70 lines
1.9 KiB
TypeScript
70 lines
1.9 KiB
TypeScript
import { randomBytes } from "crypto"
|
|
|
|
export type Prefix = "evt" | "ses" | "msg" | "per" | "que" | "prt" | "pty" | "tool" | "wrk"
|
|
|
|
const LENGTH = 26
|
|
|
|
// State for monotonic ID generation
|
|
let lastTimestamp = 0
|
|
let counter = 0
|
|
|
|
export function ascending(prefix: Prefix, given?: string) {
|
|
return generateID(prefix, "ascending", given)
|
|
}
|
|
|
|
export function descending(prefix: Prefix, given?: string) {
|
|
return generateID(prefix, "descending", given)
|
|
}
|
|
|
|
function generateID(prefix: Prefix, direction: "descending" | "ascending", given?: string): string {
|
|
if (!given) {
|
|
return create(prefix, direction)
|
|
}
|
|
|
|
if (!given.startsWith(prefix)) {
|
|
throw new Error(`ID ${given} does not start with ${prefix}`)
|
|
}
|
|
return given
|
|
}
|
|
|
|
function randomBase62(length: number): string {
|
|
const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
|
|
let result = ""
|
|
const bytes = randomBytes(length)
|
|
for (let i = 0; i < length; i++) {
|
|
result += chars[bytes[i] % 62]
|
|
}
|
|
return result
|
|
}
|
|
|
|
export function create(prefix: string, direction: "descending" | "ascending", timestamp?: number): string {
|
|
const currentTimestamp = timestamp ?? Date.now()
|
|
|
|
if (currentTimestamp !== lastTimestamp) {
|
|
lastTimestamp = currentTimestamp
|
|
counter = 0
|
|
}
|
|
counter++
|
|
|
|
let now = BigInt(currentTimestamp) * BigInt(0x1000) + BigInt(counter)
|
|
|
|
now = direction === "descending" ? ~now : now
|
|
|
|
const timeBytes = Buffer.alloc(6)
|
|
for (let i = 0; i < 6; i++) {
|
|
timeBytes[i] = Number((now >> BigInt(40 - 8 * i)) & BigInt(0xff))
|
|
}
|
|
|
|
return prefix + "_" + timeBytes.toString("hex") + randomBase62(LENGTH - 12)
|
|
}
|
|
|
|
/** Extract timestamp from an ascending ID. Does not work with descending IDs. */
|
|
export function timestamp(id: string): number {
|
|
const prefix = id.split("_")[0]
|
|
const hex = id.slice(prefix.length + 1, prefix.length + 13)
|
|
const encoded = BigInt("0x" + hex)
|
|
return Number(encoded / BigInt(0x1000))
|
|
}
|
|
|
|
export * as Identifier from "./id"
|