/* ===========================================================

 * JFreeChart : a free chart library for the Java(tm) platform

 * ===========================================================

 *

 * (C) Copyright 2000-2004, 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., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 

 * in the United States and other countries.]

 *

 * ---------------

 * XYDataItem.java

 * ---------------

 * (C) Copyright 2003, 2004, by Object Refinery Limited.

 *

 * Original Author:  David Gilbert (for Object Refinery Limited);

 * Contributor(s):   -;

 *

 * $Id: XYDataItem.java,v 1.1 2004/08/31 15:36:12 mungady Exp $

 *

 * Changes

 * -------

 * 05-Aug-2003 : Renamed XYDataPair --> XYDataItem (DG);

 * 03-Feb-2004 : Fixed bug in equals() method (DG);

 *

 */



package org.jfree.data.xy;



import java.io.Serializable;



import org.jfree.util.ObjectUtils;



/**

 * Represents one (x, y) data item for an {@link XYSeries}.

 */

public class XYDataItem implements Cloneable, Comparable, Serializable {



    /** The x-value. */

    private Number x;



    /** The y-value. */

    private Number y;



    /**

     * Constructs a new data item.

     *

     * @param x  the x-value (<code>null</code> NOT permitted).

     * @param y  the y-value (<code>null</code> permitted).

     */

    public XYDataItem(Number x, Number y) {

        if (x == null) {

            throw new IllegalArgumentException("Null 'x' argument.");

        }

        this.x = x;

        this.y = y;

    }



    /**

     * Constructs a new data item.

     *

     * @param x  the x-value.

     * @param y  the y-value.

     */

    public XYDataItem(double x, double y) {

        this(new Double(x), new Double(y));

    }



    /**

     * Returns the x-value.

     *

     * @return The x-value (never <code>null</code>).

     */

    public Number getX() {

        return this.x;

    }



    /**

     * Returns the y-value.

     *

     * @return the y-value (possibly <code>null</code>).

     */

    public Number getY() {

        return this.y;

    }



    /**

     * Sets the y-value for this data item.  Note that there is no corresponding method to 

     * change the x-value.

     *

     * @param y  the new y-value (<code>null</code> permitted).

     */

    public void setY(Number y) {

        this.y = y;

    }



    /**

     * Returns an integer indicating the order of this object relative to another object.

     * <P>

     * For the order we consider only the x-value:

     * negative == "less-than", zero == "equal", positive == "greater-than".

     *

     * @param o1  the object being compared to.

     *

     * @return  an integer indicating the order of this data pair object

     *      relative to another object.

     */

    public int compareTo(final Object o1) {



        final int result;



        // CASE 1 : Comparing to another TimeSeriesDataPair object

        // -------------------------------------------------------

        if (o1 instanceof XYDataItem) {

            final XYDataItem dataItem = (XYDataItem) o1;

            final double compare = this.x.doubleValue() - dataItem.getX().doubleValue();

            if (compare > 0.0) {

                result = 1;

            }

            else {

                if (compare < 0.0) {

                    result = -1;

                }

                else {

                    result = 0;

                }

            }

        }



        // CASE 2 : Comparing to a general object

        // ---------------------------------------------

        else {

            // consider time periods to be ordered after general objects

            result = 1;

        }



        return result;



    }



    /**

     * Returns a clone of this object.

     *

     * @return a clone.

     * 

     * @throws CloneNotSupportedException not thrown by this class, but subclasses may differ.

     */

    public Object clone() throws CloneNotSupportedException {

        return super.clone();

    }

    

    /**

     * Tests if this object is equal to another.

     *

     * @param o  the object to test against for equality (<code>null</code> permitted).

     *

     * @return A boolean.

     */

    public boolean equals(Object o) {



        if (o == null) {

            return false;

        }

        if (o == this) {

            return true;

        }



        if (o instanceof XYDataItem) {

            final XYDataItem item = (XYDataItem) o;

            if (!this.x.equals(item.x)) {

                return false;

            }

            if (!ObjectUtils.equal(this.y, item.y)) {

                return false;

            }



            return true;

        }



        return false;



    }



    /**

     * Returns a hash code.

     * 

     * @return A hash code.

     */

    public int hashCode() {

        int result;

        result = this.x.hashCode();

        result = 29 * result + (this.y != null ? this.y.hashCode() : 0);

        return result;

    }

    

}

