export type AdapterResponse = {
  result?: string | object;
  time?: number;
  error?: Error;
};

const STATSIG_PREFIX = 'statsig';

export enum DataAdapterKeyPath {
  V1Rulesets = '/v1/download_config_specs',
  V2Rulesets = '/v2/download_config_specs',
  V1IDLists = '/v1/get_id_lists',
  IDList = 'id_list',
}

export enum CompressFormat {
  PlainText = 'plain_text',
  Gzip = 'gzip', // We don't support this yet, for future usage
}

export function getDataAdapterKey(
  hashedSDKKey: string,
  path: DataAdapterKeyPath,
  format: CompressFormat = CompressFormat.PlainText,
  idListName: string | undefined = undefined,
): string {
  if (path == DataAdapterKeyPath.IDList) {
    return `${STATSIG_PREFIX}|${path}::${String(idListName)}|${format}|${hashedSDKKey}`;
  } else {
    return `${STATSIG_PREFIX}|${path}|${format}|${hashedSDKKey}`;
  }
}

/**
 * An adapter for implementing custom storage of config specs.
 * Useful for backing up data in memory.
 * Can also be used to bootstrap Statsig server.
 */
export interface IDataAdapter {
  /**
   * Returns the data stored for a specific key
   * @param key - Key of stored item to fetch
   */
  get(key: string): Promise<AdapterResponse>;

  /**
   * Updates data stored for each key
   * @param key - Key of stored item to update
   * @param value - New value to store
   * @param time - Time of update
   */
  set(key: string, value: string, time?: number): Promise<void>;

  /**
   * Startup tasks to run before any fetch/update calls can be made
   */
  initialize(): Promise<void>;

  /**
   * Cleanup tasks to run when statsig is shutdown
   */
  shutdown(): Promise<void>;

  /**
   * Determines whether the SDK should poll for updates from
   * the data adapter for the given key
   * @param key - Key of stored item to poll from data adapter
   */
  supportsPollingUpdatesFor?(key: DataAdapterKeyPath): boolean;
}