package dom.traversal;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.TreeWalker;
import org.apache.xerces.dom.TreeWalkerImpl;
import org.w3c.dom.traversal.NodeFilter;
import org.apache.xerces.parsers.DOMParser;
import org.xml.sax.InputSource;
import java.io.StringReader;
import java.util.Vector;

public class TestWalker {
	// this many children of root node
	private static final int NUM_BRANCH = 10;
	// this many children of each branch node
	private static final int NUM_TWIG = 10;
	// this many children for each twig node
	private static final int NUM_LEAF = 11;
	// this many children for each twig node
	private static final String SEARCH_VALUE = "Leaf1.1.1";

	public TestWalker() {
		try {
			runTest(parseXML(createXML()));
		} catch (StackOverflowError e) {
			System.out.println(e);
		}
	} // end constructor()

	// Creates a TreeWalker with a simple name filter and loops
	// through each node returned until the document is finished.
	private void runTest(Document doc) {
		// Create non-filtering TreeWalker.
		{
			System.out.println("Testing firstChild()...");
			TreeWalker simpleWalker = new 
				TreeWalkerImpl(doc, NodeFilter.SHOW_ALL, null, true);
			Node node = simpleWalker.firstChild(); // root
			node = simpleWalker.firstChild(); // rootheader
			node = simpleWalker.firstChild(); // null
			if (node != null) {
				System.out.println("FAILED: got " 
								   + node.getNodeName() 
								   + " but expected null");
			} else {
				System.out.println("PASSED");
			}
		}


		System.out.println("Testing nextNode()...");
		// Create TreeWalker with inline filter.
		// The filter simply looks for a node with a specific value
		TreeWalker walker = new 
			TreeWalkerImpl(doc, NodeFilter.SHOW_ALL,
						   new NodeFilter() {
								   public short acceptNode (Node n) {
									   String testValue = n.getNodeValue();
									   if (testValue == null) {
										   return FILTER_SKIP;
									   }
									   if (testValue.equals(SEARCH_VALUE)) {
										   return FILTER_ACCEPT;
									   }
									   return FILTER_SKIP;
								   } // end acceptNode(Node)
							   }, true);
		// Loop until done.
		long startTime;
		long endTime;
		Vector matchingNodes = new Vector();
		startTime = System.currentTimeMillis();
		Node node = walker.nextNode();
		while (node != null) {
			matchingNodes.addElement(node);
			node = walker.nextNode();
		}
		endTime = System.currentTimeMillis();
		check(matchingNodes);
		double runTime = (double)(endTime - startTime);
		System.out.println("approximately " + (runTime/1000.0) + 
						   " seconds");

		// Try going backwards
		System.out.println("Testing previousNode()...");
		
		// Start at the last node in the tree
		Node lastNode = doc;
		while (lastNode.getLastChild() != null) {
			lastNode = lastNode.getLastChild();
		}
		walker.setCurrentNode(lastNode);
		matchingNodes = new Vector();
		startTime = System.currentTimeMillis();
		node = walker.previousNode();
		while (node != null) {
			matchingNodes.addElement(node);
			node = walker.previousNode();
		}
		endTime = System.currentTimeMillis();
		check(matchingNodes);
		runTime = (double)(endTime - startTime);
		System.out.println("approximately " + (runTime/1000.0) + 
						   " seconds");
	} // end runTest()

	// Determines whether matching nodes contains exactly 1 Node and
	// whether that 1 Node has a value of SEARCH_VALUE
	private void check(Vector matchingNodes) {
		if (matchingNodes.size() != 1) {
			System.out.println("FAILED: found " 
							   + matchingNodes.size() 
							   + " matching nodes "
							   + " but expected 1");
		} else {
			String value = ((Node)matchingNodes.elementAt(0)).getNodeValue();
			if (! value.equals(SEARCH_VALUE)) {
				System.out.println("FAILED: found " + value
								   + " but expected " + SEARCH_VALUE);
			} else {
				System.out.println("PASSED");
			}
		}
	}

	// Parses given String and returns a Document
	private Document parseXML(String xmlSrc) {
		// Double check accuracy of created xml:
		// System.out.println("Source:\n" + xmlSrc);
		DOMParser parser = new DOMParser();
		InputSource in = new InputSource(new StringReader(xmlSrc));
		try { parser.parse(in);
		} catch (Exception e) {e.printStackTrace();System.exit(1);}
		return parser.getDocument();
	} // end parseXML()

	// Creates a simple Document based on global parameters.
	// The root has NUM_BRANCH children, each has NUM_TWIG children,
	// and each of those has NUM_LEAF children.
	private String createXML() {
		StringBuffer xmlSrc = new StringBuffer();
		xmlSrc.append("<?xml version=\"1.0\"?>\n");
		xmlSrc.append("<root><rootheader></rootheader>\n");
		for (int x=0; x < NUM_BRANCH; x++) {
			xmlSrc.append
				("\t<branch><branchheader>Branch"+x+"</branchheader>\n");
			xmlSrc.append
				("\t\t<resource>Resource"+x+"</resource>\n");
			for (int y=0; y<NUM_TWIG; y++) {
				xmlSrc.append
					("\t\t<twig><twigheader>Twig"+x+"."+y+
					 "</twigheader>\n");
				for (int z=0; z<NUM_LEAF; z++)
					xmlSrc.append
						("\t\t\t<leaf>Leaf"+x+"."+y+"."+z+"</leaf>\n");
				xmlSrc.append("\t\t</twig>\n");
			}
			xmlSrc.append("\t</branch>\n");
		}
		xmlSrc.append("<rootfooter>The End</rootfooter>\n");
		xmlSrc.append("</root>");
		return xmlSrc.toString();
	} // end createXML()

	// Usage: java TestWalker
	public static void main(String[] args) {
		TestWalker bob = new TestWalker();
	} // end main
} // end class TestWalker