// oncepad-send.mjs — create a OncePad secret from a script or CI job. Node 20+, no dependencies.
//
//   curl -O https://www.eff.org/files/2016/09/08/eff_short_wordlist_2_0.txt
//   printf '%s' "$DB_PASSWORD" | node oncepad-send.mjs
//
// Prints the link on stdout and the passphrase on stderr: send them on two different channels.
import { readFileSync } from "node:fs";

const BASE = "https://oncepad.com";
const WORDS = readFileSync("eff_short_wordlist_2_0.txt", "utf8")
  .trim()
  .split("\n")
  .map((line) => line.split("\t")[1]);

// A uniform index in [0, n): rejection sampling, so no word is more likely than another.
function randIndex(n) {
  const limit = 2 ** 32 - (2 ** 32 % n);
  const buf = new Uint32Array(1);
  do crypto.getRandomValues(buf);
  while (buf[0] >= limit);
  return buf[0] % n;
}

// Seven DISTINCT list words, lowercase, single spaces (~72 bits). The reveal page only accepts list
// words, so a phrase built any other way could not be typed in.
function passphrase(n = 7) {
  const words = new Set();
  while (words.size < n) words.add(WORDS[randIndex(WORDS.length)]);
  return [...words].join(" ");
}

// Suite 0x02: blob = 0x02 | salt(16) | iv(12) | AES-256-GCM(ciphertext + tag),
// key = PBKDF2-HMAC-SHA256(passphrase, salt, 600000), AAD = 0x02 0x02 | salt | iv.
async function seal(plaintext, phrase) {
  const salt = crypto.getRandomValues(new Uint8Array(16));
  const iv = crypto.getRandomValues(new Uint8Array(12));
  const material = await crypto.subtle.importKey("raw", new TextEncoder().encode(phrase), "PBKDF2", false, ["deriveKey"]);
  const key = await crypto.subtle.deriveKey(
    { name: "PBKDF2", hash: "SHA-256", salt, iterations: 600000 },
    material,
    { name: "AES-GCM", length: 256 },
    false,
    ["encrypt"],
  );
  const aad = new Uint8Array([0x02, 0x02, ...salt, ...iv]);
  const ct = await crypto.subtle.encrypt({ name: "AES-GCM", iv, additionalData: aad }, key, plaintext);
  return new Uint8Array([0x02, ...salt, ...iv, ...new Uint8Array(ct)]);
}

const phrase = passphrase();
const blob = await seal(readFileSync(0), phrase);
const res = await fetch(`${BASE}/api/secrets`, {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({ blob: Buffer.from(blob).toString("base64url") }),
});
if (!res.ok) throw new Error(`OncePad answered ${res.status}`);
const { id } = await res.json();

console.log(`${BASE}/s/${id}`);
console.error(`passphrase: ${phrase}`);