WktStandard.java

/**
 * Copyright (c) Codice Foundation
 * <p/>
 * This 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 3 of the
 * License, or any later version.
 * <p/>
 * 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. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package ddf.util;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang.StringUtils;

import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKTReader;

/**
 * <p>
 * WktStandard supports converting WKT into standard representations based on the WKT grammar in the
 * OpenGIS Simple Feature Access specification.
 * </p>
 * <p>
 * DDF normalizes MULTIPOINT geometries to the style defined by the WKT grammar. For example,
 * <code>MULTIPOINT ((0 0), (10 10))</code> is in the normalized format. Some systems require a
 * different format of MULTIPOINT. The previous example would denormalize as
 * <code>MULTIPOINT (0 0, 10 10)</code>
 * </p>
 *
 * @author ddf.isgs@lmco.com
 *
 */
public class WktStandard {

    private static final GeometryFactory GEOMETRY_FACTORY = new GeometryFactory();

    private static final Pattern WKT_MULTIPOINT_PATTERN = Pattern.compile(
            "MULTIPOINT\\s*\\(((\\s*\\(\\s*\\-?\\d+(\\.\\d*)?\\s+\\-?\\d+(\\.\\d*)?\\s*\\)\\s*,?\\s*)+)\\)",
            Pattern.CASE_INSENSITIVE);

    /**
     * Hiding class constructor since this is a utility class
     */
    private WktStandard() {

    }

    /**
     * Normalize the given WKT to conform to the WKT grammar.
     *
     *
     * @param wkt
     *            WKT to normalize
     * @return normalized WKT
     */
    public static String normalize(String wkt) {
        if (StringUtils.isBlank(wkt)) {
            return wkt;
        }

        WKTReader wktReader = new WKTReader(GEOMETRY_FACTORY);
        try {
            // using JTS to normalize WKT into the correct format
            return wktReader.read(wkt).toText();
        } catch (ParseException e) {
            throw new IllegalArgumentException("Cannot parse wkt.", e);
        }
    }

    /**
     * Denormalize the given WKT to support backwards compatibility.
     *
     * @param wkt
     *            wkt to denormalize
     * @return denormalized WKT
     */
    public static String denormalize(String wkt) {
        if (wkt == null) {
            return wkt;
        }

        Matcher matcher = WKT_MULTIPOINT_PATTERN.matcher(wkt);
        if (matcher.find()) {
            matcher.reset();
            StringBuffer resultWkt = new StringBuffer(wkt.length());
            while (matcher.find()) {
                String currentMultiPoint = matcher.group(0);
                String currentMultiPointText = matcher.group(1);

                matcher.appendReplacement(resultWkt, currentMultiPoint
                                .replace(currentMultiPointText,
                                        currentMultiPointText.replaceAll("[\\(\\)]", "")));
            }
            matcher.appendTail(resultWkt);

            return resultWkt.toString();
        } else {
            return wkt;
        }
    }
}