package redis

import (
	"fmt"
	"sync"

	"apigo.cc/go/id"
)

type IDMaker struct {
	rd           *Redis
	secCurrent   uint64
	secIndexMax  uint64
	secIndexNext uint64
	lock         sync.Mutex
	maker        *id.IDMaker
}

func NewIDMaker(rd *Redis) *IDMaker {
	im := &IDMaker{rd: rd}
	im.maker = id.NewIDMaker(im.makeSecIndex)
	return im
}

func (im *IDMaker) makeSecIndex(sec uint64) uint64 {
	im.lock.Lock()
	defer im.lock.Unlock()

	if im.secCurrent == sec && im.secIndexNext <= im.secIndexMax {
		idx := im.secIndexNext
		im.secIndexNext++
		return idx
	}

	im.secCurrent = sec
	key := fmt.Sprintf("_SecIdx_%d", sec)
	// 每次 from Redis 预取 100 个序列号
	max := uint64(im.rd.INCRBY(key, 100))
	if max < 100 {
		return 0
	}
	im.secIndexMax = max
	im.secIndexNext = max - 99
	idx := im.secIndexNext
	im.secIndexNext++
	if max <= 100 {
		im.rd.EXPIRE(key, 10)
	}
	return idx
}

func (im *IDMaker) Get(size int) string {
	return im.maker.Get(size)
}

func (im *IDMaker) GetForMysql(size int) string {
	return im.maker.GetForMysql(size)
}

func (im *IDMaker) GetForPostgreSQL(size int) string {
	return im.maker.GetForPostgreSQL(size)
}