/*
    * Copyright 2002-2014 the original author or authors.
    *
    * 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.
   */
  
  package org.springframework.web.portlet;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  import org.springframework.util.CollectionUtils;
  import org.springframework.util.ObjectUtils;
  
  /**
   * Handler execution chain, consisting of handler object and any handler interceptors.
   * Returned by HandlerMapping's {@link HandlerMapping#getHandler} method.
   *
   * @author Juergen Hoeller
   * @author John A. Lewis
   * @since 2.0
   * @see HandlerInterceptor
   */
  public class HandlerExecutionChain {
  
  	private final Object handler;
  
  	private HandlerInterceptor[] interceptors;
  
  	private List<HandlerInterceptor> interceptorList;
  
  
  	/**
  	 * Create a new HandlerExecutionChain.
  	 * @param handler the handler object to execute
  	 */
  	public HandlerExecutionChain(Object handler) {
  		this(handler, (HandlerInterceptor[]) null);
  	}
  
  	/**
  	 * Create a new HandlerExecutionChain.
  	 * @param handler the handler object to execute
  	 * @param interceptors the array of interceptors to apply
  	 * (in the given order) before the handler itself executes
  	 */
  	public HandlerExecutionChain(Object handler, HandlerInterceptor... interceptors) {
  		if (handler instanceof HandlerExecutionChain) {
  			HandlerExecutionChain originalChain = (HandlerExecutionChain) handler;
  			this.handler = originalChain.getHandler();
  			this.interceptorList = new ArrayList<HandlerInterceptor>();
  			CollectionUtils.mergeArrayIntoCollection(originalChain.getInterceptors(), this.interceptorList);
  			CollectionUtils.mergeArrayIntoCollection(interceptors, this.interceptorList);
  		}
  		else {
  			this.handler = handler;
  			this.interceptors = interceptors;
  		}
  	}
  
  
  	/**
  	 * Return the handler object to execute.
  	 * @return the handler object
  	 */
  	public Object getHandler() {
  		return this.handler;
  	}
  
  	public void addInterceptor(HandlerInterceptor interceptor) {
  		initInterceptorList().add(interceptor);
  	}
  
  	public void addInterceptors(HandlerInterceptor... interceptors) {
  		if (!ObjectUtils.isEmpty(interceptors)) {
  			initInterceptorList().addAll(Arrays.asList(interceptors));
  		}
  	}
  
  	private List<HandlerInterceptor> initInterceptorList() {
  		if (this.interceptorList == null) {
  			this.interceptorList = new ArrayList<HandlerInterceptor>();
  			if (this.interceptors != null) {
  				// An interceptor array specified through the constructor
  				this.interceptorList.addAll(Arrays.asList(this.interceptors));
  			}
  		}
  		this.interceptors = null;
 		return this.interceptorList;
 	}
 
 	/**
 	 * Return the array of interceptors to apply (in the given order).
 	 * @return the array of HandlerInterceptors instances (may be {@code null})
 	 */
 	public HandlerInterceptor[] getInterceptors() {
 		if (this.interceptors == null && this.interceptorList != null) {
 			this.interceptors = this.interceptorList.toArray(new HandlerInterceptor[this.interceptorList.size()]);
 		}
 		return this.interceptors;
 	}
 
 
 	/**
 	 * Delegates to the handler's {@code toString()}.
 	 */
 	@Override
 	public String toString() {
 		return String.valueOf(this.handler);
 	}
 
 }