'use strict';

const { AsyncWrap, Providers } = process.binding('async_wrap');
const { Buffer } = require('buffer');
const { scrypt: _scrypt } = process.binding('crypto');
const {
  ERR_CRYPTO_SCRYPT_INVALID_PARAMETER,
  ERR_CRYPTO_SCRYPT_NOT_SUPPORTED,
  ERR_INVALID_CALLBACK,
} = require('internal/errors').codes;
const {
  checkIsArrayBufferView,
  checkIsUint,
  getDefaultEncoding,
} = require('internal/crypto/util');

const defaults = {
  N: 16384,
  r: 8,
  p: 1,
  maxmem: 32 << 20,  // 32 MB, matches SCRYPT_MAX_MEM.
};

function scrypt(password, salt, keylen, options, callback = defaults) {
  if (callback === defaults) {
    callback = options;
    options = defaults;
  }

  options = check(password, salt, keylen, options);
  const { N, r, p, maxmem } = options;
  ({ password, salt, keylen } = options);

  if (typeof callback !== 'function')
    throw new ERR_INVALID_CALLBACK();

  const encoding = getDefaultEncoding();
  const keybuf = Buffer.alloc(keylen);

  const wrap = new AsyncWrap(Providers.SCRYPTREQUEST);
  wrap.ondone = (ex) => {  // Retains keybuf while request is in flight.
    if (ex) return callback.call(wrap, ex);
    if (encoding === 'buffer') return callback.call(wrap, null, keybuf);
    callback.call(wrap, null, keybuf.toString(encoding));
  };

  handleError(keybuf, password, salt, N, r, p, maxmem, wrap);
}

function scryptSync(password, salt, keylen, options = defaults) {
  options = check(password, salt, keylen, options);
  const { N, r, p, maxmem } = options;
  ({ password, salt, keylen } = options);
  const keybuf = Buffer.alloc(keylen);
  handleError(keybuf, password, salt, N, r, p, maxmem);
  const encoding = getDefaultEncoding();
  if (encoding === 'buffer') return keybuf;
  return keybuf.toString(encoding);
}

function handleError(keybuf, password, salt, N, r, p, maxmem, wrap) {
  const ex = _scrypt(keybuf, password, salt, N, r, p, maxmem, wrap);

  if (ex === undefined)
    return;

  if (ex === null)
    throw new ERR_CRYPTO_SCRYPT_INVALID_PARAMETER();  // Bad N, r, p, or maxmem.

  throw ex;  // Scrypt operation failed, exception object contains details.
}

function check(password, salt, keylen, options, callback) {
  if (_scrypt === undefined)
    throw new ERR_CRYPTO_SCRYPT_NOT_SUPPORTED();

  password = checkIsArrayBufferView('password', password);
  salt = checkIsArrayBufferView('salt', salt);
  keylen = checkIsUint('keylen', keylen);

  let { N, r, p, maxmem } = defaults;
  if (options && options !== defaults) {
    if (options.hasOwnProperty('N')) N = checkIsUint('N', options.N);
    if (options.hasOwnProperty('r')) r = checkIsUint('r', options.r);
    if (options.hasOwnProperty('p')) p = checkIsUint('p', options.p);
    if (options.hasOwnProperty('maxmem'))
      maxmem = checkIsUint('maxmem', options.maxmem);
    if (N === 0) N = defaults.N;
    if (r === 0) r = defaults.r;
    if (p === 0) p = defaults.p;
    if (maxmem === 0) maxmem = defaults.maxmem;
  }

  return { password, salt, keylen, N, r, p, maxmem };
}

module.exports = { scrypt, scryptSync };