/* Copyright (C) 2014 A.Vontobel  
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * The license is in LICENCE-GPL.txt.
 * If not, see http://www.gnu.org/licenses/old-licenses/gpl-2.0.html.
 */

package net.sf.drawj2d.cmd.geom;

import java.util.ArrayList;
import java.util.Arrays;
import org.hecl.*;
import no.geosoft.cc.geometry.Geometry;

/**
 * GeomIntersectlinepathCmd implements the "geom.intersectlinepath" command, which returns
 * the first intersection point of the extensions of a line with a path.
 * If the extension of the line does not intersect the path, an exception is raised.
 */

public class GeomIntersectlinepathCmd implements Command {
    boolean debug = false;
    
    public GeomIntersectlinepathCmd () {
    }
    
    @Override
    public Thing cmdCode(Interp interp, Thing[] argv) throws HeclException {
        assert argv.length > 0;
        if (debug) System.out.println(argv[0].toString());
        
        ArrayList singleargv = splitArgv(argv);
        // Convert the arguments from thing to double.
        int nbsingleargs = singleargv.size(); // without command from argv[0]
        double[] argd = new double[nbsingleargs];
        for (int i = 0; i < nbsingleargs; i++) {
            argd[i] = NumberThing.asNumber(singleargv.get(i)).doubleValue();
        }
        
        String answer;
        
        if (argd.length >= 8 && argd.length % 2 == 0) {
            assert (argd.length - 4) % 2 == 0: "nb of arguments not even";
            int n = (argd.length - 4) / 2;
            double[] pathx = new double[n];
            double[] pathy = new double[n];
            for (int i = 0; i < n; i++) {
                pathx[i] = argd[4 + 2 * i];
                pathy[i] = argd[5 + 2 * i];
            }
            
            double[] intersection = new double[2];
            int intersectionType;
            boolean intersectionfound = false;
            for (int i = 1; i < n; i++) {
                if (intersectionfound) break;
                
                intersectionType = Geometry.findLineSegmentIntersection(argd[0], argd[1], argd[2], argd[3], pathx[i-1], pathy[i-1], pathx[i], pathy[i], intersection);
                switch (intersectionType) {
                    case 1: // Linienabschnitte schneiden sich
                        intersectionfound = true;
                        break;
                    case 0: // Verlängerung der Abschnitte schneiden sich.
                        double[] ponline = Geometry.computePointOnLine(argd[0], argd[1], intersection[0], intersection[1], 1.1);
                        int intersectionTypePath = Geometry.findLineSegmentIntersection(argd[0], argd[1], ponline[0], ponline[1], pathx[i-1], pathy[i-1], pathx[i], pathy[i], intersection);
                        if (intersectionTypePath == 1) intersectionfound = true;
                        else {
                            assert intersectionTypePath == 0;
                        }
                        break;
                    case -1: // Linien parallel
                        break;
                    case -2: // Linien liegen aufeinander
                        if (debug) System.out.println("Linien aufeinander liegend");
                        break;
                    default:
                        assert false;
                }
            }
            
            if (intersectionfound) {
                String xstr = StringThing.get(DoubleThing.create(intersection[0]));
                String ystr = StringThing.get(DoubleThing.create(intersection[1]));
                answer = xstr + " " + ystr;
            } else {
                answer = "none none"; // not used
                // We prefer to raise an error messages over undefined behaviour
                throw new HeclException ("No intersection point.");
            }
        } else {
            throw new HeclException ("Illegal nb of arguments.");
        }
	return new Thing(answer);
    }
    
    /** Make a list of arguments (without command in argv[0]). 
     * Split List arguments to single arguments. */
    private ArrayList splitArgv(Thing[] argv) throws HeclException {
        ArrayList singleargv = new ArrayList(argv.length);
        for (int i = 1; i < argv.length; i++) {
            Thing[] currentargv = ListThing.getArray(argv[i]);
            singleargv.addAll(Arrays.asList(currentargv));
        }
        return singleargv;
    }
}