/*-
 * ============LICENSE_START=======================================================
 * ONAP - SO
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.openecomp.mso.client.dmaap;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.concurrent.TimeUnit;

import org.openecomp.mso.client.dmaap.exceptions.DMaaPConsumerFailure;
import org.openecomp.mso.client.dmaap.exceptions.ExceededMaximumPollingTime;
import org.openecomp.mso.client.dmaap.rest.RestConsumer;

import com.google.common.base.Stopwatch;

public abstract class DmaapConsumer extends DmaapClient {

	public DmaapConsumer() throws FileNotFoundException, IOException {
		super("dmaap/default-consumer.properties");
	}
	
	public Consumer getConsumer() throws FileNotFoundException, IOException {
		return new RestConsumer(this.properties);
	}
	public boolean consume() throws Exception {
		
		Consumer mrConsumer = this.getConsumer();
		int iterations = 0;
		boolean accepted = false;
		Stopwatch stopwatch = Stopwatch.createUnstarted();
		try {
			while (this.continuePolling()) {
				if (stopwatch.elapsed(TimeUnit.MILLISECONDS) >= this.getMaximumElapsedTime()) {
					final String message = "exceeded maximum retries on " + this.getRequestId() + " on " + this.getTopic();
					auditLogger.error(message);
					throw new ExceededMaximumPollingTime(message);
				}
				stopwatch.start();
				Iterable<String> itr = mrConsumer.fetch();
				stopwatch.stop();
				for (String message : itr) {
					if (!accepted && this.isAccepted(message)) {
						auditLogger.info("accepted message found for " + this.getRequestId() + " on " + this.getTopic());
						accepted = true;
					} 
					if (accepted) {
						if (this.isFailure(message)) {
							this.stopProcessingMessages();
							auditLogger.info("received dmaap message: " + message);
							final String errorMsg = "failure received from dmaap topic " + this.getTopic();
							auditLogger.error(errorMsg);
							throw new DMaaPConsumerFailure(errorMsg);
						} else {
							auditLogger.info("received dmaap message: " + message);
							this.processMessage(message);
						}
					}
				}
				iterations++;
			}
			return true;
		} catch (Exception e ) {
			throw e;
		} finally {
			if (stopwatch.isRunning()) {
				stopwatch.stop();
			}
		}
	}
	
	/**
	 * Should this consumer continue to consume messages from the topic?
	 * @return
	 */
	public abstract boolean continuePolling();
	/**
	 * Process a message from a DMaaP topic
	 * 
	 * @param message
	 * @throws Exception
	 */
	public abstract void processMessage(String message) throws Exception;
	/**
	 * Has the request been accepted by the receiving system?
	 * Should the consumer move to processing messages?
	 * 
	 * @param message
	 * @return
	 */
	public abstract boolean isAccepted(String message);
	/**
	 * has the request failed?
	 * 
	 * @param message
	 * @return
	 */
	public abstract boolean isFailure(String message);
	/**
	 * The request id to filter messages on
	 * @return
	 */
	public abstract String getRequestId();
	/**
	 * Logic that defines when the consumer should stop processing messages
	 */
	public abstract void stopProcessingMessages();
	
	/**
	 * time in milliseconds
	 */
	public int getMaximumElapsedTime() {
		return 180000;
	}
}