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

92.31% Statements 36/39
100% Branches 5/5
100% Functions 6/6
91.67% Lines 33/36

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     /**
     * @license
     * Copyright 2019 Google Inc.
     *
     * 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 { createInstallation } from '../api/create-installation';
    import { AppConfig } from '../interfaces/app-config';
    import {
      InProgressInstallationEntry,
      InstallationEntry,
      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 } from './generate-fid';
    import { remove, set, update } from './idb-manager';

    export interface InstallationEntryWithRegistrationPromise {
      installationEntry: InstallationEntry;
      registrationPromise?: Promise<void>;
    }

    /**
     * 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<void> | undefined;

      return {
        installationEntry: await update(
          appConfig,
          (oldEntry?: InstallationEntry): InstallationEntry => {
            const installationEntry = updateOrCreateFid(oldEntry);
            const entryWithPromise = triggerRegistrationIfNecessary(
              appConfig,
              installationEntry
            );
            registrationPromise = entryWithPromise.registrationPromise;
            return entryWithPromise.installationEntry;
          }
        ),
        registrationPromise
      };
    }

    function updateOrCreateFid(
      oldEntry: InstallationEntry | undefined
    ): InstallationEntry {
      const entry: InstallationEntry = oldEntry || {
        fid: generateFid(),
        registrationStatus: RequestStatus.NOT_STARTED
      };

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

      return entry;
    }

    /**
     * If the Firebase Installation is not registered yet, this will trigger the registration
     * and return an InProgressInstallationEntry.
     */
    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<void> {
      try {
        const registeredInstallationEntry = await createInstallation(
          appConfig,
          installationEntry
        );
        await 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. */
    async function waitUntilFidRegistration(appConfig: AppConfig): Promise<void> {
      // 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) {
        throw ERROR_FACTORY.create(ErrorCode.CREATE_INSTALLATION_FAILED);
      }
    }

    /**
     * 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?: InstallationEntry): InstallationEntry => {
          if (!oldEntry) {
            throw ERROR_FACTORY.create(ErrorCode.INSTALLATION_NOT_FOUND);
          }

          if (hasInstallationRequestTimedOut(oldEntry)) {
            return {
              fid: oldEntry.fid,
              registrationStatus: RequestStatus.NOT_STARTED
            };
          }

          return oldEntry;
        }
      );
    }

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