/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */ 
package org.apache.jasper.parser;


import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;


/**
 * Simplified implementation of a Node from a Document Object Model (DOM)
 * parse of an XML document.  This class is used to represent a DOM tree
 * so that the XML parser's implementation of <code>org.w3c.dom</code> need
 * not be visible to the remainder of Jasper.
 * <p>
 * <strong>WARNING</strong> - Construction of a new tree, or modifications
 * to an existing one, are not thread-safe and such accesses must be
 * synchronized.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.2 $ $Date: 2001/02/16 22:17:08 $
 */

public class TreeNode {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new node with no parent.
     *
     * @param name The name of this node
     */
    public TreeNode(String name) {

        this(name, null);

    }


    /**
     * Construct a new node with the specified parent.
     *
     * @param name The name of this node
     * @param parent The node that is the parent of this node
     */
    public TreeNode(String name, TreeNode parent) {

        super();
        this.name = name;
        this.parent = parent;
        if (this.parent != null)
            this.parent.addChild(this);

    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The attributes of this node, keyed by attribute name,
     * Instantiated only if required.
     */
    protected HashMap attributes = null;


    /**
     * The body text associated with this node (if any).
     */
    protected String body = null;


    /**
     * The children of this node, instantiated only if required.
     */
    protected ArrayList children = null;


    /**
     * The name of this node.
     */
    protected String name = null;


    /**
     * The parent node of this node.
     */
    protected TreeNode parent = null;


    // --------------------------------------------------------- Public Methods


    /**
     * Add an attribute to this node, replacing any existing attribute
     * with the same name.
     *
     * @param name The attribute name to add
     * @param value The new attribute value
     */
    public void addAttribute(String name, String value) {

        if (attributes == null)
            attributes = new HashMap();
        attributes.put(name, value);

    }


    /**
     * Add a new child node to this node.
     *
     * @param node The new child node
     */
    public void addChild(TreeNode node) {

        if (children == null)
            children = new ArrayList();
        children.add(node);

    }


    /**
     * Return the value of the specified node attribute if it exists, or
     * <code>null</code> otherwise.
     *
     * @param name Name of the requested attribute
     */
    public String findAttribute(String name) {

        if (attributes == null)
            return (null);
        else
            return ((String) attributes.get(name));

    }


    /**
     * Return an Iterator of the attribute names of this node.  If there are
     * no attributes, an empty Iterator is returned.
     */
    public Iterator findAttributes() {

        if (attributes == null)
            return (Collections.EMPTY_LIST.iterator());
        else
            return (attributes.keySet().iterator());

    }


    /**
     * Return the first child node of this node with the specified name,
     * if there is one; otherwise, return <code>null</code>.
     *
     * @param name Name of the desired child element
     */
    public TreeNode findChild(String name) {

        if (children == null)
            return (null);
        Iterator items = children.iterator();
        while (items.hasNext()) {
            TreeNode item = (TreeNode) items.next();
            if (name.equals(item.getName()))
                return (item);
        }
        return (null);

    }


    /**
     * Return an Iterator of all children of this node.  If there are no
     * children, an empty Iterator is returned.
     */
    public Iterator findChildren() {

        if (children == null)
            return (Collections.EMPTY_LIST.iterator());
        else
            return (children.iterator());

    }


    /**
     * Return an Iterator over all children of this node that have the
     * specified name.  If there are no such children, an empty Iterator
     * is returned.
     *
     * @param name Name used to select children
     */
    public Iterator findChildren(String name) {

        if (children == null)
            return (Collections.EMPTY_LIST.iterator());

        ArrayList results = new ArrayList();
        Iterator items = children.iterator();
        while (items.hasNext()) {
            TreeNode item = (TreeNode) items.next();
            if (name.equals(item.getName()))
                results.add(item);
        }
        return (results.iterator());

    }


    /**
     * Return the body text associated with this node (if any).
     */
    public String getBody() {

        return (this.body);

    }


    /**
     * Return the name of this node.
     */
    public String getName() {

        return (this.name);

    }


    /**
     * Remove any existing value for the specified attribute name.
     *
     * @param name The attribute name to remove
     */
    public void removeAttribute(String name) {

        if (attributes != null)
            attributes.remove(name);

    }


    /**
     * Remove a child node from this node, if it is one.
     *
     * @param node The child node to remove
     */
    public void removeNode(TreeNode node) {

        if (children != null)
            children.remove(node);

    }


    /**
     * Set the body text associated with this node (if any).
     *
     * @param body The body text (if any)
     */
    public void setBody(String body) {

        this.body = body;

    }


    /**
     * Return a String representation of this TreeNode.
     */
    public String toString() {

        StringBuffer sb = new StringBuffer();
        toString(sb, 0, this);
        return (sb.toString());

    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Append to the specified StringBuffer a character representation of
     * this node, with the specified amount of indentation.
     *
     * @param sb The StringBuffer to append to
     * @param indent Number of characters of indentation
     * @param node The TreeNode to be printed
     */
    protected void toString(StringBuffer sb, int indent,
                            TreeNode node) {

        int indent2 = indent + 2;

        // Reconstruct an opening node
        for (int i = 0; i < indent; i++)
            sb.append(' ');
        sb.append('<');
        sb.append(node.getName());
        Iterator names = node.findAttributes();
        while (names.hasNext()) {
            sb.append(' ');
            String name = (String) names.next();
            sb.append(name);
            sb.append("=\"");
            String value = node.findAttribute(name);
            sb.append(value);
            sb.append("\"");
        }
        sb.append(">\n");

        // Reconstruct the body text of this node (if any)
        String body = node.getBody();
        if ((body != null) && (body.length() > 0)) {
            for (int i = 0; i < indent2; i++)
                sb.append(' ');
            sb.append(body);
            sb.append("\n");
        }

        // Reconstruct child nodes with extra indentation
        Iterator children = node.findChildren();
        while (children.hasNext()) {
            TreeNode child = (TreeNode) children.next();
            toString(sb, indent2, child);
        }

        // Reconstruct a closing node marker
        for (int i = 0; i < indent; i++)
            sb.append(' ');
        sb.append("</");
        sb.append(node.getName());
        sb.append(">\n");

    }


}
