/**
 * Проверка хеша в формате Werkzeug 3 (scrypt:… / pbkdf2:…).
 * @see https://github.com/pallets/werkzeug/blob/main/src/werkzeug/security.py
 */
import crypto from 'crypto';

/**
 * @param {string} pwhash
 * @param {string} password
 * @returns {boolean}
 */
function hashInternal(method, salt, password) {
  const methodParts = method.split(':');
  const kind = methodParts[0];
  const saltBytes = Buffer.from(salt, 'utf8');
  const passwordBytes = Buffer.from(password, 'utf8');

  if (kind === 'scrypt') {
    const n = methodParts[1] ? parseInt(methodParts[1], 10) : 2 ** 15;
    const r = methodParts[2] ? parseInt(methodParts[2], 10) : 8;
    const p = methodParts[3] ? parseInt(methodParts[3], 10) : 1;
    const maxmem = 132 * n * r * p;
    return crypto
      .scryptSync(passwordBytes, saltBytes, 64, { N: n, r, p, maxmem })
      .toString('hex');
  }

  if (kind === 'pbkdf2') {
    const hashName = methodParts[1] || 'sha256';
    const iterStr = methodParts[2];
    if (!iterStr) {
      throw new Error('pbkdf2: missing iterations');
    }
    const iterations = parseInt(iterStr, 10);
    return crypto
      .pbkdf2Sync(passwordBytes, saltBytes, iterations, 32, hashName)
      .toString('hex');
  }

  throw new Error(`Invalid hash method: ${kind}`);
}

/**
 * @param {string} pwhash
 * @param {string} password
 * @returns {boolean}
 */
export function checkWerkzeugPassword(pwhash, password) {
  if (!pwhash || pwhash.length < 3) {
    return false;
  }
  const parts = pwhash.split('$');
  if (parts.length < 3) {
    return false;
  }
  const hashval = parts.pop();
  const salt = parts.pop();
  const method = parts.join('$');
  if (!method || !salt || !hashval) {
    return false;
  }
  let computed;
  try {
    computed = hashInternal(method, salt, password);
  } catch {
    return false;
  }
  const a = Buffer.from(computed, 'hex');
  const b = Buffer.from(hashval, 'hex');
  if (a.length !== b.length) {
    return false;
  }
  return crypto.timingSafeEqual(a, b);
}