/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library 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;
 *    version 2.1 of the License.
 *
 *    This library 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.
 */
package org.geotools.renderer.crs;

import org.geotools.geometry.jts.ReferencedEnvelope;
import org.geotools.referencing.CRS;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.geotools.referencing.operation.projection.MapProjection;
import org.geotools.referencing.operation.projection.PolarStereographic;
import org.geotools.referencing.operation.projection.TransverseMercator;
import org.geotools.referencing.operation.projection.MapProjection.AbstractProvider;
import org.opengis.parameter.ParameterValue;

/**
 * Returns a {@link ProjectionHandler} for the {@link TransverseMercator} projection
 * that will cut geometries 45° away from the projection central meridian  
 * 
 * @author Andrea Aime - OpenGeo
 *
 * @source $URL: http://svn.osgeo.org/geotools/trunk/modules/library/render/src/main/java/org/geotools/renderer/crs/PolarStereographicHandlerFactory.java $
 */
public class PolarStereographicHandlerFactory implements ProjectionHandlerFactory {

    public ProjectionHandler getHandler(ReferencedEnvelope renderingEnvelope, boolean wrap) {
        MapProjection mapProjection = CRS.getMapProjection(renderingEnvelope
                .getCoordinateReferenceSystem());
        if (renderingEnvelope != null && mapProjection instanceof PolarStereographic) {
            boolean north;
            // variant B uses standard_parallel
            ParameterValue<?> stdParallel = mapProjection.getParameterValues().parameter(
                    AbstractProvider.STANDARD_PARALLEL_1.getName().getCode());
            if(stdParallel != null) {
                north = stdParallel.doubleValue() > 0;
            } else {
                // variant A uses latitude of origin
                ParameterValue<?> latOrigin = mapProjection.getParameterValues().parameter(
                        AbstractProvider.LATITUDE_OF_ORIGIN.getName().getCode());
                if(latOrigin != null) {
                    north = latOrigin.doubleValue() > 0;
                } else {
                    return null;
                }
            }

            ReferencedEnvelope validArea;
            if(north) {
                validArea = new ReferencedEnvelope(-Double.MAX_VALUE, Double.MAX_VALUE, -0, 90, DefaultGeographicCRS.WGS84);
            } else {
                validArea = new ReferencedEnvelope(-Double.MAX_VALUE, Double.MAX_VALUE, -90, 0, DefaultGeographicCRS.WGS84);
            }
            
            return new ProjectionHandler(renderingEnvelope, validArea);
        }

        return null;
    }

}