import { Buffer } from "node:buffer";
import {
  createCipheriv,
  createDecipheriv,
  randomBytes,
  scrypt,
} from "node:crypto";

type Encrypted = {
  salt: string;
  iv: string;
  enc: string;
  authTag: string;
};

const deriveKey = (key: string, salt: Buffer) =>
  new Promise<Buffer>((res, rej) =>
    scrypt(key, salt, 32, (err, k) => {
      if (err) rej(err);
      else res(k);
    })
  );

async function encrypt(text: string, key: string): Promise<Encrypted> {
  const salt = randomBytes(32);
  const k = await deriveKey(key, salt);

  const iv = randomBytes(16);
  const enc = createCipheriv("aes-256-gcm", k, iv);
  const ciphertext = enc.update(text, "binary", "binary") + enc.final("binary");

  return {
    salt: salt.toString("binary"),
    iv: iv.toString("binary"),
    enc: ciphertext,
    authTag: enc.getAuthTag().toString("binary"),
  };
}

async function decrypt(enc: Encrypted, key: string) {
  const k = await deriveKey(key, Buffer.from(enc.salt, "binary"));
  const dec = createDecipheriv("aes-256-gcm", k, Buffer.from(enc.iv, "binary"));

  const out = dec.update(enc.enc, "binary", "binary");
  dec.setAuthTag(Buffer.from(enc.authTag, "binary"));
  return out + dec.final("binary");
}

const test = await encrypt("abcdefghi", "key");
test.enc = "";
console.log(await decrypt(test, "")); // no error