/* Copyright (C) 2003 Internet Archive.
    *
    * This file is part of the Heritrix web crawler (crawler.archive.org).
    *
    * Heritrix is free software; you can redistribute it and/or modify
    * it under the terms of the GNU Lesser Public License as published by
    * the Free Software Foundation; either version 2.1 of the License, or
    * any later version.
    *
   * Heritrix 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 Public License for more details.
   *
   * You should have received a copy of the GNU Lesser Public License
   * along with Heritrix; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   * Created on Nov 17, 2003
   *
   * To change the template for this generated file go to
   * Window>Preferences>Java>Code Generation>Code and Comments
   */
  package org.archive.crawler.extractor;
  
  import java.io.IOException;
  import java.util.logging.Logger;
  import java.util.regex.Matcher;
  
  import org.apache.commons.httpclient.URIException;
  import org.apache.commons.lang.StringEscapeUtils;
  import org.archive.crawler.datamodel.CoreAttributeConstants;
  import org.archive.crawler.datamodel.CrawlURI;
  import org.archive.crawler.framework.CrawlController;
  import org.archive.io.ReplayCharSequence;
  import org.archive.net.UURI;
  import org.archive.util.DevUtils;
  import org.archive.util.TextUtils;
  import org.archive.util.UriUtils;
  
  /***
   * Processes Javascript files for strings that are likely to be
   * crawlable URIs.
   *
   * @contributor gojomo
   * @contributor szznax
   *
   */
  public class ExtractorJS extends Extractor implements CoreAttributeConstants {
  
      private static final long serialVersionUID = -2231962381454717720L;
  
      private static Logger LOGGER =
          Logger.getLogger("org.archive.crawler.extractor.ExtractorJS");
  
      // finds whitespace-free strings in Javascript
      // (areas between paired ' or " characters, possibly backslash-quoted
      // on the ends, but not in the middle)
      static final String JAVASCRIPT_STRING_EXTRACTOR =
          "(////{0,8}+(?:\"|\'))(//S{0,"+UURI.MAX_URL_LENGTH+"}?)(?://1)";
      // GROUPS:
      // (G1) ' or " with optional leading backslashes
      // (G2) whitespace-free string delimited on boths ends by G1
  
  
      protected long numberOfCURIsHandled = 0;
      protected static long numberOfLinksExtracted = 0;
  
      
      // URIs known to produce false-positives with the current JS extractor.
      // e.g. currently (2.0.3) the JS extractor produces 13 false-positive 
      // URIs from http://www.google-analytics.com/urchin.js and only 2 
      // good URIs, which are merely one pixel images.
      // TODO: remove this blacklist when JS extractor is improved 
      protected final static String[] EXTRACTOR_URI_EXCEPTIONS = {
          "http://www.google-analytics.com/urchin.js"
          };
      
      /***
       * @param name
       */
      public ExtractorJS(String name) {
          super(name, "JavaScript extractor. Link extraction on JavaScript" +
                  " files (.js).");
      }
  
      /* (non-Javadoc)
       * @see org.archive.crawler.framework.Processor#process(org.archive.crawler.datamodel.CrawlURI)
       */
      public void extract(CrawlURI curi) {
          // special-cases, for when we know our current JS extractor does poorly.
          // TODO: remove this test when JS extractor is improved 
          for (String s: EXTRACTOR_URI_EXCEPTIONS) {
              if (curi.toString().equals(s))
                  return;
          }
              
          if (!isHttpTransactionContentToProcess(curi)) {
              return;
         }
         String contentType = curi.getContentType();
         if ((contentType == null)) {
             return;
         }
         // If content type is not js and if the viaContext
         // does not begin with 'script', return.
         if((contentType.indexOf("javascript") < 0) &&
             (contentType.indexOf("jscript") < 0) &&
             (contentType.indexOf("ecmascript") < 0) &&
             (!curi.toString().toLowerCase().endsWith(".js")) &&
             (curi.getViaContext() == null || !curi.getViaContext().
                 toString().toLowerCase().startsWith("script"))) {
             return;
         }
 
         this.numberOfCURIsHandled++;
 
         ReplayCharSequence cs = null;
         try {
             cs = curi.getHttpRecorder().getReplayCharSequence();
         } catch (IOException e) {
             curi.addLocalizedError(this.getName(), e,
             	"Failed get of replay char sequence.");
         }
         if (cs == null) {
             LOGGER.warning("Failed getting ReplayCharSequence: " +
                 curi.toString());
             return;
         }
 
         try {
             try {
                 numberOfLinksExtracted += considerStrings(curi, cs,
                         getController(), true);
             } catch (StackOverflowError e) {
                 DevUtils.warnHandle(e, "ExtractorJS StackOverflowError");
             }
             // Set flag to indicate that link extraction is completed.
             curi.linkExtractorFinished();
         } finally {
             // Done w/ the ReplayCharSequence. Close it.
             if (cs != null) {
                 try {
                     cs.close();
                 } catch (IOException ioe) {
                     LOGGER.warning(TextUtils.exceptionToString(
                         "Failed close of ReplayCharSequence.", ioe));
                 }
             }
         }
     }
 
     public static long considerStrings(CrawlURI curi, CharSequence cs,
             CrawlController controller, boolean handlingJSFile) {
         long foundLinks = 0;
         Matcher strings =
             TextUtils.getMatcher(JAVASCRIPT_STRING_EXTRACTOR, cs);
         while(strings.find()) {
             CharSequence subsequence =
                 cs.subSequence(strings.start(2), strings.end(2));
 
             if(UriUtils.isLikelyUriJavascriptContextLegacy(subsequence)) {
                 String string = subsequence.toString();
                 string = StringEscapeUtils.unescapeJavaScript(string);
                 string = UriUtils.speculativeFixup(string, curi.getUURI());
                 foundLinks++;
                 try {
                     if (handlingJSFile) {
                         curi.createAndAddLinkRelativeToVia(string,
                             Link.JS_MISC, Link.SPECULATIVE_HOP);
                     } else {
                         curi.createAndAddLinkRelativeToBase(string,
                             Link.JS_MISC, Link.SPECULATIVE_HOP);
                     }
                 } catch (URIException e) {
                     // There may not be a controller (e.g. If we're being run
                     // by the extractor tool).
                     if (controller != null) {
                         controller.logUriError(e, curi.getUURI(), string);
                     } else {
                         LOGGER.info(curi + ", " + string + ": " +
                             e.getMessage());
                     }
                 }
             } else {
                foundLinks += considerStrings(curi, subsequence,
                    controller, handlingJSFile);
             }
         }
         TextUtils.recycleMatcher(strings);
         return foundLinks;
     }
 
     /*
      * (non-Javadoc)
      * 
      * @see org.archive.crawler.framework.Processor#report()
      */
     public String report() {
         StringBuffer ret = new StringBuffer();
         ret.append("Processor: org.archive.crawler.extractor.ExtractorJS\n");
         ret.append("  Function:          Link extraction on JavaScript code\n");
         ret.append("  CrawlURIs handled: " + numberOfCURIsHandled + "\n");
         ret.append("  Links extracted:   " + numberOfLinksExtracted + "\n\n");
 
         return ret.toString();
     }
 }