package discovery

import (
	"context"
	"encoding/json"
	"fmt"
	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/client/v3/naming/endpoints"
	"sonet/pkg/utils/logger"
	"sonet/pkg/utils/shutdown"
	"time"
)

func EtcdDialUrl(serviceName string) string {
	return fmt.Sprintf("etcd:///%s", serviceName)
}

func EtcdRegistry(client *clientv3.Client, server *Server) (err error) {
	em, err := endpoints.NewManager(client, server.Name)
	if err != nil {
		return
	}
	ip, port, err := RegisterIpPort(server.Addr)
	if err != nil {
		return
	}

	server.Addr = fmt.Sprintf("%s:%d", ip, port)
	// 序列化 metadata 信息
	meta := "{}"
	if server.Attrs != nil {
		bytes, e := json.Marshal(server.Attrs)
		if e != nil {
			err = e
			return
		}
		meta = string(bytes)
	}

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	lease, err := client.Grant(ctx, DefaultRegisterTTL) // 使用租约注册端点确保如果主机无法维持保活心跳, 从服务中删除
	if err != nil {
		return
	}
	endpointKey := fmt.Sprintf("%s/%s", server.Name, ip)
	err = em.AddEndpoint(ctx,
		endpointKey,
		endpoints.Endpoint{
			Addr:     server.Addr,
			Metadata: meta,
		},
		clientv3.WithLease(lease.ID),
	)

	// keepalive lease
	keepAliveCh, err := client.KeepAlive(context.Background(), lease.ID)
	doneCh := make(chan bool)
	c := func() {
		doneCh <- true
		<-doneCh
	}
	shutdown.AddShutdownHook(c)
	go func() {
		for {
			select {
			case <-doneCh: // async... not done
				logger.Info("keepalive done")
				ctx, c := context.WithTimeout(context.Background(), time.Second*5)
				_, _ = client.Revoke(ctx, lease.ID)
				c()
				doneCh <- true
				return
			case _ = <-keepAliveCh:
			}
		}
	}()
	return
}