// Catalano Machine Learning Library
// The Catalano Framework
//
// Copyright © Diego Catalano, 2012-2016
// diego.catalano at live.com
//
// Copyright © Andrew Kirillov, 2007-2008
// andrew.kirillov@gmail.com
//
//    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 2.1 of the License, or (at your option) any later version.
//
//    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.
//
//    You should have received a copy of the GNU Lesser General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//

package Catalano.MachineLearning.Exploration;

import java.util.Arrays;

/**
 * Tabu search exploration policy.
 * The class implements simple tabu search exploration policy,
 * allowing to set certain actions as tabu for a specified amount of
 * iterations. The actual exploration and choosing from non-tabu actions
 * is done by base exploration policy.
 * @author Diego Catalano
 */
public class TabuSearchExploration implements IExplorationPolicy {
    private int actions;
    private int[] tabuActions = null;
    private IExplorationPolicy basePolicy;

    /**
     * Initializes a new instance of the TabuSearchExploration
     * @param actions Total actions count.
     * @param basePolicy Base exploration policy.
     */
    public TabuSearchExploration(int actions, IExplorationPolicy basePolicy) {
        this.actions = actions;
        this.basePolicy = basePolicy;
        tabuActions = new int[actions];
    }

    /**
     * Base exploration policy.
     * @return Base policy
     */
    public IExplorationPolicy getBasePolicy() {
        return basePolicy;
    }

    /**
     * Base exploration policy.
     * Base exploration policy is the policy, which is used to choose from non-tabu actions.
     * @param basePolicy 
     */
    public void setBasePolicy(IExplorationPolicy basePolicy) {
        this.basePolicy = basePolicy;
    }
    
    @Override
    public int ChooseAction(double[] actionEstimates){
        // get amount of non-tabu actions
        int nonTabuActions = actions;
        for ( int i = 0; i < actions; i++ )
        {
            if ( tabuActions[i] != 0 )
            {
                nonTabuActions--;
            }
        }

        // allowed actions
        double[] allowedActionEstimates = new double[nonTabuActions];
        int[]    allowedActionMap = new int[nonTabuActions];

        for ( int i = 0, j = 0; i < actions; i++ )
        {
            if ( tabuActions[i] == 0 )
            {
                // allowed action
                allowedActionEstimates[j] = actionEstimates[i];
                allowedActionMap[j] = i;
                j++;
            }
            else
            {
                // decrease tabu time of tabu action
                tabuActions[i]--;
            }
        }

        return allowedActionMap[basePolicy.ChooseAction( allowedActionEstimates )];
    }
    
    /**
     * Reset tabu list.
     * Clears tabu list making all actions allowed.
     */
    public void ResetTabuList( )
    {
        //Array.Clear( tabuActions, 0, actions );
        Arrays.fill(tabuActions, 0, actions,0);
    }
    
}