/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2006, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * 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 Street, Fifth Floor, Boston, MA  02110-1301, 
 * USA.  
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 *
 * --------------------
 * TimePeriodValue.java
 * --------------------
 * (C) Copyright 2003-2006, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: TimePeriodValue.java,v 1.4.2.2 2006/10/03 15:16:33 mungady Exp $
 *
 * Changes
 * -------
 * 22-Apr-2003 : Version 1 (DG);
 * 03-Oct-2006 : Added null argument check to constructor (DG);
 *
 */

package org.jfree.data.time;

import java.io.Serializable;

/**
 * Represents a time period and an associated value.
 */
public class TimePeriodValue implements Cloneable, Serializable {

    /** For serialization. */
    private static final long serialVersionUID = 3390443360845711275L;
    
    /** The time period. */
    private TimePeriod period;

    /** The value associated with the time period. */
    private Number value;

    /**
     * Constructs a new data item.
     *
     * @param period  the time period (<code>null</code> not permitted).
     * @param value  the value associated with the time period.
     * 
     * @throws IllegalArgumentException if <code>period</code> is 
     *     <code>null</code>.
     */
    public TimePeriodValue(TimePeriod period, Number value) {
        if (period == null) {
            throw new IllegalArgumentException("Null 'period' argument.");
        }
        this.period = period;
        this.value = value;
    }

    /**
     * Constructs a new data item.
     *
     * @param period  the time period (<code>null</code> not permitted).
     * @param value  the value associated with the time period.
     * 
     * @throws IllegalArgumentException if <code>period</code> is 
     *     <code>null</code>.
     */
    public TimePeriodValue(TimePeriod period, double value) {
        this(period, new Double(value));
    }

    /**
     * Returns the time period.
     *
     * @return The time period (never <code>null</code>).
     */
    public TimePeriod getPeriod() {
        return this.period;
    }

    /**
     * Returns the value.
     *
     * @return The value (possibly <code>null</code>).
     * 
     * @see #setValue(Number)
     */
    public Number getValue() {
        return this.value;
    }

    /**
     * Sets the value for this data item.
     *
     * @param value  the new value (<code>null</code> permitted).
     * 
     * @see #getValue()
     */
    public void setValue(Number value) {
        this.value = value;
    }

    /**
     * Tests this object for equality with the target object.
     *
     * @param obj  the object (<code>null</code> permitted).
     *
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof TimePeriodValue)) {
            return false;
        }

        TimePeriodValue timePeriodValue = (TimePeriodValue) obj;

        if (this.period != null ? !this.period.equals(timePeriodValue.period) 
                : timePeriodValue.period != null) {
            return false;
        }
        if (this.value != null ? !this.value.equals(timePeriodValue.value) 
                : timePeriodValue.value != null) {
            return false;
        }

        return true;
    }

    /**
     * Returns a hash code value for the object.
     *
     * @return The hashcode
     */
    public int hashCode() {
        int result;
        result = (this.period != null ? this.period.hashCode() : 0);
        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
        return result;
    }

    /**
     * Clones the object.
     * <P>
     * Note: no need to clone the period or value since they are immutable 
     * classes.
     *
     * @return A clone.
     */
    public Object clone() {
        Object clone = null;
        try {
            clone = super.clone();
        }
        catch (CloneNotSupportedException e) { // won't get here...
            e.printStackTrace();
        }
        return clone;
    }

}
