/*
 * $Id: MultiSplitLayout.java,v 1.15 2005/10/26 14:29:54 hansmuller Exp $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.mathpiper.ui.gui;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.IOException;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import javax.swing.UIManager;


/**
 * The MultiSplitLayout layout manager recursively arranges its
 * components in row and column groups called "Splits".  Elements of
 * the layout are separated by gaps called "Dividers".  The overall
 * layout is defined with a simple tree model whose nodes are 
 * instances of MultiSplitLayout.Split, MultiSplitLayout.Divider, 
 * and MultiSplitLayout.Leaf. Named Leaf nodes represent the space 
 * allocated to a component that was added with a constraint that
 * matches the Leaf's name.  Extra space is distributed
 * among row/column siblings according to their 0.0 to 1.0 weight.
 * If no weights are specified then the last sibling always gets
 * all of the extra space, or space reduction.
 * 
 * <p>
 * Although MultiSplitLayout can be used with any Container, it's
 * the default layout manager for MultiSplitPane.  MultiSplitPane
 * supports interactively dragging the Dividers, accessibility, 
 * and other features associated with split panes.
 * 
 * <p>
 * All properties in this class are bound: when a properties value
 * is changed, all PropertyChangeListeners are fired.
 * 
 * @author Hans Muller
 * @see MultiSplitPane
 */

public class MultiSplitLayout implements LayoutManager {
    private final Map<String, Component> childMap = new HashMap<String, Component>();
    private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);
    private Node model;
    private int dividerSize;
    private boolean floatingDividers = true;

    /**
     * Create a MultiSplitLayout with a default model with a single
     * Leaf node named "default".  
     * 
     * #see setModel
     */
    public MultiSplitLayout() { 
	this(new Leaf("default"));
    }
    
    /**
     * Create a MultiSplitLayout with the specified model.
     * 
     * #see setModel
     */
    public MultiSplitLayout(Node model) {
	this.model = model;
        this.dividerSize = UIManager.getInt("SplitPane.dividerSize"); 
	if (this.dividerSize == 0) {
            this.dividerSize = 7;
        }
    }

    public void addPropertyChangeListener(PropertyChangeListener listener) {
        if (listener != null) {
	    pcs.addPropertyChangeListener(listener);
        }
    }
    public void removePropertyChangeListener(PropertyChangeListener listener) {
        if (listener != null) {
	    pcs.removePropertyChangeListener(listener);
        }
    }
    public PropertyChangeListener[] getPropertyChangeListeners() {
        return pcs.getPropertyChangeListeners();
    }

    private void firePCS(String propertyName, Object oldValue, Object newValue) {
	if (!(oldValue != null && newValue != null && oldValue.equals(newValue))) {
	    pcs.firePropertyChange(propertyName, oldValue, newValue);
        }
    }

    /**
     * Return the root of the tree of Split, Leaf, and Divider nodes
     * that define this layout.  
     * 
     * @return the value of the model property
     * @see #setModel
     */
    public Node getModel() { return model; }

    /**
     * Set the root of the tree of Split, Leaf, and Divider nodes
     * that define this layout.  The model can be a Split node
     * (the typical case) or a Leaf.  The default value of this
     * property is a Leaf named "default".
     * 
     * @param model the root of the tree of Split, Leaf, and Divider node
     * @throws IllegalArgumentException if model is a Divider or null
     * @see #getModel
     */
    public void setModel(Node model) {
	if ((model == null) || (model instanceof Divider)) {
	    throw new IllegalArgumentException("invalid model");
	}
	Node oldModel = model;
	this.model = model;
	firePCS("model", oldModel, model);
    }

    /**
     * Returns the width of Dividers in Split rows, and the height of 
     * Dividers in Split columns.
     *
     * @return the value of the dividerSize property
     * @see #setDividerSize
     */
    public int getDividerSize() { return dividerSize; }

    /**
     * Sets the width of Dividers in Split rows, and the height of 
     * Dividers in Split columns.  The default value of this property
     * is the same as for JSplitPane Dividers.
     *
     * @param dividerSize the size of dividers (pixels)
     * @throws IllegalArgumentException if dividerSize < 0
     * @see #getDividerSize
     */
    public void setDividerSize(int dividerSize) {
	if (dividerSize < 0) {
	    throw new IllegalArgumentException("invalid dividerSize");
	}
	int oldDividerSize = this.dividerSize;
	this.dividerSize = dividerSize;
	firePCS("dividerSize", oldDividerSize, dividerSize);
    }

    /**
     * @return the value of the floatingDividers property
     * @see #setFloatingDividers
     */
    public boolean getFloatingDividers() { return floatingDividers; }


    /**
     * If true, Leaf node bounds match the corresponding component's 
     * preferred size and Splits/Dividers are resized accordingly.  
     * If false then the Dividers define the bounds of the adjacent
     * Split and Leaf nodes.  Typically this property is set to false
     * after the (MultiSplitPane) user has dragged a Divider.
     * 
     * @see #getFloatingDividers
     */
    public void setFloatingDividers(boolean floatingDividers) {
	boolean oldFloatingDividers = this.floatingDividers;
	this.floatingDividers = floatingDividers;
	firePCS("floatingDividers", oldFloatingDividers, floatingDividers);
    }


    /** 
     * Add a component to this MultiSplitLayout.  The
     * <code>name</code> should match the name property of the Leaf
     * node that represents the bounds of <code>child</code>.  After
     * layoutContainer() recomputes the bounds of all of the nodes in
     * the model, it will set this child's bounds to the bounds of the
     * Leaf node with <code>name</code>.  Note: if a component was already
     * added with the same name, this method does not remove it from 
     * its parent.  
     * 
     * @param name identifies the Leaf node that defines the child's bounds
     * @param child the component to be added
     * @see #removeLayoutComponent
     */
    public void addLayoutComponent(String name, Component child) {
	if (name == null) {
	    throw new IllegalArgumentException("name not specified");
	}
	childMap.put(name, child);
    }

    /**
     * Removes the specified component from the layout.
     * 
     * @param child the component to be removed
     * @see #addLayoutComponent
     */
    public void removeLayoutComponent(Component child) {
	String name = child.getName();
	if (name != null) {
	    childMap.remove(name);
	}
    }

    private Component childForNode(Node node) {
	if (node instanceof Leaf) {
	    Leaf leaf = (Leaf)node;
	    String name = leaf.getName();
	    return (name != null) ? childMap.get(name) : null;
	}
	return null;
    }


    private Dimension preferredComponentSize(Node node) {
	Component child = childForNode(node);
	return (child != null) ? child.getPreferredSize() : new Dimension(0, 0);
	
    }

    private Dimension minimumComponentSize(Node node) {
	Component child = childForNode(node);
	return (child != null) ? child.getMinimumSize() : new Dimension(0, 0);
	
    }

    private Dimension preferredNodeSize(Node root) {
	if (root instanceof Leaf) {
	    return preferredComponentSize(root);
	}
	else if (root instanceof Divider) {
	    int dividerSize = getDividerSize();
	    return new Dimension(dividerSize, dividerSize);
	}
	else {
	    Split split = (Split)root;
	    List<Node> splitChildren = split.getChildren();
	    int width = 0;
	    int height = 0;
	    if (split.isRowLayout()) { 
		for(Node splitChild : splitChildren) {
		    Dimension size = preferredNodeSize(splitChild);
		    width += size.width;
		    height = Math.max(height, size.height);
		}
	    }
	    else {
		for(Node splitChild : splitChildren) {
		    Dimension size = preferredNodeSize(splitChild);
		    width = Math.max(width, size.width);
		    height += size.height;
		}
	    }
	    return new Dimension(width, height);
	}
    }

    private Dimension minimumNodeSize(Node root) {
	if (root instanceof Leaf) {
	    Component child = childForNode(root);
	    return (child != null) ? child.getMinimumSize() : new Dimension(0, 0);
	}
	else if (root instanceof Divider) {
	    int dividerSize = getDividerSize();
	    return new Dimension(dividerSize, dividerSize);
	}
	else {
	    Split split = (Split)root;
	    List<Node> splitChildren = split.getChildren();
	    int width = 0;
	    int height = 0;
	    if (split.isRowLayout()) { 
		for(Node splitChild : splitChildren) {
		    Dimension size = minimumNodeSize(splitChild);
		    width += size.width;
		    height = Math.max(height, size.height);
		}
	    }
	    else {
		for(Node splitChild : splitChildren) {
		    Dimension size = minimumNodeSize(splitChild);
		    width = Math.max(width, size.width);
		    height += size.height;
		}
	    }
	    return new Dimension(width, height);
	}
    }

    private Dimension sizeWithInsets(Container parent, Dimension size) {
	Insets insets = parent.getInsets();
	int width = size.width + insets.left + insets.right;
	int height = size.height + insets.top + insets.bottom;
	return new Dimension(width, height);
    }

    public Dimension preferredLayoutSize(Container parent) {
	Dimension size = preferredNodeSize(getModel());
	return sizeWithInsets(parent, size);
    }

    public Dimension minimumLayoutSize(Container parent) {
	Dimension size = minimumNodeSize(getModel());
	return sizeWithInsets(parent, size);
    }


    private Rectangle boundsWithYandHeight(Rectangle bounds, double y, double height) {
	Rectangle r = new Rectangle();
	r.setBounds((int)(bounds.getX()), (int)y, (int)(bounds.getWidth()), (int)height);
	return r;
    }

    private Rectangle boundsWithXandWidth(Rectangle bounds, double x, double width) {
	Rectangle r = new Rectangle();
	r.setBounds((int)x, (int)(bounds.getY()), (int)width, (int)(bounds.getHeight()));
	return r;
    }


    private void minimizeSplitBounds(Split split, Rectangle bounds) {
	Rectangle splitBounds = new Rectangle(bounds.x, bounds.y, 0, 0);
	List<Node> splitChildren = split.getChildren();
	Node lastChild = splitChildren.get(splitChildren.size() - 1);
	Rectangle lastChildBounds = lastChild.getBounds();
	if (split.isRowLayout()) {
	    int lastChildMaxX = lastChildBounds.x + lastChildBounds.width;
	    splitBounds.add(lastChildMaxX, bounds.y + bounds.height);
	}
	else {
	    int lastChildMaxY = lastChildBounds.y + lastChildBounds.height;
	    splitBounds.add(bounds.x + bounds.width, lastChildMaxY);
	}
	split.setBounds(splitBounds);
    }


    private void layoutShrink(Split split, Rectangle bounds) {
	Rectangle splitBounds = split.getBounds();
	ListIterator<Node> splitChildren = split.getChildren().listIterator();
	Node lastWeightedChild = split.lastWeightedChild();

	if (split.isRowLayout()) {
	    int totalWidth = 0;          // sum of the children's widths
	    int minWeightedWidth = 0;    // sum of the weighted childrens' min widths
	    int totalWeightedWidth = 0;  // sum of the weighted childrens' widths
	    for(Node splitChild : split.getChildren()) {
		int nodeWidth = splitChild.getBounds().width;
		int nodeMinWidth = Math.min(nodeWidth, minimumNodeSize(splitChild).width);
		totalWidth += nodeWidth;
		if (splitChild.getWeight() > 0.0) {
		    minWeightedWidth += nodeMinWidth;
		    totalWeightedWidth += nodeWidth;
		}
	    }

	    double x = bounds.getX();
	    double extraWidth = splitBounds.getWidth() - bounds.getWidth();
	    double availableWidth = extraWidth;
	    boolean onlyShrinkWeightedComponents = 
		(totalWeightedWidth - minWeightedWidth) > extraWidth;

	    while(splitChildren.hasNext()) {
		Node splitChild = splitChildren.next();
		Rectangle splitChildBounds = splitChild.getBounds();
		double minSplitChildWidth = minimumNodeSize(splitChild).getWidth();
		double splitChildWeight = (onlyShrinkWeightedComponents)
		    ? splitChild.getWeight()
		    : (splitChildBounds.getWidth() / (double)totalWidth);

		if (!splitChildren.hasNext()) {
		    double newWidth =  Math.max(minSplitChildWidth, bounds.getMaxX() - x); 
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, newWidth);
		    layout2(splitChild, newSplitChildBounds);
		}
		else if ((availableWidth > 0.0) && (splitChildWeight > 0.0)) {
		    double allocatedWidth = Math.rint(splitChildWeight * extraWidth);
		    double oldWidth = splitChildBounds.getWidth();
		    double newWidth = Math.max(minSplitChildWidth, oldWidth - allocatedWidth);
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, newWidth);
		    layout2(splitChild, newSplitChildBounds);
		    availableWidth -= (oldWidth - splitChild.getBounds().getWidth());
		}
		else {
		    double existingWidth = splitChildBounds.getWidth();
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, existingWidth);
		    layout2(splitChild, newSplitChildBounds);
		}
		x = splitChild.getBounds().getMaxX();
	    }
	}

	else {
	    int totalHeight = 0;          // sum of the children's heights
	    int minWeightedHeight = 0;    // sum of the weighted childrens' min heights
	    int totalWeightedHeight = 0;  // sum of the weighted childrens' heights
	    for(Node splitChild : split.getChildren()) {
		int nodeHeight = splitChild.getBounds().height;
		int nodeMinHeight = Math.min(nodeHeight, minimumNodeSize(splitChild).height);
		totalHeight += nodeHeight;
		if (splitChild.getWeight() > 0.0) {
		    minWeightedHeight += nodeMinHeight;
		    totalWeightedHeight += nodeHeight;
		}
	    }

	    double y = bounds.getY();
	    double extraHeight = splitBounds.getHeight() - bounds.getHeight();
	    double availableHeight = extraHeight;
	    boolean onlyShrinkWeightedComponents = 
		(totalWeightedHeight - minWeightedHeight) > extraHeight;

	    while(splitChildren.hasNext()) {
		Node splitChild = splitChildren.next();
		Rectangle splitChildBounds = splitChild.getBounds();
		double minSplitChildHeight = minimumNodeSize(splitChild).getHeight();
		double splitChildWeight = (onlyShrinkWeightedComponents)
		    ? splitChild.getWeight()
		    : (splitChildBounds.getHeight() / (double)totalHeight);

		if (!splitChildren.hasNext()) {
		    double oldHeight = splitChildBounds.getHeight();
		    double newHeight =  Math.max(minSplitChildHeight, bounds.getMaxY() - y); 
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, newHeight);
		    layout2(splitChild, newSplitChildBounds);
		    availableHeight -= (oldHeight - splitChild.getBounds().getHeight());
		}
		else if ((availableHeight > 0.0) && (splitChildWeight > 0.0)) {
		    double allocatedHeight = Math.rint(splitChildWeight * extraHeight);
		    double oldHeight = splitChildBounds.getHeight();
		    double newHeight = Math.max(minSplitChildHeight, oldHeight - allocatedHeight);
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, newHeight);
		    layout2(splitChild, newSplitChildBounds);
		    availableHeight -= (oldHeight - splitChild.getBounds().getHeight());
		}
		else {
		    double existingHeight = splitChildBounds.getHeight();
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, existingHeight);
		    layout2(splitChild, newSplitChildBounds);
		}
		y = splitChild.getBounds().getMaxY();
	    }
	}

	/* The bounds of the Split node root are set to be 
	 * big enough to contain all of its children. Since 
	 * Leaf children can't be reduced below their 
	 * (corresponding java.awt.Component) minimum sizes, 
	 * the size of the Split's bounds maybe be larger than
	 * the bounds we were asked to fit within.
	 */
	minimizeSplitBounds(split, bounds);
    }


    private void layoutGrow(Split split, Rectangle bounds) {
	Rectangle splitBounds = split.getBounds();
	ListIterator<Node> splitChildren = split.getChildren().listIterator();
	Node lastWeightedChild = split.lastWeightedChild();

	/* Layout the Split's child Nodes' along the X axis.  The bounds 
	 * of each child will have the same y coordinate and height as the 
	 * layoutGrow() bounds argument.  Extra width is allocated to the 
	 * to each child with a non-zero weight:
	 *     newWidth = currentWidth + (extraWidth * splitChild.getWeight())
	 * Any extraWidth "left over" (that's availableWidth in the loop
	 * below) is given to the last child.  Note that Dividers always
	 * have a weight of zero, and they're never the last child.
	 */
	if (split.isRowLayout()) {
	    double x = bounds.getX();
	    double extraWidth = bounds.getWidth() - splitBounds.getWidth();
	    double availableWidth = extraWidth;

	    while(splitChildren.hasNext()) {
		Node splitChild = splitChildren.next();
		Rectangle splitChildBounds = splitChild.getBounds();
		double splitChildWeight = splitChild.getWeight();

		if (!splitChildren.hasNext()) {  
		    double newWidth = bounds.getMaxX() - x; 
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, newWidth);
		    layout2(splitChild, newSplitChildBounds);
		}
		else if ((availableWidth > 0.0) && (splitChildWeight > 0.0)) {
		    double allocatedWidth = (splitChild.equals(lastWeightedChild)) 
			? availableWidth
			: Math.rint(splitChildWeight * extraWidth);
		    double newWidth = splitChildBounds.getWidth() + allocatedWidth;
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, newWidth);
		    layout2(splitChild, newSplitChildBounds);
		    availableWidth -= allocatedWidth;
		}
		else {
		    double existingWidth = splitChildBounds.getWidth();
		    Rectangle newSplitChildBounds = boundsWithXandWidth(bounds, x, existingWidth);
		    layout2(splitChild, newSplitChildBounds);
		}
		x = splitChild.getBounds().getMaxX();
	    }
	}

	/* Layout the Split's child Nodes' along the Y axis.  The bounds 
	 * of each child will have the same x coordinate and width as the 
	 * layoutGrow() bounds argument.  Extra height is allocated to the 
	 * to each child with a non-zero weight:
	 *     newHeight = currentHeight + (extraHeight * splitChild.getWeight())
	 * Any extraHeight "left over" (that's availableHeight in the loop
	 * below) is given to the last child.  Note that Dividers always
	 * have a weight of zero, and they're never the last child.
	 */
	else {
	    double y = bounds.getY();
	    double extraHeight = bounds.getMaxY() - splitBounds.getHeight();
	    double availableHeight = extraHeight;

	    while(splitChildren.hasNext()) {
		Node splitChild = splitChildren.next();
		Rectangle splitChildBounds = splitChild.getBounds();
		double splitChildWeight = splitChild.getWeight();
		
		if (!splitChildren.hasNext()) {
		    double newHeight = bounds.getMaxY() - y; 
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, newHeight);
		    layout2(splitChild, newSplitChildBounds);
		}
		else if ((availableHeight > 0.0) && (splitChildWeight > 0.0)) {
		    double allocatedHeight = (splitChild.equals(lastWeightedChild)) 
			? availableHeight
			: Math.rint(splitChildWeight * extraHeight);
		    double newHeight = splitChildBounds.getHeight() + allocatedHeight;
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, newHeight);
		    layout2(splitChild, newSplitChildBounds);
		    availableHeight -= allocatedHeight;
		}
		else {
		    double existingHeight = splitChildBounds.getHeight();
		    Rectangle newSplitChildBounds = boundsWithYandHeight(bounds, y, existingHeight);
		    layout2(splitChild, newSplitChildBounds);
		}
		y = splitChild.getBounds().getMaxY();
	    }
	}
    }


    /* Second pass of the layout algorithm: branch to layoutGrow/Shrink
     * as needed.
     */
   private void layout2(Node root, Rectangle bounds) {
	if (root instanceof Leaf) {
	    Component child = childForNode(root);
	    if (child != null) {
		child.setBounds(bounds);
	    }
	    root.setBounds(bounds);
	}
	else if (root instanceof Divider) {
	    root.setBounds(bounds);
	}
	else if (root instanceof Split) {
	    Split split = (Split)root;
	    boolean grow = split.isRowLayout() 
		? (split.getBounds().width <= bounds.width)
		: (split.getBounds().height <= bounds.height);
	    if (grow) {
		layoutGrow(split, bounds);
		root.setBounds(bounds);
	    }
	    else {
		layoutShrink(split, bounds);
                // split.setBounds() called in layoutShrink()
	    }
	}
    }


    /* First pass of the layout algorithm.
     * 
     * If the Dividers are "floating" then set the bounds of each
     * node to accomodate the preferred size of all of the 
     * Leaf's java.awt.Components.  Otherwise, just set the bounds
     * of each Leaf/Split node so that it's to the left of (for
     * Split.isRowLayout() Split children) or directly above
     * the Divider that follows.
     * 
     * This pass sets the bounds of each Node in the layout model.  It
     * does not resize any of the parent Container's
     * (java.awt.Component) children.  That's done in the second pass,
     * see layoutGrow() and layoutShrink().
     */
    private void layout1(Node root, Rectangle bounds) {
	if (root instanceof Leaf) {
	    root.setBounds(bounds);
	}
	else if (root instanceof Split) {
	    Split split = (Split)root;
	    Iterator<Node> splitChildren = split.getChildren().iterator();
	    Rectangle childBounds = null;
	    int dividerSize = getDividerSize();
	    
	    /* Layout the Split's child Nodes' along the X axis.  The bounds 
	     * of each child will have the same y coordinate and height as the 
	     * layout1() bounds argument.  
	     * 
	     * Note: the column layout code - that's the "else" clause below
	     * this if, is identical to the X axis (rowLayout) code below.
	     */
	    if (split.isRowLayout()) {
		double x = bounds.getX();
		while(splitChildren.hasNext()) {
		    Node splitChild = splitChildren.next();
		    Divider dividerChild = 
			(splitChildren.hasNext()) ? (Divider)(splitChildren.next()) : null;

		    double childWidth = 0.0;
		    if (getFloatingDividers()) {
			childWidth = preferredNodeSize(splitChild).getWidth();
		    }
		    else {
			if (dividerChild != null) {
			    childWidth = dividerChild.getBounds().getX() - x;
			}
			else {
			    childWidth = split.getBounds().getMaxX() - x;
			}
		    }
		    childBounds = boundsWithXandWidth(bounds, x, childWidth);
		    layout1(splitChild, childBounds);

		    if (getFloatingDividers() && (dividerChild != null)) {
			double dividerX = childBounds.getMaxX();
			Rectangle dividerBounds = boundsWithXandWidth(bounds, dividerX, dividerSize);
			dividerChild.setBounds(dividerBounds);
		    }
		    if (dividerChild != null) {
			x = dividerChild.getBounds().getMaxX();
		    }
		}
	    }

	    /* Layout the Split's child Nodes' along the Y axis.  The bounds 
	     * of each child will have the same x coordinate and width as the 
	     * layout1() bounds argument.  The algorithm is identical to what's
	     * explained above, for the X axis case.
	     */
	    else {
		double y = bounds.getY();
		while(splitChildren.hasNext()) {
		    Node splitChild = splitChildren.next();
		    Divider dividerChild = 
			(splitChildren.hasNext()) ? (Divider)(splitChildren.next()) : null;

		    double childHeight = 0.0;
		    if (getFloatingDividers()) {
			childHeight = preferredNodeSize(splitChild).getHeight();
		    }
		    else {
			if (dividerChild != null) {
			    childHeight = dividerChild.getBounds().getY() - y;
			}
			else {
			    childHeight = split.getBounds().getMaxY() - y;
			}
		    }
		    childBounds = boundsWithYandHeight(bounds, y, childHeight);
		    layout1(splitChild, childBounds);

		    if (getFloatingDividers() && (dividerChild != null)) {
			double dividerY = childBounds.getMaxY();
			Rectangle dividerBounds = boundsWithYandHeight(bounds, dividerY, dividerSize);
			dividerChild.setBounds(dividerBounds);
		    }
		    if (dividerChild != null) {
			y = dividerChild.getBounds().getMaxY();
		    }
		}
	    }
	    /* The bounds of the Split node root are set to be just
	     * big enough to contain all of its children, but only
	     * along the axis it's allocating space on.  That's 
	     * X for rows, Y for columns.  The second pass of the 
	     * layout algorithm - see layoutShrink()/layoutGrow() 
	     * allocates extra space.
	     */
	    minimizeSplitBounds(split, bounds);
	}
    }

    /** 
     * The specified Node is either the wrong type or was configured
     * incorrectly.
     */
    public static class InvalidLayoutException extends RuntimeException {
	private final Node node;
	public InvalidLayoutException (String msg, Node node) {
	    super(msg);
	    this.node = node;
	}
	/** 
	 * @return the invalid Node.
	 */
	public Node getNode() { return node; }
    }

    private void throwInvalidLayout(String msg, Node node) {
	throw new InvalidLayoutException(msg, node);
    }

    private void checkLayout(Node root) {
	if (root instanceof Split) {
	    Split split = (Split)root;
	    if (split.getChildren().size() <= 2) {
		throwInvalidLayout("Split must have > 2 children", root);
	    }
	    Iterator<Node> splitChildren = split.getChildren().iterator();
	    double weight = 0.0;
	    while(splitChildren.hasNext()) {
		Node splitChild = splitChildren.next();
		if (splitChild instanceof Divider) {
		    throwInvalidLayout("expected a Split or Leaf Node", splitChild);
		}
		if (splitChildren.hasNext()) {
		    Node dividerChild = splitChildren.next();
		    if (!(dividerChild instanceof Divider)) {
			throwInvalidLayout("expected a Divider Node", dividerChild);
		    }
		}
		weight += splitChild.getWeight();
		checkLayout(splitChild);
	    }
	    if (weight > 1.0) {
		throwInvalidLayout("Split children's total weight > 1.0", root);
	    }
	}
    }

    /** 
     * Compute the bounds of all of the Split/Divider/Leaf Nodes in 
     * the layout model, and then set the bounds of each child component
     * with a matching Leaf Node.
     */
    public void layoutContainer(Container parent) {
	checkLayout(getModel());
	Insets insets = parent.getInsets();
	Dimension size = parent.getSize();
	int width = size.width - (insets.left + insets.right);
	int height = size.height - (insets.top + insets.bottom);
	Rectangle bounds = new Rectangle(insets.left, insets.top, width, height);
	layout1(getModel(), bounds); 
	layout2(getModel(), bounds); 
    }


    private Divider dividerAt(Node root, int x, int y) {
	if (root instanceof Divider) {
            Divider divider = (Divider)root;
	    return (divider.getBounds().contains(x, y)) ? divider : null;
	}
	else if (root instanceof Split) {
	    Split split = (Split)root;
	    for(Node child : split.getChildren()) {
		if (child.getBounds().contains(x, y)) {
		    return dividerAt(child, x, y);
		}
	    }
	}
	return null;
    }

    /** 
     * Return the Divider whose bounds contain the specified
     * point, or null if there isn't one.
     * 
     * @param x x coordinate
     * @param y y coordinate
     * @return the Divider at x,y
     */
    public Divider dividerAt(int x, int y) {
	return dividerAt(getModel(), x, y);
    }

    private boolean nodeOverlapsRectangle(Node node, Rectangle r2) {
	Rectangle r1 = node.getBounds();
	return 
	    (r1.x <= (r2.x + r2.width)) && ((r1.x + r1.width) >= r2.x) &&
	    (r1.y <= (r2.y + r2.height)) && ((r1.y + r1.height) >= r2.y);
    }

    private List<Divider> dividersThatOverlap(Node root, Rectangle r) {
	if (nodeOverlapsRectangle(root, r) && (root instanceof Split)) {
	    List<Divider> dividers = new ArrayList();
	    for(Node child : ((Split)root).getChildren()) {
		if (child instanceof Divider) {
		    if (nodeOverlapsRectangle(child, r)) {
			dividers.add((Divider)child);
		    }
		}
		else if (child instanceof Split) {
		    dividers.addAll(dividersThatOverlap(child, r));
		}
	    }
            return dividers;
	}
	else {
	    return Collections.emptyList();
	}
    }

    /**
     * Return the Dividers whose bounds overlap the specified
     * Rectangle.
     * 
     * @param r target Rectangle
     * @return the Dividers that overlap r
     * @throws IllegalArgumentException if the Rectangle is null
     */
    public List<Divider> dividersThatOverlap(Rectangle r) {
	if (r == null) {
	    throw new IllegalArgumentException("null Rectangle");
	}
	return dividersThatOverlap(getModel(), r);
    }


    /** 
     * Base class for the nodes that model a MultiSplitLayout.
     */
    public static abstract class Node {
	private Split parent = null;  
	private Rectangle bounds = new Rectangle();
	private double weight = 0.0;

	/** 
	 * Returns the Split parent of this Node, or null.
	 *
	 * @return the value of the parent property.
	 * @see #setParent
	 */
	public Split getParent() { return parent; }

	/**
	 * Set the value of this Node's parent property.  The default
	 * value of this property is null.
	 * 
	 * @param parent a Split or null
	 * @see #getParent
	 */
	public void setParent(Split parent) {
	    this.parent = parent;
	}
	
	/**
	 * Returns the bounding Rectangle for this Node.
	 * 
	 * @return the value of the bounds property.
	 * @see #setBounds
	 */
	public Rectangle getBounds() { 
	    return new Rectangle(this.bounds);
	}

	/**
	 * Set the bounding Rectangle for this node.  The value of 
	 * bounds may not be null.  The default value of bounds
	 * is equal to <code>new Rectangle(0,0,0,0)</code>.
	 * 
	 * @param bounds the new value of the bounds property
	 * @throws IllegalArgumentException if bounds is null
	 * @see #getBounds
	 */
	public void setBounds(Rectangle bounds) {
	    if (bounds == null) {
		throw new IllegalArgumentException("null bounds");
	    }
	    this.bounds = new Rectangle(bounds);
	}

	/** 
	 * Value between 0.0 and 1.0 used to compute how much space
	 * to add to this sibling when the layout grows or how
	 * much to reduce when the layout shrinks.
	 * 
	 * @return the value of the weight property
	 * @see #setWeight
	 */
	public double getWeight() { return weight; }

	/** 
	 * The weight property is a between 0.0 and 1.0 used to
	 * compute how much space to add to this sibling when the
	 * layout grows or how much to reduce when the layout shrinks.
	 * If rowLayout is true then this node's width grows
	 * or shrinks by (extraSpace * weight).  If rowLayout is false,
	 * then the node's height is changed.  The default value
	 * of weight is 0.0.
	 * 
	 * @param weight a double between 0.0 and 1.0
	 * @see #getWeight
	 * @see MultiSplitLayout#layoutContainer
	 * @throws IllegalArgumentException if weight is not between 0.0 and 1.0
	 */
	public void setWeight(double weight) {
	    if ((weight < 0.0)|| (weight > 1.0)) {
		throw new IllegalArgumentException("invalid weight");
	    }
	    this.weight = weight;
	}

	private Node siblingAtOffset(int offset) {
	    Split parent = getParent();
	    if (parent == null) { return null; }
	    List<Node> siblings = parent.getChildren();
	    int index = siblings.indexOf(this);
	    if (index == -1) { return null; }
	    index += offset;
	    return ((index > -1) && (index < siblings.size())) ? siblings.get(index) : null;
	}
	    
	/** 
	 * Return the Node that comes after this one in the parent's
	 * list of children, or null.  If this node's parent is null,
	 * or if it's the last child, then return null.
	 * 
	 * @return the Node that comes after this one in the parent's list of children.
	 * @see #previousSibling
	 * @see #getParent
	 */
	public Node nextSibling() {
	    return siblingAtOffset(+1);
	}

	/** 
	 * Return the Node that comes before this one in the parent's
	 * list of children, or null.  If this node's parent is null,
	 * or if it's the last child, then return null.
	 * 
	 * @return the Node that comes before this one in the parent's list of children.
	 * @see #nextSibling
	 * @see #getParent
	 */
	public Node previousSibling() {
	    return siblingAtOffset(-1);
	}
    }

    /** 
     * Defines a vertical or horizontal subdivision into two or more
     * tiles.
     */
    public static class Split extends Node {
	private List<Node> children = Collections.emptyList();
	private boolean rowLayout = true;

	/**
	 * Returns true if the this Split's children are to be 
	 * laid out in a row: all the same height, left edge
	 * equal to the previous Node's right edge.  If false,
	 * children are laid on in a column.
	 * 
	 * @return the value of the rowLayout property.
	 * @see #setRowLayout
	 */
	public boolean isRowLayout() { return rowLayout; }

	/**
	 * Set the rowLayout property.  If true, all of this Split's
	 * children are to be laid out in a row: all the same height,
	 * each node's left edge equal to the previous Node's right
	 * edge.  If false, children are laid on in a column.  Default
	 * value is true.
	 * 
	 * @param rowLayout true for horizontal row layout, false for column
	 * @see #isRowLayout
	 */
	public void setRowLayout(boolean rowLayout) {
	    this.rowLayout = rowLayout;
	}

	/** 
	 * Returns this Split node's children.  The returned value
	 * is not a reference to the Split's internal list of children
	 * 
	 * @return the value of the children property.
	 * @see #setChildren
	 */
	public List<Node> getChildren() { 
	    return new ArrayList<Node>(children);
	}

	/**
	 * Set's the children property of this Split node.  The parent
	 * of each new child is set to this Split node, and the parent
	 * of each old child (if any) is set to null.  This method
	 * defensively copies the incoming List.  Default value is
	 * an empty List.
	 * 
	 * @param children List of children
	 * @see #getChildren
	 * @throws IllegalArgumentException if children is null
	 */
	public void setChildren(List<Node> children) {
	    if (children == null) {
		throw new IllegalArgumentException("children must be a non-null List");
	    }
	    for(Node child : this.children) {
		child.setParent(null);
	    }
	    this.children = new ArrayList<Node>(children);
	    for(Node child : this.children) {
		child.setParent(this);
	    }
	}

	/**
	 * Convenience method that returns the last child whose weight
	 * is > 0.0.
	 * 
	 * @return the last child whose weight is > 0.0.
	 * @see #getChildren
	 * @see Node#getWeight
	 */
	public final Node lastWeightedChild() {
	    List<Node> children = getChildren();
	    Node weightedChild = null;
	    for(Node child : children) {
		if (child.getWeight() > 0.0) {
		    weightedChild = child;
		}
	    }
	    return weightedChild;
	}

	public String toString() {
	    int nChildren = getChildren().size();
	    StringBuffer sb = new StringBuffer("MultiSplitLayout.Split");
	    sb.append(isRowLayout() ? " ROW [" : " COLUMN [");
	    sb.append(nChildren + ((nChildren == 1) ? " child" : " children"));
	    sb.append("] ");
	    sb.append(getBounds());
	    return sb.toString();
	}
    }


    /**
     * Models a java.awt Component child.
     */
    public static class Leaf extends Node {
	private String name = "";

	/**
	 * Create a Leaf node.  The default value of name is "". 
	 */
	public Leaf() { }

	/**
	 * Create a Leaf node with the specified name.  Name can not
	 * be null.
	 * 
	 * @param name value of the Leaf's name property
	 * @throws IllegalArgumentException if name is null
	 */
	public Leaf(String name) {
	    if (name == null) {
		throw new IllegalArgumentException("name is null");
	    }
	    this.name = name;
	}

	/**
	 * Return the Leaf's name.
	 * 
	 * @return the value of the name property.
	 * @see #setName
	 */
	public String getName() { return name; }

	/**
	 * Set the value of the name property.  Name may not be null.
	 * 
	 * @param name value of the name property
	 * @throws IllegalArgumentException if name is null
	 */
	public void setName(String name) {
	    if (name == null) {
		throw new IllegalArgumentException("name is null");
	    }
	    this.name = name;
	}

	public String toString() {
	    StringBuffer sb = new StringBuffer("MultiSplitLayout.Leaf");
	    sb.append(" \"");
	    sb.append(getName());
	    sb.append("\""); 
	    sb.append(" weight=");
	    sb.append(getWeight());
	    sb.append(" ");
	    sb.append(getBounds());
	    return sb.toString();
	}
    }


    /** 
     * Models a single vertical/horiztonal divider.
     */
    public static class Divider extends Node {
	/**
	 * Convenience method, returns true if the Divider's parent
	 * is a Split row (a Split with isRowLayout() true), false
	 * otherwise. In other words if this Divider's major axis
	 * is vertical, return true.
	 * 
	 * @return true if this Divider is part of a Split row.
	 */
	public final boolean isVertical() {
	    Split parent = getParent();
	    return (parent != null) ? parent.isRowLayout() : false;
	}

	/** 
	 * Dividers can't have a weight, they don't grow or shrink.
	 * @throws UnsupportedOperationException
	 */
	public void setWeight(double weight) {
	    throw new UnsupportedOperationException();
	}

	public String toString() {
	    return "MultiSplitLayout.Divider " + getBounds().toString();
	}
    }


    private static void throwParseException(StreamTokenizer st, String msg) throws Exception {
	throw new Exception("MultiSplitLayout.parseModel Error: " + msg);
    }

    private static void parseAttribute(String name, StreamTokenizer st, Node node) throws Exception {
	if ((st.nextToken() != '=')) {
	    throwParseException(st, "expected '=' after " + name);
	}
	if (name.equalsIgnoreCase("WEIGHT")) {
	    if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
		node.setWeight(st.nval);
	    }
	    else { 
		throwParseException(st, "invalid weight");
	    }
	}
	else if (name.equalsIgnoreCase("NAME")) {
	    if (st.nextToken() == StreamTokenizer.TT_WORD) {
		if (node instanceof Leaf) {
		    ((Leaf)node).setName(st.sval);
		}
		else {
		    throwParseException(st, "can't specify name for " + node);
		}
	    }
	    else {
		throwParseException(st, "invalid name");
	    }
	}
	else {
	    throwParseException(st, "unrecognized attribute \"" + name + "\"");
	}
    }

    private static void addSplitChild(Split parent, Node child) {
	List<Node> children = new ArrayList(parent.getChildren());
	if (children.size() == 0) {
	    children.add(child);
	}
	else {
	    children.add(new Divider());
	    children.add(child);
	}
	parent.setChildren(children);
    }

    private static void parseLeaf(StreamTokenizer st, Split parent) throws Exception {
	Leaf leaf = new Leaf();
	int token;
	while ((token = st.nextToken()) != StreamTokenizer.TT_EOF) {
	    if (token == ')') {
		break;
	    }
	    if (token == StreamTokenizer.TT_WORD) {
		parseAttribute(st.sval, st, leaf);
	    }
	    else {
		throwParseException(st, "Bad Leaf: " + leaf);
	    }
	}
	addSplitChild(parent, leaf);
    }

    private static void parseSplit(StreamTokenizer st, Split parent) throws Exception {
	int token;
	while ((token = st.nextToken()) != StreamTokenizer.TT_EOF) {
	    if (token == ')') {
		break;
	    }
	    else if (token == StreamTokenizer.TT_WORD) {
		if (st.sval.equalsIgnoreCase("WEIGHT")) {
		    parseAttribute(st.sval, st, parent);
		}
		else {
		    addSplitChild(parent, new Leaf(st.sval));
		}
	    }
	    else if (token == '(') {
		if ((token = st.nextToken()) != StreamTokenizer.TT_WORD) {
		    throwParseException(st, "invalid node type");
		}
		String nodeType = st.sval.toUpperCase();
		if (nodeType.equals("LEAF")) {
		    parseLeaf(st, parent);
		}
		else if (nodeType.equals("ROW") || nodeType.equals("COLUMN")) {
		    Split split = new Split();
		    split.setRowLayout(nodeType.equals("ROW"));
		    addSplitChild(parent, split);
		    parseSplit(st, split);
		}
		else {
		    throwParseException(st, "unrecognized node type '" + nodeType + "'");
		}
	    }
	}
    }

    private static Node parseModel (Reader r) {
	StreamTokenizer st = new StreamTokenizer(r);
	try {
	    Split root = new Split();
	    parseSplit(st, root);
	    return root.getChildren().get(0);
	}
	catch (Exception e) {
	    System.err.println(e);
	}
	finally {
	    try { r.close(); } catch (IOException ignore) {}
	}
	return null;
    }

    /**
     * A convenience method that converts a string to a 
     * MultiSplitLayout model (a tree of Nodes) using a 
     * a simple syntax.  Nodes are represented by 
     * parenthetical expressions whose first token 
     * is one of ROW/COLUMN/LEAF.  ROW and COLUMN specify
     * horizontal and vertical Split nodes respectively, 
     * LEAF specifies a Leaf node.  A Leaf's name and 
     * weight can be specified with attributes, 
     * name=<i>myLeafName</i> weight=<i>myLeafWeight</i>.
     * Similarly, a Split's weight can be specified with
     * weight=<i>mySplitWeight</i>.
     * 
     * <p> For example, the following expression generates
     * a horizontal Split node with three children:
     * the Leafs named left and right, and a Divider in 
     * between:
     * <pre>
     * (ROW (LEAF name=left) (LEAF name=right weight=1.0))
     * </pre>
     * 
     * <p> Dividers should not be included in the string, 
     * they're added automatcially as needed.  Because 
     * Leaf nodes often only need to specify a name, one
     * can specify a Leaf by just providing the name.
     * The previous example can be written like this:
     * <pre>
     * (ROW left (LEAF name=right weight=1.0))
     * </pre>
     * 
     * <p>Here's a more complex example.  One row with
     * three elements, the first and last of which are columns
     * with two leaves each:
     * <pre>
     * (ROW (COLUMN weight=0.5 left.top left.bottom) 
     *      (LEAF name=middle)
     *      (COLUMN weight=0.5 right.top right.bottom))
     * </pre>
     * 
     * 
     * <p> This syntax is not intended for archiving or 
     * configuration files .  It's just a convenience for
     * examples and tests.
     * 
     * @return the Node root of a tree based on s.
     */
    public static Node parseModel(String s) {
	return parseModel(new StringReader(s));
    }


    private static void printModel(String indent, Node root) {
	if (root instanceof Split) {
	    Split split = (Split)root;
	    System.out.println(indent + split);
	    for(Node child : split.getChildren()) {
		printModel(indent + "  ", child);
	    }
	}
	else {
	    System.out.println(indent + root);
	}
    }

    /** 
     * Print the tree with enough detail for simple debugging.
     */
    public static void printModel(Node root) {
	printModel("", root);
    }
}

