// XMLDotReader.java
// Use jaxp.jar and crimson.jar in the /usr/class/cs108/jar directory
// in your CLASSPATH
// (updated to use SAX-2 which has slightly different prototypes
import java.io.*;
import java.util.*;


import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;


/**
 This is a simple class that can read state out of an XML file
 using a SAX state-machine parser.
 
 http://java.sun.com/xml/jaxp-1.1/docs/api/
 
 In this case, we support data like this, where the flip
 node switches x,y...
	 
	<?xml version="1.0" encoding="UTF-8"?>

	<dots>
		<dot x="81" y="67" />
		<dot x="175" y="122" />
		<flip>
			<dot x="175" y="122" />
			<dot x="209" y="71" />
		</flip>
		<dot x="209" y="71" />
	</dots>


 Based on the JAXP sample code, updated for SAX-2 where the
 prototypes for for startElement() and endElement() changed.
*/
public class XMLDotReader extends DefaultHandler
{
	
	public static void main (String argv [])
	{
		if (argv.length != 1) {
			System.err.println ("Usage: cmd filename");
			System.exit (1);
		}
		
		
		try {
			XMLDotReader xr = new XMLDotReader();
			InputStream in = new BufferedInputStream( new FileInputStream(new File(argv[0])));
			xr.read(in);
		} catch (Throwable t) {
			t.printStackTrace ();
		}

	}		

	/**
	 Read the XML in the given file
	*/
	public void read(InputStream stream)  {
		try {
			SAXParserFactory factory = SAXParserFactory.newInstance();
			SAXParser saxParser = factory.newSAXParser();
			clear();
			saxParser.parse(stream, this);
		}
		catch (Exception e) {
			e.printStackTrace();
		}
	}
	

	public XMLDotReader() {
		clear();
	}
	
	
	// State we keep track of -- like a state machine,
	// where startElement() etc. keep getting called
	private int x;
	private int y;
	private boolean flip;
	
	
	public void clear() {
		x = -1;
		y = -1;
		flip = false;
	}	

	//===========================================================
	// SAX DocumentHandler methods
	//===========================================================


	public void startDocument ()
	throws SAXException
	{
		//System.out.println("startDocument");
	}

	public void endDocument ()
	throws SAXException
	{
		//System.out.println("startDocument");
	}

	
	/**
	 Called for each node
	 -look at localName and atts to see the node state
	 -process that node if appropriate
	 -or, update our state to affect future calls to startElem()
	 or characters()
	 
	 NOTE: With SAX-2, the arguments to startElement() changed
	*/
	public void startElement (String namespaceURI, String localName,
								String rawName, Attributes atts)
	throws SAXException
	{
		//System.out.println("start element:" + localName);
		if (localName.equals("dot")) {
			x = Integer.parseInt(atts.getValue("x"));
			y = Integer.parseInt(atts.getValue("y"));
			
			if (flip) {
				int temp = x; x = y; y = temp;
			}
			
			// do something with our x,y state (could wait for endElement)
			System.out.println(x + ", " + y);		}
		else if (localName.equals("flip")) {
			flip = true;
		}
	}

	// Called at the end of each element --
	// arguments changed with SAX-2
	public void endElement(java.lang.String uri,
							java.lang.String localName,
							java.lang.String qName)
	throws SAXException
	{
		//System.out.println("end element:" + localName);
		
		if (localName.equals("flip")) {
			flip = false;
		}
	}

	// Called for characters between nodes
	public void characters (char buf [], int offset, int len)
	throws SAXException
	{
		//String s = new String(buf, offset, len);
		//s = s.trim();
		//if (!s.equals("")) {
			//System.out.println("characters:" + s);
		//}
	}
}