/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2014 by RapidMiner and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapidminer.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.learner.associations;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;

import com.rapidminer.tools.Tools;

/**
 * A frequent item set contains a set of frequent {@link Item}s.
 * 
 * @author Sebastian Land, Ingo Mierswa
 */
public class FrequentItemSet implements Comparable<FrequentItemSet>, Cloneable, Serializable {

    private static final long serialVersionUID = 180867073198503510L;

    private ArrayList<Item> items;

    private int frequency;

    public FrequentItemSet() {
        this.items = new ArrayList<Item>(1);
    }

    public FrequentItemSet(ArrayList<Item> items, int frequency) {
        this.items = items;
        Collections.sort(this.items);
        this.frequency = frequency;
    }

    public void addItem(Item item, int frequency) {
        items.add(item);
        Collections.sort(this.items);
        this.frequency = frequency;
    }

    public Collection<Item> getItems() {
        return items;
    }

    public Item getItem(int index) {
        return items.get(index);
    }

    public int getNumberOfItems() {
        return items.size();
    }

    public int getFrequency() {
        return frequency;
    }

    /**
     * This method compares FrequentItemSets. It first compares the length of items sets, then the items itself. If they are the same, the Sets are
     * equal.
     */
    @Override
    public int compareTo(FrequentItemSet o) {
        // compare size
        Collection<Item> hisItems = o.getItems();
        if (items.size() < hisItems.size()) {
            return -1;
        } else if (items.size() > hisItems.size()) {
            return 1;
        } else {
            // compare items
            Iterator<Item> iterator = hisItems.iterator();
            for (Item myCurrentItem : this.items) {
                int relation = myCurrentItem.compareTo(iterator.next());
                if (relation != 0) {
                    return relation;
                }
            }
            // equal sets
            return 0;
        }
    }

    /**
     * this method returns true if the frequent Items set are equal in size and items.
     */
    @Override
    public boolean equals(Object o) {
        if (o instanceof FrequentItemSet) {
            return (this.compareTo((FrequentItemSet) o) == 0);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return items.hashCode();
    }

    /**
     * This method returns a representation of the items
     */
    public String getItemsAsString() {
        StringBuffer buffer = new StringBuffer();
        Iterator<Item> iterator = items.iterator();
        while (iterator.hasNext()) {
            buffer.append(iterator.next().toString());
            if (iterator.hasNext()) {
                buffer.append(", ");
            }
        }
        return buffer.toString();
    }

    /**
     * This method should return a proper String representation of this frequent Item Set
     */
    @Override
    public String toString() {
        StringBuffer buffer = new StringBuffer();
        Iterator<Item> iterator = items.iterator();
        while (iterator.hasNext()) {
            buffer.append(iterator.next().toString());
            if (iterator.hasNext()) {
                buffer.append(", ");
            }
        }
        buffer.append(", frequency: ");
        buffer.append(Tools.formatNumber(frequency));
        return buffer.toString();
    }

    @Override
    public Object clone() {
        return new FrequentItemSet(new ArrayList<Item>(items), frequency);
    }
}