/**
 * Copyright 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 { OptimizelyConfig, DatafileOptions } from '../../shared_types'
import { ProjectConfig } from '../project_config'

interface ProjectConfigManagerConfig {
  datafile?: string,
  datafileOptions?: DatafileOptions,
  // TODO[OASIS-6649]: Don't use object type
  // eslint-disable-next-line  @typescript-eslint/ban-types
  jsonSchemaValidator?: object,
  sdkKey?: string,
}

/**
* ProjectConfigManager provides project config objects via its methods
* getConfig and onUpdate. It uses a DatafileManager to fetch datafiles. It is
* responsible for parsing and validating datafiles, and converting datafile
* string into project config objects.
* @param     {ProjectConfig}        config
* @param     {string}               config.datafile
* @param     {Object}               config.datafileOptions
* @param     {Object}               config.jsonSchemaValidator
* @param     {string}               config.sdkKey
*/
export function createProjectConfigManager(config: ProjectConfigManagerConfig): ProjectConfigManager;

export interface ProjectConfigManager {

  /**
   * Returns the current project config object, or null if no project config object
   * is available
   * @return {ProjectConfig|null}
   */
  getConfig(): ProjectConfig | null;

  /**
   * Add a listener for project config updates. The listener will be called
   * whenever this instance has a new project config object available.
   * Returns a dispose function that removes the subscription
   * @param  {Function}            listener
   * @return {Function}
   */
  onUpdate(listener: (config: ProjectConfig) => void): (() => void) | null;

  /**
   * Returns a Promise that fulfills when this ProjectConfigManager is ready to
   * use (meaning it has a valid project config object), or has failed to become
   * ready.
   *
   * Failure can be caused by the following:
   * - At least one of sdkKey or datafile is not provided in the constructor argument
   * - The provided datafile was invalid
   * - The datafile provided by the datafile manager was invalid
   * - The datafile manager failed to fetch a datafile
   *
   * The returned Promise is fulfilled with a result object containing these
   * properties:
   *    - success (boolean): True if this instance is ready to use with a valid
   *                         project config object, or false if it failed to
   *                         become ready
   *    - reason (string=):  If success is false, this is a string property with
   *                         an explanatory message.
   * @return {Promise}
   */
  onReady(): Promise<{ success: boolean; reason?: string }>;

  /**
   * Returns the optimizely config object
   * @return {OptimizelyConfig}
   */
  getOptimizelyConfig(): OptimizelyConfig;

  /**
   * Stop the internal datafile manager and remove all update listeners
   * @return {void}
   */
  stop(): void;
}