package q5

import (
	"fmt"
	"time"
)

const Q5_EPOCH = 1419120000000

const MACHINE_ID_BIT_NUM = 12
const SEQUNCE_ID_BIT_NUM = 10
const MAX_MACHINE_ID = (1 << MACHINE_ID_BIT_NUM) - 1
const MAX_SEQUNCE_ID = (1 << SEQUNCE_ID_BIT_NUM) - 1

type Uuid struct {
	machineId        int32
	sequenceId       int32
	lastGenerateTick int64
}

func (this *Uuid) Generate() int64 {
	var value int64
	tick := GetTickCount()
	if tick == this.lastGenerateTick {
		this.sequenceId++
		if this.sequenceId >= MAX_SEQUNCE_ID {
			for tick <= this.lastGenerateTick {
				time.Sleep(time.Millisecond * 1)
				tick = GetTickCount()
			}
			this.sequenceId = 0
		}
	} else {
		this.sequenceId = 0
	}
	this.lastGenerateTick = tick
	// 保留后41位时间
	value = (tick - Q5_EPOCH) << 22
	//中间12位是机器ID
	value |= int64((int64(this.machineId) & int64(MAX_MACHINE_ID)) << SEQUNCE_ID_BIT_NUM)
	//最后10位是sequenceID
	value |= int64(this.sequenceId & MAX_SEQUNCE_ID)
	return value
}

func (this *Uuid) SetMachineId(macId int32) {
	if macId > MAX_MACHINE_ID || macId < 1 {
		panic(fmt.Sprintf("Uuid.SetMachineId error %d", macId))
	}
	this.machineId = macId
}