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.examples;
  
  import java.util.List;
  import java.util.Random;
  
  import reactor.core.publisher.Mono;
  
  import org.springframework.beans.factory.ObjectProvider;
  import org.springframework.cloud.client.ServiceInstance;
  import org.springframework.cloud.client.loadbalancer.DefaultResponse;
  import org.springframework.cloud.client.loadbalancer.EmptyResponse;
  import org.springframework.cloud.client.loadbalancer.Response;
  import org.springframework.cloud.loadbalancer.core.NoopServiceInstanceListSupplier;
  import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer;
  import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
  
  /**
   * Self-defined randomLoadBalancer.
   *
   * @author fangjian0423, MieAh
   */
  public class RandomLoadBalancer implements ReactorServiceInstanceLoadBalancer {
  
  	private ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;
  
  	private final String serviceId;
  
  	private final Random random;
  
  	public RandomLoadBalancer(
  			ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider,
  			String serviceId) {
  		this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
  		this.serviceId = serviceId;
  		this.random = new Random();
  	}
  
  	@Override
  	public Mono<Response<ServiceInstance>> choose(
  			org.springframework.cloud.client.loadbalancer.Request request) {
  		ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider
  				.getIfAvailable(NoopServiceInstanceListSupplier::new);
  
  		return supplier.get().next().map(this::getInstanceResponse);
  	}
  
  	@Override
  	public Mono<Response<ServiceInstance>> choose() {
  		ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider
  				.getIfAvailable(NoopServiceInstanceListSupplier::new);
  		return supplier.get().next().map(this::getInstanceResponse);
  	}
  
  	private Response<ServiceInstance> getInstanceResponse(
  			List<ServiceInstance> instances) {
  		if (instances.isEmpty()) {
  			return new EmptyResponse();
  		}
  		ServiceInstance instance = instances.get(random.nextInt(instances.size()));
  
  		return new DefaultResponse(instance);
  	}
  
  }
  