package org.frameworkset.web.request.async;

import java.util.List;

import org.apache.log4j.Logger;
import org.frameworkset.web.servlet.mvc.NativeWebRequest;

/**
 * Assists with the invocation of {@link DeferredResultProcessingInterceptor}'s.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
class DeferredResultInterceptorChain {

	private static final Logger logger = Logger.getLogger(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);
			}
		}
	}

}