/* Copyright 2002-2004 Elliotte Rusty Harold
   
   This library is free software; you can redistribute it and/or modify
   it under the terms of version 2.1 of the GNU Lesser General Public 
   License as published by the Free Software Foundation.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
   GNU Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the 
   Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
   Boston, MA 02111-1307  USA
   
   You can contact Elliotte Rusty Harold by sending e-mail to
   elharo@metalab.unc.edu. Please include the word "XOM" in the
   subject line. The XOM home page is located at http://www.xom.nu/
*/

package nu.xom.benchmarks;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

import nu.xom.Builder;
import nu.xom.DocType;
import nu.xom.Document;
import nu.xom.Node;
import nu.xom.ParsingException;
import nu.xom.Serializer;
import nu.xom.ValidityException;

/**
 * 
 * <p>
 * Benchmark performance against a specified URL for
 * building, tree-walking, and serializing.
 * </p>
 * 
 * @author Elliotte Rusty Harold
 * @version 1.0
 *
 */
class TreeWalker {

    public static void main(String[] args) {
     
        if (args.length <= 0) {
          System.out.println(
            "Usage: java nu.xom.benchmarks.TreeWalker URL"
          );
          return; 
        }
         
        TreeWalker iterator = new TreeWalker();
        Builder parser = new Builder();
        try {
            // Separate out the basic I/O by parsing document,
            // and then serializing into a byte array. This caches
            // the document and removes any dependence on the DTD.
            Document doc = parser.build(args[0]);
            DocType type = doc.getDocType();
            if (type != null) {
                doc.removeChild(type);   
            }
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            Serializer serializer = new Serializer(out);
            serializer.write(doc);
            serializer.flush();
            out.close();
            byte[] data = out.toByteArray(); 
                       
            warmup(data, parser, iterator, 5, args[0]);
            
            // try to avoid garbage collection pauses
            System.gc(); System.gc(); System.gc();
            
            long prebuild = System.currentTimeMillis();         
            // Read the entire document into memory
            Document document = build(data, args[0], parser);
            long postbuild = System.currentTimeMillis();
            System.out.println((postbuild - prebuild) 
              + "ms to build the tree");  
           
            long prewalk = System.currentTimeMillis();         
            // Process it starting at the root
            walkTree(iterator, document);
            long postwalk = System.currentTimeMillis();
            System.out.println((postwalk - prewalk) 
              + "ms to walk tree");
            
            OutputStream result = new ByteArrayOutputStream(3000000);

            long preserialize = System.currentTimeMillis();
            serialize(document, result);
            long postserialize = System.currentTimeMillis();
            System.out.println((postserialize - preserialize) 
              + "ms to serialize the tree in UTF-8");

            out = new ByteArrayOutputStream(4000000);
            long preprettyserialize = System.currentTimeMillis();
            prettyPrint(document, result);
            long postprettyserialize = System.currentTimeMillis();
            System.out.println(
             (postprettyserialize - preprettyserialize) 
              + "ms to pretty print the tree in UTF-8");

            long preUTF16serialize = System.currentTimeMillis();
            serializeUTF16(document, result);
            long postUTF16serialize = System.currentTimeMillis();
            System.out.println((postUTF16serialize - preUTF16serialize)
              + "ms to serialize the tree in UTF-16");
        }
        catch (IOException ex) { 
          System.out.println(ex); 
        }
        catch (ParsingException ex) { 
          System.out.println(ex); 
        }
  
    }

    private static void serializeUTF16(
      Document document, OutputStream out)
        throws UnsupportedEncodingException, IOException {
        Serializer serializer = new Serializer(out, "UTF-16");
        serializer.write(document);
        serializer.flush();
    }

    private static void prettyPrint(
      Document document, OutputStream out)
        throws UnsupportedEncodingException, IOException {
        Serializer serializer = new Serializer(out, "UTF-8");
        serializer.setIndent(2);
        serializer.setMaxLength(72);
        serializer.write(document);
        serializer.flush();
    }

    private static void serialize(Document document, OutputStream out)
        throws UnsupportedEncodingException, IOException {
        Serializer serializer = new Serializer(out, "UTF-8");
        serializer.write(document);
        serializer.flush();
    }

    private static void walkTree(TreeWalker iterator, Document doc)
      throws IOException {
        iterator.followNode(doc);
    }
    
    private static Document build(
      byte[] data, String base, Builder parser)
      throws ParsingException, ValidityException, IOException {
        InputStream raw = new BufferedInputStream(
          new ByteArrayInputStream(data)
        );
        Document document = parser.build(raw, base); 
        return document;
    } 

    private static void warmup(byte[] data, Builder parser, 
      TreeWalker iterator, int numPasses, String base) 
      throws IOException, ParsingException {
        for (int i = 0; i < numPasses; i++) {
            InputStream raw = new BufferedInputStream(
              new ByteArrayInputStream(data)
            );    
            Document doc = parser.build(raw, base);
            walkTree(iterator, doc);
            serialize(doc, new ByteArrayOutputStream(3000000));
            prettyPrint(doc, new ByteArrayOutputStream(4000000));
            serializeUTF16(doc, new ByteArrayOutputStream(4000000));
        }
    }

    // note use of recursion
    public void followNode(Node node) throws IOException {
    
        for (int i = 0; i < node.getChildCount(); i++) {
            followNode(node.getChild(i));
        }
    
    }

}