/*
 * The JTS Topology Suite is a collection of Java classes that
 * implement the fundamental operations required to validate a given
 * geo-spatial data set to a known topological specification.
 *
 * Copyright (C) 2001 Vivid Solutions
 *
 * 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; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; 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.revolsys.geometry.linearref;

import com.revolsys.geometry.model.Geometry;
import com.revolsys.geometry.model.LineString;
import com.revolsys.geometry.model.Point;

/**
 * Determines the location of a subline along a linear {@link Geometry}.
 * The location is reported as a pair of {@link LinearLocation}s.
 * <p>
 * <b>Note:</b> Currently this algorithm is not guaranteed to
 * return the correct substring in some situations where
 * an endpoint of the test line occurs more than once in the input line.
 * (However, the common case of a ring is always handled correctly).
 */
class LocationIndexOfLine {
  /**
   * MD - this algorithm has been extracted into a class
   * because it is intended to validate that the subline truly is a subline,
   * and also to use the internal vertex information to unambiguously locate the subline.
   */
  public static LinearLocation[] indicesOf(final Geometry linearGeom, final Geometry subLine) {
    final LocationIndexOfLine locater = new LocationIndexOfLine(linearGeom);
    return locater.indicesOf(subLine);
  }

  private final Geometry linearGeom;

  public LocationIndexOfLine(final Geometry linearGeom) {
    this.linearGeom = linearGeom;
  }

  public LinearLocation[] indicesOf(final Geometry subLine) {
    final Point startPt = ((LineString)subLine.getGeometry(0)).getPoint(0);
    final LineString lastLine = (LineString)subLine.getGeometry(subLine.getGeometryCount() - 1);
    final Point endPt = lastLine.getPoint(lastLine.getVertexCount() - 1);

    final LocationIndexOfPoint locPt = new LocationIndexOfPoint(this.linearGeom);
    final LinearLocation[] subLineLoc = new LinearLocation[2];
    subLineLoc[0] = locPt.indexOf(startPt);

    // check for case where subline is zero length
    if (subLine.getLength() == 0.0) {
      subLineLoc[1] = (LinearLocation)subLineLoc[0].clone();
    } else {
      subLineLoc[1] = locPt.indexOfAfter(endPt, subLineLoc[0]);
    }
    return subLineLoc;
  }
}