49 lines
1.1 KiB
TypeScript
49 lines
1.1 KiB
TypeScript
import { randomBytes } from "crypto"
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export namespace Identifier {
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const LENGTH = 26
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// State for monotonic ID generation
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let lastTimestamp = 0
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let counter = 0
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export function ascending() {
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return create(false)
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}
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export function descending() {
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return create(true)
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}
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function randomBase62(length: number): string {
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const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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let result = ""
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const bytes = randomBytes(length)
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for (let i = 0; i < length; i++) {
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result += chars[bytes[i] % 62]
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}
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return result
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}
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export function create(descending: boolean, timestamp?: number): string {
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const currentTimestamp = timestamp ?? Date.now()
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if (currentTimestamp !== lastTimestamp) {
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lastTimestamp = currentTimestamp
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counter = 0
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}
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counter++
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let now = BigInt(currentTimestamp) * BigInt(0x1000) + BigInt(counter)
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now = descending ? ~now : now
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const timeBytes = Buffer.alloc(6)
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for (let i = 0; i < 6; i++) {
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timeBytes[i] = Number((now >> BigInt(40 - 8 * i)) & BigInt(0xff))
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}
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return timeBytes.toString("hex") + randomBase62(LENGTH - 12)
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}
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}
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