package org.cpsolver.ifs.termination;

import org.cpsolver.ifs.model.Value;
import org.cpsolver.ifs.model.Variable;
import org.cpsolver.ifs.solution.Solution;
import org.cpsolver.ifs.util.DataProperties;

/**
 * General implementation of termination condition for minimal perturbation
 * problem. <br>
 * <br>
 * Solver stops when a timeout is reached (expressed either by the number of
 * iterations or by a time) or when an acceptable complete (all variables are
 * assigned) solution is found. The acceptance of a solution is expressed either
 * by the minimal number of variables assigned to not-initial values or by the
 * perturbations penalty. <br>
 * <br>
 * Parameters: <br>
 * <table border='1' summary='Related Solver Parameters'>
 * <tr>
 * <th>Parameter</th>
 * <th>Type</th>
 * <th>Comment</th>
 * </tr>
 * <tr>
 * <td>Termination.StopWhenComplete</td>
 * <td>{@link Double}</td>
 * <td>if true, solver stops when a complete solution is found</td>
 * </tr>
 * <tr>
 * <td>Termination.MaxIters</td>
 * <td>{@link Integer}</td>
 * <td>if zero or positive, solver stops when the given number of iteration is
 * reached</td>
 * </tr>
 * <tr>
 * <td>Termination.TimeOut</td>
 * <td>{@link Double}</td>
 * <td>if zero or positive, solver stops when the given timeout (given in
 * seconds) is reached</td>
 * </tr>
 * <tr>
 * <td>Termination.MinPerturbances</td>
 * <td>{@link Integer}</td>
 * <td>if zero or positive, solver stops when the solution is complete and the
 * number of variables with non-initial values is below or equal to this limit</td>
 * </tr>
 * <tr>
 * <td>Termination.MinPerturbationPenalty</td>
 * <td>{@link Double}</td>
 * <td>if zero or positive, solver stops when the solution is complete and when
 * the perturbation penaly of the solution is below or equal to this limit</td>
 * </tr>
 * </table>
 * 
 * @see org.cpsolver.ifs.solver.Solver
 * @see org.cpsolver.ifs.perturbations.PerturbationsCounter
 * 
 * @version IFS 1.3 (Iterative Forward Search)<br>
 *          Copyright (C) 2006 - 2014 Tomas Muller<br>
 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
 * <br>
 *          This library 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 of the
 *          License, or (at your option) any later version. <br>
 * <br>
 *          This library 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 General Public License for more details. <br>
 * <br>
 *          You should have received a copy of the GNU Lesser General Public
 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
 *
 * @param <V> Variable
 * @param <T> Value
 **/
public class MPPTerminationCondition<V extends Variable<V, T>, T extends Value<V, T>> implements
        TerminationCondition<V, T> {
    protected static org.apache.log4j.Logger sLogger = org.apache.log4j.Logger.getLogger(MPPTerminationCondition.class);
    private int iMinPerturbances;
    private int iMaxIter;
    private double iTimeOut;
    private double iMinPertPenalty;
    private boolean iStopWhenComplete;

    public MPPTerminationCondition(DataProperties properties) {
        iMaxIter = properties.getPropertyInt("Termination.MaxIters", -1);
        iTimeOut = properties.getPropertyDouble("Termination.TimeOut", -1.0);
        iMinPerturbances = properties.getPropertyInt("Termination.MinPerturbances", -1);
        iStopWhenComplete = properties.getPropertyBoolean("Termination.StopWhenComplete", false);
        iMinPertPenalty = properties.getPropertyDouble("Termination.MinPerturbationPenalty", -1.0);
    }

    public MPPTerminationCondition(int maxIter, double timeout, int minPerturbances) {
        iMaxIter = maxIter;
        iMinPerturbances = minPerturbances;
        iTimeOut = timeout;
    }

    @Override
    public boolean canContinue(Solution<V, T> currentSolution) {
        if (iMinPerturbances >= 0 && currentSolution.getAssignment().nrUnassignedVariables(currentSolution.getModel()) == 0
                && currentSolution.getModel().perturbVariables(currentSolution.getAssignment()).size() <= iMinPerturbances) {
            sLogger.info("A complete solution with allowed number of perturbances found.");
            return false;
        }
        if (iMinPertPenalty >= 0.0
                && currentSolution.getAssignment().nrUnassignedVariables(currentSolution.getModel()) == 0
                && currentSolution.getPerturbationsCounter().getPerturbationPenalty(currentSolution.getAssignment(), currentSolution.getModel()) <= iMinPertPenalty) {
            sLogger.info("A complete solution with allowed perturbation penalty found.");
            return false;
        }
        if (iMaxIter >= 0 && currentSolution.getIteration() >= iMaxIter) {
            sLogger.info("Maximum number of iteration reached.");
            return false;
        }
        if (iTimeOut >= 0 && currentSolution.getTime() > iTimeOut) {
            sLogger.info("Timeout reached.");
            return false;
        }
        if (iStopWhenComplete || (iMaxIter < 0 && iTimeOut < 0)) {
            boolean ret = (currentSolution.getAssignment().nrUnassignedVariables(currentSolution.getModel()) != 0);
            if (!ret)
                sLogger.info("Complete solution found.");
            return ret;
        }
        return true;
    }

}
