/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2001-2002 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xalan.xslt;

import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;

import java.lang.reflect.Method;
import java.lang.reflect.Field;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import java.util.StringTokenizer;
import java.util.Vector;

// Used in append* methods only
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * Utility class to report simple information about the environment.
 * Simplistic reporting about certain classes found in your JVM may 
 * help answer some FAQs for simple problems.
 *
 * <p>Usage-command line:  
 * <code>
 * java org.apache.xalan.xslt.EnvironmentCheck [-out outFile]
 * </code></p>
 * 
 * <p>Usage-from program:  
 * <code>
 * boolean environmentOK = 
 * (new EnvironmentCheck()).checkEnvironment(yourPrintWriter);
 * </code></p>
 *
 * <p>Usage-from stylesheet:  
 * <code><pre>
 *    &lt;?xml version="1.0"?&gt;
 *    &lt;xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"
 *        xmlns:xalan="http://xml.apache.org/xalan"
 *        exclude-result-prefixes="xalan"&gt;
 *    &lt;xsl:output indent="yes"/&gt;
 *    &lt;xsl:template match="/"&gt;
 *      &lt;xsl:copy-of select="xalan:checkEnvironment()"/&gt;
 *    &lt;/xsl:template&gt;
 *    &lt;/xsl:stylesheet&gt;
 * </pre></code></p>
 *  
 * <p>Xalan users reporting problems are encouraged to use this class 
 * to see if there are potential problems with their actual 
 * Java environment <b>before</b> reporting a bug.  Note that you 
 * should both check from the JVM/JRE's command line as well as 
 * temporarily calling checkEnvironment() directly from your code, 
 * since the classpath may differ (especially for servlets, etc).</p>
 *
 * <p>Also see http://xml.apache.org/xalan-j/faq.html</p>
 *
 * <p>Note: This class is pretty simplistic: it does a fairly simple 
 * unordered search of the classpath; it only uses Class.forName() 
 * to load things, not actually querying the classloader; so the 
 * results are not necessarily definitive nor will it find all 
 * problems related to environment setup.  Also, you should avoid 
 * calling this in deployed production code, both because it is 
 * quite slow and because it forces classes to get loaded.</p>
 *
 * <p>Note: This class explicitly has very limited compile-time 
 * dependencies to enable easy compilation and usage even when 
 * Xalan, DOM/SAX/JAXP, etc. are not present.</p>
 * 
 * <p>Note: for an improved version of this utility, please see 
 * the xml-commons' project Which utility which does the same kind 
 * of thing but in a much simpler manner.</p>
 *
 * @author Shane_Curcuru@us.ibm.com
 * @version $Id$
 */
public class EnvironmentCheck
{

  /**
   * Command line runnability: checks for [-out outFilename] arg.
   * <p>Command line entrypoint; Sets output and calls 
   * {@link #checkEnvironment(PrintWriter)}.</p>
   * @param args command line args
   */
  public static void main(String[] args)
  {
    // Default to System.out, autoflushing
    PrintWriter sendOutputTo = new PrintWriter(System.out, true);

    // Read our simplistic input args, if supplied
    for (int i = 0; i < args.length; i++)
    {
      if ("-out".equalsIgnoreCase(args[i]))
      {
        i++;

        if (i < args.length)
        {
          try
          {
            sendOutputTo = new PrintWriter(new FileWriter(args[i], true));
          }
          catch (Exception e)
          {
            System.err.println("# WARNING: -out " + args[i] + " threw "
                               + e.toString());
          }
        }
        else
        {
          System.err.println(
            "# WARNING: -out argument should have a filename, output sent to console");
        }
      }
    }

    EnvironmentCheck app = new EnvironmentCheck();
    app.checkEnvironment(sendOutputTo);
  }

  /**
   * Programmatic entrypoint: Report on basic Java environment 
   * and CLASSPATH settings that affect Xalan.
   *
   * <p>Note that this class is not advanced enough to tell you 
   * everything about the environment that affects Xalan, and 
   * sometimes reports errors that will not actually affect 
   * Xalan's behavior.  Currently, it very simplistically 
   * checks the JVM's environment for some basic properties and 
   * logs them out; it will report a problem if it finds a setting 
   * or .jar file that is <i>likely</i> to cause problems.</p>
   *
   * <p>Advanced users can peruse the code herein to help them 
   * investigate potential environment problems found; other users 
   * may simply send the output from this tool along with any bugs 
   * they submit to help us in the debugging process.</p>
   *
   * @param pw PrintWriter to send output to; can be sent to a 
   * file that will look similar to a Properties file; defaults 
   * to System.out if null
   * @return true if your environment appears to have no major 
   * problems; false if potential environment problems found
   * @see #getEnvironmentHash()
   */
  public boolean checkEnvironment(PrintWriter pw)
  {

    // Use user-specified output writer if non-null
    if (null != pw)
      outWriter = pw;

    // Setup a hash to store various environment information in
    Hashtable hash = getEnvironmentHash();

    // Check for ERROR keys in the hashtable, and print report
    boolean environmentHasErrors = writeEnvironmentReport(hash);

    if (environmentHasErrors)
    {
      // Note: many logMsg calls have # at the start to 
      //  fake a property-file like output
      logMsg("# WARNING: Potential problems found in your environment!");
      logMsg("#    Check any 'ERROR' items above against the Xalan FAQs");
      logMsg("#    to correct potential problems with your classes/jars");
      logMsg("#    http://xml.apache.org/xalan-j/faq.html");
      if (null != outWriter)
        outWriter.flush();
      return false;
    }
    else
    {
      logMsg("# YAHOO! Your environment seems to be OK.");
      if (null != outWriter)
        outWriter.flush();
      return true;
    }
  }

  /**
   * Fill a hash with basic environment settings that affect Xalan.
   *
   * <p>Worker method called from various places.</p>
   * <p>Various system and CLASSPATH, etc. properties are put into 
   * the hash as keys with a brief description of the current state 
   * of that item as the value.  Any serious problems will be put in 
   * with a key that is prefixed with {@link #ERROR 'ERROR.'} so it
   * stands out in any resulting report; also a key with just that 
   * constant will be set as well for any error.</p>
   * <p>Note that some legitimate cases are flaged as potential 
   * errors - namely when a developer recompiles xalan.jar on their 
   * own - and even a non-error state doesn't guaruntee that 
   * everything in the environment is correct.  But this will help 
   * point out the most common classpath and system property
   * problems that we've seen.</p>   
   *
   * @return Hashtable full of useful environment info about Xalan 
   * and related system properties, etc.
   */
  public Hashtable getEnvironmentHash()
  {
    // Setup a hash to store various environment information in
    Hashtable hash = new Hashtable();

    // Call various worker methods to fill in the hash
    //  These are explicitly separate for maintenance and so 
    //  advanced users could call them standalone
    checkJAXPVersion(hash);
    checkProcessorVersion(hash);
    checkParserVersion(hash);
    checkAntVersion(hash);
    checkDOMVersion(hash);
    checkSAXVersion(hash);
    checkSystemProperties(hash);

    return hash;
  }

  /**
   * Dump a basic Xalan environment report to outWriter.  
   *
   * <p>This dumps a simple header and then each of the entries in 
   * the Hashtable to our PrintWriter; it does special processing 
   * for entries that are .jars found in the classpath.</p>
   *
   * @param h Hashtable of items to report on; presumably
   * filled in by our various check*() methods
   * @return true if your environment appears to have no major 
   * problems; false if potential environment problems found
   * @see #appendEnvironmentReport(Node, Document, Hashtable)
   * for an equivalent that appends to a Node instead
   */
  protected boolean writeEnvironmentReport(Hashtable h)
  {

    if (null == h)
    {
      logMsg("# ERROR: writeEnvironmentReport called with null Hashtable");
      return false;
    }

    boolean errors = false;

    logMsg(
      "#---- BEGIN writeEnvironmentReport($Revision$): Useful stuff found: ----");

    // Fake the Properties-like output
    for (Enumeration enum = h.keys(); 
         enum.hasMoreElements();
        /* no increment portion */
        )
    {
      Object key = enum.nextElement();
      String keyStr = (String) key;
      try
      {
        // Special processing for classes found..
        if (keyStr.startsWith(FOUNDCLASSES))
        {
          Vector v = (Vector) h.get(keyStr);
          errors |= logFoundJars(v, keyStr);
        }
        // ..normal processing for all other entries
        else
        {
          // Note: we could just check for the ERROR key by itself, 
          //    since we now set that, but since we have to go 
          //    through the whole hash anyway, do it this way,
          //    which is safer for maintenance
          if (keyStr.startsWith(ERROR))
          {
            errors = true;
          }
          logMsg(keyStr + "=" + h.get(keyStr));
        }
      }
      catch (Exception e)
      {
        logMsg("Reading-" + key + "= threw: " + e.toString());
      }
    }

    logMsg(
      "#----- END writeEnvironmentReport: Useful properties found: -----");

    return errors;
  }

  /** Prefixed to hash keys that signify serious problems.  */
  public static final String ERROR = "ERROR.";

  /** Added to descriptions that signify potential problems.  */
  public static final String WARNING = "WARNING.";

  /** Value for any error found.  */
  public static final String ERROR_FOUND = "At least one error was found!";

  /** Prefixed to hash keys that signify version numbers.  */
  public static final String VERSION = "version.";

  /** Prefixed to hash keys that signify .jars found in classpath.  */
  public static final String FOUNDCLASSES = "foundclasses.";

  /** Marker that a class or .jar was found.  */
  public static final String CLASS_PRESENT = "present-unknown-version";

  /** Marker that a class or .jar was not found.  */
  public static final String CLASS_NOTPRESENT = "not-present";

  /** Listing of common .jar files that include Xalan-related classes.  */
  public String[] jarNames =
  {
    "xalan.jar", "xalansamples.jar", "xalanj1compat.jar", "xalanservlet.jar",
    "xerces.jar",       // Xerces-J 1.x
    "xercesImpl.jar",   // Xerces-J 2.x
    "testxsl.jar", 
    "crimson.jar", 
    "lotusxsl.jar", 
    "jaxp.jar", "parser.jar", "dom.jar", "sax.jar", "xml.jar", 
    "xml-apis.jar",
    "xsltc.jar"
  };

  /**
   * Print out report of .jars found in a classpath. 
   *
   * Takes the information encoded from a checkPathForJars() 
   * call and dumps it out to our PrintWriter.
   *
   * @param v Vector of Hashtables of .jar file info
   * @param desc description to print out in header
   *
   * @return false if OK, true if any .jars were reported 
   * as having errors
   * @see #checkPathForJars(String, String[])
   */
  protected boolean logFoundJars(Vector v, String desc)
  {

    if ((null == v) || (v.size() < 1))
      return false;

    boolean errors = false;

    logMsg("#---- BEGIN Listing XML-related jars in: " + desc + " ----");

    for (int i = 0; i < v.size(); i++)
    {
      Hashtable subhash = (Hashtable) v.elementAt(i);

      for (Enumeration enum = subhash.keys(); 
           enum.hasMoreElements();
           /* no increment portion */
          )
      {
        Object key = enum.nextElement();
        String keyStr = (String) key;
        try
        {
          if (keyStr.startsWith(ERROR))
          {
            errors = true;
          }
          logMsg(keyStr + "=" + subhash.get(keyStr));

        }
        catch (Exception e)
        {
          errors = true;
          logMsg("Reading-" + key + "= threw: " + e.toString());
        }
      }
    }

    logMsg("#----- END Listing XML-related jars in: " + desc + " -----");

    return errors;
  }

  /**
   * Stylesheet extension entrypoint: Dump a basic Xalan 
   * environment report from getEnvironmentHash() to a Node.  
   * 
   * <p>Copy of writeEnvironmentReport that creates a Node suitable 
   * for other processing instead of a properties-like text output.
   * </p>
   * @param container Node to append our report to
   * @param factory Document providing createElement, etc. services
   * @param h Hash presumably from {@link #getEnvironmentHash()}
   * @see #writeEnvironmentReport(Hashtable)
   * for an equivalent that writes to a PrintWriter instead
   */
  public void appendEnvironmentReport(Node container, Document factory, Hashtable h)
  {
    if ((null == container) || (null == factory))
    {
      return;
    }
  
    try
    {
      Element envCheckNode = factory.createElement("EnvironmentCheck");
      envCheckNode.setAttribute("version", "$Revision$");
      container.appendChild(envCheckNode);

      if (null == h)
      {
        Element statusNode = factory.createElement("status");
        statusNode.setAttribute("result", "ERROR");
        statusNode.appendChild(factory.createTextNode("appendEnvironmentReport called with null Hashtable!"));
        envCheckNode.appendChild(statusNode);
        return;
      }

      boolean errors = false;

      Element hashNode = factory.createElement("environment");
      envCheckNode.appendChild(hashNode);
      
      for (Enumeration enum = h.keys(); 
           enum.hasMoreElements();
          /* no increment portion */
          )
      {
        Object key = enum.nextElement();
        String keyStr = (String) key;
        try
        {
          // Special processing for classes found..
          if (keyStr.startsWith(FOUNDCLASSES))
          {
            Vector v = (Vector) h.get(keyStr);
            // errors |= logFoundJars(v, keyStr);
            errors |= appendFoundJars(hashNode, factory, v, keyStr);
          }
          // ..normal processing for all other entries
          else 
          {
            // Note: we could just check for the ERROR key by itself, 
            //    since we now set that, but since we have to go 
            //    through the whole hash anyway, do it this way,
            //    which is safer for maintenance
            if (keyStr.startsWith(ERROR))
            {
              errors = true;
            }
            Element node = factory.createElement("item");
            node.setAttribute("key", keyStr);
            node.appendChild(factory.createTextNode((String)h.get(keyStr)));
            hashNode.appendChild(node);
          }
        }
        catch (Exception e)
        {
          errors = true;
          Element node = factory.createElement("item");
          node.setAttribute("key", keyStr);
          node.appendChild(factory.createTextNode(ERROR + " Reading " + key + " threw: " + e.toString()));
          hashNode.appendChild(node);
        }
      } // end of for...

      Element statusNode = factory.createElement("status");
      statusNode.setAttribute("result", (errors ? "ERROR" : "OK" ));
      envCheckNode.appendChild(statusNode);
    }
    catch (Exception e2)
    {
      System.err.println("appendEnvironmentReport threw: " + e2.toString());
      e2.printStackTrace();
    }
  }    

  /**
   * Print out report of .jars found in a classpath. 
   *
   * Takes the information encoded from a checkPathForJars() 
   * call and dumps it out to our PrintWriter.
   *
   * @param container Node to append our report to
   * @param factory Document providing createElement, etc. services
   * @param v Vector of Hashtables of .jar file info
   * @param desc description to print out in header
   *
   * @return false if OK, true if any .jars were reported 
   * as having errors
   * @see #checkPathForJars(String, String[])
   */
  protected boolean appendFoundJars(Node container, Document factory, 
        Vector v, String desc)
  {

    if ((null == v) || (v.size() < 1))
      return false;

    boolean errors = false;

    for (int i = 0; i < v.size(); i++)
    {
      Hashtable subhash = (Hashtable) v.elementAt(i);

      for (Enumeration enum = subhash.keys(); 
           enum.hasMoreElements();
           /* no increment portion */
          )
      {
        Object key = enum.nextElement();
        try
        {
          String keyStr = (String) key;
          if (keyStr.startsWith(ERROR))
          {
            errors = true;
          }
          Element node = factory.createElement("foundJar");
          node.setAttribute("name", keyStr.substring(0, keyStr.indexOf("-")));
          node.setAttribute("desc", keyStr.substring(keyStr.indexOf("-") + 1));
          node.appendChild(factory.createTextNode((String)subhash.get(keyStr)));
          container.appendChild(node);
        }
        catch (Exception e)
        {
          errors = true;
          Element node = factory.createElement("foundJar");
          node.appendChild(factory.createTextNode(ERROR + " Reading " + key + " threw: " + e.toString()));
          container.appendChild(node);
        }
      }
    }
    return errors;
  }

  /**
   * Fillin hash with info about SystemProperties.  
   *
   * Logs java.class.path and other likely paths; then attempts 
   * to search those paths for .jar files with Xalan-related classes.
   *
   * //@todo NOTE: We don't actually search java.ext.dirs for 
   * //  *.jar files therein! This should be updated
   *
   * @param h Hashtable to put information in
   * @see #jarNames
   * @see #checkPathForJars(String, String[])
   */
  protected void checkSystemProperties(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    // Grab java version for later use
    try
    {
      String javaVersion = System.getProperty("java.version");

      h.put("java.version", javaVersion);
    }
    catch (SecurityException se)
    {

      // For applet context, etc.
      h.put(
        "java.version",
        "WARNING: SecurityException thrown accessing system version properties");
    }

    // Printout jar files on classpath(s) that may affect operation
    //  Do this in order
    try
    {

      // This is present in all JVM's
      String cp = System.getProperty("java.class.path");

      h.put("java.class.path", cp);

      Vector classpathJars = checkPathForJars(cp, jarNames);

      if (null != classpathJars)
        h.put(FOUNDCLASSES + "java.class.path", classpathJars);

      // Also check for JDK 1.2+ type classpaths
      String othercp = System.getProperty("sun.boot.class.path");

      if (null != othercp)
      {
        h.put("sun.boot.class.path", othercp);

        classpathJars = checkPathForJars(othercp, jarNames);

        if (null != classpathJars)
          h.put(FOUNDCLASSES + "sun.boot.class.path", classpathJars);
      }

      //@todo NOTE: We don't actually search java.ext.dirs for 
      //  *.jar files therein! This should be updated
      othercp = System.getProperty("java.ext.dirs");

      if (null != othercp)
      {
        h.put("java.ext.dirs", othercp);

        classpathJars = checkPathForJars(othercp, jarNames);

        if (null != classpathJars)
          h.put(FOUNDCLASSES + "java.ext.dirs", classpathJars);
      }

      //@todo also check other System properties' paths?
      //  v2 = checkPathForJars(System.getProperty("sun.boot.library.path"), jarNames);   // ?? may not be needed
      //  v3 = checkPathForJars(System.getProperty("java.library.path"), jarNames);   // ?? may not be needed
    }
    catch (SecurityException se2)
    {
      // For applet context, etc.
      h.put(
        "java.class.path",
        "WARNING: SecurityException thrown accessing system classpath properties");
    }
  }

  /**
   * Cheap-o listing of specified .jars found in the classpath. 
   *
   * cp should be separated by the usual File.pathSeparator.  We 
   * then do a simplistic search of the path for any requested 
   * .jar filenames, and return a listing of their names and 
   * where (apparently) they came from.
   *
   * @param cp classpath to search
   * @param jars array of .jar base filenames to look for
   *
   * @return Vector of Hashtables filled with info about found .jars
   * @see #jarNames
   * @see #logFoundJars(Vector, String)
   * @see #appendFoundJars(Node, Document, Vector, String )
   * @see #getApparentVersion(String, long)
   */
  protected Vector checkPathForJars(String cp, String[] jars)
  {

    if ((null == cp) || (null == jars) || (0 == cp.length())
            || (0 == jars.length))
      return null;

    Vector v = new Vector();
    StringTokenizer st = new StringTokenizer(cp, File.pathSeparator);

    while (st.hasMoreTokens())
    {

      // Look at each classpath entry for each of our requested jarNames
      String filename = st.nextToken();

      for (int i = 0; i < jars.length; i++)
      {
        if (filename.indexOf(jars[i]) > -1)
        {
          File f = new File(filename);

          if (f.exists())
          {

            // If any requested jarName exists, report on 
            //  the details of that .jar file
            try
            {
              Hashtable h = new Hashtable(2);
              // Note "-" char is looked for in appendFoundJars
              h.put(jars[i] + "-path", f.getAbsolutePath());
              h.put(jars[i] + "-apparent.version",
                    getApparentVersion(jars[i], f.length()));
              v.addElement(h);
            }
            catch (Exception e)
            {

              /* no-op, don't add it  */
            }
          }
          else
          {
            Hashtable h = new Hashtable(2);
            // Note "-" char is looked for in appendFoundJars
            h.put(jars[i] + "-path", WARNING + " Classpath entry: " 
                  + filename + " does not exist");
            h.put(jars[i] + "-apparent.version", CLASS_NOTPRESENT);
            v.addElement(h);
          }
        }
      }
    }

    return v;
  }

  /**
   * Cheap-o method to determine the product version of a .jar.   
   *
   * Currently does a lookup into a local table of some recent 
   * shipped Xalan builds to determine where the .jar probably 
   * came from.  Note that if you recompile Xalan or Xerces 
   * yourself this will likely report a potential error, since 
   * we can't certify builds other than the ones we ship.
   * Only reports against selected posted Xalan-J builds.
   *
   * //@todo actually look up version info in manifests
   *
   * @param jarName base filename of the .jarfile
   * @param jarSize size of the .jarfile
   *
   * @return String describing where the .jar file probably 
   * came from
   */
  protected String getApparentVersion(String jarName, long jarSize)
  {
    // If we found a matching size and it's for our 
    //  jar, then return it's description
    // Lookup in static jarVersions Hashtable
    String foundSize = (String) jarVersions.get(new Long(jarSize));

    if ((null != foundSize) && (foundSize.startsWith(jarName)))
    {
      return foundSize;
    }
    else
    {
      if ("xerces.jar".equalsIgnoreCase(jarName)
              || "xercesImpl.jar".equalsIgnoreCase(jarName)
              || "xalan.jar".equalsIgnoreCase(jarName))
      {

        // For xalan.jar and xerces.jar/xercesImpl.jar, which we ship together:
        // The jar is not from a shipped copy of xalan-j, so 
        //  it's up to the user to ensure that it's compatible
        return jarName + " " + WARNING + CLASS_PRESENT;
      }
      else
      {

        // Otherwise, it's just a jar we don't have the version info calculated for
        return jarName + " " + CLASS_PRESENT;
      }
    }
  }

  /**
   * Report version information about JAXP interfaces.
   *
   * Currently distinguishes between JAXP 1.0.1 and JAXP 1.1, 
   * and not found; only tests the interfaces, and does not 
   * check for reference implementation versions.
   *
   * @param h Hashtable to put information in
   */
  protected void checkJAXPVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    final Class noArgs[] = new Class[0];
    Class clazz = null;

    try
    {
      final String JAXP1_CLASS = "javax.xml.parsers.DocumentBuilder";
      final String JAXP11_METHOD = "getDOMImplementation";

      clazz = classForName(JAXP1_CLASS);

      Method method = clazz.getMethod(JAXP11_METHOD, noArgs);

      // If we succeeded, we at least have JAXP 1.1 available
      h.put(VERSION + "JAXP", "1.1");
    }
    catch (Exception e)
    {
      if (null != clazz)
      {

        // We must have found the class itself, just not the 
        //  method, so we (probably) have JAXP 1.0.1
        h.put(ERROR + VERSION + "JAXP", "1.0.1");
        h.put(ERROR, ERROR_FOUND);
      }
      else
      {
        // We couldn't even find the class, and don't have 
        //  any JAXP support at all, or only have the 
        //  transform half of it
        h.put(ERROR + VERSION + "JAXP", CLASS_NOTPRESENT);
        h.put(ERROR, ERROR_FOUND);
      }
    }
  }

  /**
   * Report product version information from Xalan-J.
   *
   * Looks for version info in xalan.jar from Xalan-J products.
   *
   * @param h Hashtable to put information in
   */
  protected void checkProcessorVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    try
    {
      final String XALAN1_VERSION_CLASS =
        "org.apache.xalan.xslt.XSLProcessorVersion";
      Class clazz = classForName(XALAN1_VERSION_CLASS);

      // Found Xalan-J 1.x, grab it's version fields
      StringBuffer buf = new StringBuffer();
      Field f = clazz.getField("PRODUCT");

      buf.append(f.get(null));
      buf.append(';');

      f = clazz.getField("LANGUAGE");

      buf.append(f.get(null));
      buf.append(';');

      f = clazz.getField("S_VERSION");

      buf.append(f.get(null));
      buf.append(';');
      h.put(VERSION + "xalan1", buf.toString());
    }
    catch (Exception e1)
    {
      h.put(VERSION + "xalan1", CLASS_NOTPRESENT);
    }

    try
    {
      // NOTE: This is the old Xalan 2.0, 2.1, 2.2 version class, 
      //    is being replaced by class below
      final String XALAN2_VERSION_CLASS =
        "org.apache.xalan.processor.XSLProcessorVersion";
      Class clazz = classForName(XALAN2_VERSION_CLASS);

      // Found Xalan-J 2.x, grab it's version fields
      StringBuffer buf = new StringBuffer();
      Field f = clazz.getField("S_VERSION");
      buf.append(f.get(null));

      h.put(VERSION + "xalan2x", buf.toString());
    }
    catch (Exception e2)
    {
      h.put(VERSION + "xalan2x", CLASS_NOTPRESENT);
    }
    try
    {
      // NOTE: This is the new Xalan 2.2+ version class
      final String XALAN2_2_VERSION_CLASS =
        "org.apache.xalan.Version";
      final String XALAN2_2_VERSION_METHOD = "getVersion";
      final Class noArgs[] = new Class[0];

      Class clazz = classForName(XALAN2_2_VERSION_CLASS);
      Method method = clazz.getMethod(XALAN2_2_VERSION_METHOD, noArgs);
      Object returnValue = method.invoke(null, new Object[0]);

      h.put(VERSION + "xalan2_2", (String)returnValue);
    }
    catch (Exception e2)
    {
      h.put(VERSION + "xalan2_2", CLASS_NOTPRESENT);
    }
  }

  /**
   * Report product version information from common parsers.
   *
   * Looks for version info in xerces.jar/xercesImpl.jar/crimson.jar.
   *
   * //@todo actually look up version info in crimson manifest
   *
   * @param h Hashtable to put information in
   */
  protected void checkParserVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    try
    {
      final String XERCES1_VERSION_CLASS = "org.apache.xerces.framework.Version";
      Class clazz = classForName(XERCES1_VERSION_CLASS);

      // Found Xerces-J 1.x, grab it's version fields
      Field f = clazz.getField("fVersion");
      String parserVersion = (String) f.get(null);

      h.put(VERSION + "xerces1", parserVersion);
    }
    catch (Exception e)
    {
      h.put(VERSION + "xerces1", CLASS_NOTPRESENT);
    }

    // Look for xerces1 and xerces2 parsers separately
    try
    {
      final String XERCES2_VERSION_CLASS = "org.apache.xerces.impl.Version";
      Class clazz = classForName(XERCES2_VERSION_CLASS);

      // Found Xerces-J 2.x, grab it's version fields
      Field f = clazz.getField("fVersion");
      String parserVersion = (String) f.get(null);

      h.put(VERSION + "xerces2", parserVersion);
    }
    catch (Exception e)
    {
      h.put(VERSION + "xerces2", CLASS_NOTPRESENT);
    }

    try
    {
      final String CRIMSON_CLASS = "org.apache.crimson.parser.Parser2";
      Class clazz = classForName(CRIMSON_CLASS);

      //@todo determine specific crimson version
      h.put(VERSION + "crimson", CLASS_PRESENT);
    }
    catch (Exception e)
    {
      h.put(VERSION + "crimson", CLASS_NOTPRESENT);
    }
  }

  /**
   * Report product version information from Ant.
   *
   * @param h Hashtable to put information in
   */
  protected void checkAntVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    try
    {
      final String ANT_VERSION_CLASS = "org.apache.tools.ant.Main";
      final String ANT_VERSION_METHOD = "getAntVersion"; // noArgs
      final Class noArgs[] = new Class[0];

      Class clazz = classForName(ANT_VERSION_CLASS);
      Method method = clazz.getMethod(ANT_VERSION_METHOD, noArgs);
      Object returnValue = method.invoke(null, new Object[0]);

      h.put(VERSION + "ant", (String)returnValue);
    }
    catch (Exception e)
    {
      h.put(VERSION + "ant", CLASS_NOTPRESENT);
    }
  }

  /**
   * Report version info from DOM interfaces. 
   *
   * Currently distinguishes between pre-DOM level 2, the DOM 
   * level 2 working draft, the DOM level 2 final draft, 
   * and not found.
   *
   * @param h Hashtable to put information in
   */
  protected void checkDOMVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    final String DOM_LEVEL2_CLASS = "org.w3c.dom.Document";
    final String DOM_LEVEL2_METHOD = "createElementNS";  // String, String
    final String DOM_LEVEL2WD_CLASS = "org.w3c.dom.Node";
    final String DOM_LEVEL2WD_METHOD = "supported";  // String, String
    final String DOM_LEVEL2FD_CLASS = "org.w3c.dom.Node";
    final String DOM_LEVEL2FD_METHOD = "isSupported";  // String, String
    final Class twoStringArgs[] = { java.lang.String.class,
                                    java.lang.String.class };

    try
    {
      Class clazz = classForName(DOM_LEVEL2_CLASS);
      Method method = clazz.getMethod(DOM_LEVEL2_METHOD, twoStringArgs);

      // If we succeeded, we have loaded interfaces from a 
      //  level 2 DOM somewhere
      h.put(VERSION + "DOM", "2.0");

      try
      {

        // Check for the working draft version, which is 
        //  commonly found, but won't work anymore
        clazz = classForName(DOM_LEVEL2WD_CLASS);
        method = clazz.getMethod(DOM_LEVEL2WD_METHOD, twoStringArgs);

        h.put(ERROR + VERSION + "DOM.draftlevel", "2.0wd");
        h.put(ERROR, ERROR_FOUND);
      }
      catch (Exception e2)
      {
        try
        {

          // Check for the final draft version as well
          clazz = classForName(DOM_LEVEL2FD_CLASS);
          method = clazz.getMethod(DOM_LEVEL2FD_METHOD, twoStringArgs);

          h.put(VERSION + "DOM.draftlevel", "2.0fd");
        }
        catch (Exception e3)
        {
          h.put(ERROR + VERSION + "DOM.draftlevel", "2.0unknown");
          h.put(ERROR, ERROR_FOUND);
        }
      }
    }
    catch (Exception e)
    {
      h.put(ERROR + VERSION + "DOM",
            "ERROR attempting to load DOM level 2 class: " + e.toString());
      h.put(ERROR, ERROR_FOUND);
    }

    //@todo load an actual DOM implmementation and query it as well
    //@todo load an actual DOM implmementation and check if 
    //  isNamespaceAware() == true, which is needed to parse 
    //  xsl stylesheet files into a DOM
  }

  /**
   * Report version info from SAX interfaces. 
   *
   * Currently distinguishes between SAX 2, SAX 2.0beta2, 
   * SAX1, and not found.
   *
   * @param h Hashtable to put information in
   */
  protected void checkSAXVersion(Hashtable h)
  {

    if (null == h)
      h = new Hashtable();

    final String SAX_VERSION1_CLASS = "org.xml.sax.Parser";
    final String SAX_VERSION1_METHOD = "parse";  // String
    final String SAX_VERSION2_CLASS = "org.xml.sax.XMLReader";
    final String SAX_VERSION2_METHOD = "parse";  // String
    final String SAX_VERSION2BETA_CLASSNF = "org.xml.sax.helpers.AttributesImpl";
    final String SAX_VERSION2BETA_METHODNF = "setAttributes";  // Attributes
    final Class oneStringArg[] = { java.lang.String.class };
    // Note this introduces a minor compile dependency on SAX...
    final Class attributesArg[] = { org.xml.sax.Attributes.class };

    try
    {
      // This method was only added in the final SAX 2.0 release; 
      //  see changes.html "Changes from SAX 2.0beta2 to SAX 2.0prerelease"
      Class clazz = classForName(SAX_VERSION2BETA_CLASSNF);
      Method method = clazz.getMethod(SAX_VERSION2BETA_METHODNF, attributesArg);

      // If we succeeded, we have loaded interfaces from a 
      //  real, final SAX version 2.0 somewhere
      h.put(VERSION + "SAX", "2.0");
    }
    catch (Exception e)
    {
      // If we didn't find the SAX 2.0 class, look for a 2.0beta2
      h.put(ERROR + VERSION + "SAX",
            "ERROR attempting to load SAX version 2 class: " + e.toString());
      h.put(ERROR, ERROR_FOUND);
            
      try
      {
        Class clazz = classForName(SAX_VERSION2_CLASS);
        Method method = clazz.getMethod(SAX_VERSION2_METHOD, oneStringArg);

        // If we succeeded, we have loaded interfaces from a 
        //  SAX version 2.0beta2 or earlier; these might work but 
        //  you should really have the final SAX 2.0 
        h.put(VERSION + "SAX-backlevel", "2.0beta2-or-earlier");
      }
      catch (Exception e2)
      {
        // If we didn't find the SAX 2.0beta2 class, look for a 1.0 one
        h.put(ERROR + VERSION + "SAX",
              "ERROR attempting to load SAX version 2 class: " + e.toString());
        h.put(ERROR, ERROR_FOUND);
          
        try
        {
          Class clazz = classForName(SAX_VERSION1_CLASS);
          Method method = clazz.getMethod(SAX_VERSION1_METHOD, oneStringArg);

          // If we succeeded, we have loaded interfaces from a 
          //  SAX version 1.0 somewhere; which won't work very 
          //  well for JAXP 1.1 or beyond!
          h.put(VERSION + "SAX-backlevel", "1.0");
        }
        catch (Exception e3)
        {
          // If we didn't find the SAX 2.0 class, look for a 1.0 one
          // Note that either 1.0 or no SAX are both errors
          h.put(ERROR + VERSION + "SAX-backlevel",
                "ERROR attempting to load SAX version 1 class: " + e3.toString());
            
        }
      }
    }
  }

  /** 
   * Worker method to load a class.  
   * Factor out loading classes for future use and JDK differences.  
   * Copied from javax.xml.*.FactoryFinder
   * @param className name of class to load from 
   * an appropriate classLoader
   * @return the class asked for
   */
  protected static Class classForName(String className)
        throws ClassNotFoundException
  {
    ClassLoader classLoader = findClassLoader();
    if (classLoader == null) 
    {
      return Class.forName(className);
    } 
    else 
    {
      return classLoader.loadClass(className);
    }
  }
  
  /**
   * Worker method to figure out which ClassLoader to use.  
   * For JDK 1.2 and later use the context ClassLoader. 
   * Copied from javax.xml.*.FactoryFinder
   * @return the appropriate ClassLoader
   */
  protected static ClassLoader findClassLoader()
        throws ClassNotFoundException
  {
    ClassLoader classLoader = null;
    Method m = null;

    try 
    {
      m = Thread.class.getMethod("getContextClassLoader", null);
    } 
    catch (NoSuchMethodException e) 
    {
      // Assume that we are running JDK 1.1, use the current ClassLoader
      return EnvironmentCheck.class.getClassLoader();
    }
    try 
    {
      return (ClassLoader) m.invoke(Thread.currentThread(), null);
    } 
    catch (Exception e) 
    {
      throw new RuntimeException(e.toString());
    }
  }

  /** 
   * Manual table of known .jar sizes.  
   * Only includes shipped versions of certain projects.
   * key=jarsize, value=jarname ' from ' distro name
   * Note assumption: two jars cannot have the same size!
   *
   * @see #getApparentVersion(String, long)
   */
  protected static Hashtable jarVersions = new Hashtable();

  /** 
   * Static initializer for jarVersions table.  
   * Doing this just once saves time and space.
   *
   * @see #getApparentVersion(String, long)
   */
  static 
  {
    // Note: hackish Hashtable, this could use improvement
    jarVersions.put(new Long(857192), "xalan.jar from xalan-j_1_1");
    jarVersions.put(new Long(440237), "xalan.jar from xalan-j_1_2");
    jarVersions.put(new Long(436094), "xalan.jar from xalan-j_1_2_1");
    jarVersions.put(new Long(426249), "xalan.jar from xalan-j_1_2_2");
    jarVersions.put(new Long(702536), "xalan.jar from xalan-j_2_0_0");
    jarVersions.put(new Long(720930), "xalan.jar from xalan-j_2_0_1");
    jarVersions.put(new Long(732330), "xalan.jar from xalan-j_2_1_0");
    jarVersions.put(new Long(872241), "xalan.jar from xalan-j_2_2_D10");
    jarVersions.put(new Long(882739), "xalan.jar from xalan-j_2_2_D11");
    jarVersions.put(new Long(923866), "xalan.jar from xalan-j_2_2_0");
    jarVersions.put(new Long(905872), "xalan.jar from xalan-j_2_3_D1");
    jarVersions.put(new Long(906122), "xalan.jar from xalan-j_2_3_0");
    // Impossible to get exact number, so don't use this: jarVersions.put(new Long(), "xalan.jar from xalan-j_2_4_D1");

    jarVersions.put(new Long(857171), "xalan.jar from lotusxsl-j_1_0_1");
    jarVersions.put(new Long(802165), "xalan.jar from lotusxsl-j_2_0_0");
    jarVersions.put(new Long(857692), "xalan.jar from lotusxsl-j_2_2");

    jarVersions.put(new Long(596540), "xsltc.jar from xalan-j_2_2_0");
    jarVersions.put(new Long(590247), "xsltc.jar from xalan-j_2_3_D1");
    jarVersions.put(new Long(589914), "xsltc.jar from xalan-j_2_3_0");
    jarVersions.put(new Long(1306667), "xsltc.jar from xalan-j_2_4_D1");
    jarVersions.put(new Long(1268634), "xsltc.jar-bundled from xalan-j_2_3_0");

    jarVersions.put(new Long(100196), "xml-apis.jar from xalan-j_2_2_0 or xalan-j_2_3_D1");
    jarVersions.put(new Long(108484), "xml-apis.jar from xalan-j_2_3_0,2_4_D1 from xml-commons-1.0.b2");

    // If the below were more common I would update it to report 
    //  errors better; but this is so old hardly anyone has it
    jarVersions.put(new Long(424490), "xalan.jar from Xerces Tools releases - ERROR:DO NOT USE!");

    jarVersions.put(new Long(1591855), "xerces.jar from xalan-j_1_1 from xerces-1...");
    jarVersions.put(new Long(1498679), "xerces.jar from xalan-j_1_2 from xerces-1_2_0.bin");
    jarVersions.put(new Long(1484896), "xerces.jar from xalan-j_1_2_1 from xerces-1_2_1.bin");
    jarVersions.put(new Long(804460),  "xerces.jar from xalan-j_1_2_2 from xerces-1_2_2.bin");
    jarVersions.put(new Long(1499244), "xerces.jar from xalan-j_2_0_0 from xerces-1_2_3.bin");
    jarVersions.put(new Long(1605266), "xerces.jar from xalan-j_2_0_1 from xerces-1_3_0.bin");
    jarVersions.put(new Long(904030), "xerces.jar from xalan-j_2_1_0 from xerces-1_4.bin");
    jarVersions.put(new Long(1190776), "xerces.jar from lotusxsl_1_0_1 apparently-from xerces-1_0_3.bin");
    jarVersions.put(new Long(1489400), "xerces.jar from lotusxsl-j_2_0_0 from XML4J-3_1_1");
    jarVersions.put(new Long(1787796), "xerces.jar from lotusxsl-j_2_2 or xerces-1_4_1.bin");
    jarVersions.put(new Long(904030), "xerces.jar from xerces-1_4_0.bin");
    jarVersions.put(new Long(1802885), "xerces.jar from xerces-1_4_2.bin");
    jarVersions.put(new Long(1734594), "xerces.jar from Xerces-J-bin.2.0.0.beta3");
    jarVersions.put(new Long(1808883), "xerces.jar from xalan-j_2_2_D10,D11,D12 or xerces-1_4_3.bin");
    jarVersions.put(new Long(1803877), "xerces.jar from XML4J-3_2_1");
    jarVersions.put(new Long(1812019), "xerces.jar from xalan-j_2_2_0");
    jarVersions.put(new Long(1720292), "xercesImpl.jar from xalan-j_2_3_D1");
    jarVersions.put(new Long(1730053), "xercesImpl.jar from xalan-j_2_3_0 from xerces-2_0_0");
    jarVersions.put(new Long(1728861), "xercesImpl.jar from xalan-j_2_4_D1 from xerces-2_0_1");

    jarVersions.put(new Long(37485), "xalanj1compat.jar from xalan-j_2_0_0");
    jarVersions.put(new Long(38100), "xalanj1compat.jar from xalan-j_2_0_1");

    jarVersions.put(new Long(18779), "xalanservlet.jar from xalan-j_2_0_0");
    jarVersions.put(new Long(21453), "xalanservlet.jar from xalan-j_2_0_1");

    // For those who've downloaded JAXP from sun
    jarVersions.put(new Long(5618), "jaxp.jar from jaxp1.0.1");
    jarVersions.put(new Long(136133), "parser.jar from jaxp1.0.1");
    jarVersions.put(new Long(28404), "jaxp.jar from jaxp-1.1");
    jarVersions.put(new Long(187162), "crimson.jar from jaxp-1.1");
    jarVersions.put(new Long(801714), "xalan.jar from jaxp-1.1");
    jarVersions.put(new Long(196399), "crimson.jar from crimson-1.1.1");
    jarVersions.put(new Long(33323), "jaxp.jar from crimson-1.1.1 or jakarta-ant-1.4.1b1");
    jarVersions.put(new Long(152717), "crimson.jar from crimson-1.1.2beta2");
    jarVersions.put(new Long(88143), "xml-apis.jar from crimson-1.1.2beta2");
    jarVersions.put(new Long(206384), "crimson.jar from crimson-1.1.3 or jakarta-ant-1.4.1b1");

    // jakarta-ant: since many people use ant these days
    jarVersions.put(new Long(136198), "parser.jar from jakarta-ant-1.3 or 1.2");
    jarVersions.put(new Long(5537), "jaxp.jar from jakarta-ant-1.3 or 1.2");

    // Various LotusXSL versions, which are based on Xalan code 
    //  (LotusXSL was donated by Lotus to Apache to become Xalan)
    jarVersions.put(new Long(120274), "lotusxsl.jar from lotusxsl-0_16_4");
    jarVersions.put(new Long(120293), "lotusxsl.jar from lotusxsl-0_16_5");
    jarVersions.put(new Long(283777), "lotusxsl.jar from lotusxsl-0_17_2");
    jarVersions.put(new Long(305577), "lotusxsl.jar from lotusxsl-0_17_3");
    jarVersions.put(new Long(304500), "lotusxsl.jar from lotusxsl-0_17_4");
    jarVersions.put(new Long(714959), "lotusxsl.jar from lotusxsl-0_18_1");
    jarVersions.put(new Long(717674), "lotusxsl.jar from lotusxsl-0_18_2");
    jarVersions.put(new Long(752343), "lotusxsl.jar from lotusxsl-0_18_3");
    jarVersions.put(new Long(907101), "lotusxsl.jar from lotusxsl-0_18_4");
  }

  /** Simple PrintWriter we send output to; defaults to System.out.  */
  protected PrintWriter outWriter = new PrintWriter(System.out, true);

  /**
   * Bottleneck output: calls outWriter.println(s).  
   * @param s String to print
   */
  protected void logMsg(String s)
  {
    outWriter.println(s);
  }
}