/*
    * 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.context.request.async;
  
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.springframework.web.context.request.NativeWebRequest;
  
  /**
   * Assists with the invocation of {@link DeferredResultProcessingInterceptor}'s.
   *
   * @author Rossen Stoyanchev
   * @since 3.2
   */
  class DeferredResultInterceptorChain {
  
  	private static final Log logger = LogFactory.getLog(DeferredResultInterceptorChain.class);
  
  	private final List<DeferredResultProcessingInterceptor> interceptors;
  
  	private int preProcessingIndex = -1;
  
  
  	public DeferredResultInterceptorChain(List<DeferredResultProcessingInterceptor> interceptors) {
  		this.interceptors = interceptors;
  	}
  
  	public void applyBeforeConcurrentHandling(NativeWebRequest request, DeferredResult<?> deferredResult) throws Exception {
  		for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
  			interceptor.beforeConcurrentHandling(request, deferredResult);
  		}
  	}
  
  	public void applyPreProcess(NativeWebRequest request, DeferredResult<?> deferredResult) throws Exception {
  		for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
  			interceptor.preProcess(request, deferredResult);
  			this.preProcessingIndex++;
  		}
  	}
  
  	public Object applyPostProcess(NativeWebRequest request,  DeferredResult<?> deferredResult, Object concurrentResult) {
  		try {
  			for (int i = this.preProcessingIndex; i >= 0; i--) {
  				this.interceptors.get(i).postProcess(request, deferredResult, concurrentResult);
  			}
  		}
  		catch (Throwable t) {
  			return t;
  		}
  		return concurrentResult;
  	}
  
  	public void triggerAfterTimeout(NativeWebRequest request, DeferredResult<?> deferredResult) throws Exception {
  		for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
  			if (deferredResult.isSetOrExpired()) {
  				return;
  			}
  			if (!interceptor.handleTimeout(request, deferredResult)){
  				break;
  			}
  		}
  	}
  
  	public void triggerAfterCompletion(NativeWebRequest request, DeferredResult<?> deferredResult) {
  		for (int i = this.preProcessingIndex; i >= 0; i--) {
  			try {
  				this.interceptors.get(i).afterCompletion(request, deferredResult);
  			}
  			catch (Throwable t) {
  				logger.error("afterCompletion error", t);
  			}
  		}
  	}
  
  }