/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2010, 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.grid.oblong;

import org.geotools.geometry.jts.ReferencedEnvelope;
import org.geotools.grid.PolygonBuilder;
import org.geotools.grid.PolygonElement;
import org.geotools.grid.Neighbor;

/**
 * Used by {@code Oblongs} class to build grids.
 *
 * @author mbedward
 * @since 2.7
 *
 *
 * @source $URL: http://svn.osgeo.org/geotools/trunk/modules/unsupported/grid/src/main/java/org/geotools/grid/oblong/OblongBuilder.java $
 * @version $Id: Hexagon.java 35637 2010-06-01 09:24:43Z mbedward $
 */
public class OblongBuilder extends PolygonBuilder {
    private final double elementWidth;
    private final double elementHeight;

    OblongBuilder(ReferencedEnvelope bounds, double width, double height) {
        super(bounds);
        this.elementWidth = width;
        this.elementHeight = height;
    }

    @Override
    public boolean isValidNeighbor(Neighbor neighbor) {
        return true;
    }

    /**
     * Creates a new {@code Oblong} positioned at the given neighbor position
     * relative to the reference element.
     *
     * @param el the reference oblong
     *
     * @param neighbor a neighbour position
     *
     * @return a new {@code Oblong} object
     *
     * @throws IllegalArgumentException if either argument is {@code null} or
     *         if {@code el} is not an instance of {@code Oblong}
     */
    @Override
    public Oblong createNeighbor(PolygonElement el, Neighbor neighbor) {
        if (el == null || neighbor == null) {
            throw new IllegalArgumentException(
                    "el and neighbour position must both be non-null");
        }

        if (!(el instanceof Oblong)) {
            throw new IllegalArgumentException("el must be an instance of Oblong");
        }

        Oblong oblong = (Oblong) el;
        ReferencedEnvelope bounds = oblong.getBounds();
        double dx, dy;

        switch (neighbor) {
            case LEFT:
                dx = -bounds.getWidth();
                dy = 0.0;
                break;

            case LOWER:
                dx = 0.0;
                dy = -bounds.getHeight();
                break;

            case LOWER_LEFT:
                dx = -bounds.getWidth();
                dy = -bounds.getHeight();
                break;

            case LOWER_RIGHT:
                dx = bounds.getWidth();
                dy = -bounds.getHeight();
                break;

            case RIGHT:
                dx = bounds.getWidth();
                dy = 0.0;
                break;

            case UPPER:
                dx = 0.0;
                dy = bounds.getHeight();
                break;

            case UPPER_LEFT:
                dx = -bounds.getWidth();
                dy = bounds.getHeight();
                break;

            case UPPER_RIGHT:
                dx = bounds.getWidth();
                dy = bounds.getHeight();
                break;

            default:
                throw new IllegalArgumentException("Unrecognized value for neighbor");
        }

        return Oblongs.create(bounds.getMinX() + dx, bounds.getMinY() + dy,
                bounds.getWidth(), bounds.getHeight(),
                bounds.getCoordinateReferenceSystem());
    }

    @Override
    public boolean isValidDenseVertexSpacing(double v) {
        return v > 0 && v < Math.min(elementWidth, elementHeight) / 2.0;
    }

    @Override
    public PolygonElement getFirstElement() {
        return Oblongs.create(
                gridBounds.getMinX(), gridBounds.getMinY(),
                elementWidth, elementHeight, gridBounds.getCoordinateReferenceSystem());
    }

    @Override
    public PolygonElement getNextXElement(PolygonElement el) {
        return createNeighbor(el, Neighbor.RIGHT);
    }

    @Override
    public PolygonElement getNextYElement(PolygonElement el) {
        return createNeighbor(el, Neighbor.UPPER);
    }

}