import java.io.IOException;
import java.util.Iterator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.tools.ant.filters.StringInputStream;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class XMLParserUtil {
	public static String findFirstTagContent(String response, String tag) {
		return getFirstElement(response,tag).getTextContent();
	}

	public static Element getFirstElement(String response,String tag) {
		NodeList nl = buildDocument(response).getElementsByTagName(tag);
		if(nl.getLength() >0 ){
			return (Element) nl.item(0);
		}
		return null;
	}

	public static Element getLastElement(Document dom,String tag){
		NodeList nl = dom.getElementsByTagName(tag);

		int size = nl.getLength();
		if (size == 0) {
			return null;
		}

		return (Element) nl.item(size - 1);
	}

	public static Iterator<Element> getElements(String xml,String tag){
		return getElements(buildDocument(xml),tag);
	}

	public static Iterator<Element> getElements(Document dom,String tag){
		final NodeList nl = dom.getElementsByTagName(tag);
		return new Iterator<Element>(){
			private int index = 0;
			public boolean hasNext() {
				return index < nl.getLength();
			}

			public Element next() {
				Element el = (Element) nl.item(index);
				index++;
				return el;
			}

			public void remove() {
				throw new UnsupportedOperationException("unsupported");
			}

		};
	}

	public static Element getFirstElement(Element parent,String tag) {
		NodeList nl = parent.getElementsByTagName(tag);
		if(nl.getLength() >0 ){
			return (Element) nl.item(0);
		}
		return null;
	}

	public static Document buildDocument(String response) {
		// get the factory
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {
			// Using factory get an instance of document builder
			DocumentBuilder db = dbf.newDocumentBuilder();
			// parse using builder to get DOM representation of the XML file
			Document dom = db.parse(new StringInputStream(response));
			return dom;

		} catch (ParserConfigurationException pce) {
			throw new IllegalArgumentException("Invalid xml input[" + response
					+ "]", pce);
		} catch (SAXException se) {
			throw new IllegalArgumentException("Invalid xml input[" + response
					+ "]", se);
		} catch (IOException ioe) {
			throw new IllegalArgumentException("Invalid xml input[" + response
					+ "]", ioe);
		}
	}


}