}

Geometry*
GeometryFactory::createEllipse(const osg::Vec3d& center,
                               const Distance&   radiusMajor,
                               const Distance&   radiusMinor,
                               const Angle&      rotationAngle,
                               unsigned          numSegments,
                               Geometry*         geomToUse) const
{
    Geometry* geom = geomToUse ? geomToUse : new Polygon();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double ravgM = 0.5*(radiusMajor.as(Units::METERS) + radiusMinor.as(Units::METERS));
        double segLen = ravgM / 8.0;
        double circumference = 2*osg::PI*ravgM;
        numSegments = (unsigned)::ceil(circumference / segLen);
    }
    
    double segAngle = 2.0*osg::PI/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS) - osg::PI_2;

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double t = angle - osg::PI_2;
            double clat, clon;

            double rA = (b*b-a*a)*cos(2*t - 2*g) + a*a + b*b;
            double q = sqrt(2.0)*a*b*sqrt(rA);
            double r = q/rA;

            GeoMath::destination( lat, lon, angle, r, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }
    else
    {
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS) - osg::PI_2;
        double sing = sin(g), cosg = cos(g);

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double t = angle - osg::PI_2;
            double cost = cos(t), sint = sin(t);
            double x = center.x() + a*cost*cosg - b*sint*sing;
            double y = center.y() + a*cost*sing + b*sint*cosg;

            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    return geom;
}

Geometry*
GeometryFactory::createEllipticalArc(const osg::Vec3d& center,
                                     const Distance&   radiusMajor,
                                     const Distance&   radiusMinor,
                                     const Angle&      rotationAngle,
                                     const Angle&      start,
                                     const Angle&      end,
                                     unsigned          numSegments,
                                     Geometry*         geomToUse,
                                     bool              pie) const
{
    Geometry* geom = geomToUse ? geomToUse : new LineString();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double ravgM = 0.5*(radiusMajor.as(Units::METERS) + radiusMinor.as(Units::METERS));
        double segLen = ravgM / 8.0;
        double circumference = 2*osg::PI*ravgM;
        numSegments = (unsigned)::ceil(circumference / segLen);
    }

    double startRad = std::min( start.as(Units::RADIANS), end.as(Units::RADIANS) );// - osg::PI_2;
    double endRad   = std::max( start.as(Units::RADIANS), end.as(Units::RADIANS) );// - osg::PI_2;

    if ( endRad == startRad )
    {
        endRad += 2*osg::PI;
    }

    double span     = endRad - startRad;
    double step     = span/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS) - osg::PI_2;

        for( unsigned i=0; i<=numSegments; i++ )
        {
            double angle = startRad + step*(double)i;
            double t = angle - osg::PI_2;
            double clat, clon;

            double rA = (b*b-a*a)*cos(2*t - 2*g) + a*a + b*b;
            double q = sqrt(2.0)*a*b*sqrt(rA);
            double r = q/rA;

            GeoMath::destination( lat, lon, angle, r, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }
    else
    {
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS);
        double sing = sin(g), cosg = cos(g);

        for( unsigned i=0; i<=numSegments; i++ )
        {
            double angle = startRad + step*(double)i;
            double cost = cos(angle), sint = sin(angle);
            double x = center.x() + a*sint*cosg + b*cost*sing;
            double y = center.y() + b*cost*cosg - a*sint*sing;

            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    if (pie && (geom->getTotalPointCount() > 0) && ((startRad + 2*osg::PI) != endRad))
    {
        geom->push_back(center);
        geom->push_back(geom->at(0));
    }

    return geom;
}

Geometry*
GeometryFactory::createRectangle(const osg::Vec3d& center,
                                 const Distance&   width,
                                 const Distance&   height ) const
{
    Geometry* geom = new Polygon();
    
    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double halfWidthMeters  = width.as(Units::METERS) / 2.0;
        double halfHeightMeters  = height.as(Units::METERS) / 2.0;   

        double eastLon, eastLat;
        double westLon, westLat;
        double northLon, northLat;
        double southLon, southLat;
        
        GeoMath::destination( lat, lon, osg::DegreesToRadians( 90.0 ), halfWidthMeters, eastLat, eastLon, earthRadius );
        GeoMath::destination( lat, lon, osg::DegreesToRadians( -90.0 ), halfWidthMeters, westLat, westLon, earthRadius );
        GeoMath::destination( lat, lon, osg::DegreesToRadians( 0.0 ),  halfHeightMeters, northLat, northLon, earthRadius );
        GeoMath::destination( lat, lon, osg::DegreesToRadians( 180.0 ), halfHeightMeters, southLat, southLon, earthRadius );


        geom->push_back( osg::RadiansToDegrees( westLon ), osg::RadiansToDegrees( southLat ), center.z());
        geom->push_back( osg::RadiansToDegrees( eastLon ), osg::RadiansToDegrees( southLat ), center.z());
        geom->push_back( osg::RadiansToDegrees( eastLon ), osg::RadiansToDegrees( northLat ), center.z());
        geom->push_back( osg::RadiansToDegrees( westLon ), osg::RadiansToDegrees( northLat ), center.z());        
    }

    else
    {
        double halfWidthMeters = width.as(Units::METERS) / 2.0;
        double halfHeightMeters = height.as(Units::METERS) / 2.0;

        
        geom->push_back( center.x() - halfWidthMeters, center.y() - halfHeightMeters, center.z());
        geom->push_back( center.x() + halfWidthMeters, center.y() - halfHeightMeters, center.z());
        geom->push_back( center.x() + halfWidthMeters, center.y() + halfHeightMeters, center.z());
        geom->push_back( center.x() - halfWidthMeters, center.y() + halfHeightMeters, center.z());        
    }

    return geom;
}
