/*
 * JBoss, Home of Professional Open Source.
 *
 * Copyright 2007, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package de.lbank.tomcat.authenticator;

import static org.apache.catalina.authenticator.Constants.FORM_ACTION;
import static org.apache.catalina.authenticator.Constants.FORM_PASSWORD;
import static org.apache.catalina.authenticator.Constants.FORM_PRINCIPAL_NOTE;
import static org.apache.catalina.authenticator.Constants.FORM_USERNAME;
import static org.apache.catalina.authenticator.Constants.SESS_PASSWORD_NOTE;
import static org.apache.catalina.authenticator.Constants.SESS_USERNAME_NOTE;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.security.Principal;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Realm;
import org.apache.catalina.Session;
import org.apache.catalina.authenticator.FormAuthenticator;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.deploy.LoginConfig;
import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.CharChunk;
import org.apache.tomcat.util.buf.MessageBytes;
import org.jboss.logging.Logger;
import org.jboss.security.negotiation.MessageFactory;
import org.jboss.security.negotiation.NegotiationException;
import org.jboss.security.negotiation.NegotiationMessage;
import org.jboss.security.negotiation.common.MessageTrace;
import org.jboss.security.negotiation.common.NegotiationContext;
import org.picketbox.commons.cipher.Base64;


/**
 * An authenticator to manage Negotiation based authentication in connection with the
 * Negotiation login module.
 *
 * @author darran.lofthouse@jboss.com
 * @author jochen.riedlinger@l-bank.de
 * @version $Revision: 111912 $
 */
public class NegotiationAuthenticator extends FormAuthenticator
{

   private static final Logger log = Logger.getLogger(NegotiationAuthenticator.class);

   private static final String NEGOTIATE = "Negotiate";

   private static final String BASIC = "Basic"; //L-Bank

   private static final String NEGOTIATION_CONTEXT = "NEGOTIATION_CONTEXT";

   private static final String FORM_METHOD = "FORM";

   protected String getNegotiateScheme()
   {
      return NEGOTIATE;
   }

   /**
    *
    * @return
    */
   protected String getBasicScheme() //L-Bank
   {
      return BASIC;
   }

   @Override
   public boolean authenticate(final Request request, final HttpServletResponse response, final LoginConfig config)
         throws IOException
   {

      boolean DEBUG = log.isDebugEnabled();
      log.trace("Authenticating user");

      Principal principal = request.getUserPrincipal();
      if (principal != null)
      {
         if (log.isTraceEnabled())
            log.trace("Already authenticated '" + principal.getName() + "'");
         return true;
      }

      String contextPath = request.getContextPath();
      String requestURI = request.getDecodedRequestURI();
      boolean loginAction = requestURI.startsWith(contextPath) && requestURI.endsWith(FORM_ACTION);
      if (loginAction)
      {
         Realm realm = context.getRealm();
         String username = request.getParameter(FORM_USERNAME);
         String password = request.getParameter(FORM_PASSWORD);
         principal = realm.authenticate(username, password);
         if (principal == null)
         {
            RequestDispatcher disp = context.getServletContext().getRequestDispatcher(config.getErrorPage());
            try
            {
               disp.forward(request.getRequest(), response);
            }
            catch (ServletException e)
            {
               IOException ex = new IOException("Unable to forward to error page.");
               ex.initCause(e);

               throw ex;
            }
            return false;
         }

         Session session = request.getSessionInternal();
         requestURI = savedRequestURL(session);

         session.setNote(FORM_PRINCIPAL_NOTE, principal);
         session.setNote(SESS_USERNAME_NOTE, username);
         session.setNote(SESS_PASSWORD_NOTE, password);

         register(request, response, principal, FORM_METHOD, username, password);
         response.sendRedirect(response.encodeRedirectURL(requestURI));

         return false;
      }

      String negotiateScheme = getNegotiateScheme();

      if (DEBUG)
         log.debug("Header - " + request.getHeader("Authorization"));
      String authHeader = request.getHeader("Authorization");
      if (authHeader == null)
      {

         log.debug("No Authorization Header, initiating negotiation");
         initiateNegotiation(request, response, config);

         return false;
      }
      else if (authHeader.startsWith(negotiateScheme + " ") == false)
      {
    	  if (authHeader.startsWith(getBasicScheme() + " ")) {

    		  MessageBytes messagebytes = request.getCoyoteRequest().getMimeHeaders().getValue("Authorization");
    		  messagebytes.toBytes();
    		  ByteChunk byteChunk = messagebytes.getByteChunk();

    		  boolean successfulAuthenticated = false;
    		  if (byteChunk.startsWithIgnoreCase(getBasicScheme() + " ", 0)) {
				int offsetLength = getBasicScheme().length() + 1;
    			byteChunk.setOffset(byteChunk.getOffset() + offsetLength);
    			CharChunk charChunk = messagebytes.getCharChunk();
    			org.apache.catalina.util.Base64.decode(byteChunk, charChunk);

    			successfulAuthenticated = this.handleBasic(request, response, charChunk);

    			byteChunk.setOffset(byteChunk.getOffset() - offsetLength);
    		  }

    		  return successfulAuthenticated;

          } else {
        	  throw new IOException("Invalid 'Authorization' header.");
          }
      }



      String authTokenBase64 = authHeader.substring(negotiateScheme.length() + 1);
      byte[] authToken = Base64.decode(authTokenBase64);
      ByteArrayInputStream authTokenIS = new ByteArrayInputStream(authToken);
      MessageTrace.logRequestBase64(authTokenBase64);
      MessageTrace.logRequestHex(authToken);

      Session session = request.getSessionInternal();
      NegotiationContext negotiationContext = (NegotiationContext) session.getNote(NEGOTIATION_CONTEXT);
      if (negotiationContext == null)
      {
         log.debug("Creating new NegotiationContext");
         negotiationContext = new NegotiationContext();
         session.setNote(NEGOTIATION_CONTEXT, negotiationContext);
      }

      String username = negotiationContext.getUsername();
      if (username == null || username.length() == 0)
      {
         username = session.getId() + "_" + String.valueOf(System.currentTimeMillis());
         negotiationContext.setUsername(username);
      }
      String authenticationMethod = "";
      try
      {
         // Set the ThreadLocal association.
         negotiationContext.associate();

         MessageFactory mf = MessageFactory.newInstance();
         if (mf.accepts(authTokenIS) == false)
         {
            throw new IOException("Unsupported negotiation mechanism.");
         }

         NegotiationMessage requestMessage = mf.createMessage(authTokenIS);
         negotiationContext.setRequestMessage(requestMessage);

         Realm realm = context.getRealm();
         principal = realm.authenticate(username, (String) null);

         authenticationMethod = negotiationContext.getAuthenticationMethod();

         if (DEBUG && principal != null)
            log.debug("authenticated principal = " + principal);

         NegotiationMessage responseMessage = negotiationContext.getResponseMessage();
         if (responseMessage != null)
         {
            ByteArrayOutputStream responseMessageOS = new ByteArrayOutputStream();
            responseMessage.writeTo(responseMessageOS, true);
            String responseHeader = responseMessageOS.toString();

            MessageTrace.logResponseBase64(responseHeader);

            response.setHeader("WWW-Authenticate", negotiateScheme + " " + responseHeader);
         }

      }
      catch (NegotiationException e)
      {
         IOException ioe = new IOException("Error processing " + negotiateScheme + " header.");
         ioe.initCause(e);
         throw ioe;
      }
      finally
      {
         // Clear the headers and remove the ThreadLocal association.
         negotiationContext.clear();
      }

      if (principal == null)
      {
         response.sendError(Response.SC_UNAUTHORIZED);
      }
      else
      {
         register(request, response, principal, authenticationMethod, username, null);
      }

      return (principal != null);
   }

   private void initiateNegotiation(final Request request, final HttpServletResponse response, final LoginConfig config)
         throws IOException
   {
      String loginPage = config.getLoginPage();
      if (loginPage != null)
      {
         // TODO - Logic to cache and restore request.
         ServletContext servletContext = context.getServletContext();
         RequestDispatcher disp = servletContext.getRequestDispatcher(loginPage);

         try
         {
            Session session = request.getSessionInternal();
            saveRequest(request, session);

            disp.include(request.getRequest(), response);
            response.setHeader("WWW-Authenticate", getNegotiateScheme());
            response.setStatus(Response.SC_UNAUTHORIZED);
         }
         catch (ServletException e)
         {
            IOException ex = new IOException("Unable to include loginPage");
            ex.initCause(e);

            throw ex;
         }

      }
      else
      {
         response.setHeader("WWW-Authenticate", getNegotiateScheme());
         response.addHeader("WWW-Authenticate", getBasicScheme() + " realm=\"" + config.getRealmName().toUpperCase() + "\"");// L-Bank
         response.sendError(Response.SC_UNAUTHORIZED);
      }

      response.flushBuffer();
   }

   protected boolean handleBasic(Request request, HttpServletResponse response, CharChunk charchunk) {
		String username;
		String password;
		username = null;
		password = null;
		int i = charchunk.indexOf(':');
		if (i < 0) {
			username = charchunk.toString();
		} else {
			char ac[] = charchunk.getBuffer();
			username = new String(ac, 0, i);
			password = new String(ac, i + 1, charchunk.getEnd() - i - 1);
		}
		try {

			Realm realm = context.getRealm();
        	Principal principal = realm.authenticate(username, password);

        	if (principal == null) {
        		response.sendError(Response.SC_UNAUTHORIZED);
        		return false;
        	}

        	Session session = request.getSessionInternal();
        	session.setNote(FORM_PRINCIPAL_NOTE, principal);
            session.setNote(SESS_USERNAME_NOTE, username);
            session.setNote(SESS_PASSWORD_NOTE, password);

        	register(request, response, principal, getBasicScheme(), username, password);
			return true;

		} catch (Exception e) {
			log.info("Could not verify password - wrong password given or maybe LoginModule is misconfigured!", e);
			return false;
		}

	}
}