package module

import (
	"context"
	"errors"
	"fmt"
	"git.hlsq.asia/mmorpg/service-common/db/etcd"
	"git.hlsq.asia/mmorpg/service-common/utils"
	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/client/v3/concurrency"
	"math/rand"
)

// Snowflake 雪花模块
type Snowflake struct {
	DefaultModule
	snowflakeSession *concurrency.Session
}

func (m *Snowflake) Init() error {
	node, session, err := acquire(context.Background(), 1, 1000)
	if err != nil {
		return err
	}
	m.snowflakeSession = session
	utils.InitSnowflake(node)
	return nil
}

func (m *Snowflake) Stop() error {
	_ = m.snowflakeSession.Close()
	return nil
}

func acquire(ctx context.Context, min, max int) (int64, *concurrency.Session, error) {
	nums := rand.Perm(max - min + 1)
	for i := range nums {
		nums[i] += min
	}

	for _, n := range nums {
		key := fmt.Sprintf("node/num/%d", n)

		session, err := concurrency.NewSession(
			etcd.GetClient().Raw(),
			concurrency.WithContext(ctx),
		)
		if err != nil {
			return 0, nil, utils.ErrorsWrap(fmt.Errorf("etcd NewSession error: %v", err))
		}

		txnResp, _ := etcd.GetClient().Raw().Txn(ctx).
			If(clientv3.Compare(clientv3.CreateRevision(key), "=", 0)).
			Then(clientv3.OpPut(key, "", clientv3.WithLease(session.Lease()))).
			Commit()

		if txnResp.Succeeded {
			return int64(n), session, nil
		} else {
			_ = session.Close()
		}
	}
	return 0, nil, utils.ErrorsWrap(errors.New("etcd num empty"), "acquire error")
}