baqend/lib/intersection/TokenStorage.ts

Baqend JavaScript SDK

import { hmac } from '../util';
import type { GlobalStorage } from './GlobalStorage';
import type { WebStorage } from './WebStorage';

export interface TokenData {
  val: any;
  sig: string;
  createdAt: number;
  data: string;
  expireAt: number;
}

export interface TokenStorageFactory {
  /**
   * Creates a new tokenStorage which persist tokens for the given origin
   * @param origin The origin where the token contains to
   * @return The initialized token storage
   */
  create(origin: string): Promise<TokenStorage>
}

export class TokenStorage {
  static GLOBAL: typeof GlobalStorage;

  static WEB_STORAGE: typeof WebStorage;

  static hmac = hmac;

  /**
   * The actual stored token
   */
  tokenData: TokenData | null;

  /**
   * The origin of the token
   */
  origin: string;

  /**
   * Indicates if the token should keep temporary only or should be persisted for later sessions
   */
  temporary: boolean;

  /**
   * Parse a token string in its components
   * @param token The token string to parse, time values are returned as timestamps
   * @return The parsed token data
   */
  static parse(token: string): TokenData {
    return {
      val: token,
      createdAt: parseInt(token.substring(0, 8), 16) * 1000,
      expireAt: parseInt(token.substring(8, 16), 16) * 1000,
      sig: token.substring(token.length - 40),
      data: token.substring(0, token.length - 40),
    };
  }

  /**
   * Get the stored token
   * @return The token or undefined, if no token is available
   */
  get token(): string {
    return this.tokenData ? this.tokenData.val : null;
  }

  static create(origin: string) {
    return Promise.resolve(new TokenStorage(origin));
  }

  /**
   * @param origin The origin where the token belongs to
   * @param token The initial token
   * @param temporary If the token should be saved temporary or permanently
   */
  constructor(origin: string, token?: string | null, temporary?: boolean) {
    this.tokenData = token ? TokenStorage.parse(token) : null;
    this.origin = origin;
    this.temporary = !!temporary;
  }

  /**
   * Use the underlying storage implementation to save the token
   * @param origin The origin where the token belongs to
   * @param token The initial token
   * @param temporary If the token should be saved temporary or permanently
   * @return
   */
  protected saveToken(origin: string, token: string | null, temporary: boolean): void {
    // eslint-disable-next-line no-underscore-dangle
    if (this._saveToken !== TokenStorage.prototype._saveToken) {
      // eslint-disable-next-line no-console
      console.log('Using deprecated TokenStorage._saveToken implementation.');
      // eslint-disable-next-line no-underscore-dangle
      this._saveToken(origin, token, temporary);
    }
  }

  /**
   * Use the underlying storage implementation to save the token
   * @param origin The origin where the token belongs to
   * @param token The initial token
   * @param temporary If the token should be saved temporary or permanently
   * @return
   * @deprecated Use TokenStorage#saveToken instead
   * @protected
   */
  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  protected _saveToken(origin: string, token: string | null, temporary: boolean): void {}

  /**
   * Update the token for the givin origin, the operation may be asynchronous
   * @param token The token to store or <code>null</code> to remove the token
   */
  update(token: string | null) {
    const t = token ? TokenStorage.parse(token) : null;
    if (this.tokenData && t && this.tokenData.expireAt > t.expireAt) {
      // an older token was fetched from the cache, so ignore it
      return;
    }

    this.tokenData = t;
    this.saveToken(this.origin, token, this.temporary);
  }

  /**
   * Derives a resource token from the stored origin token and signs the resource with the generated resource token
   *
   * @param resource The resource which will be accessible with the returned token
   * @param sign Sign the given resource with a token, if sign is false the resource will only be encoded to a path
   * @return A resource token which can only be used to access the specified resource
   */
  signPath(resource: string, sign: boolean = true): Promise<string> {
    const { tokenData } = this;
    const result = Promise.resolve(resource.split('/').map(encodeURIComponent).join('/'));

    if (!tokenData || !sign) {
      return result;
    }

    return result.then((path) => TokenStorage.hmac(path + tokenData.data, tokenData.sig)
      .then((hash) => `${path}?BAT=${tokenData.data + hash}`))
      .catch((e) => {
        // eslint-disable-next-line no-console
        console.warn('Can\'t sign the resource, run the SDK on a secured origin, or provide an alternative hmac implementation on TokenStorage.hmac', e);
        return result;
      });
  }
}