package mxdx1;

import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;

public abstract class ServiceClient implements ServiceObserver {
    private ServiceRegistry registry;
    private Map<String, List<ServiceInfo>> serviceCache;

    public ServiceClient() {
        this.registry = ServiceRegistry.getInstance();
        this.serviceCache = new ConcurrentHashMap<>();
    }

    // 订阅服务
    public void subscribe(String serviceName) {
        registry.addObserver(serviceName, this);
        // 初始化缓存
        serviceCache.put(serviceName, registry.discover(serviceName));
    }

    // 调用服务（简化实现）
    public String invoke(String serviceName, String method, String param) {
        List<ServiceInfo> services = serviceCache.get(serviceName);
        if (services == null || services.isEmpty()) {
            return "No available service: " + serviceName;
        }
        // 简单负载均衡：随机选择
        ServiceInfo service = services.get(new Random().nextInt(services.size()));
        return "Invoke " + serviceName + " on " + service.getHost() + ":" + service.getPort() 
               + " result: " + mockInvoke(service, method, param);
    }

    // 模拟远程调用
    private String mockInvoke(ServiceInfo service, String method, String param) {
        // 实际项目中这里会通过网络调用服务
        return "Mock result for " + method + "(" + param + ")";
    }

    // 服务变更通知
    @Override
    public void onServiceChanged(String serviceName, List<ServiceInfo> serviceInfos) {
        System.out.println("Service " + serviceName + " changed, new list: " + serviceInfos);
        serviceCache.put(serviceName, serviceInfos);
    }
}