/*
 * Copyright 2013-2018 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 com.alibaba.cloud.dubbo.registry.event;

import java.util.Collection;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.event.ApplicationEventMulticaster;
import org.springframework.context.event.SimpleApplicationEventMulticaster;

import static java.util.Collections.unmodifiableCollection;

/**
 * An event raised after the {@link ServiceInstance instances} of one service has been
 * changed.
 *
 * @author <a href="mailto:mercyblitz@gmail.com">Mercy</a>
 */
public class ServiceInstancesChangedEvent extends ApplicationEvent {

	private final String serviceName;

	private final Collection<ServiceInstance> serviceInstances;

	/**
	 * Current event has been processed or not. Typically, Spring Event was based on sync
	 * {@link ApplicationEventMulticaster}
	 *
	 * @see SimpleApplicationEventMulticaster
	 */
	private boolean processed = false;

	/**
	 * @param serviceName The name of service that was changed
	 * @param serviceInstances all {@link ServiceInstance service instances}
	 * @throws IllegalArgumentException if source is null.
	 */
	public ServiceInstancesChangedEvent(String serviceName,
			Collection<ServiceInstance> serviceInstances) {
		super(serviceName);
		this.serviceName = serviceName;
		this.serviceInstances = unmodifiableCollection(serviceInstances);
	}

	/**
	 * @return The name of service that was changed
	 */
	public String getServiceName() {
		return serviceName;
	}

	/**
	 * @return all {@link ServiceInstance service instances}.
	 */
	public Collection<ServiceInstance> getServiceInstances() {
		return serviceInstances;
	}

	/**
	 * Mark current event being processed.
	 */
	public void processed() {
		processed = true;
	}

	/**
	 * Current event has been processed or not.
	 * @return if processed, return <code>true</code>, or <code>false</code>
	 */
	public boolean isProcessed() {
		return processed;
	}

}
