// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { bytesToUuid } from "./_common.ts";

const UUID_RE = new RegExp(
  "^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$",
  "i",
);

/**
 * Validates the UUID v4
 * @param id UUID value
 */
export function validate(id: string): boolean {
  return UUID_RE.test(id);
}

/** Generates a RFC4122 v4 UUID (pseudo-randomly-based) */
export function generate(): string {
  const rnds = crypto.getRandomValues(new Uint8Array(16));

  rnds[6] = (rnds[6] & 0x0f) | 0x40; // Version 4
  rnds[8] = (rnds[8] & 0x3f) | 0x80; // Variant 10

  return bytesToUuid(rnds);
}