/*

  * 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.env;

 import org.apache.shiro.mgt.SecurityManager;

 import org.apache.shiro.util.Destroyable;

 import org.apache.shiro.util.LifecycleUtils;

 import java.util.Map;

 import java.util.concurrent.ConcurrentHashMap;

 /**

  * Simple/default {@code Environment} implementation that stores Shiro objects as key-value pairs in a

  * {@link java.util.Map Map} instance.  The key is the object name, the value is the object itself.

  *

  * @since 1.2

  */

 public class DefaultEnvironment implements NamedObjectEnvironment, Destroyable {

     /**

      * The default name under which the application's {@code SecurityManager} instance may be acquired, equal to

      * {@code securityManager}.

      */

     public static final String DEFAULT_SECURITY_MANAGER_KEY = "securityManager";

     protected final Map<String, Object> objects;

     private String securityManagerName;

     /**

      * Creates a new instance with a thread-safe {@link ConcurrentHashMap} backing map.

      */

     public DefaultEnvironment() {

         this(new ConcurrentHashMap<String, Object>());

     }

     /**

      * Creates a new instance with the specified backing map.

      *

      * @param seed backing map to use to maintain Shiro objects.

      */

     @SuppressWarnings({"unchecked"})

     public DefaultEnvironment(Map<String, ?> seed) {

         this.securityManagerName = DEFAULT_SECURITY_MANAGER_KEY;

         if (seed == null) {

             throw new IllegalArgumentException("Backing map cannot be null.");

         }

         this.objects = (Map<String, Object>) seed;

     }

     /**

      * Returns the application's {@code SecurityManager} instance accessible in the backing map using the

      * {@link #getSecurityManagerName() securityManagerName} property as the lookup key.

      * <p/>

      * This implementation guarantees that a non-null instance is always returned, as this is expected for

      * Environment API end-users.  If subclasses have the need to perform the map lookup without this guarantee

      * (for example, during initialization when the instance may not have been added to the map yet), the

      * {@link #lookupSecurityManager()} method is provided as an alternative.

      *

      * @return the application's {@code SecurityManager} instance accessible in the backing map using the

      *         {@link #getSecurityManagerName() securityManagerName} property as the lookup key.

      */

     public SecurityManager getSecurityManager() throws IllegalStateException {

         SecurityManager securityManager = lookupSecurityManager();

         if (securityManager == null) {

             throw new IllegalStateException("No SecurityManager found in Environment.  This is an invalid " +

                     "environment state.");

         }

         return securityManager;

     }

     public void setSecurityManager(SecurityManager securityManager) {

         if (securityManager == null) {

             throw new IllegalArgumentException("Null SecurityManager instances are not allowed.");

         }

         String name = getSecurityManagerName();

         setObject(name, securityManager);

     }

     /**

      * Looks up the {@code SecurityManager} instance in the backing map without performing any non-null guarantees.

      *

      * @return the {@code SecurityManager} in the backing map, or {@code null} if it has not yet been populated.

      */

     protected SecurityManager lookupSecurityManager() {

         String name = getSecurityManagerName();

         return getObject(name, SecurityManager.class);

     }

     /**

      * Returns the name of the {@link SecurityManager} instance in the backing map.  Used as a key to lookup the

      * instance.  Unless set otherwise, the default is {@code securityManager}.

      *

      * @return the name of the {@link SecurityManager} instance in the backing map.  Used as a key to lookup the

      *         instance.

      */

     public String getSecurityManagerName() {

         return securityManagerName;

     }

     /**

      * Sets the name of the {@link SecurityManager} instance in the backing map.  Used as a key to lookup the

      * instance.  Unless set otherwise, the default is {@code securityManager}.

      *

      * @param securityManagerName the name of the {@link SecurityManager} instance in the backing map.  Used as a key

      *                            to lookup the instance. 

      */

     public void setSecurityManagerName(String securityManagerName) {

         this.securityManagerName = securityManagerName;

     }

     /**

      * Returns the live (modifiable) internal objects collection.

      *

      * @return the live (modifiable) internal objects collection.

      */

     public Map<String,Object> getObjects() {

         return this.objects;

     }

     @SuppressWarnings({"unchecked"})

     public <T> T getObject(String name, Class<T> requiredType) throws RequiredTypeException {

         if (name == null) {

             throw new NullPointerException("name parameter cannot be null.");

         }

         if (requiredType == null) {

             throw new NullPointerException("requiredType parameter cannot be null.");

         }

         Object o = this.objects.get(name);

         if (o == null) {

             return null;

         }

         if (!requiredType.isInstance(o)) {

             String msg = "Object named '" + name + "' is not of required type [" + requiredType.getName() + "].";

             throw new RequiredTypeException(msg);

         }

         return (T)o;

     }

     public void setObject(String name, Object instance) {

         if (name == null) {

             throw new NullPointerException("name parameter cannot be null.");

         }

         if (instance == null) {

             this.objects.remove(name);

         } else {

             this.objects.put(name, instance);

         }

     }

     public void destroy() throws Exception {

         LifecycleUtils.destroy(this.objects.values());

     }

 }