package org.paneris.bibliomania.metasearch.bob;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.net.URL;

 import org.apache.oro.text.regex.MalformedPatternException;

 import org.apache.oro.text.regex.Perl5Compiler;

 import org.apache.oro.text.regex.Perl5Matcher;

 import org.apache.oro.text.regex.Perl5Pattern;

 import org.apache.oro.text.regex.StringSubstitution;

 import org.apache.oro.text.regex.Util;

 import org.melati.util.IoUtils;

 import org.melati.util.MelatiRuntimeException;

 import org.melati.util.UnexpectedExceptionException;

 import org.paneris.bibliomania.metasearch.util.HackParser;

 import org.paneris.bibliomania.metasearch.util.TimeoutThread;

 public class Session {

   public static final String frontPageURL =

     "http://bookshop.blackwell.co.uk/cgi-bin/BOB2?BV_Operation=Dyn_LoginReceive&BV_ServiceName=BOB&form%25login_type=guest&form%25failure=/service_error.html&form%25success=/bob/bob_main.html.tmpl";

   public String sessionID, engineID;

   public Session(String sessionID, String engineID) {

     this.sessionID = sessionID;

     this.engineID = engineID;

   }

   public String queryParams() {

     return "BV_SessionID=" + sessionID + "&BV_EngineID=" + engineID;

   }

   public String toString() {

     return queryParams();

   }

   private static final Object bobSessionMon = new Object();

   private static Session bobSession = null;

   private static Exception bobSessionException = null;

   public static class NoSessionIDException extends MelatiRuntimeException {

     /**

      * 

      */

     private static final long serialVersionUID = 1L;

     public String getMessage() {

       return "Couldn't extract session ID from front page";

     }

   }

   private static void newSession() throws OpenException {

     System.err.println("BOB: establishing new session");

     try {

       TimeoutThread timeout = TimeoutThread.forCurrentThread(20000);

       try {

         FrontPage fp =

           new FrontPage(IoUtils.slurp(new URL(frontPageURL), 32768));

         if (fp.sessionID == null)

           throw new NoSessionIDException();

         bobSession = new Session(fp.sessionID, fp.engineID);

         bobSessionException = null;

       } finally {

         timeout.stop();

       }

     } catch (Exception e) {

       bobSessionException = e;

       throw new OpenException(e);

     }

   }

   private static class SessionRenewer extends Thread {

     public SessionRenewer() {

       setDaemon(true);

     }

     public void run() {

       try {

         for (;;) {

           try {

             newSession();

           } catch (Exception e) {

             System.err.println("BOB SessionRenewer:");

             e.printStackTrace();

           } finally {

             synchronized (bobSessionMon) {

               bobSessionMon.notifyAll();

             }

           }

           Thread.sleep(5 * 60 * 1000);

         }

       } catch (InterruptedException e) {

       } finally {

         sessionRenewer = null;

       }

     }

   }

   private static SessionRenewer sessionRenewer = null;

   private static synchronized void checkSessionRenewer() {

     if (sessionRenewer == null)

        (sessionRenewer = new SessionRenewer()).start();

   }

   static Session bobSession() {

     checkSessionRenewer();

     if (bobSession == null) {

       try {

         synchronized (bobSessionMon) {

           if (bobSession == null)

             bobSessionMon.wait();

         }

       } catch (InterruptedException e) {

         throw new OpenException(e);

       }

     }

     if (bobSession == null)

       throw new OpenException(bobSessionException);

     return bobSession;

   }

   private static Perl5Pattern bv__IDParam;

   static {

     try {

       bv__IDParam =

         (Perl5Pattern) (new Perl5Compiler()).compile(

           "BV_(Session|Engine)ID=[^&]*&?",

           0);

     } catch (MalformedPatternException e) {

       throw new UnexpectedExceptionException(e);

     }

   }

   private static final StringSubstitution empty = new StringSubstitution();

   public static String urlInCurrentSession(String url) {

     String urlWithoutSession =

       Util.substitute(

         new Perl5Matcher(),

         bv__IDParam,

         empty,

         url,

         Util.SUBSTITUTE_ALL);

     return urlWithoutSession + '&' + bobSession().queryParams();

   }

   private static String contentDumpPrefix = null;

   private static int contentDumpIndex = 0;

   private static byte[] contentUsingCurrentSession(

     String url,

     int estimate,

     int limit)

     throws IOException {

     byte[] content = IoUtils.slurp(new URL(urlInCurrentSession(url)), 32768);

     String dp = contentDumpPrefix;

     if (dp != null) {

       try {

         OutputStream o =

           new FileOutputStream(contentDumpPrefix + contentDumpIndex++ +".html");

         try {

           o.write(content);

         } finally {

           try {

             o.close();

           } catch (IOException e) {

           }

         }

       } catch (Exception e) {

         System.err.println("Can't write dump!");

       }

     }

     return content;

   }

   private static final byte[] timeoutExplan =

     "current session timing out".getBytes();

   public static byte[] content(String url, int estimate, int limit)

     throws IOException {

     byte[] it = contentUsingCurrentSession(url, estimate, limit);

     if (HackParser.indexOf(it, timeoutExplan) != -1) {

       newSession();

       return contentUsingCurrentSession(url, estimate, limit);

     } else

       return it;

   }

 }