/**
 * @description: 
 * @author: bubao
 */
class Genid {
 /**
 *Creates an instance of Genid.
 * @author bubao
 * @param {{
 * Method: 1, // 雪花计算方法,(1-漂移算法|2-传统算法),默认 1
 * BaseTime: 1577836800000, // 基础时间(ms 单位),不能超过当前系统时间
 * WorkerId: Number, // 机器码,必须由外部设定,最大值 2^WorkerIdBitLength-1
 * WorkerIdBitLength: 6, // 机器码位长,默认值 6,取值范围 [1, 15](要求:序列数位长+机器码位长不超过 22)
 * SeqBitLength: 6, // 序列数位长,默认值 6,取值范围 [3, 21](要求:序列数位长+机器码位长不超过 22)
 * MaxSeqNumber: 5, // 最大序列数(含),设置范围 [MinSeqNumber, 2^SeqBitLength-1],默认值 0,表示最大序列数取最大值(2^SeqBitLength-1])
 * MinSeqNumber: 5, // 最小序列数(含),默认值 5,取值范围 [5, MaxSeqNumber],每毫秒的前 5 个序列数对应编号 0-4 是保留位,其中 1-4 是时间回拨相应预留位,0 是手工新值预留位
 * TopOverCostCount: 2000// 最大漂移次数(含),默认 2000,推荐范围 500-10000(与计算能力有关)
 * }} options
 * @memberof Genid
 */
 constructor(options) {
 if (options.WorkerId === undefined) {
 throw new Error("lost WorkerId");
 }
 // 1.BaseTime
 const BaseTime = 1577836800000;
 if (!options.BaseTime || options.BaseTime < 0) {
 options.BaseTime = BaseTime;
 }
 // 2.WorkerIdBitLength
 const WorkerIdBitLength = 6;
 if (!options.WorkerIdBitLength || options.WorkerIdBitLength < 0) {
 options.WorkerIdBitLength = WorkerIdBitLength;
 }

 // 4.SeqBitLength
 const SeqBitLength = 6;
 if (!options.SeqBitLength || options.SeqBitLength < 0) {
 options.SeqBitLength = SeqBitLength;
 }
 // 5.MaxSeqNumber
 const MaxSeqNumber = (1 << SeqBitLength) - 1;
 if (options.MaxSeqNumber <= 0 || options.MaxSeqNumber === undefined) {
 options.MaxSeqNumber = MaxSeqNumber;
 }
 // 6.MinSeqNumber
 const MinSeqNumber = 5;
 if (!options.MinSeqNumber || options.MinSeqNumber < 0) {
 options.MinSeqNumber = MinSeqNumber;
 }
 // 7.Others
 const topOverCostCount = 2000;
 if (!options.TopOverCostCount || options.TopOverCostCount < 0) {
 options.TopOverCostCount = topOverCostCount;
 }

 if (options.Method !== 2) {
 options.Method = 1;
 } else {
 options.Method = 2;
 }

 this.Method = BigInt(options.Method);
 this.BaseTime = BigInt(options.BaseTime);
 this.WorkerId = BigInt(options.WorkerId);
 this.WorkerIdBitLength = BigInt(options.WorkerIdBitLength);
 this.SeqBitLength = BigInt(options.SeqBitLength);
 this.MaxSeqNumber = BigInt(options.MaxSeqNumber);
 this.MinSeqNumber = BigInt(options.MinSeqNumber);
 this.TopOverCostCount = BigInt(options.TopOverCostCount);

 const timestampShift = this.WorkerIdBitLength + this.SeqBitLength;
 const currentSeqNumber = this.MinSeqNumber;

 this._TimestampShift = timestampShift;
 this._CurrentSeqNumber = currentSeqNumber;

 this._LastTimeTick = 0;
 this._TurnBackTimeTick = 0;
 this._TurnBackIndex = 0;
 this._IsOverCost = false;
 this._OverCostCountInOneTerm = 0;
 }

 // DoGenIDAction .
 DoGenIdAction(OverCostActionArg) { }

 BeginOverCostAction(useTimeTick) { }

 EndOverCostAction(useTimeTick) {
 // if m1._TermIndex > 10000 {
 // m1._TermIndex = 0
 // }
 }

 BeginTurnBackAction(useTimeTick) { }

 EndTurnBackAction(useTimeTick) { }

 NextOverCostId() {
 const currentTimeTick = this.GetCurrentTimeTick();
 if (currentTimeTick > this._LastTimeTick) {
 // this.EndOverCostAction(currentTimeTick)
 this._LastTimeTick = currentTimeTick;
 this._CurrentSeqNumber = this.MinSeqNumber;
 this._IsOverCost = false;
 this._OverCostCountInOneTerm = 0;
 // this._GenCountInOneTerm = 0
 return this.CalcId(this._LastTimeTick);
 }
 if (this._OverCostCountInOneTerm >= this.TopOverCostCount) {
 // this.EndOverCostAction(currentTimeTick)
 this._LastTimeTick = this.GetNextTimeTick();
 this._CurrentSeqNumber = this.MinSeqNumber;
 this._IsOverCost = false;
 this._OverCostCountInOneTerm = 0;
 // this._GenCountInOneTerm = 0
 return this.CalcId(this._LastTimeTick);
 }
 if (this._CurrentSeqNumber > this.MaxSeqNumber) {
 this._LastTimeTick++;
 this._CurrentSeqNumber = this.MinSeqNumber;
 this._IsOverCost = true;
 this._OverCostCountInOneTerm++;
 // this._GenCountInOneTerm++

 return this.CalcId(this._LastTimeTick);
 }

 // this._GenCountInOneTerm++
 return this.CalcId(this._LastTimeTick);
 }

 NextNormalId() {
 const currentTimeTick = this.GetCurrentTimeTick();
 if (currentTimeTick < this._LastTimeTick) {
 if (this._TurnBackTimeTick < 1) {
 this._TurnBackTimeTick = this._LastTimeTick - 1;
 this._TurnBackIndex++;
 // 每毫秒序列数的前 5 位是预留位,0 用于手工新值,1-4 是时间回拨次序
 // 支持 4 次回拨次序(避免回拨重叠导致 ID 重复),可无限次回拨(次序循环使用)。
 if (this._TurnBackIndex > 4) {
 this._TurnBackIndex = 1;
 }
 this.BeginTurnBackAction(this._TurnBackTimeTick);
 }
 
 return this.CalcTurnBackId(this._TurnBackTimeTick);
 }
 
 // 时间追平时,_TurnBackTimeTick 清零
 if (this._TurnBackTimeTick > 0) {
 this.EndTurnBackAction(this._TurnBackTimeTick);
 this._TurnBackTimeTick = 0;
 }

 if (currentTimeTick > this._LastTimeTick) {
 this._LastTimeTick = currentTimeTick;
 this._CurrentSeqNumber = this.MinSeqNumber;
 return this.CalcId(this._LastTimeTick);
 }

 if (this._CurrentSeqNumber > this.MaxSeqNumber) {
 this.BeginOverCostAction(currentTimeTick);
 // this._TermIndex++
 this._LastTimeTick++;
 this._CurrentSeqNumber = this.MinSeqNumber;
 this._IsOverCost = true;
 this._OverCostCountInOneTerm = 1;
 // this._GenCountInOneTerm = 1

 return this.CalcId(this._LastTimeTick);
 }

 return this.CalcId(this._LastTimeTick);
 }

 CalcId(useTimeTick) {
 const result = BigInt(useTimeTick << this._TimestampShift) + BigInt(this.WorkerId << this.SeqBitLength) + BigInt(this._CurrentSeqNumber);
 this._CurrentSeqNumber++;
 return result;
 }

 CalcTurnBackId(useTimeTick) {
 const result = BigInt(useTimeTick << this._TimestampShift) + BigInt(this.WorkerId << this.SeqBitLength) + BigInt(this._TurnBackIndex);
 this._TurnBackTimeTick--;
 return result;
 }

 GetCurrentTimeTick() {
 const millis = BigInt((new Date()).valueOf());
 return millis - this.BaseTime;
 }

 GetNextTimeTick() {
 let tempTimeTicker = this.GetCurrentTimeTick();
 while (tempTimeTicker <= this._LastTimeTick) {
 tempTimeTicker = this.GetCurrentTimeTick();
 }
 return tempTimeTicker;
 }


 /**
 * 生成ID
 * @returns 始终输出number类型,超过时throw error
 */
 NextNumber() {
 if (this._IsOverCost) {
 //
 let id = this.NextOverCostId()
 if (id >= 9007199254740992n)
 throw Error(`${id.toString()} over max of Number 9007199254740992`)

 return parseInt(id.toString())
 } else {
 //
 let id = this.NextNormalId()
 if (id >= 9007199254740992n)
 throw Error(`${id.toString()} over max of Number 9007199254740992`)

 return parseInt(id.toString())
 }
 }

 /**
 * 生成ID
 * @returns 根据输出数值判断,小于number最大值时输出number类型,大于时输出bigint
 */
 NextId() {
 if (this._IsOverCost) {
 let id = this.NextOverCostId()
 if (id >= 9007199254740992n)
 return id
 else
 return parseInt(id)
 } else {
 let id = this.NextNormalId()
 if (id >= 9007199254740992n)
 return id
 else
 return parseInt(id)
 }
 }

 /**
 * 生成ID
 * @returns 始终输出bigint类型
 */
 NextBigId() {
 if (this._IsOverCost) {
 //
 return this.NextOverCostId()
 } else {
 //
 return this.NextNormalId()
 }
 }
}

module.exports = Genid;