/*
 * @(#)DefaultTreeModel.java	1.41 00/02/02
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package javax.swing.tree;

import java.util.*;
import java.awt.*;
import java.io.*;
import javax.swing.event.*;

/**
 * A simple tree data model that uses TreeNodes.
 * For further information and examples that use DefaultTreeModel,
 * see <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html">How to Use Trees</a>
 * in <em>The Java Tutorial.</em>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @version 1.41 02/02/00
 * @author Rob Davis
 * @author Ray Ryan
 * @author Scott Violet
 */
public class DefaultTreeModel implements Serializable, TreeModel {
    /** Root of the tree. */
    protected TreeNode root;
    /** Listeners. */
    protected EventListenerList listenerList = new EventListenerList();
    /**
      * Determines how the <code>isLeaf</code> method figures
      * out if a node is a leaf node. If true, a node is a leaf 
      * node if it does not allow children. (If it allows 
      * children, it is not a leaf node, even if no children
      * are present.) That lets you distinguish between <i>folder</i>
      * nodes and <i>file</i> nodes in a file system, for example.
      * <p>
      * If this value is false, then any node which has no 
      * children is a leaf node, and any node may acquire 
      * children.
      *
      * @see TreeNode#getAllowsChildren
      * @see TreeModel#isLeaf
      * @see #setAsksAllowsChildren
      */
    protected boolean asksAllowsChildren;


    /**
      * Creates a tree in which any node can have children.
      *
      * @param root a TreeNode object that is the root of the tree
      * @see #DefaultTreeModel(TreeNode, boolean)
      */
     public DefaultTreeModel(TreeNode root) {
        this(root, false);
    }

    /**
      * Creates a tree specifying whether any node can have children,
      * or whether only certain nodes can have children.
      *
      * @param root a TreeNode object that is the root of the tree
      * @param askAllowsChildren a boolean, false if any node can
      *        have children, true if each node is asked to see if
      *        it can have children
      * @see #asksAllowsChildren
      */
    public DefaultTreeModel(TreeNode root, boolean asksAllowsChildren) {
        super();
        if (root == null) {
            throw new IllegalArgumentException("root is null");
        }
        this.root = root;
        this.asksAllowsChildren = asksAllowsChildren;
    }

    /**
      * Sets whether or not to test leafness by asking getAllowsChildren()
      * or isLeaf() to the TreeNodes.  If newvalue is true, getAllowsChildren()
      * is messaged, otherwise isLeaf() is messaged.
      */
    public void setAsksAllowsChildren(boolean newValue) {
        asksAllowsChildren = newValue;
    }

    /**
      * Tells how leaf nodes are determined.
      *
      * @return true if only nodes which do not allow children are
      *         leaf nodes, false if nodes which have no children
      *         (even if allowed) are leaf nodes
      * @see #asksAllowsChildren
      */
    public boolean asksAllowsChildren() {
        return asksAllowsChildren;
    }

    /**
     * Sets the root to <code>root</code>. This will throw an
     * IllegalArgumentException if <code>root</code> is null.
     */
    public void setRoot(TreeNode root) {
	if(root == null)
	    throw new IllegalArgumentException("Root of tree is not allowed to be null");
	this.root = root;
	nodeStructureChanged(root);
    }

    /**
     * Returns the root of the tree.  Returns null only if the tree has
     * no nodes.
     *
     * @return  the root of the tree
     */
    public Object getRoot() {
        return root;
    }

    /**
     * Returns the index of child in parent.
     */
    public int getIndexOfChild(Object parent, Object child) {
        if(parent == null || child == null)
            return -1;
        return ((TreeNode)parent).getIndex((TreeNode)child);
    }

    /**
     * Returns the child of <I>parent</I> at index <I>index</I> in the parent's
     * child array.  <I>parent</I> must be a node previously obtained from
     * this data source. This should not return null if <i>index</i>
     * is a valid index for <i>parent</i> (that is <i>index</i> >= 0 &&
     * <i>index</i> < getChildCount(<i>parent</i>)).
     *
     * @param   parent  a node in the tree, obtained from this data source
     * @return  the child of <I>parent</I> at index <I>index</I>
     */
    public Object getChild(Object parent, int index) {
        return ((TreeNode)parent).getChildAt(index);
    }

    /**
     * Returns the number of children of <I>parent</I>.  Returns 0 if the node
     * is a leaf or if it has no children.  <I>parent</I> must be a node
     * previously obtained from this data source.
     *
     * @param   parent  a node in the tree, obtained from this data source
     * @return  the number of children of the node <I>parent</I>
     */
    public int getChildCount(Object parent) {
        return ((TreeNode)parent).getChildCount();
    }

    /** 
     * Returns whether the specified node is a leaf node.
     * The way the test is performed depends on the
     * <code>askAllowsChildren</code> setting.
     *
     * @param node the node to check
     * @return true if the node is a leaf node
     *
     * @see #asksAllowsChildren
     * @see TreeModel#isLeaf
     */
    public boolean isLeaf(Object node) {
        if(asksAllowsChildren)
            return !((TreeNode)node).getAllowsChildren();
        return ((TreeNode)node).isLeaf();
    }

    /**
     * Invoke this method if you've modified the TreeNodes upon which this
     * model depends.  The model will notify all of its listeners that the
     * model has changed.
     */
    public void reload() {
        reload(root);
    }

    /**
      * This sets the user object of the TreeNode identified by path
      * and posts a node changed.  If you use custom user objects in
      * the TreeModel you're going to need to subclass this and
      * set the user object of the changed node to something meaningful.
      */
    public void valueForPathChanged(TreePath path, Object newValue) {
	MutableTreeNode   aNode = (MutableTreeNode)path.getLastPathComponent();

        aNode.setUserObject(newValue);
        nodeChanged(aNode);
    }

    /**
     * Invoked this to insert newChild at location index in parents children.
     * This will then message nodesWereInserted to create the appropriate
     * event. This is the preferred way to add children as it will create
     * the appropriate event.
     */
    public void insertNodeInto(MutableTreeNode newChild,
                               MutableTreeNode parent, int index){
        parent.insert(newChild, index);

        int[]           newIndexs = new int[1];

        newIndexs[0] = index;
        nodesWereInserted(parent, newIndexs);
    }

    /**
     * Message this to remove node from its parent. This will message
     * nodesWereRemoved to create the appropriate event. This is the
     * preferred way to remove a node as it handles the event creation
     * for you.
     */
    public void removeNodeFromParent(MutableTreeNode node) {
        MutableTreeNode         parent = (MutableTreeNode)node.getParent();

        if(parent == null)
            throw new IllegalArgumentException("node does not have a parent.");

        int[]            childIndex = new int[1];
        Object[]         removedArray = new Object[1];

        childIndex[0] = parent.getIndex(node);
        parent.remove(childIndex[0]);
        removedArray[0] = node;
        nodesWereRemoved(parent, childIndex, removedArray);
    }

    /**
      * Invoke this method after you've changed how node is to be
      * represented in the tree.
      */
    public void nodeChanged(TreeNode node) {
        if(listenerList != null && node != null) {
            TreeNode         parent = node.getParent();

            if(parent != null) {
                int        anIndex = parent.getIndex(node);
                if(anIndex != -1) {
                    int[]        cIndexs = new int[1];

                    cIndexs[0] = anIndex;
                    nodesChanged(parent, cIndexs);
                }
            }
	    else if (node == getRoot()) {
		nodesChanged(node, null);
	    }
        }
    }

    /**
     * Invoke this method if you've modified the TreeNodes upon which this
     * model depends.  The model will notify all of its listeners that the
     * model has changed below the node <code>node</code> (PENDING).
     */
    public void reload(TreeNode node) {
        if(node != null) {
            fireTreeStructureChanged(this, getPathToRoot(node), null, null);
        }
    }

    /**
      * Invoke this method after you've inserted some TreeNodes into
      * node.  childIndices should be the index of the new elements and
      * must be sorted in ascending order.
      */
    public void nodesWereInserted(TreeNode node, int[] childIndices) {
        if(listenerList != null && node != null && childIndices != null
           && childIndices.length > 0) {
            int               cCount = childIndices.length;
            Object[]          newChildren = new Object[cCount];

            for(int counter = 0; counter < cCount; counter++)
                newChildren[counter] = node.getChildAt(childIndices[counter]);
            fireTreeNodesInserted(this, getPathToRoot(node), childIndices, 
                                  newChildren);
        }
    }
    
    /**
      * Invoke this method after you've removed some TreeNodes from
      * node.  childIndices should be the index of the removed elements and
      * must be sorted in ascending order. And removedChildren should be
      * the array of the children objects that were removed.
      */
    public void nodesWereRemoved(TreeNode node, int[] childIndices,
                                 Object[] removedChildren) {
        if(node != null && childIndices != null) {
            fireTreeNodesRemoved(this, getPathToRoot(node), childIndices, 
                                 removedChildren);
        }
    }

    /**
      * Invoke this method after you've changed how the children identified by
      * childIndicies are to be represented in the tree.
      */
    public void nodesChanged(TreeNode node, int[] childIndices) {
        if(node != null) {
	    if (childIndices != null) {
		int            cCount = childIndices.length;

		if(cCount > 0) {
		    Object[]       cChildren = new Object[cCount];

		    for(int counter = 0; counter < cCount; counter++)
			cChildren[counter] = node.getChildAt
			    (childIndices[counter]);
		    fireTreeNodesChanged(this, getPathToRoot(node),
					 childIndices, cChildren);
		}
	    }
	    else if (node == getRoot()) {
		fireTreeNodesChanged(this, getPathToRoot(node), null, null);
	    }
        }
    }

    /**
      * Invoke this method if you've totally changed the children of
      * node and its childrens children...  This will post a
      * treeStructureChanged event.
      */
    public void nodeStructureChanged(TreeNode node) {
        if(node != null) {
           fireTreeStructureChanged(this, getPathToRoot(node), null, null);
        }
    }

    /**
     * Builds the parents of node up to and including the root node,
     * where the original node is the last element in the returned array.
     * The length of the returned array gives the node's depth in the
     * tree.
     * 
     * @param aNode the TreeNode to get the path for
     * @param an array of TreeNodes giving the path from the root to the
     *        specified node. 
     */
    public TreeNode[] getPathToRoot(TreeNode aNode) {
        return getPathToRoot(aNode, 0);
    }

    /**
     * Builds the parents of node up to and including the root node,
     * where the original node is the last element in the returned array.
     * The length of the returned array gives the node's depth in the
     * tree.
     * 
     * @param aNode  the TreeNode to get the path for
     * @param depth  an int giving the number of steps already taken towards
     *        the root (on recursive calls), used to size the returned array
     * @return an array of TreeNodes giving the path from the root to the
     *         specified node 
     */
    protected TreeNode[] getPathToRoot(TreeNode aNode, int depth) {
        TreeNode[]              retNodes;
	// This method recurses, traversing towards the root in order
	// size the array. On the way back, it fills in the nodes,
	// starting from the root and working back to the original node.

        /* Check for null, in case someone passed in a null node, or
           they passed in an element that isn't rooted at root. */
        if(aNode == null) {
            if(depth == 0)
                return null;
            else
                retNodes = new TreeNode[depth];
        }
        else {
            depth++;
            if(aNode == root)
                retNodes = new TreeNode[depth];
            else
                retNodes = getPathToRoot(aNode.getParent(), depth);
            retNodes[retNodes.length - depth] = aNode;
        }
        return retNodes;
    }

    //
    //  Events
    //

    /**
     * Adds a listener for the TreeModelEvent posted after the tree changes.
     *
     * @see     #removeTreeModelListener
     * @param   l       the listener to add
     */
    public void addTreeModelListener(TreeModelListener l) {
        listenerList.add(TreeModelListener.class, l);
    }

    /**
     * Removes a listener previously added with <B>addTreeModelListener()</B>.
     *
     * @see     #addTreeModelListener
     * @param   l       the listener to remove
     */  
    public void removeTreeModelListener(TreeModelListener l) {
        listenerList.remove(TreeModelListener.class, l);
    }

    /*
     * Notify all listeners that have registered interest for
     * notification on this event type.  The event instance 
     * is lazily created using the parameters passed into 
     * the fire method.
     * @see EventListenerList
     */
    protected void fireTreeNodesChanged(Object source, Object[] path, 
                                        int[] childIndices, 
                                        Object[] children) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        TreeModelEvent e = null;
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==TreeModelListener.class) {
                // Lazily create the event:
                if (e == null)
                    e = new TreeModelEvent(source, path, 
                                           childIndices, children);
                ((TreeModelListener)listeners[i+1]).treeNodesChanged(e);
            }          
        }
    }

    /*
     * Notify all listeners that have registered interest for
     * notification on this event type.  The event instance 
     * is lazily created using the parameters passed into 
     * the fire method.
     * @see EventListenerList
     */
    protected void fireTreeNodesInserted(Object source, Object[] path, 
                                        int[] childIndices, 
                                        Object[] children) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        TreeModelEvent e = null;
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==TreeModelListener.class) {
                // Lazily create the event:
                if (e == null)
                    e = new TreeModelEvent(source, path, 
                                           childIndices, children);
                ((TreeModelListener)listeners[i+1]).treeNodesInserted(e);
            }          
        }
    }

    /*
     * Notify all listeners that have registered interest for
     * notification on this event type.  The event instance 
     * is lazily created using the parameters passed into 
     * the fire method.
     * @see EventListenerList
     */
    protected void fireTreeNodesRemoved(Object source, Object[] path, 
                                        int[] childIndices, 
                                        Object[] children) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        TreeModelEvent e = null;
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==TreeModelListener.class) {
                // Lazily create the event:
                if (e == null)
                    e = new TreeModelEvent(source, path, 
                                           childIndices, children);
                ((TreeModelListener)listeners[i+1]).treeNodesRemoved(e);
            }          
        }
    }

    /*
     * Notify all listeners that have registered interest for
     * notification on this event type.  The event instance 
     * is lazily created using the parameters passed into 
     * the fire method.
     * @see EventListenerList
     */
    protected void fireTreeStructureChanged(Object source, Object[] path, 
                                        int[] childIndices, 
                                        Object[] children) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        TreeModelEvent e = null;
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==TreeModelListener.class) {
                // Lazily create the event:
                if (e == null)
                    e = new TreeModelEvent(source, path, 
                                           childIndices, children);
                ((TreeModelListener)listeners[i+1]).treeStructureChanged(e);
            }          
        }
    }

    /**
     * Return an array of all the listeners of the given type that 
     * were added to this model. 
     *
     * @returns all of the objects recieving <em>listenerType</em> notifications 
     *          from this model
     * 
     * @since 1.3
     */
    public EventListener[] getListeners(Class listenerType) { 
	return listenerList.getListeners(listenerType); 
    }

    // Serialization support.  
    private void writeObject(ObjectOutputStream s) throws IOException {
        Vector      values = new Vector();

        s.defaultWriteObject();
        // Save the root, if its Serializable.
        if(root != null && root instanceof Serializable) {
            values.addElement("root");
            values.addElement(root);
        }
        s.writeObject(values);
    }

    private void readObject(ObjectInputStream s) 
        throws IOException, ClassNotFoundException {
        s.defaultReadObject();

        Vector          values = (Vector)s.readObject();
        int             indexCounter = 0;
        int             maxCounter = values.size();

        if(indexCounter < maxCounter && values.elementAt(indexCounter).
           equals("root")) {
            root = (TreeNode)values.elementAt(++indexCounter);
            indexCounter++;
        }
    }


} // End of class DefaultTreeModel