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diff --git a/frontend-old/node_modules/@firebase/remote-config/dist/index.cjs.js b/frontend-old/node_modules/@firebase/remote-config/dist/index.cjs.js
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+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+var app = require('@firebase/app');
+var util = require('@firebase/util');
+var component = require('@firebase/component');
+var logger = require('@firebase/logger');
+require('@firebase/installations');
+
+const name = "@firebase/remote-config";
+const version = "0.7.0";
+
+/**
+ * @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.
+ */
+/**
+ * Shims a minimal AbortSignal.
+ *
+ * <p>AbortController's AbortSignal conveniently decouples fetch timeout logic from other aspects
+ * of networking, such as retries. Firebase doesn't use AbortController enough to justify a
+ * polyfill recommendation, like we do with the Fetch API, but this minimal shim can easily be
+ * swapped out if/when we do.
+ */
+class RemoteConfigAbortSignal {
+    constructor() {
+        this.listeners = [];
+    }
+    addEventListener(listener) {
+        this.listeners.push(listener);
+    }
+    abort() {
+        this.listeners.forEach(listener => listener());
+    }
+}
+
+/**
+ * @license
+ * Copyright 2020 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.
+ */
+const RC_COMPONENT_NAME = 'remote-config';
+const RC_CUSTOM_SIGNAL_MAX_ALLOWED_SIGNALS = 100;
+const RC_CUSTOM_SIGNAL_KEY_MAX_LENGTH = 250;
+const RC_CUSTOM_SIGNAL_VALUE_MAX_LENGTH = 500;
+
+/**
+ * @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.
+ */
+const ERROR_DESCRIPTION_MAP = {
+    ["already-initialized" /* ErrorCode.ALREADY_INITIALIZED */]: 'Remote Config already initialized',
+    ["registration-window" /* ErrorCode.REGISTRATION_WINDOW */]: 'Undefined window object. This SDK only supports usage in a browser environment.',
+    ["registration-project-id" /* ErrorCode.REGISTRATION_PROJECT_ID */]: 'Undefined project identifier. Check Firebase app initialization.',
+    ["registration-api-key" /* ErrorCode.REGISTRATION_API_KEY */]: 'Undefined API key. Check Firebase app initialization.',
+    ["registration-app-id" /* ErrorCode.REGISTRATION_APP_ID */]: 'Undefined app identifier. Check Firebase app initialization.',
+    ["storage-open" /* ErrorCode.STORAGE_OPEN */]: 'Error thrown when opening storage. Original error: {$originalErrorMessage}.',
+    ["storage-get" /* ErrorCode.STORAGE_GET */]: 'Error thrown when reading from storage. Original error: {$originalErrorMessage}.',
+    ["storage-set" /* ErrorCode.STORAGE_SET */]: 'Error thrown when writing to storage. Original error: {$originalErrorMessage}.',
+    ["storage-delete" /* ErrorCode.STORAGE_DELETE */]: 'Error thrown when deleting from storage. Original error: {$originalErrorMessage}.',
+    ["fetch-client-network" /* ErrorCode.FETCH_NETWORK */]: 'Fetch client failed to connect to a network. Check Internet connection.' +
+        ' Original error: {$originalErrorMessage}.',
+    ["fetch-timeout" /* ErrorCode.FETCH_TIMEOUT */]: 'The config fetch request timed out. ' +
+        ' Configure timeout using "fetchTimeoutMillis" SDK setting.',
+    ["fetch-throttle" /* ErrorCode.FETCH_THROTTLE */]: 'The config fetch request timed out while in an exponential backoff state.' +
+        ' Configure timeout using "fetchTimeoutMillis" SDK setting.' +
+        ' Unix timestamp in milliseconds when fetch request throttling ends: {$throttleEndTimeMillis}.',
+    ["fetch-client-parse" /* ErrorCode.FETCH_PARSE */]: 'Fetch client could not parse response.' +
+        ' Original error: {$originalErrorMessage}.',
+    ["fetch-status" /* ErrorCode.FETCH_STATUS */]: 'Fetch server returned an HTTP error status. HTTP status: {$httpStatus}.',
+    ["indexed-db-unavailable" /* ErrorCode.INDEXED_DB_UNAVAILABLE */]: 'Indexed DB is not supported by current browser',
+    ["custom-signal-max-allowed-signals" /* ErrorCode.CUSTOM_SIGNAL_MAX_ALLOWED_SIGNALS */]: 'Setting more than {$maxSignals} custom signals is not supported.',
+    ["stream-error" /* ErrorCode.CONFIG_UPDATE_STREAM_ERROR */]: 'The stream was not able to connect to the backend: {$originalErrorMessage}.',
+    ["realtime-unavailable" /* ErrorCode.CONFIG_UPDATE_UNAVAILABLE */]: 'The Realtime service is unavailable: {$originalErrorMessage}',
+    ["update-message-invalid" /* ErrorCode.CONFIG_UPDATE_MESSAGE_INVALID */]: 'The stream invalidation message was unparsable: {$originalErrorMessage}',
+    ["update-not-fetched" /* ErrorCode.CONFIG_UPDATE_NOT_FETCHED */]: 'Unable to fetch the latest config: {$originalErrorMessage}'
+};
+const ERROR_FACTORY = new util.ErrorFactory('remoteconfig' /* service */, 'Remote Config' /* service name */, ERROR_DESCRIPTION_MAP);
+// Note how this is like typeof/instanceof, but for ErrorCode.
+function hasErrorCode(e, errorCode) {
+    return e instanceof util.FirebaseError && e.code.indexOf(errorCode) !== -1;
+}
+
+/**
+ * @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.
+ */
+const DEFAULT_VALUE_FOR_BOOLEAN = false;
+const DEFAULT_VALUE_FOR_STRING = '';
+const DEFAULT_VALUE_FOR_NUMBER = 0;
+const BOOLEAN_TRUTHY_VALUES = ['1', 'true', 't', 'yes', 'y', 'on'];
+class Value {
+    constructor(_source, _value = DEFAULT_VALUE_FOR_STRING) {
+        this._source = _source;
+        this._value = _value;
+    }
+    asString() {
+        return this._value;
+    }
+    asBoolean() {
+        if (this._source === 'static') {
+            return DEFAULT_VALUE_FOR_BOOLEAN;
+        }
+        return BOOLEAN_TRUTHY_VALUES.indexOf(this._value.toLowerCase()) >= 0;
+    }
+    asNumber() {
+        if (this._source === 'static') {
+            return DEFAULT_VALUE_FOR_NUMBER;
+        }
+        let num = Number(this._value);
+        if (isNaN(num)) {
+            num = DEFAULT_VALUE_FOR_NUMBER;
+        }
+        return num;
+    }
+    getSource() {
+        return this._source;
+    }
+}
+
+/**
+ * @license
+ * Copyright 2020 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.
+ */
+/**
+ *
+ * @param app - The {@link @firebase/app#FirebaseApp} instance.
+ * @param options - Optional. The {@link RemoteConfigOptions} with which to instantiate the
+ *     Remote Config instance.
+ * @returns A {@link RemoteConfig} instance.
+ *
+ * @public
+ */
+function getRemoteConfig(app$1 = app.getApp(), options = {}) {
+    app$1 = util.getModularInstance(app$1);
+    const rcProvider = app._getProvider(app$1, RC_COMPONENT_NAME);
+    if (rcProvider.isInitialized()) {
+        const initialOptions = rcProvider.getOptions();
+        if (util.deepEqual(initialOptions, options)) {
+            return rcProvider.getImmediate();
+        }
+        throw ERROR_FACTORY.create("already-initialized" /* ErrorCode.ALREADY_INITIALIZED */);
+    }
+    rcProvider.initialize({ options });
+    const rc = rcProvider.getImmediate();
+    if (options.initialFetchResponse) {
+        // We use these initial writes as the initialization promise since they will hydrate the same
+        // fields that `storageCache.loadFromStorage` would set.
+        rc._initializePromise = Promise.all([
+            rc._storage.setLastSuccessfulFetchResponse(options.initialFetchResponse),
+            rc._storage.setActiveConfigEtag(options.initialFetchResponse?.eTag || ''),
+            rc._storage.setActiveConfigTemplateVersion(options.initialFetchResponse.templateVersion || 0),
+            rc._storageCache.setLastSuccessfulFetchTimestampMillis(Date.now()),
+            rc._storageCache.setLastFetchStatus('success'),
+            rc._storageCache.setActiveConfig(options.initialFetchResponse?.config || {})
+        ]).then();
+        // The `storageCache` methods above set their in-memory fields synchronously, so it's
+        // safe to declare our initialization complete at this point.
+        rc._isInitializationComplete = true;
+    }
+    return rc;
+}
+/**
+ * Makes the last fetched config available to the getters.
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @returns A `Promise` which resolves to true if the current call activated the fetched configs.
+ * If the fetched configs were already activated, the `Promise` will resolve to false.
+ *
+ * @public
+ */
+async function activate(remoteConfig) {
+    const rc = util.getModularInstance(remoteConfig);
+    const [lastSuccessfulFetchResponse, activeConfigEtag] = await Promise.all([
+        rc._storage.getLastSuccessfulFetchResponse(),
+        rc._storage.getActiveConfigEtag()
+    ]);
+    if (!lastSuccessfulFetchResponse ||
+        !lastSuccessfulFetchResponse.config ||
+        !lastSuccessfulFetchResponse.eTag ||
+        !lastSuccessfulFetchResponse.templateVersion ||
+        lastSuccessfulFetchResponse.eTag === activeConfigEtag) {
+        // Either there is no successful fetched config, or is the same as current active
+        // config.
+        return false;
+    }
+    await Promise.all([
+        rc._storageCache.setActiveConfig(lastSuccessfulFetchResponse.config),
+        rc._storage.setActiveConfigEtag(lastSuccessfulFetchResponse.eTag),
+        rc._storage.setActiveConfigTemplateVersion(lastSuccessfulFetchResponse.templateVersion)
+    ]);
+    return true;
+}
+/**
+ * Ensures the last activated config are available to the getters.
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ *
+ * @returns A `Promise` that resolves when the last activated config is available to the getters.
+ * @public
+ */
+function ensureInitialized(remoteConfig) {
+    const rc = util.getModularInstance(remoteConfig);
+    if (!rc._initializePromise) {
+        rc._initializePromise = rc._storageCache.loadFromStorage().then(() => {
+            rc._isInitializationComplete = true;
+        });
+    }
+    return rc._initializePromise;
+}
+/**
+ * Fetches and caches configuration from the Remote Config service.
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @public
+ */
+async function fetchConfig(remoteConfig) {
+    const rc = util.getModularInstance(remoteConfig);
+    // Aborts the request after the given timeout, causing the fetch call to
+    // reject with an `AbortError`.
+    //
+    // <p>Aborting after the request completes is a no-op, so we don't need a
+    // corresponding `clearTimeout`.
+    //
+    // Locating abort logic here because:
+    // * it uses a developer setting (timeout)
+    // * it applies to all retries (like curl's max-time arg)
+    // * it is consistent with the Fetch API's signal input
+    const abortSignal = new RemoteConfigAbortSignal();
+    setTimeout(async () => {
+        // Note a very low delay, eg < 10ms, can elapse before listeners are initialized.
+        abortSignal.abort();
+    }, rc.settings.fetchTimeoutMillis);
+    const customSignals = rc._storageCache.getCustomSignals();
+    if (customSignals) {
+        rc._logger.debug(`Fetching config with custom signals: ${JSON.stringify(customSignals)}`);
+    }
+    // Catches *all* errors thrown by client so status can be set consistently.
+    try {
+        await rc._client.fetch({
+            cacheMaxAgeMillis: rc.settings.minimumFetchIntervalMillis,
+            signal: abortSignal,
+            customSignals
+        });
+        await rc._storageCache.setLastFetchStatus('success');
+    }
+    catch (e) {
+        const lastFetchStatus = hasErrorCode(e, "fetch-throttle" /* ErrorCode.FETCH_THROTTLE */)
+            ? 'throttle'
+            : 'failure';
+        await rc._storageCache.setLastFetchStatus(lastFetchStatus);
+        throw e;
+    }
+}
+/**
+ * Gets all config.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @returns All config.
+ *
+ * @public
+ */
+function getAll(remoteConfig) {
+    const rc = util.getModularInstance(remoteConfig);
+    return getAllKeys(rc._storageCache.getActiveConfig(), rc.defaultConfig).reduce((allConfigs, key) => {
+        allConfigs[key] = getValue(remoteConfig, key);
+        return allConfigs;
+    }, {});
+}
+/**
+ * Gets the value for the given key as a boolean.
+ *
+ * Convenience method for calling <code>remoteConfig.getValue(key).asBoolean()</code>.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param key - The name of the parameter.
+ *
+ * @returns The value for the given key as a boolean.
+ * @public
+ */
+function getBoolean(remoteConfig, key) {
+    return getValue(util.getModularInstance(remoteConfig), key).asBoolean();
+}
+/**
+ * Gets the value for the given key as a number.
+ *
+ * Convenience method for calling <code>remoteConfig.getValue(key).asNumber()</code>.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param key - The name of the parameter.
+ *
+ * @returns The value for the given key as a number.
+ *
+ * @public
+ */
+function getNumber(remoteConfig, key) {
+    return getValue(util.getModularInstance(remoteConfig), key).asNumber();
+}
+/**
+ * Gets the value for the given key as a string.
+ * Convenience method for calling <code>remoteConfig.getValue(key).asString()</code>.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param key - The name of the parameter.
+ *
+ * @returns The value for the given key as a string.
+ *
+ * @public
+ */
+function getString(remoteConfig, key) {
+    return getValue(util.getModularInstance(remoteConfig), key).asString();
+}
+/**
+ * Gets the {@link Value} for the given key.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param key - The name of the parameter.
+ *
+ * @returns The value for the given key.
+ *
+ * @public
+ */
+function getValue(remoteConfig, key) {
+    const rc = util.getModularInstance(remoteConfig);
+    if (!rc._isInitializationComplete) {
+        rc._logger.debug(`A value was requested for key "${key}" before SDK initialization completed.` +
+            ' Await on ensureInitialized if the intent was to get a previously activated value.');
+    }
+    const activeConfig = rc._storageCache.getActiveConfig();
+    if (activeConfig && activeConfig[key] !== undefined) {
+        return new Value('remote', activeConfig[key]);
+    }
+    else if (rc.defaultConfig && rc.defaultConfig[key] !== undefined) {
+        return new Value('default', String(rc.defaultConfig[key]));
+    }
+    rc._logger.debug(`Returning static value for key "${key}".` +
+        ' Define a default or remote value if this is unintentional.');
+    return new Value('static');
+}
+/**
+ * Defines the log level to use.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param logLevel - The log level to set.
+ *
+ * @public
+ */
+function setLogLevel(remoteConfig, logLevel) {
+    const rc = util.getModularInstance(remoteConfig);
+    switch (logLevel) {
+        case 'debug':
+            rc._logger.logLevel = logger.LogLevel.DEBUG;
+            break;
+        case 'silent':
+            rc._logger.logLevel = logger.LogLevel.SILENT;
+            break;
+        default:
+            rc._logger.logLevel = logger.LogLevel.ERROR;
+    }
+}
+/**
+ * Dedupes and returns an array of all the keys of the received objects.
+ */
+function getAllKeys(obj1 = {}, obj2 = {}) {
+    return Object.keys({ ...obj1, ...obj2 });
+}
+/**
+ * Sets the custom signals for the app instance.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param customSignals - Map (key, value) of the custom signals to be set for the app instance. If
+ * a key already exists, the value is overwritten. Setting the value of a custom signal to null
+ * unsets the signal. The signals will be persisted locally on the client.
+ *
+ * @public
+ */
+async function setCustomSignals(remoteConfig, customSignals) {
+    const rc = util.getModularInstance(remoteConfig);
+    if (Object.keys(customSignals).length === 0) {
+        return;
+    }
+    // eslint-disable-next-line guard-for-in
+    for (const key in customSignals) {
+        if (key.length > RC_CUSTOM_SIGNAL_KEY_MAX_LENGTH) {
+            rc._logger.error(`Custom signal key ${key} is too long, max allowed length is ${RC_CUSTOM_SIGNAL_KEY_MAX_LENGTH}.`);
+            return;
+        }
+        const value = customSignals[key];
+        if (typeof value === 'string' &&
+            value.length > RC_CUSTOM_SIGNAL_VALUE_MAX_LENGTH) {
+            rc._logger.error(`Value supplied for custom signal ${key} is too long, max allowed length is ${RC_CUSTOM_SIGNAL_VALUE_MAX_LENGTH}.`);
+            return;
+        }
+    }
+    try {
+        await rc._storageCache.setCustomSignals(customSignals);
+    }
+    catch (error) {
+        rc._logger.error(`Error encountered while setting custom signals: ${error}`);
+    }
+}
+// TODO: Add public document for the Remote Config Realtime API guide on the Web Platform.
+/**
+ * Starts listening for real-time config updates from the Remote Config backend and automatically
+ * fetches updates from the Remote Config backend when they are available.
+ *
+ * @remarks
+ * If a connection to the Remote Config backend is not already open, calling this method will
+ * open it. Multiple listeners can be added by calling this method again, but subsequent calls
+ * re-use the same connection to the backend.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ * @param observer - The {@link ConfigUpdateObserver} to be notified of config updates.
+ * @returns An {@link Unsubscribe} function to remove the listener.
+ *
+ * @public
+ */
+function onConfigUpdate(remoteConfig, observer) {
+    const rc = util.getModularInstance(remoteConfig);
+    rc._realtimeHandler.addObserver(observer);
+    return () => {
+        rc._realtimeHandler.removeObserver(observer);
+    };
+}
+
+/**
+ * @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.
+ */
+/**
+ * Implements the {@link RemoteConfigClient} abstraction with success response caching.
+ *
+ * <p>Comparable to the browser's Cache API for responses, but the Cache API requires a Service
+ * Worker, which requires HTTPS, which would significantly complicate SDK installation. Also, the
+ * Cache API doesn't support matching entries by time.
+ */
+class CachingClient {
+    constructor(client, storage, storageCache, logger) {
+        this.client = client;
+        this.storage = storage;
+        this.storageCache = storageCache;
+        this.logger = logger;
+    }
+    /**
+     * Returns true if the age of the cached fetched configs is less than or equal to
+     * {@link Settings#minimumFetchIntervalInSeconds}.
+     *
+     * <p>This is comparable to passing `headers = { 'Cache-Control': max-age <maxAge> }` to the
+     * native Fetch API.
+     *
+     * <p>Visible for testing.
+     */
+    isCachedDataFresh(cacheMaxAgeMillis, lastSuccessfulFetchTimestampMillis) {
+        // Cache can only be fresh if it's populated.
+        if (!lastSuccessfulFetchTimestampMillis) {
+            this.logger.debug('Config fetch cache check. Cache unpopulated.');
+            return false;
+        }
+        // Calculates age of cache entry.
+        const cacheAgeMillis = Date.now() - lastSuccessfulFetchTimestampMillis;
+        const isCachedDataFresh = cacheAgeMillis <= cacheMaxAgeMillis;
+        this.logger.debug('Config fetch cache check.' +
+            ` Cache age millis: ${cacheAgeMillis}.` +
+            ` Cache max age millis (minimumFetchIntervalMillis setting): ${cacheMaxAgeMillis}.` +
+            ` Is cache hit: ${isCachedDataFresh}.`);
+        return isCachedDataFresh;
+    }
+    async fetch(request) {
+        // Reads from persisted storage to avoid cache miss if callers don't wait on initialization.
+        const [lastSuccessfulFetchTimestampMillis, lastSuccessfulFetchResponse] = await Promise.all([
+            this.storage.getLastSuccessfulFetchTimestampMillis(),
+            this.storage.getLastSuccessfulFetchResponse()
+        ]);
+        // Exits early on cache hit.
+        if (lastSuccessfulFetchResponse &&
+            this.isCachedDataFresh(request.cacheMaxAgeMillis, lastSuccessfulFetchTimestampMillis)) {
+            return lastSuccessfulFetchResponse;
+        }
+        // Deviates from pure decorator by not honoring a passed ETag since we don't have a public API
+        // that allows the caller to pass an ETag.
+        request.eTag =
+            lastSuccessfulFetchResponse && lastSuccessfulFetchResponse.eTag;
+        // Falls back to service on cache miss.
+        const response = await this.client.fetch(request);
+        // Fetch throws for non-success responses, so success is guaranteed here.
+        const storageOperations = [
+            // Uses write-through cache for consistency with synchronous public API.
+            this.storageCache.setLastSuccessfulFetchTimestampMillis(Date.now())
+        ];
+        if (response.status === 200) {
+            // Caches response only if it has changed, ie non-304 responses.
+            storageOperations.push(this.storage.setLastSuccessfulFetchResponse(response));
+        }
+        await Promise.all(storageOperations);
+        return response;
+    }
+}
+
+/**
+ * @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.
+ */
+/**
+ * Attempts to get the most accurate browser language setting.
+ *
+ * <p>Adapted from getUserLanguage in packages/auth/src/utils.js for TypeScript.
+ *
+ * <p>Defers default language specification to server logic for consistency.
+ *
+ * @param navigatorLanguage Enables tests to override read-only {@link NavigatorLanguage}.
+ */
+function getUserLanguage(navigatorLanguage = navigator) {
+    return (
+    // Most reliable, but only supported in Chrome/Firefox.
+    (navigatorLanguage.languages && navigatorLanguage.languages[0]) ||
+        // Supported in most browsers, but returns the language of the browser
+        // UI, not the language set in browser settings.
+        navigatorLanguage.language
+    // Polyfill otherwise.
+    );
+}
+
+/**
+ * @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.
+ */
+/**
+ * Implements the Client abstraction for the Remote Config REST API.
+ */
+class RestClient {
+    constructor(firebaseInstallations, sdkVersion, namespace, projectId, apiKey, appId) {
+        this.firebaseInstallations = firebaseInstallations;
+        this.sdkVersion = sdkVersion;
+        this.namespace = namespace;
+        this.projectId = projectId;
+        this.apiKey = apiKey;
+        this.appId = appId;
+    }
+    /**
+     * Fetches from the Remote Config REST API.
+     *
+     * @throws a {@link ErrorCode.FETCH_NETWORK} error if {@link GlobalFetch#fetch} can't
+     * connect to the network.
+     * @throws a {@link ErrorCode.FETCH_PARSE} error if {@link Response#json} can't parse the
+     * fetch response.
+     * @throws a {@link ErrorCode.FETCH_STATUS} error if the service returns an HTTP error status.
+     */
+    async fetch(request) {
+        const [installationId, installationToken] = await Promise.all([
+            this.firebaseInstallations.getId(),
+            this.firebaseInstallations.getToken()
+        ]);
+        const urlBase = window.FIREBASE_REMOTE_CONFIG_URL_BASE ||
+            'https://firebaseremoteconfig.googleapis.com';
+        const url = `${urlBase}/v1/projects/${this.projectId}/namespaces/${this.namespace}:fetch?key=${this.apiKey}`;
+        const headers = {
+            'Content-Type': 'application/json',
+            'Content-Encoding': 'gzip',
+            // Deviates from pure decorator by not passing max-age header since we don't currently have
+            // service behavior using that header.
+            'If-None-Match': request.eTag || '*'
+            // TODO: Add this header once CORS error is fixed internally.
+            //'X-Firebase-RC-Fetch-Type': `${fetchType}/${fetchAttempt}`
+        };
+        const requestBody = {
+            /* eslint-disable camelcase */
+            sdk_version: this.sdkVersion,
+            app_instance_id: installationId,
+            app_instance_id_token: installationToken,
+            app_id: this.appId,
+            language_code: getUserLanguage(),
+            custom_signals: request.customSignals
+            /* eslint-enable camelcase */
+        };
+        const options = {
+            method: 'POST',
+            headers,
+            body: JSON.stringify(requestBody)
+        };
+        // This logic isn't REST-specific, but shimming abort logic isn't worth another decorator.
+        const fetchPromise = fetch(url, options);
+        const timeoutPromise = new Promise((_resolve, reject) => {
+            // Maps async event listener to Promise API.
+            request.signal.addEventListener(() => {
+                // Emulates https://heycam.github.io/webidl/#aborterror
+                const error = new Error('The operation was aborted.');
+                error.name = 'AbortError';
+                reject(error);
+            });
+        });
+        let response;
+        try {
+            await Promise.race([fetchPromise, timeoutPromise]);
+            response = await fetchPromise;
+        }
+        catch (originalError) {
+            let errorCode = "fetch-client-network" /* ErrorCode.FETCH_NETWORK */;
+            if (originalError?.name === 'AbortError') {
+                errorCode = "fetch-timeout" /* ErrorCode.FETCH_TIMEOUT */;
+            }
+            throw ERROR_FACTORY.create(errorCode, {
+                originalErrorMessage: originalError?.message
+            });
+        }
+        let status = response.status;
+        // Normalizes nullable header to optional.
+        const responseEtag = response.headers.get('ETag') || undefined;
+        let config;
+        let state;
+        let templateVersion;
+        // JSON parsing throws SyntaxError if the response body isn't a JSON string.
+        // Requesting application/json and checking for a 200 ensures there's JSON data.
+        if (response.status === 200) {
+            let responseBody;
+            try {
+                responseBody = await response.json();
+            }
+            catch (originalError) {
+                throw ERROR_FACTORY.create("fetch-client-parse" /* ErrorCode.FETCH_PARSE */, {
+                    originalErrorMessage: originalError?.message
+                });
+            }
+            config = responseBody['entries'];
+            state = responseBody['state'];
+            templateVersion = responseBody['templateVersion'];
+        }
+        // Normalizes based on legacy state.
+        if (state === 'INSTANCE_STATE_UNSPECIFIED') {
+            status = 500;
+        }
+        else if (state === 'NO_CHANGE') {
+            status = 304;
+        }
+        else if (state === 'NO_TEMPLATE' || state === 'EMPTY_CONFIG') {
+            // These cases can be fixed remotely, so normalize to safe value.
+            config = {};
+        }
+        // Normalize to exception-based control flow for non-success cases.
+        // Encapsulates HTTP specifics in this class as much as possible. Status is still the best for
+        // differentiating success states (200 from 304; the state body param is undefined in a
+        // standard 304).
+        if (status !== 304 && status !== 200) {
+            throw ERROR_FACTORY.create("fetch-status" /* ErrorCode.FETCH_STATUS */, {
+                httpStatus: status
+            });
+        }
+        return { status, eTag: responseEtag, config, templateVersion };
+    }
+}
+
+/**
+ * @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.
+ */
+/**
+ * Supports waiting on a backoff by:
+ *
+ * <ul>
+ *   <li>Promisifying setTimeout, so we can set a timeout in our Promise chain</li>
+ *   <li>Listening on a signal bus for abort events, just like the Fetch API</li>
+ *   <li>Failing in the same way the Fetch API fails, so timing out a live request and a throttled
+ *       request appear the same.</li>
+ * </ul>
+ *
+ * <p>Visible for testing.
+ */
+function setAbortableTimeout(signal, throttleEndTimeMillis) {
+    return new Promise((resolve, reject) => {
+        // Derives backoff from given end time, normalizing negative numbers to zero.
+        const backoffMillis = Math.max(throttleEndTimeMillis - Date.now(), 0);
+        const timeout = setTimeout(resolve, backoffMillis);
+        // Adds listener, rather than sets onabort, because signal is a shared object.
+        signal.addEventListener(() => {
+            clearTimeout(timeout);
+            // If the request completes before this timeout, the rejection has no effect.
+            reject(ERROR_FACTORY.create("fetch-throttle" /* ErrorCode.FETCH_THROTTLE */, {
+                throttleEndTimeMillis
+            }));
+        });
+    });
+}
+/**
+ * Returns true if the {@link Error} indicates a fetch request may succeed later.
+ */
+function isRetriableError(e) {
+    if (!(e instanceof util.FirebaseError) || !e.customData) {
+        return false;
+    }
+    // Uses string index defined by ErrorData, which FirebaseError implements.
+    const httpStatus = Number(e.customData['httpStatus']);
+    return (httpStatus === 429 ||
+        httpStatus === 500 ||
+        httpStatus === 503 ||
+        httpStatus === 504);
+}
+/**
+ * Decorates a Client with retry logic.
+ *
+ * <p>Comparable to CachingClient, but uses backoff logic instead of cache max age and doesn't cache
+ * responses (because the SDK has no use for error responses).
+ */
+class RetryingClient {
+    constructor(client, storage) {
+        this.client = client;
+        this.storage = storage;
+    }
+    async fetch(request) {
+        const throttleMetadata = (await this.storage.getThrottleMetadata()) || {
+            backoffCount: 0,
+            throttleEndTimeMillis: Date.now()
+        };
+        return this.attemptFetch(request, throttleMetadata);
+    }
+    /**
+     * A recursive helper for attempting a fetch request repeatedly.
+     *
+     * @throws any non-retriable errors.
+     */
+    async attemptFetch(request, { throttleEndTimeMillis, backoffCount }) {
+        // Starts with a (potentially zero) timeout to support resumption from stored state.
+        // Ensures the throttle end time is honored if the last attempt timed out.
+        // Note the SDK will never make a request if the fetch timeout expires at this point.
+        await setAbortableTimeout(request.signal, throttleEndTimeMillis);
+        try {
+            const response = await this.client.fetch(request);
+            // Note the SDK only clears throttle state if response is success or non-retriable.
+            await this.storage.deleteThrottleMetadata();
+            return response;
+        }
+        catch (e) {
+            if (!isRetriableError(e)) {
+                throw e;
+            }
+            // Increments backoff state.
+            const throttleMetadata = {
+                throttleEndTimeMillis: Date.now() + util.calculateBackoffMillis(backoffCount),
+                backoffCount: backoffCount + 1
+            };
+            // Persists state.
+            await this.storage.setThrottleMetadata(throttleMetadata);
+            return this.attemptFetch(request, throttleMetadata);
+        }
+    }
+}
+
+/**
+ * @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.
+ */
+const DEFAULT_FETCH_TIMEOUT_MILLIS = 60 * 1000; // One minute
+const DEFAULT_CACHE_MAX_AGE_MILLIS = 12 * 60 * 60 * 1000; // Twelve hours.
+/**
+ * Encapsulates business logic mapping network and storage dependencies to the public SDK API.
+ *
+ * See {@link https://github.com/firebase/firebase-js-sdk/blob/main/packages/firebase/compat/index.d.ts|interface documentation} for method descriptions.
+ */
+class RemoteConfig {
+    get fetchTimeMillis() {
+        return this._storageCache.getLastSuccessfulFetchTimestampMillis() || -1;
+    }
+    get lastFetchStatus() {
+        return this._storageCache.getLastFetchStatus() || 'no-fetch-yet';
+    }
+    constructor(
+    // Required by FirebaseServiceFactory interface.
+    app, 
+    // JS doesn't support private yet
+    // (https://github.com/tc39/proposal-class-fields#private-fields), so we hint using an
+    // underscore prefix.
+    /**
+     * @internal
+     */
+    _client, 
+    /**
+     * @internal
+     */
+    _storageCache, 
+    /**
+     * @internal
+     */
+    _storage, 
+    /**
+     * @internal
+     */
+    _logger, 
+    /**
+     * @internal
+     */
+    _realtimeHandler) {
+        this.app = app;
+        this._client = _client;
+        this._storageCache = _storageCache;
+        this._storage = _storage;
+        this._logger = _logger;
+        this._realtimeHandler = _realtimeHandler;
+        /**
+         * Tracks completion of initialization promise.
+         * @internal
+         */
+        this._isInitializationComplete = false;
+        this.settings = {
+            fetchTimeoutMillis: DEFAULT_FETCH_TIMEOUT_MILLIS,
+            minimumFetchIntervalMillis: DEFAULT_CACHE_MAX_AGE_MILLIS
+        };
+        this.defaultConfig = {};
+    }
+}
+
+/**
+ * @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.
+ */
+/**
+ * Converts an error event associated with a {@link IDBRequest} to a {@link FirebaseError}.
+ */
+function toFirebaseError(event, errorCode) {
+    const originalError = event.target.error || undefined;
+    return ERROR_FACTORY.create(errorCode, {
+        originalErrorMessage: originalError && originalError?.message
+    });
+}
+/**
+ * A general-purpose store keyed by app + namespace + {@link
+ * ProjectNamespaceKeyFieldValue}.
+ *
+ * <p>The Remote Config SDK can be used with multiple app installations, and each app can interact
+ * with multiple namespaces, so this store uses app (ID + name) and namespace as common parent keys
+ * for a set of key-value pairs. See {@link Storage#createCompositeKey}.
+ *
+ * <p>Visible for testing.
+ */
+const APP_NAMESPACE_STORE = 'app_namespace_store';
+const DB_NAME = 'firebase_remote_config';
+const DB_VERSION = 1;
+// Visible for testing.
+function openDatabase() {
+    return new Promise((resolve, reject) => {
+        try {
+            const request = indexedDB.open(DB_NAME, DB_VERSION);
+            request.onerror = event => {
+                reject(toFirebaseError(event, "storage-open" /* ErrorCode.STORAGE_OPEN */));
+            };
+            request.onsuccess = event => {
+                resolve(event.target.result);
+            };
+            request.onupgradeneeded = event => {
+                const db = event.target.result;
+                // We don't use 'break' in this switch statement, the fall-through
+                // behavior is what we want, because if there are multiple versions between
+                // the old version and the current version, we want ALL the migrations
+                // that correspond to those versions to run, not only the last one.
+                // eslint-disable-next-line default-case
+                switch (event.oldVersion) {
+                    case 0:
+                        db.createObjectStore(APP_NAMESPACE_STORE, {
+                            keyPath: 'compositeKey'
+                        });
+                }
+            };
+        }
+        catch (error) {
+            reject(ERROR_FACTORY.create("storage-open" /* ErrorCode.STORAGE_OPEN */, {
+                originalErrorMessage: error?.message
+            }));
+        }
+    });
+}
+/**
+ * Abstracts data persistence.
+ */
+class Storage {
+    getLastFetchStatus() {
+        return this.get('last_fetch_status');
+    }
+    setLastFetchStatus(status) {
+        return this.set('last_fetch_status', status);
+    }
+    // This is comparable to a cache entry timestamp. If we need to expire other data, we could
+    // consider adding timestamp to all storage records and an optional max age arg to getters.
+    getLastSuccessfulFetchTimestampMillis() {
+        return this.get('last_successful_fetch_timestamp_millis');
+    }
+    setLastSuccessfulFetchTimestampMillis(timestamp) {
+        return this.set('last_successful_fetch_timestamp_millis', timestamp);
+    }
+    getLastSuccessfulFetchResponse() {
+        return this.get('last_successful_fetch_response');
+    }
+    setLastSuccessfulFetchResponse(response) {
+        return this.set('last_successful_fetch_response', response);
+    }
+    getActiveConfig() {
+        return this.get('active_config');
+    }
+    setActiveConfig(config) {
+        return this.set('active_config', config);
+    }
+    getActiveConfigEtag() {
+        return this.get('active_config_etag');
+    }
+    setActiveConfigEtag(etag) {
+        return this.set('active_config_etag', etag);
+    }
+    getThrottleMetadata() {
+        return this.get('throttle_metadata');
+    }
+    setThrottleMetadata(metadata) {
+        return this.set('throttle_metadata', metadata);
+    }
+    deleteThrottleMetadata() {
+        return this.delete('throttle_metadata');
+    }
+    getCustomSignals() {
+        return this.get('custom_signals');
+    }
+    getRealtimeBackoffMetadata() {
+        return this.get('realtime_backoff_metadata');
+    }
+    setRealtimeBackoffMetadata(realtimeMetadata) {
+        return this.set('realtime_backoff_metadata', realtimeMetadata);
+    }
+    getActiveConfigTemplateVersion() {
+        return this.get('last_known_template_version');
+    }
+    setActiveConfigTemplateVersion(version) {
+        return this.set('last_known_template_version', version);
+    }
+}
+class IndexedDbStorage extends Storage {
+    /**
+     * @param appId enables storage segmentation by app (ID + name).
+     * @param appName enables storage segmentation by app (ID + name).
+     * @param namespace enables storage segmentation by namespace.
+     */
+    constructor(appId, appName, namespace, openDbPromise = openDatabase()) {
+        super();
+        this.appId = appId;
+        this.appName = appName;
+        this.namespace = namespace;
+        this.openDbPromise = openDbPromise;
+    }
+    async setCustomSignals(customSignals) {
+        const db = await this.openDbPromise;
+        const transaction = db.transaction([APP_NAMESPACE_STORE], 'readwrite');
+        const storedSignals = await this.getWithTransaction('custom_signals', transaction);
+        const updatedSignals = mergeCustomSignals(customSignals, storedSignals || {});
+        await this.setWithTransaction('custom_signals', updatedSignals, transaction);
+        return updatedSignals;
+    }
+    /**
+     * Gets a value from the database using the provided transaction.
+     *
+     * @param key The key of the value to get.
+     * @param transaction The transaction to use for the operation.
+     * @returns The value associated with the key, or undefined if no such value exists.
+     */
+    async getWithTransaction(key, transaction) {
+        return new Promise((resolve, reject) => {
+            const objectStore = transaction.objectStore(APP_NAMESPACE_STORE);
+            const compositeKey = this.createCompositeKey(key);
+            try {
+                const request = objectStore.get(compositeKey);
+                request.onerror = event => {
+                    reject(toFirebaseError(event, "storage-get" /* ErrorCode.STORAGE_GET */));
+                };
+                request.onsuccess = event => {
+                    const result = event.target.result;
+                    if (result) {
+                        resolve(result.value);
+                    }
+                    else {
+                        resolve(undefined);
+                    }
+                };
+            }
+            catch (e) {
+                reject(ERROR_FACTORY.create("storage-get" /* ErrorCode.STORAGE_GET */, {
+                    originalErrorMessage: e?.message
+                }));
+            }
+        });
+    }
+    /**
+     * Sets a value in the database using the provided transaction.
+     *
+     * @param key The key of the value to set.
+     * @param value The value to set.
+     * @param transaction The transaction to use for the operation.
+     * @returns A promise that resolves when the operation is complete.
+     */
+    async setWithTransaction(key, value, transaction) {
+        return new Promise((resolve, reject) => {
+            const objectStore = transaction.objectStore(APP_NAMESPACE_STORE);
+            const compositeKey = this.createCompositeKey(key);
+            try {
+                const request = objectStore.put({
+                    compositeKey,
+                    value
+                });
+                request.onerror = (event) => {
+                    reject(toFirebaseError(event, "storage-set" /* ErrorCode.STORAGE_SET */));
+                };
+                request.onsuccess = () => {
+                    resolve();
+                };
+            }
+            catch (e) {
+                reject(ERROR_FACTORY.create("storage-set" /* ErrorCode.STORAGE_SET */, {
+                    originalErrorMessage: e?.message
+                }));
+            }
+        });
+    }
+    async get(key) {
+        const db = await this.openDbPromise;
+        const transaction = db.transaction([APP_NAMESPACE_STORE], 'readonly');
+        return this.getWithTransaction(key, transaction);
+    }
+    async set(key, value) {
+        const db = await this.openDbPromise;
+        const transaction = db.transaction([APP_NAMESPACE_STORE], 'readwrite');
+        return this.setWithTransaction(key, value, transaction);
+    }
+    async delete(key) {
+        const db = await this.openDbPromise;
+        return new Promise((resolve, reject) => {
+            const transaction = db.transaction([APP_NAMESPACE_STORE], 'readwrite');
+            const objectStore = transaction.objectStore(APP_NAMESPACE_STORE);
+            const compositeKey = this.createCompositeKey(key);
+            try {
+                const request = objectStore.delete(compositeKey);
+                request.onerror = (event) => {
+                    reject(toFirebaseError(event, "storage-delete" /* ErrorCode.STORAGE_DELETE */));
+                };
+                request.onsuccess = () => {
+                    resolve();
+                };
+            }
+            catch (e) {
+                reject(ERROR_FACTORY.create("storage-delete" /* ErrorCode.STORAGE_DELETE */, {
+                    originalErrorMessage: e?.message
+                }));
+            }
+        });
+    }
+    // Facilitates composite key functionality (which is unsupported in IE).
+    createCompositeKey(key) {
+        return [this.appId, this.appName, this.namespace, key].join();
+    }
+}
+class InMemoryStorage extends Storage {
+    constructor() {
+        super(...arguments);
+        this.storage = {};
+    }
+    async get(key) {
+        return Promise.resolve(this.storage[key]);
+    }
+    async set(key, value) {
+        this.storage[key] = value;
+        return Promise.resolve(undefined);
+    }
+    async delete(key) {
+        this.storage[key] = undefined;
+        return Promise.resolve();
+    }
+    async setCustomSignals(customSignals) {
+        const storedSignals = (this.storage['custom_signals'] ||
+            {});
+        this.storage['custom_signals'] = mergeCustomSignals(customSignals, storedSignals);
+        return Promise.resolve(this.storage['custom_signals']);
+    }
+}
+function mergeCustomSignals(customSignals, storedSignals) {
+    const combinedSignals = {
+        ...storedSignals,
+        ...customSignals
+    };
+    // Filter out key-value assignments with null values since they are signals being unset
+    const updatedSignals = Object.fromEntries(Object.entries(combinedSignals)
+        .filter(([_, v]) => v !== null)
+        .map(([k, v]) => {
+        // Stringify numbers to store a map of string keys and values which can be sent
+        // as-is in a fetch call.
+        if (typeof v === 'number') {
+            return [k, v.toString()];
+        }
+        return [k, v];
+    }));
+    // Throw an error if the number of custom signals to be stored exceeds the limit
+    if (Object.keys(updatedSignals).length > RC_CUSTOM_SIGNAL_MAX_ALLOWED_SIGNALS) {
+        throw ERROR_FACTORY.create("custom-signal-max-allowed-signals" /* ErrorCode.CUSTOM_SIGNAL_MAX_ALLOWED_SIGNALS */, {
+            maxSignals: RC_CUSTOM_SIGNAL_MAX_ALLOWED_SIGNALS
+        });
+    }
+    return updatedSignals;
+}
+
+/**
+ * @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.
+ */
+/**
+ * A memory cache layer over storage to support the SDK's synchronous read requirements.
+ */
+class StorageCache {
+    constructor(storage) {
+        this.storage = storage;
+    }
+    /**
+     * Memory-only getters
+     */
+    getLastFetchStatus() {
+        return this.lastFetchStatus;
+    }
+    getLastSuccessfulFetchTimestampMillis() {
+        return this.lastSuccessfulFetchTimestampMillis;
+    }
+    getActiveConfig() {
+        return this.activeConfig;
+    }
+    getCustomSignals() {
+        return this.customSignals;
+    }
+    /**
+     * Read-ahead getter
+     */
+    async loadFromStorage() {
+        const lastFetchStatusPromise = this.storage.getLastFetchStatus();
+        const lastSuccessfulFetchTimestampMillisPromise = this.storage.getLastSuccessfulFetchTimestampMillis();
+        const activeConfigPromise = this.storage.getActiveConfig();
+        const customSignalsPromise = this.storage.getCustomSignals();
+        // Note:
+        // 1. we consistently check for undefined to avoid clobbering defined values
+        //   in memory
+        // 2. we defer awaiting to improve readability, as opposed to destructuring
+        //   a Promise.all result, for example
+        const lastFetchStatus = await lastFetchStatusPromise;
+        if (lastFetchStatus) {
+            this.lastFetchStatus = lastFetchStatus;
+        }
+        const lastSuccessfulFetchTimestampMillis = await lastSuccessfulFetchTimestampMillisPromise;
+        if (lastSuccessfulFetchTimestampMillis) {
+            this.lastSuccessfulFetchTimestampMillis =
+                lastSuccessfulFetchTimestampMillis;
+        }
+        const activeConfig = await activeConfigPromise;
+        if (activeConfig) {
+            this.activeConfig = activeConfig;
+        }
+        const customSignals = await customSignalsPromise;
+        if (customSignals) {
+            this.customSignals = customSignals;
+        }
+    }
+    /**
+     * Write-through setters
+     */
+    setLastFetchStatus(status) {
+        this.lastFetchStatus = status;
+        return this.storage.setLastFetchStatus(status);
+    }
+    setLastSuccessfulFetchTimestampMillis(timestampMillis) {
+        this.lastSuccessfulFetchTimestampMillis = timestampMillis;
+        return this.storage.setLastSuccessfulFetchTimestampMillis(timestampMillis);
+    }
+    setActiveConfig(activeConfig) {
+        this.activeConfig = activeConfig;
+        return this.storage.setActiveConfig(activeConfig);
+    }
+    async setCustomSignals(customSignals) {
+        this.customSignals = await this.storage.setCustomSignals(customSignals);
+    }
+}
+
+/**
+ * @license
+ * Copyright 2025 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.
+ */
+// TODO: Consolidate the Visibility monitoring API code into a shared utility function in firebase/util to be used by both packages/database and packages/remote-config.
+/**
+ * Base class to be used if you want to emit events. Call the constructor with
+ * the set of allowed event names.
+ */
+class EventEmitter {
+    constructor(allowedEvents_) {
+        this.allowedEvents_ = allowedEvents_;
+        this.listeners_ = {};
+        util.assert(Array.isArray(allowedEvents_) && allowedEvents_.length > 0, 'Requires a non-empty array');
+    }
+    /**
+     * To be called by derived classes to trigger events.
+     */
+    trigger(eventType, ...varArgs) {
+        if (Array.isArray(this.listeners_[eventType])) {
+            // Clone the list, since callbacks could add/remove listeners.
+            const listeners = [...this.listeners_[eventType]];
+            for (let i = 0; i < listeners.length; i++) {
+                listeners[i].callback.apply(listeners[i].context, varArgs);
+            }
+        }
+    }
+    on(eventType, callback, context) {
+        this.validateEventType_(eventType);
+        this.listeners_[eventType] = this.listeners_[eventType] || [];
+        this.listeners_[eventType].push({ callback, context });
+        const eventData = this.getInitialEvent(eventType);
+        if (eventData) {
+            //@ts-ignore
+            callback.apply(context, eventData);
+        }
+    }
+    off(eventType, callback, context) {
+        this.validateEventType_(eventType);
+        const listeners = this.listeners_[eventType] || [];
+        for (let i = 0; i < listeners.length; i++) {
+            if (listeners[i].callback === callback &&
+                (!context || context === listeners[i].context)) {
+                listeners.splice(i, 1);
+                return;
+            }
+        }
+    }
+    validateEventType_(eventType) {
+        util.assert(this.allowedEvents_.find(et => {
+            return et === eventType;
+        }), 'Unknown event: ' + eventType);
+    }
+}
+
+/**
+ * @license
+ * Copyright 2025 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.
+ */
+// TODO: Consolidate the Visibility monitoring API code into a shared utility function in firebase/util to be used by both packages/database and packages/remote-config.
+class VisibilityMonitor extends EventEmitter {
+    static getInstance() {
+        return new VisibilityMonitor();
+    }
+    constructor() {
+        super(['visible']);
+        let hidden;
+        let visibilityChange;
+        if (typeof document !== 'undefined' &&
+            typeof document.addEventListener !== 'undefined') {
+            if (typeof document['hidden'] !== 'undefined') {
+                // Opera 12.10 and Firefox 18 and later support
+                visibilityChange = 'visibilitychange';
+                hidden = 'hidden';
+            } // @ts-ignore
+            else if (typeof document['mozHidden'] !== 'undefined') {
+                visibilityChange = 'mozvisibilitychange';
+                hidden = 'mozHidden';
+            } // @ts-ignore
+            else if (typeof document['msHidden'] !== 'undefined') {
+                visibilityChange = 'msvisibilitychange';
+                hidden = 'msHidden';
+            } // @ts-ignore
+            else if (typeof document['webkitHidden'] !== 'undefined') {
+                visibilityChange = 'webkitvisibilitychange';
+                hidden = 'webkitHidden';
+            }
+        }
+        // Initially, we always assume we are visible. This ensures that in browsers
+        // without page visibility support or in cases where we are never visible
+        // (e.g. chrome extension), we act as if we are visible, i.e. don't delay
+        // reconnects
+        this.visible_ = true;
+        // @ts-ignore
+        if (visibilityChange) {
+            document.addEventListener(visibilityChange, () => {
+                // @ts-ignore
+                const visible = !document[hidden];
+                if (visible !== this.visible_) {
+                    this.visible_ = visible;
+                    this.trigger('visible', visible);
+                }
+            }, false);
+        }
+    }
+    getInitialEvent(eventType) {
+        util.assert(eventType === 'visible', 'Unknown event type: ' + eventType);
+        return [this.visible_];
+    }
+}
+
+/**
+ * @license
+ * Copyright 2025 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.
+ */
+const API_KEY_HEADER = 'X-Goog-Api-Key';
+const INSTALLATIONS_AUTH_TOKEN_HEADER = 'X-Goog-Firebase-Installations-Auth';
+const ORIGINAL_RETRIES = 8;
+const MAXIMUM_FETCH_ATTEMPTS = 3;
+const NO_BACKOFF_TIME_IN_MILLIS = -1;
+const NO_FAILED_REALTIME_STREAMS = 0;
+const REALTIME_DISABLED_KEY = 'featureDisabled';
+const REALTIME_RETRY_INTERVAL = 'retryIntervalSeconds';
+const TEMPLATE_VERSION_KEY = 'latestTemplateVersionNumber';
+class RealtimeHandler {
+    constructor(firebaseInstallations, storage, sdkVersion, namespace, projectId, apiKey, appId, logger, storageCache, cachingClient) {
+        this.firebaseInstallations = firebaseInstallations;
+        this.storage = storage;
+        this.sdkVersion = sdkVersion;
+        this.namespace = namespace;
+        this.projectId = projectId;
+        this.apiKey = apiKey;
+        this.appId = appId;
+        this.logger = logger;
+        this.storageCache = storageCache;
+        this.cachingClient = cachingClient;
+        this.observers = new Set();
+        this.isConnectionActive = false;
+        this.isRealtimeDisabled = false;
+        this.httpRetriesRemaining = ORIGINAL_RETRIES;
+        this.isInBackground = false;
+        this.decoder = new TextDecoder('utf-8');
+        this.isClosingConnection = false;
+        this.propagateError = (e) => this.observers.forEach(o => o.error?.(e));
+        /**
+         * HTTP status code that the Realtime client should retry on.
+         */
+        this.isStatusCodeRetryable = (statusCode) => {
+            const retryableStatusCodes = [
+                408, // Request Timeout
+                429, // Too Many Requests
+                502, // Bad Gateway
+                503, // Service Unavailable
+                504 // Gateway Timeout
+            ];
+            return !statusCode || retryableStatusCodes.includes(statusCode);
+        };
+        void this.setRetriesRemaining();
+        void VisibilityMonitor.getInstance().on('visible', this.onVisibilityChange, this);
+    }
+    async setRetriesRemaining() {
+        // Retrieve number of remaining retries from last session. The minimum retry count being one.
+        const metadata = await this.storage.getRealtimeBackoffMetadata();
+        const numFailedStreams = metadata?.numFailedStreams || 0;
+        this.httpRetriesRemaining = Math.max(ORIGINAL_RETRIES - numFailedStreams, 1);
+    }
+    /**
+     * Increment the number of failed stream attempts, increase the backoff duration, set the backoff
+     * end time to "backoff duration" after `lastFailedStreamTime` and persist the new
+     * values to storage metadata.
+     */
+    async updateBackoffMetadataWithLastFailedStreamConnectionTime(lastFailedStreamTime) {
+        const numFailedStreams = ((await this.storage.getRealtimeBackoffMetadata())?.numFailedStreams ||
+            0) + 1;
+        const backoffMillis = util.calculateBackoffMillis(numFailedStreams, 60000, 2);
+        await this.storage.setRealtimeBackoffMetadata({
+            backoffEndTimeMillis: new Date(lastFailedStreamTime.getTime() + backoffMillis),
+            numFailedStreams
+        });
+    }
+    /**
+     * Increase the backoff duration with a new end time based on Retry Interval.
+     */
+    async updateBackoffMetadataWithRetryInterval(retryIntervalSeconds) {
+        const currentTime = Date.now();
+        const backoffDurationInMillis = retryIntervalSeconds * 1000;
+        const backoffEndTime = new Date(currentTime + backoffDurationInMillis);
+        const numFailedStreams = 0;
+        await this.storage.setRealtimeBackoffMetadata({
+            backoffEndTimeMillis: backoffEndTime,
+            numFailedStreams
+        });
+        await this.retryHttpConnectionWhenBackoffEnds();
+    }
+    /**
+     * Closes the realtime HTTP connection.
+     * Note: This method is designed to be called only once at a time.
+     * If a call is already in progress, subsequent calls will be ignored.
+     */
+    async closeRealtimeHttpConnection() {
+        if (this.isClosingConnection) {
+            return;
+        }
+        this.isClosingConnection = true;
+        try {
+            if (this.reader) {
+                await this.reader.cancel();
+            }
+        }
+        catch (e) {
+            // The network connection was lost, so cancel() failed.
+            // This is expected in a disconnected state, so we can safely ignore the error.
+            this.logger.debug('Failed to cancel the reader, connection was lost.');
+        }
+        finally {
+            this.reader = undefined;
+        }
+        if (this.controller) {
+            await this.controller.abort();
+            this.controller = undefined;
+        }
+        this.isClosingConnection = false;
+    }
+    async resetRealtimeBackoff() {
+        await this.storage.setRealtimeBackoffMetadata({
+            backoffEndTimeMillis: new Date(-1),
+            numFailedStreams: 0
+        });
+    }
+    resetRetryCount() {
+        this.httpRetriesRemaining = ORIGINAL_RETRIES;
+    }
+    /**
+     * Assembles the request headers and body and executes the fetch request to
+     * establish the real-time streaming connection. This is the "worker" method
+     * that performs the actual network communication.
+     */
+    async establishRealtimeConnection(url, installationId, installationTokenResult, signal) {
+        const eTagValue = await this.storage.getActiveConfigEtag();
+        const lastKnownVersionNumber = await this.storage.getActiveConfigTemplateVersion();
+        const headers = {
+            [API_KEY_HEADER]: this.apiKey,
+            [INSTALLATIONS_AUTH_TOKEN_HEADER]: installationTokenResult,
+            'Content-Type': 'application/json',
+            'Accept': 'application/json',
+            'If-None-Match': eTagValue || '*',
+            'Content-Encoding': 'gzip'
+        };
+        const requestBody = {
+            project: this.projectId,
+            namespace: this.namespace,
+            lastKnownVersionNumber,
+            appId: this.appId,
+            sdkVersion: this.sdkVersion,
+            appInstanceId: installationId
+        };
+        const response = await fetch(url, {
+            method: 'POST',
+            headers,
+            body: JSON.stringify(requestBody),
+            signal
+        });
+        return response;
+    }
+    getRealtimeUrl() {
+        const urlBase = window.FIREBASE_REMOTE_CONFIG_URL_BASE ||
+            'https://firebaseremoteconfigrealtime.googleapis.com';
+        const urlString = `${urlBase}/v1/projects/${this.projectId}/namespaces/${this.namespace}:streamFetchInvalidations?key=${this.apiKey}`;
+        return new URL(urlString);
+    }
+    async createRealtimeConnection() {
+        const [installationId, installationTokenResult] = await Promise.all([
+            this.firebaseInstallations.getId(),
+            this.firebaseInstallations.getToken(false)
+        ]);
+        this.controller = new AbortController();
+        const url = this.getRealtimeUrl();
+        const realtimeConnection = await this.establishRealtimeConnection(url, installationId, installationTokenResult, this.controller.signal);
+        return realtimeConnection;
+    }
+    /**
+     * Retries HTTP stream connection asyncly in random time intervals.
+     */
+    async retryHttpConnectionWhenBackoffEnds() {
+        let backoffMetadata = await this.storage.getRealtimeBackoffMetadata();
+        if (!backoffMetadata) {
+            backoffMetadata = {
+                backoffEndTimeMillis: new Date(NO_BACKOFF_TIME_IN_MILLIS),
+                numFailedStreams: NO_FAILED_REALTIME_STREAMS
+            };
+        }
+        const backoffEndTime = new Date(backoffMetadata.backoffEndTimeMillis).getTime();
+        const currentTime = Date.now();
+        const retryMillis = Math.max(0, backoffEndTime - currentTime);
+        await this.makeRealtimeHttpConnection(retryMillis);
+    }
+    setIsHttpConnectionRunning(connectionRunning) {
+        this.isConnectionActive = connectionRunning;
+    }
+    /**
+     * Combines the check and set operations to prevent multiple asynchronous
+     * calls from redundantly starting an HTTP connection. This ensures that
+     * only one attempt is made at a time.
+     */
+    checkAndSetHttpConnectionFlagIfNotRunning() {
+        const canMakeConnection = this.canEstablishStreamConnection();
+        if (canMakeConnection) {
+            this.setIsHttpConnectionRunning(true);
+        }
+        return canMakeConnection;
+    }
+    fetchResponseIsUpToDate(fetchResponse, lastKnownVersion) {
+        // If there is a config, make sure its version is >= the last known version.
+        if (fetchResponse.config != null && fetchResponse.templateVersion) {
+            return fetchResponse.templateVersion >= lastKnownVersion;
+        }
+        // If there isn't a config, return true if the fetch was successful and backend had no update.
+        // Else, it returned an out of date config.
+        return this.storageCache.getLastFetchStatus() === 'success';
+    }
+    parseAndValidateConfigUpdateMessage(message) {
+        const left = message.indexOf('{');
+        const right = message.indexOf('}', left);
+        if (left < 0 || right < 0) {
+            return '';
+        }
+        return left >= right ? '' : message.substring(left, right + 1);
+    }
+    isEventListenersEmpty() {
+        return this.observers.size === 0;
+    }
+    getRandomInt(max) {
+        return Math.floor(Math.random() * max);
+    }
+    executeAllListenerCallbacks(configUpdate) {
+        this.observers.forEach(observer => observer.next(configUpdate));
+    }
+    /**
+     * Compares two configuration objects and returns a set of keys that have changed.
+     * A key is considered changed if it's new, removed, or has a different value.
+     */
+    getChangedParams(newConfig, oldConfig) {
+        const changedKeys = new Set();
+        const newKeys = new Set(Object.keys(newConfig || {}));
+        const oldKeys = new Set(Object.keys(oldConfig || {}));
+        for (const key of newKeys) {
+            if (!oldKeys.has(key) || newConfig[key] !== oldConfig[key]) {
+                changedKeys.add(key);
+            }
+        }
+        for (const key of oldKeys) {
+            if (!newKeys.has(key)) {
+                changedKeys.add(key);
+            }
+        }
+        return changedKeys;
+    }
+    async fetchLatestConfig(remainingAttempts, targetVersion) {
+        const remainingAttemptsAfterFetch = remainingAttempts - 1;
+        const currentAttempt = MAXIMUM_FETCH_ATTEMPTS - remainingAttemptsAfterFetch;
+        const customSignals = this.storageCache.getCustomSignals();
+        if (customSignals) {
+            this.logger.debug(`Fetching config with custom signals: ${JSON.stringify(customSignals)}`);
+        }
+        const abortSignal = new RemoteConfigAbortSignal();
+        try {
+            const fetchRequest = {
+                cacheMaxAgeMillis: 0,
+                signal: abortSignal,
+                customSignals,
+                fetchType: 'REALTIME',
+                fetchAttempt: currentAttempt
+            };
+            const fetchResponse = await this.cachingClient.fetch(fetchRequest);
+            let activatedConfigs = await this.storage.getActiveConfig();
+            if (!this.fetchResponseIsUpToDate(fetchResponse, targetVersion)) {
+                this.logger.debug("Fetched template version is the same as SDK's current version." +
+                    ' Retrying fetch.');
+                // Continue fetching until template version number is greater than current.
+                await this.autoFetch(remainingAttemptsAfterFetch, targetVersion);
+                return;
+            }
+            if (fetchResponse.config == null) {
+                this.logger.debug('The fetch succeeded, but the backend had no updates.');
+                return;
+            }
+            if (activatedConfigs == null) {
+                activatedConfigs = {};
+            }
+            const updatedKeys = this.getChangedParams(fetchResponse.config, activatedConfigs);
+            if (updatedKeys.size === 0) {
+                this.logger.debug('Config was fetched, but no params changed.');
+                return;
+            }
+            const configUpdate = {
+                getUpdatedKeys() {
+                    return new Set(updatedKeys);
+                }
+            };
+            this.executeAllListenerCallbacks(configUpdate);
+        }
+        catch (e) {
+            const errorMessage = e instanceof Error ? e.message : String(e);
+            const error = ERROR_FACTORY.create("update-not-fetched" /* ErrorCode.CONFIG_UPDATE_NOT_FETCHED */, {
+                originalErrorMessage: `Failed to auto-fetch config update: ${errorMessage}`
+            });
+            this.propagateError(error);
+        }
+    }
+    async autoFetch(remainingAttempts, targetVersion) {
+        if (remainingAttempts === 0) {
+            const error = ERROR_FACTORY.create("update-not-fetched" /* ErrorCode.CONFIG_UPDATE_NOT_FETCHED */, {
+                originalErrorMessage: 'Unable to fetch the latest version of the template.'
+            });
+            this.propagateError(error);
+            return;
+        }
+        const timeTillFetchSeconds = this.getRandomInt(4);
+        const timeTillFetchInMiliseconds = timeTillFetchSeconds * 1000;
+        await new Promise(resolve => setTimeout(resolve, timeTillFetchInMiliseconds));
+        await this.fetchLatestConfig(remainingAttempts, targetVersion);
+    }
+    /**
+     * Processes a stream of real-time messages for configuration updates.
+     * This method reassembles fragmented messages, validates and parses the JSON,
+     * and automatically fetches a new config if a newer template version is available.
+     * It also handles server-specified retry intervals and propagates errors for
+     * invalid messages or when real-time updates are disabled.
+     */
+    async handleNotifications(reader) {
+        let partialConfigUpdateMessage;
+        let currentConfigUpdateMessage = '';
+        while (true) {
+            const { done, value } = await reader.read();
+            if (done) {
+                break;
+            }
+            partialConfigUpdateMessage = this.decoder.decode(value, { stream: true });
+            currentConfigUpdateMessage += partialConfigUpdateMessage;
+            if (partialConfigUpdateMessage.includes('}')) {
+                currentConfigUpdateMessage = this.parseAndValidateConfigUpdateMessage(currentConfigUpdateMessage);
+                if (currentConfigUpdateMessage.length === 0) {
+                    continue;
+                }
+                try {
+                    const jsonObject = JSON.parse(currentConfigUpdateMessage);
+                    if (this.isEventListenersEmpty()) {
+                        break;
+                    }
+                    if (REALTIME_DISABLED_KEY in jsonObject &&
+                        jsonObject[REALTIME_DISABLED_KEY] === true) {
+                        const error = ERROR_FACTORY.create("realtime-unavailable" /* ErrorCode.CONFIG_UPDATE_UNAVAILABLE */, {
+                            originalErrorMessage: 'The server is temporarily unavailable. Try again in a few minutes.'
+                        });
+                        this.propagateError(error);
+                        break;
+                    }
+                    if (TEMPLATE_VERSION_KEY in jsonObject) {
+                        const oldTemplateVersion = await this.storage.getActiveConfigTemplateVersion();
+                        const targetTemplateVersion = Number(jsonObject[TEMPLATE_VERSION_KEY]);
+                        if (oldTemplateVersion &&
+                            targetTemplateVersion > oldTemplateVersion) {
+                            await this.autoFetch(MAXIMUM_FETCH_ATTEMPTS, targetTemplateVersion);
+                        }
+                    }
+                    // This field in the response indicates that the realtime request should retry after the
+                    // specified interval to establish a long-lived connection. This interval extends the
+                    // backoff duration without affecting the number of retries, so it will not enter an
+                    // exponential backoff state.
+                    if (REALTIME_RETRY_INTERVAL in jsonObject) {
+                        const retryIntervalSeconds = Number(jsonObject[REALTIME_RETRY_INTERVAL]);
+                        await this.updateBackoffMetadataWithRetryInterval(retryIntervalSeconds);
+                    }
+                }
+                catch (e) {
+                    this.logger.debug('Unable to parse latest config update message.', e);
+                    const errorMessage = e instanceof Error ? e.message : String(e);
+                    this.propagateError(ERROR_FACTORY.create("update-message-invalid" /* ErrorCode.CONFIG_UPDATE_MESSAGE_INVALID */, {
+                        originalErrorMessage: errorMessage
+                    }));
+                }
+                currentConfigUpdateMessage = '';
+            }
+        }
+    }
+    async listenForNotifications(reader) {
+        try {
+            await this.handleNotifications(reader);
+        }
+        catch (e) {
+            // If the real-time connection is at an unexpected lifecycle state when the app is
+            // backgrounded, it's expected closing the connection will throw an exception.
+            if (!this.isInBackground) {
+                // Otherwise, the real-time server connection was closed due to a transient issue.
+                this.logger.debug('Real-time connection was closed due to an exception.');
+            }
+        }
+    }
+    /**
+     * Open the real-time connection, begin listening for updates, and auto-fetch when an update is
+     * received.
+     *
+     * If the connection is successful, this method will block on its thread while it reads the
+     * chunk-encoded HTTP body. When the connection closes, it attempts to reestablish the stream.
+     */
+    async prepareAndBeginRealtimeHttpStream() {
+        if (!this.checkAndSetHttpConnectionFlagIfNotRunning()) {
+            return;
+        }
+        let backoffMetadata = await this.storage.getRealtimeBackoffMetadata();
+        if (!backoffMetadata) {
+            backoffMetadata = {
+                backoffEndTimeMillis: new Date(NO_BACKOFF_TIME_IN_MILLIS),
+                numFailedStreams: NO_FAILED_REALTIME_STREAMS
+            };
+        }
+        const backoffEndTime = backoffMetadata.backoffEndTimeMillis.getTime();
+        if (Date.now() < backoffEndTime) {
+            await this.retryHttpConnectionWhenBackoffEnds();
+            return;
+        }
+        let response;
+        let responseCode;
+        try {
+            response = await this.createRealtimeConnection();
+            responseCode = response.status;
+            if (response.ok && response.body) {
+                this.resetRetryCount();
+                await this.resetRealtimeBackoff();
+                const reader = response.body.getReader();
+                this.reader = reader;
+                // Start listening for realtime notifications.
+                await this.listenForNotifications(reader);
+            }
+        }
+        catch (error) {
+            if (this.isInBackground) {
+                // It's possible the app was backgrounded while the connection was open, which
+                // threw an exception trying to read the response. No real error here, so treat
+                // this as a success, even if we haven't read a 200 response code yet.
+                this.resetRetryCount();
+            }
+            else {
+                //there might have been a transient error so the client will retry the connection.
+                this.logger.debug('Exception connecting to real-time RC backend. Retrying the connection...:', error);
+            }
+        }
+        finally {
+            // Close HTTP connection and associated streams.
+            await this.closeRealtimeHttpConnection();
+            this.setIsHttpConnectionRunning(false);
+            // Update backoff metadata if the connection failed in the foreground.
+            const connectionFailed = !this.isInBackground &&
+                (responseCode === undefined ||
+                    this.isStatusCodeRetryable(responseCode));
+            if (connectionFailed) {
+                await this.updateBackoffMetadataWithLastFailedStreamConnectionTime(new Date());
+            }
+            // If responseCode is null then no connection was made to server and the SDK should still retry.
+            if (connectionFailed || response?.ok) {
+                await this.retryHttpConnectionWhenBackoffEnds();
+            }
+            else {
+                const errorMessage = `Unable to connect to the server. HTTP status code: ${responseCode}`;
+                const firebaseError = ERROR_FACTORY.create("stream-error" /* ErrorCode.CONFIG_UPDATE_STREAM_ERROR */, {
+                    originalErrorMessage: errorMessage
+                });
+                this.propagateError(firebaseError);
+            }
+        }
+    }
+    /**
+     * Checks whether connection can be made or not based on some conditions
+     * @returns booelean
+     */
+    canEstablishStreamConnection() {
+        const hasActiveListeners = this.observers.size > 0;
+        const isNotDisabled = !this.isRealtimeDisabled;
+        const isNoConnectionActive = !this.isConnectionActive;
+        const inForeground = !this.isInBackground;
+        return (hasActiveListeners &&
+            isNotDisabled &&
+            isNoConnectionActive &&
+            inForeground);
+    }
+    async makeRealtimeHttpConnection(delayMillis) {
+        if (!this.canEstablishStreamConnection()) {
+            return;
+        }
+        if (this.httpRetriesRemaining > 0) {
+            this.httpRetriesRemaining--;
+            await new Promise(resolve => setTimeout(resolve, delayMillis));
+            void this.prepareAndBeginRealtimeHttpStream();
+        }
+        else if (!this.isInBackground) {
+            const error = ERROR_FACTORY.create("stream-error" /* ErrorCode.CONFIG_UPDATE_STREAM_ERROR */, {
+                originalErrorMessage: 'Unable to connect to the server. Check your connection and try again.'
+            });
+            this.propagateError(error);
+        }
+    }
+    async beginRealtime() {
+        if (this.observers.size > 0) {
+            await this.makeRealtimeHttpConnection(0);
+        }
+    }
+    /**
+     * Adds an observer to the realtime updates.
+     * @param observer The observer to add.
+     */
+    addObserver(observer) {
+        this.observers.add(observer);
+        void this.beginRealtime();
+    }
+    /**
+     * Removes an observer from the realtime updates.
+     * @param observer The observer to remove.
+     */
+    removeObserver(observer) {
+        if (this.observers.has(observer)) {
+            this.observers.delete(observer);
+        }
+    }
+    /**
+     * Handles changes to the application's visibility state, managing the real-time connection.
+     *
+     * When the application is moved to the background, this method closes the existing
+     * real-time connection to save resources. When the application returns to the
+     * foreground, it attempts to re-establish the connection.
+     */
+    async onVisibilityChange(visible) {
+        this.isInBackground = !visible;
+        if (!visible) {
+            await this.closeRealtimeHttpConnection();
+        }
+        else if (visible) {
+            await this.beginRealtime();
+        }
+    }
+}
+
+/**
+ * @license
+ * Copyright 2020 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.
+ */
+function registerRemoteConfig() {
+    app._registerComponent(new component.Component(RC_COMPONENT_NAME, remoteConfigFactory, "PUBLIC" /* ComponentType.PUBLIC */).setMultipleInstances(true));
+    app.registerVersion(name, version);
+    // BUILD_TARGET will be replaced by values like esm, cjs, etc during the compilation
+    app.registerVersion(name, version, 'cjs2020');
+    function remoteConfigFactory(container, { options }) {
+        /* Dependencies */
+        // getImmediate for FirebaseApp will always succeed
+        const app$1 = container.getProvider('app').getImmediate();
+        // The following call will always succeed because rc has `import '@firebase/installations'`
+        const installations = container
+            .getProvider('installations-internal')
+            .getImmediate();
+        // Normalizes optional inputs.
+        const { projectId, apiKey, appId } = app$1.options;
+        if (!projectId) {
+            throw ERROR_FACTORY.create("registration-project-id" /* ErrorCode.REGISTRATION_PROJECT_ID */);
+        }
+        if (!apiKey) {
+            throw ERROR_FACTORY.create("registration-api-key" /* ErrorCode.REGISTRATION_API_KEY */);
+        }
+        if (!appId) {
+            throw ERROR_FACTORY.create("registration-app-id" /* ErrorCode.REGISTRATION_APP_ID */);
+        }
+        const namespace = options?.templateId || 'firebase';
+        const storage = util.isIndexedDBAvailable()
+            ? new IndexedDbStorage(appId, app$1.name, namespace)
+            : new InMemoryStorage();
+        const storageCache = new StorageCache(storage);
+        const logger$1 = new logger.Logger(name);
+        // Sets ERROR as the default log level.
+        // See RemoteConfig#setLogLevel for corresponding normalization to ERROR log level.
+        logger$1.logLevel = logger.LogLevel.ERROR;
+        const restClient = new RestClient(installations, 
+        // Uses the JS SDK version, by which the RC package version can be deduced, if necessary.
+        app.SDK_VERSION, namespace, projectId, apiKey, appId);
+        const retryingClient = new RetryingClient(restClient, storage);
+        const cachingClient = new CachingClient(retryingClient, storage, storageCache, logger$1);
+        const realtimeHandler = new RealtimeHandler(installations, storage, app.SDK_VERSION, namespace, projectId, apiKey, appId, logger$1, storageCache, cachingClient);
+        const remoteConfigInstance = new RemoteConfig(app$1, cachingClient, storageCache, storage, logger$1, realtimeHandler);
+        // Starts warming cache.
+        // eslint-disable-next-line @typescript-eslint/no-floating-promises
+        ensureInitialized(remoteConfigInstance);
+        return remoteConfigInstance;
+    }
+}
+
+/**
+ * @license
+ * Copyright 2020 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.
+ */
+// This API is put in a separate file, so we can stub fetchConfig and activate in tests.
+// It's not possible to stub standalone functions from the same module.
+/**
+ *
+ * Performs fetch and activate operations, as a convenience.
+ *
+ * @param remoteConfig - The {@link RemoteConfig} instance.
+ *
+ * @returns A `Promise` which resolves to true if the current call activated the fetched configs.
+ * If the fetched configs were already activated, the `Promise` will resolve to false.
+ *
+ * @public
+ */
+async function fetchAndActivate(remoteConfig) {
+    remoteConfig = util.getModularInstance(remoteConfig);
+    await fetchConfig(remoteConfig);
+    return activate(remoteConfig);
+}
+/**
+ * This method provides two different checks:
+ *
+ * 1. Check if IndexedDB exists in the browser environment.
+ * 2. Check if the current browser context allows IndexedDB `open()` calls.
+ *
+ * @returns A `Promise` which resolves to true if a {@link RemoteConfig} instance
+ * can be initialized in this environment, or false if it cannot.
+ * @public
+ */
+async function isSupported() {
+    if (!util.isIndexedDBAvailable()) {
+        return false;
+    }
+    try {
+        const isDBOpenable = await util.validateIndexedDBOpenable();
+        return isDBOpenable;
+    }
+    catch (error) {
+        return false;
+    }
+}
+
+/**
+ * The Firebase Remote Config Web SDK.
+ * This SDK does not work in a Node.js environment.
+ *
+ * @packageDocumentation
+ */
+/** register component and version */
+registerRemoteConfig();
+
+exports.activate = activate;
+exports.ensureInitialized = ensureInitialized;
+exports.fetchAndActivate = fetchAndActivate;
+exports.fetchConfig = fetchConfig;
+exports.getAll = getAll;
+exports.getBoolean = getBoolean;
+exports.getNumber = getNumber;
+exports.getRemoteConfig = getRemoteConfig;
+exports.getString = getString;
+exports.getValue = getValue;
+exports.isSupported = isSupported;
+exports.onConfigUpdate = onConfigUpdate;
+exports.setCustomSignals = setCustomSignals;
+exports.setLogLevel = setLogLevel;
+//# sourceMappingURL=index.cjs.js.map