// VSX.java
// A simple XML parser that builds a tree from SAX events.  The xml file
// should be passed as a commandline argument.
//

import javax.swing.*;
import javax.swing.tree.*;
import java.util.*;
import java.io.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import javax.xml.parsers.*;

public class VSX {

  public TreeModel parse(String filename) {
    SAXParserFactory factory = SAXParserFactory.newInstance();
    XMLTreeHandler handler = new XMLTreeHandler();
    try {
      // Parse the input.
      SAXParser saxParser = factory.newSAXParser();
      saxParser.parse( new File(filename), handler);
    }
    catch (Exception e) {
      System.err.println("File Read Error: " + e);
      e.printStackTrace();
      return new DefaultTreeModel(new DefaultMutableTreeNode("error"));
    }
    return new DefaultTreeModel(handler.getRoot());
  }

  public static class XMLTreeHandler extends DefaultHandler {
    private DefaultMutableTreeNode root, currentNode;  
    public DefaultMutableTreeNode getRoot() {
      return root;
    }

    // SAX Parser Handler methods...
    public void startElement(String namespaceURI, String lName, String qName,
                             Attributes attrs) throws SAXException {
      String eName = lName; // Element name
      if ("".equals(eName)) eName = qName;
      Tag t = new Tag(eName, attrs);
      DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(t);
      if (currentNode == null) {
        root = newNode;
      }
      else {
        // Must not be the root node...
        currentNode.add(newNode);
      }
      currentNode = newNode;
    }

    public void endElement(String namespaceURI, String sName, String qName)
    throws SAXException {
      currentNode = (DefaultMutableTreeNode)currentNode.getParent();
    }

    public void characters(char buf[], int offset, int len) throws SAXException {
      String s = new String(buf, offset, len).trim();
      ((Tag)currentNode.getUserObject()).addData(s);
    }
  }

  public static class Tag {
    private String name;
    private String data;
    private Attributes attr;

    public Tag(String n, Attributes a) { name = n; attr = a; }

    public String getName() { return name; }
    public Attributes getAttributes() { return attr; }
    public void setData(String d) { data = d; }
    public String getData() { return data; }

    public void addData(String d) {
      if (data == null) {
        setData(d);
      }
      else {
        data += d;
      }
    }

    public String getAttributesAsString() {
      StringBuffer buf = new StringBuffer(256);
      for (int i = 0; i < attr.getLength(); i++) {
        buf.append(attr.getQName(i));
        buf.append("=\"");
        buf.append(attr.getValue(i));
        buf.append("\"");
      }
      return buf.toString();
    }

    public String toString() {
      String a = getAttributesAsString();
      return name + ": " + a + (data == null ? "" :" (" + data + ")");
    }
  }

  public static void main(String args[]) {
    if (args.length != 1) {
      System.err.println("Usage is: java VSX testfile.xml");
      System.exit(1);
    }
    JFrame frame = new JFrame("VSX Test");
    VSX parser = new VSX();
    JTree tree = new JTree(parser.parse(args[0]));
    frame.getContentPane().add(new JScrollPane(tree));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300,400);
    frame.setVisible(true);
  }
}