/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  package org.apache.shiro.session.mgt;
  
  import org.apache.shiro.session.InvalidSessionException;
  import org.apache.shiro.session.Session;
  
  import java.io.Serializable;
  import java.util.Collection;
  import java.util.Date;
  
  /**
   * A DelegatingSession is a client-tier representation of a server side
   * {@link org.apache.shiro.session.Session Session}.
   * This implementation is basically a proxy to a server-side {@link NativeSessionManager NativeSessionManager},
   * which will return the proper results for each method call.
   * <p/>
   * <p>A <tt>DelegatingSession</tt> will cache data when appropriate to avoid a remote method invocation,
   * only communicating with the server when necessary.
   * <p/>
   * <p>Of course, if used in-process with a NativeSessionManager business POJO, as might be the case in a
   * web-based application where the web classes and server-side business pojos exist in the same
   * JVM, a remote method call will not be incurred.
   *
   * @since 0.1
   */
  public class DelegatingSession implements Session, Serializable {
  
      //TODO - complete JavaDoc
  
      private final SessionKey key;
  
      //cached fields to avoid a server-side method call if out-of-process:
      private Date startTimestamp = null;
      private String host = null;
  
      /**
       * Handle to the target NativeSessionManager that will support the delegate calls.
       */
      private final transient NativeSessionManager sessionManager;
  
  
      public DelegatingSession(NativeSessionManager sessionManager, SessionKey key) {
          if (sessionManager == null) {
              throw new IllegalArgumentException("sessionManager argument cannot be null.");
          }
          if (key == null) {
              throw new IllegalArgumentException("sessionKey argument cannot be null.");
          }
          if (key.getSessionId() == null) {
              String msg = "The " + DelegatingSession.class.getName() + " implementation requires that the " +
                      "SessionKey argument returns a non-null sessionId to support the " +
                      "Session.getId() invocations.";
              throw new IllegalArgumentException(msg);
          }
          this.sessionManager = sessionManager;
          this.key = key;
      }
  
      /**
       * @see org.apache.shiro.session.Session#getId()
       */
      public Serializable getId() {
          return key.getSessionId();
      }
  
      /**
       * @see org.apache.shiro.session.Session#getStartTimestamp()
       */
      public Date getStartTimestamp() {
          if (startTimestamp == null) {
              startTimestamp = sessionManager.getStartTimestamp(key);
          }
          return startTimestamp;
      }
  
      /**
       * @see org.apache.shiro.session.Session#getLastAccessTime()
       */
      public Date getLastAccessTime() {
          //can't cache - only business pojo knows the accurate time:
          return sessionManager.getLastAccessTime(key);
      }
 
     public long getTimeout() throws InvalidSessionException {
         return sessionManager.getTimeout(key);
     }
 
     public void setTimeout(long maxIdleTimeInMillis) throws InvalidSessionException {
         sessionManager.setTimeout(key, maxIdleTimeInMillis);
     }
 
     public String getHost() {
         if (host == null) {
             host = sessionManager.getHost(key);
         }
         return host;
     }
 
     /**
      * @see org.apache.shiro.session.Session#touch()
      */
     public void touch() throws InvalidSessionException {
         sessionManager.touch(key);
     }
 
     /**
      * @see org.apache.shiro.session.Session#stop()
      */
     public void stop() throws InvalidSessionException {
         sessionManager.stop(key);
     }
 
     /**
      * @see org.apache.shiro.session.Session#getAttributeKeys
      */
     public Collection<Object> getAttributeKeys() throws InvalidSessionException {
         return sessionManager.getAttributeKeys(key);
     }
 
     /**
      * @see org.apache.shiro.session.Session#getAttribute(Object key)
      */
     public Object getAttribute(Object attributeKey) throws InvalidSessionException {
         return sessionManager.getAttribute(this.key, attributeKey);
     }
 
     /**
      * @see Session#setAttribute(Object key, Object value)
      */
     public void setAttribute(Object attributeKey, Object value) throws InvalidSessionException {
         if (value == null) {
             removeAttribute(attributeKey);
         } else {
             sessionManager.setAttribute(this.key, attributeKey, value);
         }
     }
 
     /**
      * @see Session#removeAttribute(Object key)
      */
     public Object removeAttribute(Object attributeKey) throws InvalidSessionException {
         return sessionManager.removeAttribute(this.key, attributeKey);
     }
 }