/*
    * 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.web.session;
  
  import org.apache.shiro.session.InvalidSessionException;
  import org.apache.shiro.session.Session;
  import org.apache.shiro.util.StringUtils;
  import org.apache.shiro.web.servlet.ShiroHttpSession;
  
  import javax.servlet.http.HttpSession;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Date;
  import java.util.Enumeration;
  
  /**
   * {@link Session Session} implementation that is backed entirely by a standard servlet container
   * {@link HttpSession HttpSession} instance.  It does not interact with any of Shiro's session-related components
   * {@code SessionManager}, {@code SecurityManager}, etc, and instead satisfies all method implementations by interacting
   * with a servlet container provided {@link HttpSession HttpSession} instance.
   *
   * @since 1.0
   */
  public class HttpServletSession implements Session {
  
      private static final String HOST_SESSION_KEY = HttpServletSession.class.getName() + ".HOST_SESSION_KEY";
      private static final String TOUCH_OBJECT_SESSION_KEY = HttpServletSession.class.getName() + ".TOUCH_OBJECT_SESSION_KEY";
  
      private HttpSession httpSession = null;
  
      public HttpServletSession(HttpSession httpSession, String host) {
          if (httpSession == null) {
              String msg = "HttpSession constructor argument cannot be null.";
              throw new IllegalArgumentException(msg);
          }
          if (httpSession instanceof ShiroHttpSession) {
              String msg = "HttpSession constructor argument cannot be an instance of ShiroHttpSession.  This " +
                      "is enforced to prevent circular dependencies and infinite loops.";
              throw new IllegalArgumentException(msg);
          }
          this.httpSession = httpSession;
          if (StringUtils.hasText(host)) {
              setHost(host);
          }
      }
  
      public Serializable getId() {
          return httpSession.getId();
      }
  
      public Date getStartTimestamp() {
          return new Date(httpSession.getCreationTime());
      }
  
      public Date getLastAccessTime() {
          return new Date(httpSession.getLastAccessedTime());
      }
  
      public long getTimeout() throws InvalidSessionException {
          try {
              return httpSession.getMaxInactiveInterval() * 1000;
          } catch (Exception e) {
              throw new InvalidSessionException(e);
          }
      }
  
      public void setTimeout(long maxIdleTimeInMillis) throws InvalidSessionException {
          try {
              int timeout = Long.valueOf(maxIdleTimeInMillis / 1000).intValue();
              httpSession.setMaxInactiveInterval(timeout);
          } catch (Exception e) {
              throw new InvalidSessionException(e);
          }
      }
  
      protected void setHost(String host) {
          setAttribute(HOST_SESSION_KEY, host);
      }
  
      public String getHost() {
          return (String) getAttribute(HOST_SESSION_KEY);
      }
 
     public void touch() throws InvalidSessionException {
         //just manipulate the session to update the access time:
         try {
             httpSession.setAttribute(TOUCH_OBJECT_SESSION_KEY, TOUCH_OBJECT_SESSION_KEY);
             httpSession.removeAttribute(TOUCH_OBJECT_SESSION_KEY);
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 
     public void stop() throws InvalidSessionException {
         try {
             httpSession.invalidate();
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 
     public Collection<Object> getAttributeKeys() throws InvalidSessionException {
         try {
             Enumeration namesEnum = httpSession.getAttributeNames();
             Collection<Object> keys = null;
             if (namesEnum != null) {
                 keys = new ArrayList<Object>();
                 while (namesEnum.hasMoreElements()) {
                     keys.add(namesEnum.nextElement());
                 }
             }
             return keys;
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 
     private static String assertString(Object key) {
         if (!(key instanceof String)) {
             String msg = "HttpSession based implementations of the Shiro Session interface requires attribute keys " +
                     "to be String objects.  The HttpSession class does not support anything other than String keys.";
             throw new IllegalArgumentException(msg);
         }
         return (String) key;
     }
 
     public Object getAttribute(Object key) throws InvalidSessionException {
         try {
             return httpSession.getAttribute(assertString(key));
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 
     public void setAttribute(Object key, Object value) throws InvalidSessionException {
         try {
             httpSession.setAttribute(assertString(key), value);
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 
     public Object removeAttribute(Object key) throws InvalidSessionException {
         try {
             String sKey = assertString(key);
             Object removed = httpSession.getAttribute(sKey);
             httpSession.removeAttribute(sKey);
             return removed;
         } catch (Exception e) {
             throw new InvalidSessionException(e);
         }
     }
 }