import { createHash } from "crypto";
import type { UUID, Namespace } from "./types";

export function v5(name: string, namespace: Namespace): UUID {
  const nsBytes = Buffer.from(namespace.replace(/-/g, ""), "hex");
  const nameBytes = Buffer.from(name);
  const input = Buffer.concat([nsBytes, nameBytes]);

  const hash = createHash("sha1").update(input).digest();

  const output = Buffer.alloc(16);
  hash.copy(output, 0, 0, 16);

  output[6] = (output[6] & 0x0f) | 0x50;
  output[8] = (output[8] & 0x3f) | 0x80;

  const hex = output.toString("hex");
  return [
    hex.slice(0, 8),
    hex.slice(8, 12),
    hex.slice(12, 16),
    hex.slice(16, 20),
    hex.slice(20, 32),
  ].join("-") as UUID;
}