// str.go kee > 2021/03/18

package uuid

import (
	"gitee.com/kidy-go/utils"
	"sync/atomic"
	"time"
)

type SimpleUUID [16]byte

func New() SimpleUUID {
	var (
		uid          SimpleUUID
		clockSeq     uint32
		hardwareAddr []byte
		aTime        = time.Now()
	)
	utcTime := aTime.In(time.UTC)
	t := uint64(utcTime.Unix()-utils.TIME_BASE)*10000000 + uint64(utcTime.Nanosecond()/100)
	uid[0], uid[1], uid[2], uid[3] = byte(t>>24), byte(t>>16), byte(t>>8), byte(t)
	uid[4], uid[5] = byte(t>>40), byte(t>>32)
	uid[6], uid[7] = byte(t>>56)&0x0F, byte(t>>48)

	clock := atomic.AddUint32(&clockSeq, 1)
	uid[8] = byte(clock >> 8)
	uid[9] = byte(clock)

	copy(uid[10:], hardwareAddr)

	uid[6] |= 0x10 // set version to 1 (time based uid)
	uid[8] &= 0x3F // clear variant
	uid[8] |= 0x80 // set to IETF variant

	return uid
}

func Bytes() []byte {
	return New().Bytes()
}

func String() string {
	return New().String()
}

func ShortString() string {
	return New().ShortString()
}

func (u SimpleUUID) Bytes() []byte {
	var offsets = [...]int{0, 2, 4, 6, 9, 11, 14, 16, 19, 21, 24, 26, 28, 30, 32, 34}
	const hexString = "0123456789abcdef"
	r := make([]byte, 36)
	for i, b := range u {
		r[offsets[i]] = hexString[b>>4]
		r[offsets[i]+1] = hexString[b&0xF]
	}
	r[8] = '-'
	r[13] = '-'
	r[18] = '-'
	r[23] = '-'
	return r
}

func (u SimpleUUID) String() string {
	return string(u.Bytes())
}

func (u SimpleUUID) ShortString() string {
	return string(u.Bytes()[:8])
}