package org.cpsolver.ifs.example.tt;

import org.cpsolver.ifs.model.Value;

/**
 * Location (value, i.e., a single placement of the activity). Location encodes
 * a slot and a selection of resources.
 * 
 * @author  Tomas Muller
 * @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>.
 */
public class Location extends Value<Activity, Location> {
    private int iSlot;
    private Resource[] iResources;
    private int iNrOfDiscouragedSlots = -1;

    /**
     * Constructor.
     * 
     * @param activity
     *            parent activity
     * @param slot
     *            starting time
     * @param resources
     *            selection of resources
     */
    public Location(Activity activity, int slot, Resource[] resources) {
        super(activity);
        iSlot = slot;
        iResources = resources;
        iNrOfDiscouragedSlots = computeNrOfDiscouragedSlots();
    }

    /**
     * Constructor. slot = nrHours * day + hour
     * 
     * @param activity
     *            parent activity
     * @param day
     *            day
     * @param hour
     *            starting hour
     * @param resources
     *            required resources
     */
    public Location(Activity activity, int day, int hour, Resource[] resources) {
        super(activity);
        iSlot = ((TimetableModel) activity.getModel()).getNrHours() * day + hour;
        iResources = resources;
        iNrOfDiscouragedSlots = computeNrOfDiscouragedSlots();
    }

    /** Gets slot
     * @return slot
     **/
    public int getSlot() {
        return iSlot;
    }

    /** Gets selection of resources
     * @return selection of resources
     **/
    public Resource[] getResources() {
        return iResources;
    }

    /** Gets given resource
     * @param idx index
     * @return given resource
     **/
    public Resource getResource(int idx) {
        return iResources[idx];
    }

    /** Returns true if the given resource is used by this location 
     * @param resource given resource
     * @return true if the given resource is used by this location
     **/
    public boolean containResource(Resource resource) {
        for (int i = 0; i < iResources.length; i++)
            if (iResources[i].equals(resource))
                return true;
        return false;
    }

    /** Number of slots (over all resources) which are discouraged
     * @return number of slots (over all resources) which are discouraged
     **/
    public int getNrOfDiscouragedSlots() {
        return iNrOfDiscouragedSlots;
    }

    /** Placement value (for optimization) -- getNrOfDiscouragedSlots() is returned */
    @Override
    public double toDouble() {
        return iNrOfDiscouragedSlots;
    }

    /**
     * Computes number of discouraged slots (over all resources and the
     * activity)
     * @return number of discouraged slots
     */
    public int computeNrOfDiscouragedSlots() {
        Activity a = variable();
        int ret = 0;
        for (int i = getSlot(); i < getSlot() + a.getLength(); i++) {
            if (a.isDiscouragedSlot(i))
                ret++;
            for (int j = 0; j < getResources().length; j++)
                if (getResource(j).isDiscouragedSlot(i))
                    ret++;
        }
        return ret;
    }

    /**
     * Returns true if the location intersects with another location. This means
     * the same resource is used in the same time.
     * @param location another location
     * @return true if this location intersects with the other location
     */
    public boolean hasIntersection(Location location) {
        int s1 = getSlot();
        int l1 = variable().getLength();
        int s2 = location.getSlot();
        int l2 = location.variable().getLength();
        return !(s1 + l1 <= s2 || s2 + l2 <= s1);
    }

    /**
     * Returns true if the location is prohibited. This means that the activity
     * or a required resource has a time slot which is used by this location
     * prohibited.
     * @return true if the location is prohibited
     */
    public boolean isProhibited() {
        Activity a = variable();
        for (int i = getSlot(); i < getSlot() + a.getLength(); i++) {
            if (a.isProhibitedSlot(i))
                return true;
            for (int j = 0; j < getResources().length; j++)
                if (getResource(j).isProhibitedSlot(i))
                    return true;
        }
        return false;
    }

    @Override
    public String getName() {
        StringBuffer sb = new StringBuffer(getSlot() + "/");
        for (int i = 0; i < iResources.length; i++) {
            if (i > 0)
                sb.append(",");
            sb.append(iResources[i].getName());
        }
        return sb.toString();
    }
}
