consentAwareStorage.ts

import storage, {
  AnalyticsStorage,
  ANY,
  GLOBAL,
} from '@analytics/storage-utils';

export interface ConsentAwareStorage extends AnalyticsStorage {
  getConsent(): boolean;
  setConsent(newValue: boolean): void;
}

export default function createConsentAwareStorage(
  initialConsent: boolean = false,
): ConsentAwareStorage {
  /**
   * Storage parameter for setItem calls.  getItem and removeItem always use
   * `ALL`.
   */
  let storageMode: 'global' | 'any' = initialConsent ? ANY : GLOBAL;

  /**
   * Track the keys we have see so we know what to migrate/remove in
   * case consent status changes.
   */
  const keys: Set<string> = new Set();

  /**
   * Call to set the current persistent consent state.  Note that consent is OFF by default.
   *
   * @param newValue true if the user consents to storing analytics tracking cookies
   */
  const setConsent = (newValue: boolean): void => {
    const newStorageMode = newValue ? ANY : GLOBAL;
    const oldStorageMode = storageMode;
    if (oldStorageMode !== newStorageMode) {
      storageMode = newStorageMode;
      // Move keys to the new storage location
      for (const key of keys) {
        const removed = storage.removeItem(key);
        const oldValue = Object.values(removed)[0];
        if (typeof oldValue !== 'undefined') {
          storage.setItem(key, oldValue, { storage: newStorageMode });
        }
      }
    }
  };

  /**
   * Return the current consent status.
   */
  const getConsent = (): boolean => {
    return storageMode === ANY;
  };

  /**
   * Store an item into storage.
   *
   * If the user has given consent and no explicit storage option is provided, this is stored into
   * localStorage, cookies, or session storage based on what's available.  If there is no consent
   * or none of those storage methods are allowed by the browser it stores it into a global variable.
   *
   * When storing to localStorage or sessionStorage the value will be serialized
   * using JSON.stringify, so only objects compatible with that serialization
   * method should be used.
   *
   * @param key Key to store to
   * @param value Value - this will be serialized to JSON
   * @param options If provided this can override the default storage mode
   */
  const setItem = (
    key: string,
    value: unknown,
    options: { storage: string } | string = { storage: storageMode },
  ): void => {
    keys.add(key);
    storage.setItem(key, value, options);
  };

  /**
   * Retrieve a value that was stored using setItem.
   *
   * @param key Key to look up
   * @param options If provided this can override the default storage mode
   */
  const getItem = (
    key: string,
    options: { storage: string } | string = { storage: storageMode },
  ): unknown => {
    return storage.getItem(key, options);
  };

  /**
   * Remove an item from storage.
   *
   * @param key Key to remove
   * @param options If provided this can override the default storage mode
   */
  const removeItem = (
    key: string,
    options: { storage: string } | string = { storage: storageMode },
  ): {
    global?: any;
    localStorage?: any;
    sessionStorage?: any;
    cookie?: any;
  } => {
    keys.delete(key);
    return storage.removeItem(key);
  };

  return { getConsent, setConsent, setItem, getItem, removeItem };
}