/*
 * Copyright 2017-2019 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
 *
 *      https://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.cloud.task.batch.listener;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.batch.core.ChunkListener;
import org.springframework.batch.core.scope.context.ChunkContext;
import org.springframework.cloud.task.batch.listener.support.MessagePublisher;
import org.springframework.core.Ordered;
import org.springframework.messaging.MessageChannel;
import org.springframework.util.Assert;

/**
 * Provides informational messages around the
 * {@link org.springframework.batch.core.step.item.Chunk} of a batch job.
 *
 * The {@link ChunkListener#beforeChunk(ChunkContext)} and
 * {@link ChunkListener#afterChunk(ChunkContext)} are both no-ops in this implementation.
 * {@link ChunkListener#afterChunkError(ChunkContext)}.
 *
 * @author Ali Shahbour
 */
public class EventEmittingChunkListener implements ChunkListener, Ordered {

	private static final Log logger = LogFactory.getLog(EventEmittingChunkListener.class);

	private MessagePublisher<String> messagePublisher;

	private int order = Ordered.LOWEST_PRECEDENCE;

	public EventEmittingChunkListener(MessageChannel output) {
		Assert.notNull(output, "An output channel is required");
		this.messagePublisher = new MessagePublisher(output);
	}

	public EventEmittingChunkListener(MessageChannel output, int order) {
		this(output);
		this.order = order;
	}

	@Override
	public void beforeChunk(ChunkContext context) {
		this.messagePublisher.publish("Before Chunk Processing");
	}

	@Override
	public void afterChunk(ChunkContext context) {
		this.messagePublisher.publish("After Chunk Processing");
	}

	@Override
	public void afterChunkError(ChunkContext context) {

	}

	@Override
	public int getOrder() {
		return this.order;
	}

}
