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/*

 * The JCS Conflation Suite (JCS) is a library of Java classes that

 * can be used to build automated or semi-automated conflation solutions.

 *

 * Copyright (C) 2003 Vivid Solutions

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

 *

 * For more information, contact:

 *

 * Vivid Solutions

 * Suite #1A

 * 2328 Government Street

 * Victoria BC  V8T 5G5

 * Canada

 *

 * (250)385-6040

 * www.vividsolutions.com

 */

package com.vividsolutions.jcs.conflate.coverage.snap;

import com.vividsolutions.jts.geom.*;

import java.util.*;

/**

 * Note: this class is not thread-safe.

 */

public class CoordinateSnapper {

  public Coordinate closestPt(List closePts, Coordinate pt)

  {

    Coordinate closestPt = null;

    double minDistance = 0.0;

    for (Iterator i = closePts.iterator(); i.hasNext(); ) {

      Coordinate closePt = (Coordinate) i.next();

      double distance = closePt.distance(pt);

      if (closestPt == null || distance < minDistance) {

        closestPt = closePt;

        minDistance = distance;

      }

    }

    return closestPt;

  }

  private SlowPointIndex ptIndex;

  private Envelope queryEnv = new Envelope();

  public CoordinateSnapper(SlowPointIndex ptIndex)

  {

    this.ptIndex = ptIndex;

  }

  /**

   * Compute the closest point within the given distance, if any.

   * @param pt

   * @param distance

   * @return the reference point to snap to, if any

   *   the original point if there were no reference points within the given distance

   */

  public Coordinate snap(Coordinate pt, double distance)

  {

    queryEnv.init(pt.x - distance, pt.x + distance, pt.y - distance, pt.y + distance);

    List closePts = ptIndex.query(queryEnv);

    Coordinate closestPt = closestPt(closePts, pt);

    if (closestPt == null) return pt;

    return closestPt;

  }

}