package etcd

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/RichardKnop/machinery/v2/config"
	"github.com/RichardKnop/machinery/v2/locks/iface"
	"github.com/RichardKnop/machinery/v2/log"
	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/client/v3/concurrency"
)

var (
	ErrRedisLockFailed = errors.New("redis lock: failed to acquire lock")
)

type etcdLock struct {
	globalConf *config.Config
	conf       clientv3.Config
	cli        *clientv3.Client
	retries    int
}

func New(cnf *config.Config, endpoint string, retries int) (iface.Lock, error) {
	etcdConf := clientv3.Config{Endpoints: []string{endpoint}}
	cli, err := clientv3.New(etcdConf)
	if err != nil {
		return nil, err
	}

	lock := etcdLock{
		globalConf: cnf,
		conf:       etcdConf,
		cli:        cli,
		retries:    retries,
	}

	return &lock, nil

}

func (r etcdLock) LockWithRetries(key string, unixTsToExpireNs int64) error {
	for i := 0; i < r.retries; i++ {
		err := r.Lock(key, unixTsToExpireNs)
		if err == nil {
			// 成功拿到锁，返回
			return nil
		}

		log.INFO.Printf("acquired lock=%s failed, retries=%d", key, i)
		time.Sleep(time.Millisecond * 100)
	}
	return ErrRedisLockFailed

}

func (r etcdLock) Lock(key string, unixTsToExpireNs int64) error {
	now := time.Now().UnixNano()
	ttl := time.Duration(unixTsToExpireNs + 1 - now)
	lease := clientv3.NewLease(r.cli)

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*2)
	defer cancel()

	resp, err := lease.Grant(ctx, int64(ttl.Seconds()))
	if err != nil {
		return err
	}

	// 创建一个新的session
	s, err := concurrency.NewSession(r.cli, concurrency.WithLease(resp.ID))
	if err != nil {
		return err
	}

	key = fmt.Sprintf("/machinery/v2/lock/%s", strings.TrimRight(key, "/"))
	m := concurrency.NewMutex(s, key)

	if err := m.Lock(ctx); err != nil {
		return err
	}

	log.INFO.Printf("acquired lock=%s, duration=%s", key, ttl)
	return nil
}