// File: xmltest2.java
//
// Author: Rahul Simha
// Version: Feb 11, 2000
//
// Second example in XML tutorial

import com.ibm.xml.parser.*;
import org.w3c.dom.*;
import java.io.*;


// An error-handling class passed to the parser that
// overrides the error method.

class MyErrorHandler implements ErrorListener {
  public int error (String fname, int lineno, int charoff,
		    Object key, String mes)
  {
    System.out.println ("ERR:" + fname + " at line " + lineno +
			": " + mes);
    return 1;
  }
}


public class xmltest2 {

  // The method clean removes all nodes with "junk" data.

  public static void clean (Node n)
  {
    boolean remove = false;

    // Extract the nodename.
    String nodename = n.getNodeName();

    if (nodename != null) {
      // Removing is a possibility only if the node is of type "#text".
      if (nodename.equals ("#text"))
	remove = true;
      else
	remove = false;
    }

    // Extract the node value.
    String valueStr = n.getNodeValue();
    int len = 0;

    // Now trim and check if it needs to be removed.
    if (valueStr != null) {
      valueStr = valueStr.trim();
      len = valueStr.length();
      if (len > 0) {
        // Useful
	remove = false;
        // Put the trimmed string back in.
        n.setNodeValue (valueStr);
      }
    }

    if (remove) {
      // To remove, go to the parent node and delete from there.
      Node p = n.getParentNode();
      p.removeChild (n);
      // Recursively clean.
      clean (p);
      return;
    }

    // Continue exploration.
    if (n.hasChildNodes()) {
      NodeList nl = n.getChildNodes();
      int size = nl.getLength();
      for (int i=0; i<size; i++) {
	clean (nl.item(i));
	size = nl.getLength();
      }
    }
  }


  // Make a Node from some data.

  public static Node makeStudent (Node n, String name, String addr, String grade)
  {
    // First, clone a node.
    Node s = n.cloneNode (true);

    // Now populate the data.
    NodeList nl = s.getChildNodes();
    int size = nl.getLength();
    for (int i=0; i<size; i++) {
      Node c = nl.item (i);
      if (c.getNodeName().equals ("NAME")) {
        // Note use of the getFirstChild() method.
	Node child = c.getFirstChild();
        // Use setNodeValue to set a value string.
	child.setNodeValue (name);
      }
      if (c.getNodeName().equals ("ADDR")) {
	Node child = c.getFirstChild();
	child.setNodeValue (addr);
      }
      if (c.getNodeName().equals ("GRADE")) {
	Node child = c.getFirstChild();
	child.setNodeValue (grade);
      }
    }
    return s;
  }

  // Traverse a subtree whose root is the parameter.

  public static void traverse (Node n)
  {
    // Extract node info:
    String nodename = n.getNodeName();
    String valueStr = n.getNodeValue();
    // Print and continue traversing.
    System.out.println ("Node: " + n.getNodeName() + " value=[" + valueStr + "]");

    // Now traverse the rest of the tree in depth-first order.
    if (n.hasChildNodes()) {
      // Get the children in a list.
      NodeList nl = n.getChildNodes();
      // How many of them?
      int size = nl.getLength();
      for (int i=0; i<size; i++)
        // Recursively traverse each of the children.
	traverse (nl.item(i));
    }
  }


  public static void main (String[] argv)
  {
    if (argv.length > 0) {
      try {
	FileReader fr = new FileReader (argv[0]);

	// Pass errorhandler to parser.
	Parser p = new Parser (argv[0], new MyErrorHandler(), null);
        // The next few steps are straightforward:
	p.setKeepComment (false);
	p.setPreserveSpace (false);
	TXDocument doc = p.readStream(fr);
	Element root = doc.getDocumentElement ();

        // Always a good check:
	if (root == null) return;

        // First clean:
	System.out.println ("CLEAN ...");
	clean (root);

        // Then, traverse:
	System.out.println ("TRAVERSE ...");
	traverse (root);

        // Add a new "student" to the tree.
	System.out.println ("ADDING A NEW STUDENT: ");
	NodeList nl = doc.getElementsByTagName ("STUDENT");
	Node n = nl.item(1);
	Node s = makeStudent (n, "Dangerous Dave", "333 Ouch St", "C");
	Node parent = n.getParentNode();
        // Note the use of appendChild():
	parent.appendChild (s);

        // OK, traverse again to see what we've done.
	System.out.println ("TRAVERSE ...");
	traverse (root);
      }
      catch (IOException e) {
	System.out.println ("Usage: java xmltest2 <filename>");
      }
    }
    else {
	System.out.println ("Usage: java xmltest2 <filename>");
    }
  }
}