package mxdx1;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

//服务注册中心（单例模式）
public class ServiceRegistry {
 // 单例实例
 private static ServiceRegistry instance;
 
 // 服务存储：服务名 -> 服务列表
 private Map<String, List<ServiceInfo>> serviceMap;
 // 观察者列表：服务名 -> 观察者列表
 private Map<String, List<ServiceObserver>> observers;

 // 私有构造函数
 private ServiceRegistry() {
     serviceMap = new ConcurrentHashMap<>();
     observers = new ConcurrentHashMap<>();
 }

 // 获取单例实例
 public static synchronized ServiceRegistry getInstance() {
     if (instance == null) {
         instance = new ServiceRegistry();
     }
     return instance;
 }

 // 注册服务
 public void register(ServiceInfo serviceInfo) {
     String serviceName = serviceInfo.getServiceName();
     serviceMap.computeIfAbsent(serviceName, k -> new CopyOnWriteArrayList<>())
               .add(serviceInfo);
     // 通知观察者
     notifyObservers(serviceName);
 }

 // 注销服务
 public void unregister(ServiceInfo serviceInfo) {
     String serviceName = serviceInfo.getServiceName();
     List<ServiceInfo> services = serviceMap.get(serviceName);
     if (services != null) {
         services.remove(serviceInfo);
         // 通知观察者
         notifyObservers(serviceName);
     }
 }

 // 发现服务
 public List<ServiceInfo> discover(String serviceName) {
     return serviceMap.getOrDefault(serviceName, new ArrayList<>());
 }

 // 注册观察者
 public void addObserver(String serviceName, ServiceObserver observer) {
     observers.computeIfAbsent(serviceName, k -> new CopyOnWriteArrayList<>())
              .add(observer);
 }

 // 通知观察者
 private void notifyObservers(String serviceName) {
     List<ServiceObserver> obs = observers.get(serviceName);
     if (obs != null) {
         List<ServiceInfo> services = discover(serviceName);
         for (ServiceObserver observer : obs) {
             observer.onServiceChanged(serviceName, services);
         }
     }
 }
}