/*
 * Copyright 2012-2018 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
 *
 *      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.boot.actuate.autoconfigure.metrics.amqp;

import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.MetricsCollector;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Tags;

import org.springframework.amqp.rabbit.connection.AbstractConnectionFactory;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.boot.actuate.metrics.amqp.RabbitMetrics;
import org.springframework.context.ApplicationContext;
import org.springframework.core.Ordered;
import org.springframework.util.StringUtils;

/**
 * {@link BeanPostProcessor} that configures RabbitMQ metrics. Such arrangement is
 * necessary because a connection can be eagerly created and cached without a reference to
 * a proper {@link MetricsCollector}.
 *
 * @author Stephane Nicoll
 */
class RabbitConnectionFactoryMetricsPostProcessor implements BeanPostProcessor, Ordered {

	private static final String CONNECTION_FACTORY_SUFFIX = "connectionFactory";

	private final ApplicationContext context;

	private volatile MeterRegistry meterRegistry;

	RabbitConnectionFactoryMetricsPostProcessor(ApplicationContext context) {
		this.context = context;
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName) {
		if (bean instanceof AbstractConnectionFactory) {
			bindConnectionFactoryToRegistry(getMeterRegistry(), beanName,
					(AbstractConnectionFactory) bean);
		}
		return bean;
	}

	private void bindConnectionFactoryToRegistry(MeterRegistry registry, String beanName,
			AbstractConnectionFactory connectionFactory) {
		ConnectionFactory rabbitConnectionFactory = connectionFactory
				.getRabbitConnectionFactory();
		String connectionFactoryName = getConnectionFactoryName(beanName);
		new RabbitMetrics(rabbitConnectionFactory, Tags.of("name", connectionFactoryName))
				.bindTo(registry);
	}

	/**
	 * Get the name of a ConnectionFactory based on its {@code beanName}.
	 * @param beanName the name of the connection factory bean
	 * @return a name for the given connection factory
	 */
	private String getConnectionFactoryName(String beanName) {
		if (beanName.length() > CONNECTION_FACTORY_SUFFIX.length()
				&& StringUtils.endsWithIgnoreCase(beanName, CONNECTION_FACTORY_SUFFIX)) {
			return beanName.substring(0,
					beanName.length() - CONNECTION_FACTORY_SUFFIX.length());
		}
		return beanName;
	}

	private MeterRegistry getMeterRegistry() {
		if (this.meterRegistry == null) {
			this.meterRegistry = this.context.getBean(MeterRegistry.class);
		}
		return this.meterRegistry;
	}

	@Override
	public int getOrder() {
		return Ordered.HIGHEST_PRECEDENCE;
	}

}
