/*

  * 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.guice.web;

 import java.lang.reflect.Constructor;

 import java.util.Collections;

 import java.util.HashSet;

 import java.util.Set;

 import com.google.inject.Inject;

 import com.google.inject.Injector;

 import com.google.inject.Key;

 import com.google.inject.ProvisionException;

 import com.google.inject.spi.Dependency;

 import com.google.inject.spi.InjectionPoint;

 import com.google.inject.spi.ProviderWithDependencies;

 class AbstractInjectionProvider<T> implements ProviderWithDependencies<T> {

     private Key<T> key;

     @Inject

     Injector injector;

     private InjectionPoint constructorInjectionPoint;

     private Set<Dependency<?>> dependencies;

     public AbstractInjectionProvider(Key<T> key) {

         this.key = key;

         constructorInjectionPoint = InjectionPoint.forConstructorOf(key.getTypeLiteral());

         Set<Dependency<?>> dependencyBuilder = new HashSet<Dependency<?>>();

         dependencyBuilder.addAll(constructorInjectionPoint.getDependencies());

         for (InjectionPoint injectionPoint : InjectionPoint.forInstanceMethodsAndFields(key.getTypeLiteral())) {

             dependencyBuilder.addAll(injectionPoint.getDependencies());

         }

         this.dependencies = Collections.unmodifiableSet(dependencyBuilder);

     }

     public T get() {

         Constructor<T> constructor = getConstructor();

         Object[] params = new Object[constructor.getParameterTypes().length];

         for (Dependency<?> dependency : constructorInjectionPoint.getDependencies()) {

             params[dependency.getParameterIndex()] = injector.getInstance(dependency.getKey());

         }

         T t;

         try {

             t = constructor.newInstance(params);

         } catch (Exception e) {

             throw new ProvisionException("Could not instantiate " + key + "", e);

         }

         injector.injectMembers(t);

         return postProcess(t);

     }

     @SuppressWarnings({"unchecked"})

     private Constructor<T> getConstructor() {

         return (Constructor<T>) constructorInjectionPoint.getMember();

     }

     protected T postProcess(T t) {

         // do nothing by default

         return t;

     }

     public Set<Dependency<?>> getDependencies() {

         return dependencies;

     }

 }