93 lines
3.0 KiB
JavaScript
93 lines
3.0 KiB
JavaScript
'use strict';
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// Discord epoch (2015-01-01T00:00:00.000Z)
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const EPOCH = 1_420_070_400_000;
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let INCREMENT = BigInt(0);
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/**
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* A container for useful snowflake-related methods.
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*/
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class SnowflakeUtil extends null {
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/**
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* A {@link https://developer.twitter.com/en/docs/twitter-ids Twitter snowflake},
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* except the epoch is 2015-01-01T00:00:00.000Z.
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*
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* If we have a snowflake '266241948824764416' we can represent it as binary:
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* ```
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* 64 22 17 12 0
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* 000000111011000111100001101001000101000000 00001 00000 000000000000
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* number of ms since Discord epoch worker pid increment
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* ```
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* @typedef {string} Snowflake
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*/
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/**
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* Generates a Discord snowflake.
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* <info>This hardcodes the worker's id as 1 and the process's id as 0.</info>
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* @param {number|Date} [timestamp=Date.now()] Timestamp or date of the snowflake to generate
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* @returns {Snowflake} The generated snowflake
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*/
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static generate(timestamp = Date.now()) {
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if (timestamp instanceof Date) timestamp = timestamp.getTime();
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if (typeof timestamp !== 'number' || isNaN(timestamp)) {
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throw new TypeError(
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`"timestamp" argument must be a number (received ${isNaN(timestamp) ? 'NaN' : typeof timestamp})`,
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);
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}
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if (INCREMENT >= 4095n) INCREMENT = BigInt(0);
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// Assign WorkerId as 1 and ProcessId as 0:
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return ((BigInt(timestamp - EPOCH) << 22n) | (1n << 17n) | INCREMENT++).toString();
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}
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/**
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* A deconstructed snowflake.
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* @typedef {Object} DeconstructedSnowflake
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* @property {number} timestamp Timestamp the snowflake was created
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* @property {Date} date Date the snowflake was created
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* @property {number} workerId The worker's id in the snowflake
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* @property {number} processId The process's id in the snowflake
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* @property {number} increment Increment in the snowflake
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* @property {string} binary Binary representation of the snowflake
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*/
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/**
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* Deconstructs a Discord snowflake.
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* @param {Snowflake} snowflake Snowflake to deconstruct
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* @returns {DeconstructedSnowflake}
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*/
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static deconstruct(snowflake) {
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const bigIntSnowflake = BigInt(snowflake);
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return {
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timestamp: Number(bigIntSnowflake >> 22n) + EPOCH,
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get date() {
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return new Date(this.timestamp);
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},
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workerId: Number((bigIntSnowflake >> 17n) & 0b11111n),
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processId: Number((bigIntSnowflake >> 12n) & 0b11111n),
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increment: Number(bigIntSnowflake & 0b111111111111n),
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binary: bigIntSnowflake.toString(2).padStart(64, '0'),
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};
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}
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/**
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* Retrieves the timestamp field's value from a Discord snowflake.
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* @param {Snowflake} snowflake Snowflake to get the timestamp value from
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* @returns {number}
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*/
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static timestampFrom(snowflake) {
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return Number(BigInt(snowflake) >> 22n) + EPOCH;
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}
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/**
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* Discord's epoch value (2015-01-01T00:00:00.000Z).
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* @type {number}
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* @readonly
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*/
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static get EPOCH() {
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return EPOCH;
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}
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}
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module.exports = SnowflakeUtil;
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