/**
 * Copyright 2016, 2018-2020, Optimizely
 *
 * 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.
 */
import { sprintf } from '@optimizely/js-sdk-utils';

import { 
  ERROR_MESSAGES, 
  DATAFILE_VERSIONS,
} from '../enums';

const MODULE_NAME = 'CONFIG_VALIDATOR';
const SUPPORTED_VERSIONS = [DATAFILE_VERSIONS.V2, DATAFILE_VERSIONS.V3, DATAFILE_VERSIONS.V4];

/**
 * Validates the given config options
 * @param  {unknown} config
 * @param  {object}  config.errorHandler
 * @param  {object}  config.eventDispatcher
 * @param  {object}  config.logger
 * @return {boolean} true if the config options are valid
 * @throws If any of the config options are not valid
 */
export const validate = function(config: unknown): boolean {
  if (typeof config === 'object' && config !== null) {
    if (config['errorHandler'] && typeof config['errorHandler'].handleError !== 'function') {
      throw new Error(sprintf(ERROR_MESSAGES.INVALID_ERROR_HANDLER, MODULE_NAME));
    }
    if (config['eventDispatcher'] && typeof config['eventDispatcher'].dispatchEvent !== 'function') {
      throw new Error(sprintf(ERROR_MESSAGES.INVALID_EVENT_DISPATCHER, MODULE_NAME));
    }
    if (config['logger'] && typeof config['logger'].log !== 'function') {
      throw new Error(sprintf(ERROR_MESSAGES.INVALID_LOGGER, MODULE_NAME));
    }
    return true;
  }
  throw new Error(sprintf(ERROR_MESSAGES.INVALID_CONFIG, MODULE_NAME));
}

/**
 * Validates the datafile
 * @param {Object|string}  datafile
 * @return {Object} The datafile object if the datafile is valid
 * @throws If the datafile is not valid for any of the following reasons:
 - The datafile string is undefined
 - The datafile string cannot be parsed as a JSON object
 - The datafile version is not supported
 */
// eslint-disable-next-line
export const validateDatafile = function(datafile: unknown): any {
  if (!datafile) {
    throw new Error(sprintf(ERROR_MESSAGES.NO_DATAFILE_SPECIFIED, MODULE_NAME));
  }
  if (typeof datafile === 'string') {
    // Attempt to parse the datafile string
    try {
      datafile = JSON.parse(datafile);
    } catch (ex) {
      throw new Error(sprintf(ERROR_MESSAGES.INVALID_DATAFILE_MALFORMED, MODULE_NAME));
    }
  }
  if (typeof datafile === 'object' && !Array.isArray(datafile) && datafile !== null) {
    if (SUPPORTED_VERSIONS.indexOf(datafile['version']) === -1) {
      throw new Error(sprintf(ERROR_MESSAGES.INVALID_DATAFILE_VERSION, MODULE_NAME, datafile['version']));
    }
  }

  return datafile;
};

/**
 * Provides utility methods for validating that the configuration options are valid
 */
export default {
  validate: validate,
  validateDatafile: validateDatafile,
}