/*

  * ============================================================================

  *

  *  File:     TokenFromSpaceAuthenticator.java

  *----------------------------------------------------------------------------

  *

  * Copyright 2008 Erlend Nossum

  *

  * Licensed under the Apache License, Version 2.0 (the "License"); 

  * you may not use this file except in compliance with the License. 

  * You may obtain a copy of the License at 

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and 

  * limitations under the License.

  *

  *  Description:  See javadoc below

  *

  *  Created:      Mar 16, 2008

  * ============================================================================ 

  */

 package org.semispace.ws;

 import java.util.Random;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import org.semispace.NameValueQuery;

 import org.semispace.SemiSpaceInterface;

 /**

  * Query on simple name / value elements read from 

  * space. This implementation exist as an <b>example</b>

  * and for the benefit of junit tests. You will want

  * to implement your own version in a live situation.

  * 

  * <p>See method doc for more information.</p>

  * 

  * @see NameValueQuery

  */

 public class TokenFromSpaceAuthenticator implements TokenAuthenticator {

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

     /**

      * Default session time of 30 minutes.

      */

     private static final long DEFAULT_SESSION_LENGTH = 1000*60*30;

     private SemiSpaceInterface space;

     /** For the benefit of spring */

     public void setSpace(SemiSpaceInterface space) {

         this.space = space;

     }

     /**

      * As we use NameValueQuery from the semispace-main, we 

      * prepend the name field with <code>authname=</code> in order to 

      * avoid name clashes. 

      * @see org.semispace.ws.TokenAuthenticator#authenticate(java.lang.String, java.lang.String)

      */

     public String authenticate(String username, String password) {

         NameValueQuery nvq = new NameValueQuery();

         nvq.name = "authname="+username;

         nvq.value = password;

         NameValueQuery result = (NameValueQuery) space.readIfExists(nvq);

         if ( result != null ) {

             // User exist in space

             NameValueQuery tokenQuery = new NameValueQuery();

             tokenQuery.value = "tokenFor="+username;

             // Remove potentially existing tokens

             for ( NameValueQuery existing = tokenQuery ; existing != null ; existing = (NameValueQuery) space.takeIfExists(tokenQuery) ) {

                 // Intentional

             }

             String token = generateToken();

             tokenQuery.name = "token="+token;

             space.write(tokenQuery, DEFAULT_SESSION_LENGTH);

             return token;

         }

         return null;

     }

     /**

      * Generate a random token.

      */

     private String generateToken() {

         final Random wheel = new Random();

         String rnd = Long.toString( wheel.nextLong() & Long.MAX_VALUE , 36 );

         if ( rnd.length() > 7 ) {

             rnd = rnd.substring(0,7);

         }

         return rnd;

     }

     /**

      * Side effect: The token life was renewed

      * @return If the token was found to be valid

      * @see org.semispace.ws.TokenAuthenticator#isTokenValid(java.lang.String)

      */

     public boolean isTokenValid(String token) {

         NameValueQuery tokenQuery = new NameValueQuery();

         tokenQuery.name = "token="+token;

         NameValueQuery spaceToken = (NameValueQuery) space.take(tokenQuery, 200);

         if ( spaceToken != null ) {

             // This is in order to renew session

             space.write(spaceToken, DEFAULT_SESSION_LENGTH);

             return true;

         }

         return false;

     }

 }