/* 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.*;

/**
 * GeomExtendCmd implements the "geom.extend" command, which returns 
 * two points on the line.
 */

public class GeomExtendCmd implements Command {
    boolean debug = false;
    
    public GeomExtendCmd () {
    }
    
    @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();
        }
        
        if (argd.length < 4) throw new HeclException ("Illegal nb of arguments.");
        
        assert (argd.length >= 5);
        double x0 = argd[0];
        double y0 = argd[1];
        double x1 = argd[2];
        double y1 = argd[3];
        
        double dx = x1 - x0;
        double dy = y1 - y0;
        double L = Math.hypot(dx, dy);
        
        double[] A = new double[2];
        double[] B = new double[2];
        
        switch (argd.length) {
            case 6: // x0 y0 x1 y1 dLA dLB
                double dLA = argd[4];
                double dLB = argd[5];
                B[0] = x1 + dLB * dx/L;
                B[1] = y1 + dLB * dy/L;
                A[0] = x0 - dLA * dx/L;
                A[1] = y0 - dLA * dy/L;
                break;
            case 5: // x0 y0 x1 y1 dL
                double dL = argd[4];
                B[0] = x1 + dL * dx/L;
                B[1] = y1 + dL * dy/L;
                A[0] = x0 - dL * dx/L;
                A[1] = y0 - dL * dy/L;
                break;
            default:
                throw new HeclException ("Illegal nb of arguments.");
        }
        
        String xAstr = StringThing.get(DoubleThing.create(A[0]));
        String yAstr = StringThing.get(DoubleThing.create(A[1]));
        String xBstr = StringThing.get(DoubleThing.create(B[0]));
        String yBstr = StringThing.get(DoubleThing.create(B[1]));
        String answer = xAstr + " " + yAstr + " " + xBstr + " " + yBstr;
                
	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;
    }
}