/*
 * @(#)ElementTreePanel.java	1.4 98/06/29
 *
 * Copyright 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

import com.sun.java.swing.*;
import com.sun.java.swing.event.*;
import com.sun.java.swing.text.*;
import com.sun.java.swing.tree.*;
import com.sun.java.swing.undo.*;
import java.awt.*;
import java.util.*;

/**
 * Displays a tree showing all the elements in a text Document. Selecting
 * a node will result in reseting the selection of the JTextComponent.
 * This also becomes a CaretListener to know when the selection has changed
 * in the text to update the selected item in the tree.
 *
 * @author Scott Violet
 * @version 1.4 06/29/98
 */
public class ElementTreePanel extends JPanel implements CaretListener, DocumentListener, TreeSelectionListener {
    /** Tree showing the documents element structure. */
    protected JTree             tree;
    /** Text component showing elemenst for. */
    protected JTextComponent    editor;
    /** Model for the tree. */
    protected DefaultTreeModel  treeModel;
    /** Set to true when updatin the selection. */
    protected boolean           updatingSelection;

    public ElementTreePanel(JTextComponent editor) {
	this.editor = editor;

	Document document = editor.getDocument();

	// Create the tree.
	treeModel = new DefaultTreeModel((TreeNode)document.
					 getDefaultRootElement());
	tree = new JTree(treeModel) {
	    public String convertValueToText(Object value, boolean selected,
					     boolean expanded, boolean leaf,
					     int row, boolean hasFocus) {
		Element        e = (Element)value;
		AttributeSet   as = e.getAttributes().copyAttributes();
		String         asString;

		if(as != null) {
		    StringBuffer       retBuffer = new StringBuffer("[");
		    Enumeration        names = as.getAttributeNames();

		    while(names.hasMoreElements()) {
			Object        nextName = names.nextElement();

			if(nextName != StyleConstants.ResolveAttribute) {
			    retBuffer.append(" ");
			    retBuffer.append(nextName);
			    retBuffer.append("=");
			    retBuffer.append(as.getAttribute(nextName));
			}
		    }
		    retBuffer.append(" ]");
		    asString = retBuffer.toString();
		}
		else
		    asString = "[ ]";

		if(e.isLeaf())
		    return "LEAF: " + e.getName() + " Attributes: " + asString;
		return "Branch: " + e.getName() + " Attributes: " +
 		        asString;
	    }
	};
	tree.addTreeSelectionListener(this);
	// become a listener on the document to update the tree.
	document.addDocumentListener(this);

	// Become a CaretListener
	editor.addCaretListener(this);

	// configure the panel and frame containing it.
	setLayout(new BorderLayout());
	add(new JScrollPane(tree), BorderLayout.CENTER);

	// Add a label above tree to describe what is being shown
	JLabel     label = new JLabel("Elements that make up the current document", SwingConstants.CENTER);

	label.setFont(new Font("Dialog", Font.BOLD, 14));
	add(label, BorderLayout.NORTH);

	setPreferredSize(new Dimension(400, 400));
    }


    // DocumentListener

    /**
     * Gives notification that there was an insert into the document.  The
     * given range bounds the freshly inserted region.
     *
     * @param e the document event
     */
    public void insertUpdate(DocumentEvent e) {
	updateTree(e);
    }

    /**
     * Gives notification that a portion of the document has been
     * removed.  The range is given in terms of what the view last
     * saw (that is, before updating sticky positions).
     *
     * @param e the document event
     */
    public void removeUpdate(DocumentEvent e) {
	updateTree(e);
    }

    /**
     * Gives notification that an attribute or set of attributes changed.
     *
     * @param e the document event
     */
    public void changedUpdate(DocumentEvent e) {
	updateTree(e);
    }

    // CaretListener

    /**
     * Messaged when the selection in the editor has changed. Will update
     * the selection in the tree.
     */
    public void caretUpdate(CaretEvent e) {
	if(!updatingSelection) {
	    JTextComponent     editor = getEditor();
	    int                start = Math.min(e.getDot(), e.getMark());
	    int                end = Math.max(e.getDot(), e.getMark());
	    Vector             paths = new Vector();

	    // Build an array of all the paths to all the character elements
	    // in the selection.
	    while(start <= end) {
		TreePath    path = getPathForIndex(start);
		Element     charElement = (Element)path.getLastPathComponent();

		paths.addElement(path);
		if(start >= charElement.getEndOffset())
		    start++;
		else
		    start = charElement.getEndOffset();
	    }

	    // If more than one path was found, selected it.
	    int               numPaths = paths.size();

	    if(numPaths > 0) {
		TreePath[]    pathArray = new TreePath[numPaths];

		paths.copyInto(pathArray);
		updatingSelection = true;
		try {
		    getTree().setSelectionPaths(pathArray);
		    getTree().scrollPathToVisible(pathArray[0]);
		}
		finally {
		    updatingSelection = false;
		}
	    }
	}
    }

    // TreeSelectionListener

    /**
      * Called whenever the value of the selection changes.
      * @param e the event that characterizes the change.
      */
    public void valueChanged(TreeSelectionEvent e) {
	JTree       tree = getTree();

	if(!updatingSelection && tree.getSelectionCount() == 1) {
	    TreePath      selPath = tree.getSelectionPath();
	    Element       selElement = (Element)selPath.getLastPathComponent();

	    updatingSelection = true;
	    try {
		getEditor().select(selElement.getStartOffset(),
				   selElement.getEndOffset());
	    }
	    finally {
		updatingSelection = false;
	    }
	}
    }

    // Local methods

    /**
     * @return tree showing elements.
     */
    protected JTree getTree() {
	return tree;
    }

    /**
     * @return JTextComponent showing elements for.
     */
    protected JTextComponent getEditor() {
	return editor;
    }

    /**
     * @return root element of editor.
     */
    protected Element getRootElement() {
	return getEditor().getDocument().getDefaultRootElement();
    }

    /**
     * @return TreeModel implementation used to represent the elements.
     */
    public DefaultTreeModel getTreeModel() {
	return treeModel;
    }

    /**
     * Updates the tree based on the event type. This will invoke either
     * updateTree with the root element, or handleChange.
     */
    protected void updateTree(DocumentEvent event) {
	updatingSelection = true;
	try {
	    updateTree(event, getRootElement());
	}
	finally {
	    updatingSelection = false;
	}
    }

    /**
     * Creates TreeModelEvents based on the DocumentEvent and messages
     * the treemodel. This recursively invokes this method with children
     * elements.
     * @param event indicates what elements in the tree hierarchy have
     * changed.
     * @param element Current element to check for changes against.
     */
    protected void updateTree(DocumentEvent event, Element element) {
        DocumentEvent.ElementChange ec = event.getChange(element);

        if (ec != null) {
	    Element[]       removed = ec.getChildrenRemoved();
	    Element[]       added = ec.getChildrenAdded();
	    int             startIndex = ec.getIndex();

	    // Check for removed.
	    if(removed != null && removed.length > 0) {
		int[]            indices = new int[removed.length];

		for(int counter = 0; counter < removed.length; counter++) {
		    indices[counter] = startIndex + counter;
		}
		getTreeModel().nodesWereRemoved((TreeNode)element, indices,
						removed);
	    }
	    // check for added
	    if(added != null && added.length > 0) {
		int[]            indices = new int[added.length];

		for(int counter = 0; counter < added.length; counter++) {
		    indices[counter] = startIndex + counter;
		}
		getTreeModel().nodesWereInserted((TreeNode)element, indices);
	    }
        }
	if(!element.isLeaf()) {
	    int        startIndex = element.getElementIndex
		                       (event.getOffset());
	    int        elementCount = element.getElementCount();
	    int        endIndex = Math.min(elementCount - 1,
					   element.getElementIndex
				     (event.getOffset() + event.getLength()));

	    if(startIndex > 0 && startIndex < elementCount &&
	       element.getElement(startIndex).getStartOffset() ==
	       event.getOffset()) {
		// Force checking the previous element.
		startIndex--;
	    }
	    if(startIndex != -1 && endIndex != -1) {
		for(int counter = startIndex; counter <= endIndex; counter++) {
		    updateTree(event, element.getElement(counter));
		}
	    }
	}
	else {
	    // Element is a leaf, assume it changed
	    getTreeModel().nodeChanged((TreeNode)element);
	}
    }

    /**
     * Returns a TreePath to the element at <code>position</code>.
     */
    protected TreePath getPathForIndex(int position) {
	Element       root = getEditor().getDocument().getDefaultRootElement();
	TreePath      path = new TreePath(root);
	Element       child = root.getElement(root.getElementIndex(position));

	path = path.pathByAddingChild(child);
	while(!child.isLeaf()) {
	    child = child.getElement(child.getElementIndex(position));
	    path = path.pathByAddingChild(child);
	}
	return path;
    }
}