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.balancer;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.regex.Pattern;
  import java.util.stream.Collectors;
  
  
  import com.alibaba.cloud.commons.lang.StringUtils;
  import com.alibaba.cloud.nacos.NacosServiceInstance;
  import com.alibaba.cloud.nacos.loadbalancer.NacosLoadBalancer;
  import com.alibaba.nacos.api.naming.pojo.Instance;
  import com.alibaba.nacos.client.naming.core.Balancer;
  
  import org.springframework.cloud.client.ServiceInstance;
  
  /**
   * @author itmuch.com XuDaojie
   * @since 2021.1
   */
  public class NacosBalancer extends Balancer {
  
  	private static final String IPV4_REGEX = "((2(5[0-5]|[0-4]\\d))|[0-1]?\\d{1,2})(.((2(5[0-5]|[0-4]\\d))|[0-1]?\\d{1,2})){3}";
  
  	private static final String IPV6_KEY = "IPv6";
  
  	/**
  	 * Choose instance by weight.
  	 * @param instances Instance List
  	 * @return the chosen instance
  	 */
  	public static Instance getHostByRandomWeight2(List<Instance> instances) {
  		return getHostByRandomWeight(instances);
  	}
  
  	/**
  	 * Spring Cloud LoadBalancer Choose instance by weight.
  	 * @param serviceInstances Instance List
  	 * @return the chosen instance
  	 */
  	public static ServiceInstance getHostByRandomWeight3(
  			List<ServiceInstance> serviceInstances) {
  		Map<Instance, ServiceInstance> instanceMap = new HashMap<>();
  		List<Instance> nacosInstance = serviceInstances.stream().map(serviceInstance -> {
  			Map<String, String> metadata = serviceInstance.getMetadata();
  
  			// see
  			// com.alibaba.cloud.nacos.discovery.NacosServiceDiscovery.hostToServiceInstance()
  			Instance instance = new Instance();
  			instance.setIp(serviceInstance.getHost());
  			instance.setPort(serviceInstance.getPort());
  			instance.setWeight(Double.parseDouble(metadata.get("nacos.weight")));
  			instance.setHealthy(Boolean.parseBoolean(metadata.get("nacos.healthy")));
  			instanceMap.put(instance, serviceInstance);
  			return instance;
  		}).collect(Collectors.toList());
  
  		Instance instance = getHostByRandomWeight2(nacosInstance);
  		NacosServiceInstance nacosServiceInstance = (NacosServiceInstance) instanceMap.get(instance);
  		// When local support IPv6 address stack, referred to use IPv6 address.
  		if (StringUtils.isNotEmpty(NacosLoadBalancer.ipv6)) {
  			convertIPv4ToIPv6(nacosServiceInstance);
  		}
  		return nacosServiceInstance;
  	}
  
  	/**
  	 * There is two type Ip,using IPv6 should use IPv6 in metadata to replace IPv4 in IP
  	 * field.
  	 */
  	private static void convertIPv4ToIPv6(NacosServiceInstance instance) {
  		if (Pattern.matches(IPV4_REGEX, instance.getHost())) {
  			String ip = instance.getMetadata().get(IPV6_KEY);
  			if (StringUtils.isNotEmpty(ip)) {
  				instance.setHost(ip);
  			}
  		}
  	}
  
  }
  