content: /*
   * Copyright 2013-2023 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.nacos.discovery.reactive;
  
  import java.util.function.Function;
  
  import com.alibaba.cloud.nacos.discovery.NacosServiceDiscovery;
  import com.alibaba.cloud.nacos.discovery.ServiceCache;
  import com.alibaba.nacos.api.exception.NacosException;
  import org.reactivestreams.Publisher;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import reactor.core.publisher.Flux;
  import reactor.core.publisher.Mono;
  import reactor.core.scheduler.Schedulers;
  
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.cloud.client.ServiceInstance;
  import org.springframework.cloud.client.discovery.ReactiveDiscoveryClient;
  
  /**
   * @author <a href="mailto:echooy.mxq@gmail.com">echooymxq</a>
   * @author freeman
   **/
  public class NacosReactiveDiscoveryClient implements ReactiveDiscoveryClient {
  
  	private static final Logger log = LoggerFactory
  			.getLogger(NacosReactiveDiscoveryClient.class);
  
  	private NacosServiceDiscovery serviceDiscovery;
  
  	@Value("${spring.cloud.nacos.discovery.failure-tolerance-enabled:false}")
  	private boolean failureToleranceEnabled;
  
  	public NacosReactiveDiscoveryClient(NacosServiceDiscovery nacosServiceDiscovery) {
  		this.serviceDiscovery = nacosServiceDiscovery;
  	}
  
  	@Override
  	public String description() {
  		return "Spring Cloud Nacos Reactive Discovery Client";
  	}
  
  	@Override
  	public Flux<ServiceInstance> getInstances(String serviceId) {
  
  		return Mono.justOrEmpty(serviceId).flatMapMany(loadInstancesFromNacos())
  				.subscribeOn(Schedulers.boundedElastic());
  	}
  
  	private Function<String, Publisher<ServiceInstance>> loadInstancesFromNacos() {
  		return serviceId -> {
  			try {
  				return Mono.justOrEmpty(serviceDiscovery.getInstances(serviceId))
  						.flatMapMany(instances -> {
  							ServiceCache.setInstances(serviceId, instances);
  							return Flux.fromIterable(instances);
  						});
  			}
  			catch (NacosException e) {
  				log.error("get service instance[{}] from nacos error!", serviceId, e);
  				return failureToleranceEnabled
  						? Flux.fromIterable(ServiceCache.getInstances(serviceId))
  						: Flux.empty();
  			}
  		};
  	}
  
  	@Override
  	public Flux<String> getServices() {
  		return Flux.defer(() -> {
  			try {
  				return Mono.justOrEmpty(serviceDiscovery.getServices())
  						.flatMapMany(services -> {
  							ServiceCache.setServiceIds(services);
  							return Flux.fromIterable(services);
  						});
  			}
  			catch (Exception e) {
  				log.error("get services from nacos server fail,", e);
  				return failureToleranceEnabled
  						? Flux.fromIterable(ServiceCache.getServiceIds())
  						: Flux.empty();
  			}
  		}).subscribeOn(Schedulers.boundedElastic());
  	}
  
  }
  