/**
 * AnalyzerBeans
 * Copyright (C) 2014 Neopost - Customer Information Management
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.eobjects.analyzer.util;

import java.util.Arrays;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.metamodel.util.BaseObject;

/**
 * Represents a combination of values that are of interest to the user.
 * Typically such a combination is used to find dependencies between the values
 * of a couple of columns.
 * 
 * A ValueCombination has proper hashCode and equals methods. It also implements
 * Comparable, comparing value-by-value.
 * 
 * 
 */
public class ValueCombination<E> extends BaseObject implements Comparable<ValueCombination<E>> {

    private static final Logger logger = LoggerFactory.getLogger(ValueCombination.class);
    private final E[] _values;

    @SafeVarargs
    public ValueCombination(E... values) {
        _values = values;
    }

    @Override
    protected void decorateIdentity(List<Object> identifiers) {
        identifiers.add(_values);
    }

    public int getValueCount() {
        return _values.length;
    }

    public E getValueAt(int index) {
        return _values[index];
    }

    @Override
    public String toString() {
        return "ValueCombination[" + Arrays.toString(_values) + "]";
    }

    @Override
    public int compareTo(ValueCombination<E> o) {
        if (this.equals(o)) {
            return 0;
        }
        int count1 = this.getValueCount();
        int count2 = o.getValueCount();
        int minCount = Math.min(count1, count2);
        for (int i = 0; i < minCount; i++) {
            E value1 = this.getValueAt(i);
            E value2 = o.getValueAt(i);
            if (value1 == null || value2 == null) {
                if (value1 != null) {
                    return -1;
                }
                if (value2 != null) {
                    return 1;
                }
            } else if (value1 instanceof Comparable) {
                try {
                    @SuppressWarnings("unchecked")
                    int result = ((Comparable<E>) value1).compareTo(value2);
                    if (result != 0) {
                        return result;
                    }
                } catch (Exception e) {
                    // do nothing - the typecase to Comparable<E> was
                    // invalid
                    logger.warn("Could not compare {} and {}, comparable threw exception: {}", new Object[] { value1,
                            value2, e.getMessage() });
                    logger.debug("Comparable threw exception", e);
                }
            } else {
                logger.warn("Could not compare {} and {}, not comparable", value1, value2);
            }
        }
        int result = count1 - count2;
        if (result == 0) {
            result = -1;
        }
        return result;
    }
}