# All files / helpers get-installation-entry.ts

96.55% Statements 56/58
93.55% Branches 29/31
100% Functions 10/10
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     /**
     * @license
     * Copyright 2019 Google LLC
     *
     * 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 { createInstallationRequest } from '../api/create-installation-request';
    import { AppConfig } from '../interfaces/app-config';
    import {
      InProgressInstallationEntry,
      InstallationEntry,
      RegisteredInstallationEntry,
      RequestStatus
    } from '../interfaces/installation-entry';
    import { PENDING_TIMEOUT_MS } from '../util/constants';
    import { ERROR_FACTORY, ErrorCode, isServerError } from '../util/errors';
    import { sleep } from '../util/sleep';
    import { generateFid, INVALID_FID } from './generate-fid';
    import { remove, set, update } from './idb-manager';

    export interface InstallationEntryWithRegistrationPromise {
      installationEntry: InstallationEntry;
      /** Exist iff the installationEntry is not registered. */
      registrationPromise?: Promise<RegisteredInstallationEntry>;
    }

    /**
     * Updates and returns the InstallationEntry from the database.
     * Also triggers a registration request if it is necessary and possible.
     */
    export async function getInstallationEntry(
      appConfig: AppConfig
    ): Promise<InstallationEntryWithRegistrationPromise> {
      let registrationPromise: Promise<RegisteredInstallationEntry> | undefined;

      const installationEntry = await update(appConfig, oldEntry => {
        const installationEntry = updateOrCreateInstallationEntry(oldEntry);
        const entryWithPromise = triggerRegistrationIfNecessary(
          appConfig,
          installationEntry
        );
        registrationPromise = entryWithPromise.registrationPromise;
        return entryWithPromise.installationEntry;
      });

      if (installationEntry.fid === INVALID_FID) {
        // FID generation failed. Waiting for the FID from the server.
        return { installationEntry: await registrationPromise! };
      }

      return {
        installationEntry,
        registrationPromise
      };
    }

    /**
     * Creates a new Installation Entry if one does not exist.
     * Also clears timed out pending requests.
     */
    function updateOrCreateInstallationEntry(
      oldEntry: InstallationEntry | undefined
    ): InstallationEntry {
      const entry: InstallationEntry = oldEntry || {
        fid: generateFid(),
        registrationStatus: RequestStatus.NOT_STARTED
      };

      return clearTimedOutRequest(entry);
    }

    /**
     * If the Firebase Installation is not registered yet, this will trigger the
     * registration and return an InProgressInstallationEntry.
     *
     * If registrationPromise does not exist, the installationEntry is guaranteed
     * to be registered.
     */
    function triggerRegistrationIfNecessary(
      appConfig: AppConfig,
      installationEntry: InstallationEntry
    ): InstallationEntryWithRegistrationPromise {
      if (installationEntry.registrationStatus === RequestStatus.NOT_STARTED) {
        if (!navigator.onLine) {
          // Registration required but app is offline.
          const registrationPromiseWithError = Promise.reject(
            ERROR_FACTORY.create(ErrorCode.APP_OFFLINE)
          );
          return {
            installationEntry,
            registrationPromise: registrationPromiseWithError
          };
        }

        // Try registering. Change status to IN_PROGRESS.
        const inProgressEntry: InProgressInstallationEntry = {
          fid: installationEntry.fid,
          registrationStatus: RequestStatus.IN_PROGRESS,
          registrationTime: Date.now()
        };
        const registrationPromise = registerInstallation(
          appConfig,
          inProgressEntry
        );
        return { installationEntry: inProgressEntry, registrationPromise };
      } else if (
        installationEntry.registrationStatus === RequestStatus.IN_PROGRESS
      ) {
        return {
          installationEntry,
          registrationPromise: waitUntilFidRegistration(appConfig)
        };
      } else {
        return { installationEntry };
      }
    }

    /** This will be executed only once for each new Firebase Installation. */
    async function registerInstallation(
      appConfig: AppConfig,
      installationEntry: InProgressInstallationEntry
    ): Promise<RegisteredInstallationEntry> {
      try {
        const registeredInstallationEntry = await createInstallationRequest(
          appConfig,
          installationEntry
        );
        return set(appConfig, registeredInstallationEntry);
      } catch (e) {
        if (isServerError(e) && e.serverCode === 409) {
          // Server returned a "FID can not be used" error.
          // Generate a new ID next time.
          await remove(appConfig);
        } else {
          // Registration failed. Set FID as not registered.
          await set(appConfig, {
            fid: installationEntry.fid,
            registrationStatus: RequestStatus.NOT_STARTED
          });
        }
        throw e;
      }
    }

    /** Call if FID registration is pending in another request. */
    async function waitUntilFidRegistration(
      appConfig: AppConfig
    ): Promise<RegisteredInstallationEntry> {
      // Unfortunately, there is no way of reliably observing when a value in
      // IndexedDB changes (yet, see https://github.com/WICG/indexed-db-observers),
      // so we need to poll.

      let entry: InstallationEntry = await updateInstallationRequest(appConfig);
      while (entry.registrationStatus === RequestStatus.IN_PROGRESS) {
        // createInstallation request still in progress.
        await sleep(100);

        entry = await updateInstallationRequest(appConfig);
      }

      if (entry.registrationStatus === RequestStatus.NOT_STARTED) {
        // The request timed out or failed in a different call. Try again.
        const {
          installationEntry,
          registrationPromise
        } = await getInstallationEntry(appConfig);

        Eif (registrationPromise) {
          return registrationPromise;
        } else {
          // if there is no registrationPromise, entry is registered.
          return installationEntry as RegisteredInstallationEntry;
        }
      }

      return entry;
    }

    /**
     * Called only if there is a CreateInstallation request in progress.
     *
     * Updates the InstallationEntry in the DB based on the status of the
     * CreateInstallation request.
     *
     * Returns the updated InstallationEntry.
     */
    function updateInstallationRequest(
      appConfig: AppConfig
    ): Promise<InstallationEntry> {
      return update(appConfig, oldEntry => {
        Iif (!oldEntry) {
          throw ERROR_FACTORY.create(ErrorCode.INSTALLATION_NOT_FOUND);
        }
        return clearTimedOutRequest(oldEntry);
      });
    }

    function clearTimedOutRequest(entry: InstallationEntry): InstallationEntry {
      if (hasInstallationRequestTimedOut(entry)) {
        return {
          fid: entry.fid,
          registrationStatus: RequestStatus.NOT_STARTED
        };
      }

      return entry;
    }

    function hasInstallationRequestTimedOut(
      installationEntry: InstallationEntry
    ): boolean {
      return (
        installationEntry.registrationStatus === RequestStatus.IN_PROGRESS &&
        installationEntry.registrationTime + PENDING_TIMEOUT_MS < Date.now()
      );
    }