/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */

package org.apache.jorphan.util;

import org.apache.commons.collections.ArrayStack;

// @see org.apache.jorphan.util.TestXMLBuffer for unit tests

/**
 * Provides XML string building methods.
 * Not synchronised.
 *  
 */
public class XMLBuffer{
	private StringBuffer sb = new StringBuffer(); // the string so far
	
	private ArrayStack tags = new ArrayStack(); // opened tags
	
	public XMLBuffer(){
		
	}
	
	private void startTag(String t){
		sb.append("<");
		sb.append(t);
		sb.append(">");			
	}
	private void endTag(String t){
		sb.append("</");
		sb.append(t);
		sb.append(">");			
	}

	/**
	 * Open a tag; save on stack.
	 * 
	 * @param tagname
	 * @return this
	 */
	public XMLBuffer openTag(String tagname){
		tags.push(tagname);
		startTag(tagname);
		return this;
	}
	
	/**
	 * Close top tag from stack.
	 * 
	 * @param tagname
	 * 
	 * @return this
	 * 
	 * @throws IllegalArgumentException if the tag names do not match
	 */
	public XMLBuffer closeTag(String tagname){
		String tag = (String) tags.pop();
		if (!tag.equals(tagname)) {
			throw new IllegalArgumentException("Trying to close tag: "+tagname+" ; should be "+tag);
		}
		endTag(tag);
		return this;
	}
	
	/**
	 * Add a complete tag with content.
	 * 
	 * @param tagname
	 * @param content
	 * @return this
	 */
	public XMLBuffer tag(String tagname,String content){
		startTag(tagname);
		sb.append(content);
		endTag(tagname);
		return this;
	}

	/**
	 * Add a complete tag with content.
	 * 
	 * @param tagname
	 * @param content
	 * @return this
	 */
	public XMLBuffer tag(String tagname,StringBuffer content){
		startTag(tagname);
		sb.append(content);
		endTag(tagname);
		return this;
	}

	/**
	 * Convert the buffer to a string, closing any open tags
	 */
	public String toString(){
		while(!tags.isEmpty()){
			endTag((String)tags.pop());
		}			
		return sb.toString();
	}
}