'use strict';
////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2016 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Alan Plum
////////////////////////////////////////////////////////////////////////////////

const crypto = require('@arangodb/crypto');

module.exports = function auth(cfg) {
  if (typeof cfg === 'string') {
    cfg = {method: cfg};
  }
  if (!cfg) {
    cfg = {};
  }
  const hashMethod = cfg.method || 'sha256';
  const saltLength = cfg.saltLength || 16;

  return {
    verify(authData, password) {
      if (typeof authData === 'string') {
        authData = {hash: authData};
      } else if (!authData) {
        authData = {};
      }
      const method = authData.method || hashMethod;
      const salt = authData.salt || '';
      const storedHash = authData.hash || '';
      const generatedHash = crypto[method](salt + password);
      return crypto.constantEquals(storedHash, generatedHash);
    },

    create(password) {
      const method = hashMethod;
      const salt = crypto.genRandomAlphaNumbers(saltLength);
      const hash = crypto[method](salt + password);
      return {method, salt, hash};
    }
  };
};