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package com.vividsolutions.jtstest.function;

import com.vividsolutions.jts.algorithm.CGAlgorithms;
import com.vividsolutions.jts.algorithm.CGAlgorithmsDD;
import com.vividsolutions.jts.algorithm.RobustLineIntersector;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;

public class CGAlgorithmFunctions
{
  public static int orientationIndex(Geometry segment, Geometry ptGeom) {
    if (segment.getNumPoints() != 2 || ptGeom.getNumPoints() != 1) {
      throw new IllegalArgumentException("A must have two points and B must have one");
    }
    Coordinate[] segPt = segment.getCoordinates();
    
    Coordinate p = ptGeom.getCoordinate();
    int index = CGAlgorithms.orientationIndex(segPt[0], segPt[1], p);
    return index;
  }

  public static int orientationIndexDD(Geometry segment, Geometry ptGeom) {
    if (segment.getNumPoints() != 2 || ptGeom.getNumPoints() != 1) {
      throw new IllegalArgumentException("A must have two points and B must have one");
    }
    Coordinate[] segPt = segment.getCoordinates();
    
    Coordinate p = ptGeom.getCoordinate();
    int index = CGAlgorithmsDD.orientationIndex(segPt[0], segPt[1], p);
    return index;
  }

  public static boolean segmentIntersects(Geometry g1, Geometry g2)
  {
    Coordinate[] pt1 = g1.getCoordinates();
    Coordinate[] pt2 = g2.getCoordinates();
    RobustLineIntersector ri = new RobustLineIntersector();
    ri.computeIntersection(pt1[0], pt1[1], pt2[0], pt2[1]);
    return ri.hasIntersection();
  }
  
  public static Geometry segmentIntersection(Geometry g1, Geometry g2)
  {
    Coordinate[] pt1 = g1.getCoordinates();
    Coordinate[] pt2 = g2.getCoordinates();
    RobustLineIntersector ri = new RobustLineIntersector();
    ri.computeIntersection(pt1[0], pt1[1], pt2[0], pt2[1]);
    switch (ri.getIntersectionNum()) {
    case 0:
      // no intersection => return empty point
      return g1.getFactory().createPoint((Coordinate) null);
    case 1:
      // return point
      return g1.getFactory().createPoint(ri.getIntersection(0));
    case 2:
      // return line
      return g1.getFactory().createLineString(
          new Coordinate[] {
              ri.getIntersection(0),
              ri.getIntersection(1)
          });
    }
    return null;
  }
  
  public static Geometry segmentIntersectionDD(Geometry g1, Geometry g2)
  {
    Coordinate[] pt1 = g1.getCoordinates();
    Coordinate[] pt2 = g2.getCoordinates();
    
    // first check if there actually is an intersection
    RobustLineIntersector ri = new RobustLineIntersector();
    ri.computeIntersection(pt1[0], pt1[1], pt2[0], pt2[1]);
    if (! ri.hasIntersection()) {
      // no intersection => return empty point
      return g1.getFactory().createPoint((Coordinate) null);
    }
    
    Coordinate intPt = CGAlgorithmsDD.intersection(pt1[0], pt1[1], pt2[0], pt2[1]);
    return g1.getFactory().createPoint(intPt);
  }
  
  
}