/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2005, 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.]
 *
 * ------------------
 * KeyToGroupMap.java
 * ------------------
 * (C) Copyright 2004, 2005, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: KeyToGroupMap.java,v 1.4 2005/02/02 17:55:45 mungady Exp $
 *
 * Changes
 * -------
 * 29-Apr-2004 : Version 1 (DG);
 * 07-Jul-2004 : Added a group list to ensure group index is consistent, fixed cloning 
 *               problem (DG);
 * 
 */

package org.jfree.data;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.jfree.util.ObjectUtilities;
import org.jfree.util.PublicCloneable;

/**
 * A class that maps keys (instances of <code>Comparable</code>) to groups.
 */
public class KeyToGroupMap implements Cloneable, PublicCloneable, Serializable {
    
    /** The default group. */
    private Comparable defaultGroup;
    
    /** The groups. */
    private List groups;
    
    /** A mapping between keys and groups. */
    private Map keyToGroupMap;
    
    /**
     * Creates a new map with a default group named 'Default Group'.
     */
    public KeyToGroupMap() {
        this("Default Group");
    }
    
    /**
     * Creates a new map with the specified default group.
     * 
     * @param defaultGroup  the default group (<code>null</code> not permitted).
     */
    public KeyToGroupMap(Comparable defaultGroup) {
        if (defaultGroup == null) {
            throw new IllegalArgumentException("Null 'defaultGroup' argument.");   
        }
        this.defaultGroup = defaultGroup;
        this.groups = new ArrayList();
        this.keyToGroupMap = new HashMap();
    }
    
    /**
     * Returns the number of groups in the map.
     * 
     * @return The number of groups in the map.
     */
    public int getGroupCount() {
        return this.groups.size() + 1;
    }
    
    /**
     * Returns a list of the groups (always including the default group) in the map.  The
     * returned list is independent of the map, so altering the list will have no effect.
     * 
     * @return The groups (never <code>null</code>).
     */
    public List getGroups() {
        List result = new ArrayList();
        result.add(this.defaultGroup);
        Iterator iterator = this.groups.iterator();
        while (iterator.hasNext()) {
            Comparable group = (Comparable) iterator.next();
            if (!result.contains(group)) {
                result.add(group);   
            }
        } 
        return result;
    }
    
    /**
     * Returns the index for the group.
     * 
     * @param group  the group.
     * 
     * @return The group index (or -1 if the group is not represented within the map).
     */
    public int getGroupIndex(Comparable group) {
        int result = this.groups.indexOf(group);
        if (result < 0) {
            if (this.defaultGroup.equals(group)) {
                result = 0;
            }
        }
        else {
            result = result + 1;   
        }
        return result;   
    }
    
    /**
     * Returns the group that a key is mapped to.
     * 
     * @param key  the key (<code>null</code> not permitted).
     * 
     * @return The group (never <code>null</code>, returns the default group if there
     *         is no mapping for the specified key).
     */
    public Comparable getGroup(Comparable key) {
        if (key == null) {
            throw new IllegalArgumentException("Null 'key' argument.");   
        }
        Comparable result = this.defaultGroup;
        Comparable group = (Comparable) this.keyToGroupMap.get(key);
        if (group != null) {
            result = group;   
        }
        return result;
    }
    
    /**
     * Maps a key to a group.
     * 
     * @param key  the key (<code>null</code> not permitted).
     * @param group  the group (<code>null</code> permitted, clears any existing mapping).
     */
    public void mapKeyToGroup(Comparable key, Comparable group) {
        if (key == null) {
            throw new IllegalArgumentException("Null 'key' argument.");   
        }
        Comparable currentGroup = getGroup(key);
        if (!currentGroup.equals(this.defaultGroup)) {
            if (!currentGroup.equals(group)) {
                int count = getKeyCount(currentGroup);
                if (count == 1) {
                    this.groups.remove(currentGroup);   
                }
            }
        }
        if (group == null) {
            this.keyToGroupMap.remove(key); 
        }
        else {
            if (!this.groups.contains(group)) {
                if (!this.defaultGroup.equals(group)) {
                    this.groups.add(group);
                }
            }
            this.keyToGroupMap.put(key, group);
        }
    }
    
    /**
     * Returns the number of keys mapped to the specified group.  This method won't
     * always return an accurate result for the default group, since explicit mappings 
     * are not required for this group.
     * 
     * @param group  the group (<code>null</code> not permitted).
     * 
     * @return The key count.
     */
    public int getKeyCount(Comparable group) {
        if (group == null) {
            throw new IllegalArgumentException("Null 'group' argument.");   
        }
        int result = 0;
        Iterator iterator = this.keyToGroupMap.values().iterator();
        while (iterator.hasNext()) {
            Comparable g = (Comparable) iterator.next();
            if (group.equals(g)) {
                result++;
            }
        }
        return result;
    }
    
    /**
     * Tests the map for equality against an arbitrary object.
     * 
     * @param obj  the object to test against (<code>null</code> permitted).
     * 
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;      
        }
        if (!(obj instanceof KeyToGroupMap)) {
            return false;
        }
        KeyToGroupMap that = (KeyToGroupMap) obj;
        if (!ObjectUtilities.equal(this.defaultGroup, that.defaultGroup)) {
            return false;
        }
        if (!this.keyToGroupMap.equals(that.keyToGroupMap)) {
            return false;
        }
        return true;
    }
    
    /**
     * Returns a clone of the map.
     * 
     * @return A clone.
     * 
     * @throws CloneNotSupportedException  if there is a problem cloning the map.
     */
    public Object clone() throws CloneNotSupportedException {
        KeyToGroupMap result = (KeyToGroupMap) super.clone();
        result.defaultGroup = (Comparable) KeyToGroupMap.clone(this.defaultGroup);
        result.groups = (List) KeyToGroupMap.clone(this.groups);
        result.keyToGroupMap = (Map) KeyToGroupMap.clone(this.keyToGroupMap);
        return result;
    }
    
    /**
     * Attempts to clone the specified object using reflection.
     * 
     * @param object  the object (<code>null</code> permitted).
     * 
     * @return The cloned object, or the original object if cloning failed.
     */
    private static Object clone(Object object) {
        if (object == null) {
            return null;   
        }
        Class c = object.getClass();
        Object result = null;
        try {
            Method m = c.getMethod("clone", null);
            if (Modifier.isPublic(m.getModifiers())) {
                try {
                    result = m.invoke(object, null);
                }
                catch (Exception e) {
                    e.printStackTrace();  
                }
            }
        }
        catch (NoSuchMethodException e) {
            result = object;
        }
        return result;
    }
    
    /**
     * Returns a clone of the list.
     * 
     * @param list  the list.
     * 
     * @return A clone of the list.
     * 
     * @throws CloneNotSupportedException if the list could not be cloned.
     */
    private static Collection clone(Collection list) throws CloneNotSupportedException {
        Collection result = null;
        if (list != null) {
            try {
                List clone = (List) list.getClass().newInstance();
                Iterator iterator = list.iterator();
                while (iterator.hasNext()) {
                    clone.add(KeyToGroupMap.clone(iterator.next()));
                }
                result = clone;
            }
            catch (Exception e) {
                throw new CloneNotSupportedException("Exception.");
            }
        }
        return result;
    }

}