/* Copyright (C) 2014-2015 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;

import org.hecl.*;
import java.math.BigDecimal;
import java.math.MathContext;
import com.udojava.evalex.Expression;

/**
 * AssertCmd implements the "assert" command, which verifies that
 * an assertion is fulfilled. Actually a mathematical expression is evaluated. If it returns
 * not 1 (== true), an exception is raised.
 * assert "$h > 200" InputCheck
 */

public class AssertCmd implements Command {
    boolean debug = false;
    
    public AssertCmd () {
    }
    
    @Override
    public Thing cmdCode(Interp interp, Thing[] argv) throws HeclException {
        assert argv.length > 0;
        if (debug) System.out.println(argv[0].toString());
        
        String msg = "";
        String expression;
        
        switch (argv.length - 1) {
            case 2:
                msg = StringThing.get(argv[2]);
            case 1:
                expression = StringThing.get(argv[1]);
                break;
            default:
                throw new HeclException ("Illegal nb of arguments.");
        }
        
        // Calculate the mathematical value of the expression
        Expression expr = new Expression(expression, MathContext.DECIMAL64);
        // The expression is true if the result is 1.0
        BigDecimal result = expr.eval();
        // The comparision returns 0 in case of equality
        boolean assertioniscorrect;
        assertioniscorrect = result.compareTo(new BigDecimal(1)) == 0;
        
        if (assertioniscorrect) {
            // do nothing
            if (debug) System.out.println("Correct assertion: " + expression);
        } else {
            System.err.println("Failed assertion: " + msg);
            System.err.println(expression);
            throw new HeclException ("Assertion failed!");
        }
	return null;
    }
}