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/**
 * Copyright (C) 2010-2018 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite 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
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see .
 */
package org.evosuite.symbolic.solver;

import java.util.Collection;

import org.evosuite.symbolic.expr.Constraint;
import org.evosuite.symbolic.expr.DistanceCalculator;
import org.evosuite.symbolic.expr.IntegerConstraint;
import org.evosuite.symbolic.expr.RealConstraint;
import org.evosuite.symbolic.expr.StringConstraint;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 
 * Abstract DistanceEstimator class.
 * 
 * 
 * @author krusev
 */
public abstract class DistanceEstimator {

	static Logger log = LoggerFactory.getLogger(DistanceEstimator.class);

	// static Logger log =
	// JPF.getLogger("org.evosuite.symbolic.search.DistanceEstimator");

	private static double normalize(double x) {
		return x / (x + 1.0);
	}

	/**
	 * 
	 * getDistance
	 * 
	 * 
	 * @param constraints
	 *            a {@link java.util.Collection} object.
	 * @return normalized distance in [0,1]
	 */
	public static double getDistance(Collection> constraints) {
		double result = 0;

		DistanceCalculator distanceCalculator = new DistanceCalculator();
		try {
			for (Constraint c : constraints) {

				if (c instanceof StringConstraint) {
					StringConstraint string_constraint = (StringConstraint) c;

					try {
						double strD = (double) string_constraint.accept(
								distanceCalculator, null);
						result += normalize(strD);
						log.debug("S: " + string_constraint + " strDist "
								+ strD);
					} catch (Throwable t) {
						log.debug("S: " + string_constraint + " strDist " + t);
						result += 1.0;
					}

				} else if (c instanceof IntegerConstraint) {

					IntegerConstraint integer_constraint = (IntegerConstraint) c;
					long intD = (long) integer_constraint.accept(
							distanceCalculator, null);
					result += normalize(intD);
					log.debug("C: " + integer_constraint + " intDist " + intD);

				} else if (c instanceof RealConstraint) {
					RealConstraint real_constraint = (RealConstraint) c;
					double realD = (double) real_constraint.accept(
							distanceCalculator, null);
					
					result += normalize(realD);
					log.debug("C: " + real_constraint + " realDist " + realD);

				} else {
					throw new IllegalArgumentException(
							"DistanceCalculator: got an unknown constraint: "
									+ c);
				}
			}
			log.debug("Resulting distance: " + result);
			return Math.abs(result);

		} catch (Exception e) {
			return Double.MAX_VALUE;
		}
	}

}