/**
    * File: 	CirculinearDomain2DUtils.java
    * Project: javaGeom
    * 
    * Distributed under the LGPL License.
    *
    * Created: 16 mai 09
    */
   package math.geom2d.circulinear;
  
  import java.util.ArrayList;
  import java.util.Collection;
  
  import math.geom2d.Shape2D;
  
  
  /**
   * Some utilities for working with circulinear curves.
   * @author dlegland
   *
   */
  public class CirculinearDomain2DUtils {
  	
  	public final static CirculinearDomain2D computeBuffer(
  			CirculinearDomain2D domain, double dist) {
  		
  		ArrayList<CirculinearContour2D> rings =
  			new ArrayList<CirculinearContour2D>();
  		
  		// iterate on all continuous curves
  		for(CirculinearContour2D cont : 
  			domain.getBoundary().getContinuousCurves()) {
  			// split the curve into a set of non self-intersecting curves
  			for(CirculinearContinuousCurve2D simpleCurve : 
  				CirculinearCurve2DUtils.splitContinuousCurve(cont)) {
  				CirculinearContour2D boundary = 
  					new BoundaryPolyCirculinearCurve2D<CirculinearContinuousCurve2D>(
  							simpleCurve.getSmoothPieces());
  				// compute the rings composing the simple curve buffer
  				rings.addAll(computeBufferSimpleRing(boundary, dist));
  			}
  		}
  		
  		// All the rings are created, we can now create a new domain with the
  		// set of rings
  		return new GenericCirculinearDomain2D(
  				new CirculinearBoundarySet2D<CirculinearContour2D>(rings));
  	}
  	
  	/**
  	 * Computes the rings that form the domain of a circulinear curve which
  	 * does not self-intersect.
  	 */
  	public final static Collection<CirculinearContour2D> 
  	computeBufferSimpleRing(CirculinearContour2D curve, double d) {
  		
  		// prepare an array to store the set of rings
  		ArrayList<CirculinearContour2D> rings =
  			new ArrayList<CirculinearContour2D>();
  		
  		// the parallel in the positive side
  		CirculinearContinuousCurve2D parallel1 = curve.getParallel(d);
  		
  		// split each parallel into continuous curves
  		CirculinearCurveSet2D<CirculinearContinuousCurve2D> curves =
  			new CirculinearCurveSet2D<CirculinearContinuousCurve2D>();
  		
  		// select only curve parts which do not cross original curve
  		for(CirculinearContinuousCurve2D split : 
  				CirculinearCurve2DUtils.splitContinuousCurve(parallel1)) {
  			if(CirculinearCurve2DUtils.findIntersections(curve, split).size()==0)
  				curves.addCurve(split);
  		}
  		
  		// create a new boundary for each parallel curve
  		for(CirculinearContinuousCurve2D split : curves) {
  			rings.add(
  					new BoundaryPolyCirculinearCurve2D<CirculinearContinuousCurve2D>(
  							split.getSmoothPieces(), split.isClosed()));
  		}
  		
  		// prepare an array to store the set of rings
  		ArrayList<CirculinearContour2D> rings2 =
  			new ArrayList<CirculinearContour2D>();
  
  		// iterate on the set of rings
  		for(CirculinearContour2D ring : rings)
  			// split rings into curves which do not self-intersect
  			for(CirculinearContinuousCurve2D split : 
  				CirculinearCurve2DUtils.splitContinuousCurve(ring)) {
  				
  				// compute distance to original curve
  				// (assuming it is sufficient to compute distance to vertices
  				// of the reference curve).
  				double dist = CirculinearCurve2DUtils.getDistanceCurvePoints(
  						curve, split.getSingularPoints());
  				
  				// check if distance condition is verified
  				if(dist-d<-Shape2D.ACCURACY)
 					continue;
 				
 				// convert the set of elements to a Circulinear ring
 				rings2.add(
 						new BoundaryPolyCirculinearCurve2D<CirculinearContinuousCurve2D>(
 								split.getSmoothPieces(), split.isClosed()));
 		}
 		
 		// return the set of created rings
 		return rings2;
 	}
 }