fune/browser/components/newtab/lib/ASRouter.jsm

/* vim: set ts=2 sw=2 sts=2 et tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";

const { XPCOMUtils } = ChromeUtils.importESModule(
  "resource://gre/modules/XPCOMUtils.sys.mjs"
);
const { AppConstants } = ChromeUtils.importESModule(
  "resource://gre/modules/AppConstants.sys.mjs"
);
const lazy = {};
XPCOMUtils.defineLazyModuleGetters(lazy, {
  SnippetsTestMessageProvider:
    "resource://activity-stream/lib/SnippetsTestMessageProvider.jsm",
  PanelTestProvider: "resource://activity-stream/lib/PanelTestProvider.jsm",
  Spotlight: "resource://activity-stream/lib/Spotlight.jsm",
  ToastNotification: "resource://activity-stream/lib/ToastNotification.jsm",
  ToolbarBadgeHub: "resource://activity-stream/lib/ToolbarBadgeHub.jsm",
  ToolbarPanelHub: "resource://activity-stream/lib/ToolbarPanelHub.jsm",
  MomentsPageHub: "resource://activity-stream/lib/MomentsPageHub.jsm",
  InfoBar: "resource://activity-stream/lib/InfoBar.jsm",
  ASRouterTargeting: "resource://activity-stream/lib/ASRouterTargeting.jsm",
  ASRouterPreferences: "resource://activity-stream/lib/ASRouterPreferences.jsm",
  TARGETING_PREFERENCES:
    "resource://activity-stream/lib/ASRouterPreferences.jsm",
  ASRouterTriggerListeners:
    "resource://activity-stream/lib/ASRouterTriggerListeners.jsm",
  KintoHttpClient: "resource://services-common/kinto-http-client.js",
  Downloader: "resource://services-settings/Attachments.jsm",
  RemoteImages: "resource://activity-stream/lib/RemoteImages.jsm",
  RemoteL10n: "resource://activity-stream/lib/RemoteL10n.jsm",
  ExperimentAPI: "resource://nimbus/ExperimentAPI.jsm",
  setTimeout: "resource://gre/modules/Timer.jsm",
  NimbusFeatures: "resource://nimbus/ExperimentAPI.jsm",
  SpecialMessageActions:
    "resource://messaging-system/lib/SpecialMessageActions.jsm",
  TargetingContext: "resource://messaging-system/targeting/Targeting.jsm",
  Utils: "resource://services-settings/Utils.jsm",
});
ChromeUtils.defineESModuleGetters(lazy, {
  MacAttribution: "resource:///modules/MacAttribution.sys.mjs",
});
XPCOMUtils.defineLazyServiceGetters(lazy, {
  BrowserHandler: ["@mozilla.org/browser/clh;1", "nsIBrowserHandler"],
});
const { actionCreators: ac } = ChromeUtils.importESModule(
  "resource://activity-stream/common/Actions.sys.mjs"
);

const { CFRMessageProvider } = ChromeUtils.import(
  "resource://activity-stream/lib/CFRMessageProvider.jsm"
);
const { OnboardingMessageProvider } = ChromeUtils.import(
  "resource://activity-stream/lib/OnboardingMessageProvider.jsm"
);
const { RemoteSettings } = ChromeUtils.import(
  "resource://services-settings/remote-settings.js"
);
const { CFRPageActions } = ChromeUtils.import(
  "resource://activity-stream/lib/CFRPageActions.jsm"
);
const { AttributionCode } = ChromeUtils.importESModule(
  "resource:///modules/AttributionCode.sys.mjs"
);

// List of hosts for endpoints that serve router messages.
// Key is allowed host, value is a name for the endpoint host.
const DEFAULT_ALLOWLIST_HOSTS = {
  "activity-stream-icons.services.mozilla.com": "production",
  "snippets-admin.mozilla.org": "preview",
};
const SNIPPETS_ENDPOINT_ALLOWLIST =
  "browser.newtab.activity-stream.asrouter.allowHosts";
// Max possible impressions cap for any message
const MAX_MESSAGE_LIFETIME_CAP = 100;

const LOCAL_MESSAGE_PROVIDERS = {
  OnboardingMessageProvider,
  CFRMessageProvider,
};
const STARTPAGE_VERSION = "6";

// Remote Settings
const RS_MAIN_BUCKET = "main";
const RS_COLLECTION_L10N = "ms-language-packs"; // "ms" stands for Messaging System
const RS_PROVIDERS_WITH_L10N = ["cfr"];
const RS_FLUENT_VERSION = "v1";
const RS_FLUENT_RECORD_PREFIX = `cfr-${RS_FLUENT_VERSION}`;
const RS_DOWNLOAD_MAX_RETRIES = 2;
// This is the list of providers for which we want to cache the targeting
// expression result and reuse between calls. Cache duration is defined in
// ASRouterTargeting where evaluation takes place.
const JEXL_PROVIDER_CACHE = new Set(["snippets"]);

// To observe the app locale change notification.
const TOPIC_INTL_LOCALE_CHANGED = "intl:app-locales-changed";
const TOPIC_EXPERIMENT_FORCE_ENROLLED = "nimbus:force-enroll";
// To observe the pref that controls if ASRouter should use the remote Fluent files for l10n.
const USE_REMOTE_L10N_PREF =
  "browser.newtabpage.activity-stream.asrouter.useRemoteL10n";

const MESSAGING_EXPERIMENTS_DEFAULT_FEATURES = [
  "cfr",
  "fxms-message-1",
  "fxms-message-2",
  "fxms-message-3",
  "fxms-message-4",
  "fxms-message-5",
  "infobar",
  "moments-page",
  "pbNewtab",
  "spotlight",
];

// Experiment groups that need to report the reach event in Messaging-Experiments.
// If you're adding new groups to it, make sure they're also added in the
// `messaging_experiments.reach.objects` defined in "toolkit/components/telemetry/Events.yaml"
const REACH_EVENT_GROUPS = ["cfr", "moments-page", "infobar", "spotlight"];
const REACH_EVENT_CATEGORY = "messaging_experiments";
const REACH_EVENT_METHOD = "reach";

const MessageLoaderUtils = {
  STARTPAGE_VERSION,
  REMOTE_LOADER_CACHE_KEY: "RemoteLoaderCache",
  _errors: [],

  reportError(e) {
    console.error(e);
    this._errors.push({
      timestamp: new Date(),
      error: { message: e.toString(), stack: e.stack },
    });
  },

  get errors() {
    const errors = this._errors;
    this._errors = [];
    return errors;
  },

  /**
   * _localLoader - Loads messages for a local provider (i.e. one that lives in mozilla central)
   *
   * @param {obj} provider An AS router provider
   * @param {Array} provider.messages An array of messages
   * @returns {Array} the array of messages
   */
  _localLoader(provider) {
    return provider.messages;
  },

  async _remoteLoaderCache(storage) {
    let allCached;
    try {
      allCached =
        (await storage.get(MessageLoaderUtils.REMOTE_LOADER_CACHE_KEY)) || {};
    } catch (e) {
      // istanbul ignore next
      MessageLoaderUtils.reportError(e);
      // istanbul ignore next
      allCached = {};
    }
    return allCached;
  },

  /**
   * _remoteLoader - Loads messages for a remote provider
   *
   * @param {obj} provider An AS router provider
   * @param {string} provider.url An endpoint that returns an array of messages as JSON
   * @param {obj} options.storage A storage object with get() and set() methods for caching.
   * @returns {Promise} resolves with an array of messages, or an empty array if none could be fetched
   */
  async _remoteLoader(provider, options) {
    let remoteMessages = [];
    if (provider.url) {
      const allCached = await MessageLoaderUtils._remoteLoaderCache(
        options.storage
      );
      const cached = allCached[provider.id];
      let etag;

      if (
        cached &&
        cached.url === provider.url &&
        cached.version === STARTPAGE_VERSION
      ) {
        const { lastFetched, messages } = cached;
        if (
          !MessageLoaderUtils.shouldProviderUpdate({
            ...provider,
            lastUpdated: lastFetched,
          })
        ) {
          // Cached messages haven't expired, return early.
          return messages;
        }
        etag = cached.etag;
        remoteMessages = messages;
      }

      let headers = new Headers();
      if (etag) {
        headers.set("If-None-Match", etag);
      }

      let response;
      try {
        response = await fetch(provider.url, {
          headers,
          credentials: "omit",
        });
      } catch (e) {
        MessageLoaderUtils.reportError(e);
      }
      if (
        response &&
        response.ok &&
        response.status >= 200 &&
        response.status < 400
      ) {
        let jsonResponse;
        try {
          jsonResponse = await response.json();
        } catch (e) {
          MessageLoaderUtils.reportError(e);
          return remoteMessages;
        }
        if (jsonResponse && jsonResponse.messages) {
          remoteMessages = jsonResponse.messages.map(msg => ({
            ...msg,
            provider_url: provider.url,
          }));

          // Cache the results if this isn't a preview URL.
          if (provider.updateCycleInMs > 0) {
            etag = response.headers.get("ETag");
            const cacheInfo = {
              messages: remoteMessages,
              etag,
              lastFetched: Date.now(),
              version: STARTPAGE_VERSION,
            };

            options.storage.set(MessageLoaderUtils.REMOTE_LOADER_CACHE_KEY, {
              ...allCached,
              [provider.id]: cacheInfo,
            });
          }
        } else {
          MessageLoaderUtils.reportError(
            `No messages returned from ${provider.url}.`
          );
        }
      } else if (response) {
        MessageLoaderUtils.reportError(
          `Invalid response status ${response.status} from ${provider.url}.`
        );
      }
    }
    return remoteMessages;
  },

  /**
   * _remoteSettingsLoader - Loads messages for a RemoteSettings provider
   *
   * Note:
   * 1). The "cfr" provider requires the Fluent file for l10n, so there is
   * another file downloading phase for those two providers after their messages
   * are successfully fetched from Remote Settings. Currently, they share the same
   * attachment of the record "${RS_FLUENT_RECORD_PREFIX}-${locale}" in the
   * "ms-language-packs" collection. E.g. for "en-US" with version "v1",
   * the Fluent file is attched to the record with ID "cfr-v1-en-US".
   *
   * 2). The Remote Settings downloader is able to detect the duplicate download
   * requests for the same attachment and ignore the redundent requests automatically.
   *
   * @param {object} provider An AS router provider
   * @param {string} provider.id The id of the provider
   * @param {string} provider.collection Remote Settings collection name
   * @param {object} options
   * @param {function} options.dispatchCFRAction Action handler function
   * @returns {Promise<object[]>} Resolves with an array of messages, or an
   *                              empty array if none could be fetched
   */
  async _remoteSettingsLoader(provider, options) {
    let messages = [];
    if (provider.collection) {
      try {
        messages = await MessageLoaderUtils._getRemoteSettingsMessages(
          provider.collection
        );
        if (!messages.length) {
          MessageLoaderUtils._handleRemoteSettingsUndesiredEvent(
            "ASR_RS_NO_MESSAGES",
            provider.id,
            options.dispatchCFRAction
          );
        } else if (
          RS_PROVIDERS_WITH_L10N.includes(provider.id) &&
          lazy.RemoteL10n.isLocaleSupported(MessageLoaderUtils.locale)
        ) {
          const recordId = `${RS_FLUENT_RECORD_PREFIX}-${MessageLoaderUtils.locale}`;
          const kinto = new lazy.KintoHttpClient(lazy.Utils.SERVER_URL);
          const record = await kinto
            .bucket(RS_MAIN_BUCKET)
            .collection(RS_COLLECTION_L10N)
            .getRecord(recordId);
          if (record && record.data) {
            const downloader = new lazy.Downloader(
              RS_MAIN_BUCKET,
              RS_COLLECTION_L10N,
              "browser",
              "newtab"
            );
            // Await here in order to capture the exceptions for reporting.
            await downloader.downloadToDisk(record.data, {
              retries: RS_DOWNLOAD_MAX_RETRIES,
            });
            lazy.RemoteL10n.reloadL10n();
          } else {
            MessageLoaderUtils._handleRemoteSettingsUndesiredEvent(
              "ASR_RS_NO_MESSAGES",
              RS_COLLECTION_L10N,
              options.dispatchCFRAction
            );
          }
        }
      } catch (e) {
        MessageLoaderUtils._handleRemoteSettingsUndesiredEvent(
          "ASR_RS_ERROR",
          provider.id,
          options.dispatchCFRAction
        );
        MessageLoaderUtils.reportError(e);
      }
    }
    return messages;
  },

  /**
   * Fetch messages from a given collection in Remote Settings.
   *
   * @param {string} collection The remote settings collection identifier
   * @returns {Promise<object[]>} Resolves with an array of messages
   */
  _getRemoteSettingsMessages(collection) {
    return RemoteSettings(collection).get();
  },

  /**
   * Return messages from active Nimbus experiments and rollouts.
   *
   * @param {object} provider A messaging experiments provider.
   * @param {string[]?} provider.featureIds
   *                    An optional array of Nimbus feature IDs to check for
   *                    enrollments. If not provided, we will fall back to the
   *                    set of default features. Otherwise, if provided and
   *                    empty, we will not ingest messages from any features.
   *
   * @return {object[]} The list of messages from active enrollments, as well as
   *                    the messages defined in unenrolled branches so that they
   *                    reach events can be recorded (if we record reach events
   *                    for that feature).
   */
  async _experimentsAPILoader(provider) {
    // Allow tests to override the set of featureIds
    const featureIds = Array.isArray(provider.featureIds)
      ? provider.featureIds
      : MESSAGING_EXPERIMENTS_DEFAULT_FEATURES;
    let experiments = [];
    for (const featureId of featureIds) {
      let featureAPI = lazy.NimbusFeatures[featureId];
      let experimentData = lazy.ExperimentAPI.getExperimentMetaData({
        featureId,
      });

      // We are not enrolled in any experiment or rollout for this feature, so
      // we can skip the feature.
      if (
        !experimentData &&
        !lazy.ExperimentAPI.getRolloutMetaData({ featureId })
      ) {
        continue;
      }

      let message = featureAPI.getAllVariables();

      if (message?.id) {
        // Cache the Nimbus feature ID on the message because there is not a 1-1
        // correspondance between templates and features. This is used when
        // recording expose events (see |sendTriggerMessage|).
        message._nimbusFeature = featureId;
        experiments.push(message);
      }

      if (!REACH_EVENT_GROUPS.includes(featureId)) {
        continue;
      }

      // If we are in a rollout, we do not have sibling branches.
      if (experimentData) {
        // Check other sibling branches for triggers, add them to the return
        // array if found any. The `forReachEvent` label is used to identify
        // those branches so that they would only used to record the Reach
        // event.
        const branches =
          (await lazy.ExperimentAPI.getAllBranches(experimentData.slug)) || [];
        for (const branch of branches) {
          let branchValue = branch[featureId].value;
          if (
            branch.slug !== experimentData.branch.slug &&
            branchValue?.trigger
          ) {
            experiments.push({
              forReachEvent: { sent: false, group: featureId },
              experimentSlug: experimentData.slug,
              branchSlug: branch.slug,
              ...branchValue,
            });
          }
        }
      }
    }

    return experiments;
  },

  _handleRemoteSettingsUndesiredEvent(event, providerId, dispatchCFRAction) {
    if (dispatchCFRAction) {
      dispatchCFRAction(
        ac.ASRouterUserEvent({
          action: "asrouter_undesired_event",
          event,
          message_id: "n/a",
          event_context: providerId,
        })
      );
    }
  },

  /**
   * _getMessageLoader - return the right loading function given the provider's type
   *
   * @param {obj} provider An AS Router provider
   * @returns {func} A loading function
   */
  _getMessageLoader(provider) {
    switch (provider.type) {
      case "remote":
        return this._remoteLoader;
      case "remote-settings":
        return this._remoteSettingsLoader;
      case "remote-experiments":
        return this._experimentsAPILoader;
      case "local":
      default:
        return this._localLoader;
    }
  },

  /**
   * shouldProviderUpdate - Given the current time, should a provider update its messages?
   *
   * @param {any} provider An AS Router provider
   * @param {int} provider.updateCycleInMs The number of milliseconds we should wait between updates
   * @param {Date} provider.lastUpdated If the provider has been updated, the time the last update occurred
   * @param {Date} currentTime The time we should check against. (defaults to Date.now())
   * @returns {bool} Should an update happen?
   */
  shouldProviderUpdate(provider, currentTime = Date.now()) {
    return (
      !(provider.lastUpdated >= 0) ||
      currentTime - provider.lastUpdated > provider.updateCycleInMs
    );
  },

  async _loadDataForProvider(provider, options) {
    const loader = this._getMessageLoader(provider);
    let messages = await loader(provider, options);
    // istanbul ignore if
    if (!messages) {
      messages = [];
      MessageLoaderUtils.reportError(
        new Error(
          `Tried to load messages for ${provider.id} but the result was not an Array.`
        )
      );
    }

    return { messages };
  },

  /**
   * loadMessagesForProvider - Load messages for a provider, given the provider's type.
   *
   * @param {obj} provider An AS Router provider
   * @param {string} provider.type An AS Router provider type (defaults to "local")
   * @param {obj} options.storage A storage object with get() and set() methods for caching.
   * @param {func} options.dispatchCFRAction dispatch an action the main AS Store
   * @returns {obj} Returns an object with .messages (an array of messages) and .lastUpdated (the time the messages were updated)
   */
  async loadMessagesForProvider(provider, options) {
    let { messages } = await this._loadDataForProvider(provider, options);
    // Filter out messages we temporarily want to exclude
    if (provider.exclude && provider.exclude.length) {
      messages = messages.filter(
        message => !provider.exclude.includes(message.id)
      );
    }
    const lastUpdated = Date.now();
    return {
      messages: messages
        .map(messageData => {
          const message = {
            weight: 100,
            ...messageData,
            groups: messageData.groups || [],
            provider: provider.id,
          };

          return message;
        })
        .filter(message => message.weight > 0),
      lastUpdated,
      errors: MessageLoaderUtils.errors,
    };
  },

  /**
   * cleanupCache - Removes cached data of removed providers.
   *
   * @param {Array} providers A list of activer AS Router providers
   */
  async cleanupCache(providers, storage) {
    const ids = providers.filter(p => p.type === "remote").map(p => p.id);
    const cache = await MessageLoaderUtils._remoteLoaderCache(storage);
    let dirty = false;
    for (let id in cache) {
      if (!ids.includes(id)) {
        delete cache[id];
        dirty = true;
      }
    }
    if (dirty) {
      await storage.set(MessageLoaderUtils.REMOTE_LOADER_CACHE_KEY, cache);
    }
  },

  /**
   * The locale to use for RemoteL10n.
   *
   * This may map the app's actual locale into something that RemoteL10n
   * supports.
   */
  get locale() {
    const localeMap = {
      "ja-JP-macos": "ja-JP-mac",

      // While it's not a valid locale, "und" is commonly observed on
      // Linux platforms. Per l10n team, it's reasonable to fallback to
      // "en-US", therefore, we should allow the fetch for it.
      und: "en-US",
    };

    const locale = Services.locale.appLocaleAsBCP47;
    return localeMap[locale] ?? locale;
  },
};

/**
 * @class _ASRouter - Keeps track of all messages, UI surfaces, and
 * handles blocking, rotation, etc. Inspecting ASRouter.state will
 * tell you what the current displayed message is in all UI surfaces.
 *
 * Note: This is written as a constructor rather than just a plain object
 * so that it can be more easily unit tested.
 */
class _ASRouter {
  constructor(localProviders = LOCAL_MESSAGE_PROVIDERS) {
    this.initialized = false;
    this.clearChildMessages = null;
    this.clearChildProviders = null;
    this.updateAdminState = null;
    this.sendTelemetry = null;
    this.dispatchCFRAction = null;
    this._storage = null;
    this._resetInitialization();
    this._state = {
      providers: [],
      messageBlockList: [],
      messageImpressions: {},
      messages: [],
      groups: [],
      errors: [],
      localeInUse: Services.locale.appLocaleAsBCP47,
    };
    this._experimentChangedListeners = new Map();
    this._triggerHandler = this._triggerHandler.bind(this);
    this._localProviders = localProviders;
    this.blockMessageById = this.blockMessageById.bind(this);
    this.unblockMessageById = this.unblockMessageById.bind(this);
    this.handleMessageRequest = this.handleMessageRequest.bind(this);
    this.addImpression = this.addImpression.bind(this);
    this._handleTargetingError = this._handleTargetingError.bind(this);
    this.onPrefChange = this.onPrefChange.bind(this);
    this._onLocaleChanged = this._onLocaleChanged.bind(this);
    this.isUnblockedMessage = this.isUnblockedMessage.bind(this);
    this.unblockAll = this.unblockAll.bind(this);
    this.forceWNPanel = this.forceWNPanel.bind(this);
    this._onExperimentForceEnrolled = this._onExperimentForceEnrolled.bind(
      this
    );
    this.forcePBWindow = this.forcePBWindow.bind(this);
    Services.telemetry.setEventRecordingEnabled(REACH_EVENT_CATEGORY, true);
  }

  async onPrefChange(prefName) {
    if (lazy.TARGETING_PREFERENCES.includes(prefName)) {
      let invalidMessages = [];
      // Notify all tabs of messages that have become invalid after pref change
      const context = this._getMessagesContext();
      const targetingContext = new lazy.TargetingContext(context);

      for (const msg of this.state.messages.filter(this.isUnblockedMessage)) {
        if (!msg.targeting) {
          continue;
        }
        const isMatch = await targetingContext.evalWithDefault(msg.targeting);
        if (!isMatch) {
          invalidMessages.push(msg.id);
        }
      }
      this.clearChildMessages(invalidMessages);
    } else {
      // Update message providers and fetch new messages on pref change
      this._loadLocalProviders();
      let invalidProviders = await this._updateMessageProviders();
      if (invalidProviders.length) {
        this.clearChildProviders(invalidProviders);
      }
      await this.loadMessagesFromAllProviders();
      // Any change in user prefs can disable or enable groups
      await this.setState(state => ({
        groups: state.groups.map(this._checkGroupEnabled),
      }));
    }
  }

  // Fetch and decode the message provider pref JSON, and update the message providers
  async _updateMessageProviders() {
    lazy.ASRouterPreferences.console.debug("entering updateMessageProviders");

    const previousProviders = this.state.providers;
    const providers = await Promise.all(
      [
        // If we have added a `preview` provider, hold onto it
        ...previousProviders.filter(p => p.id === "preview"),
        // The provider should be enabled and not have a user preference set to false
        ...lazy.ASRouterPreferences.providers.filter(
          p =>
            p.enabled &&
            lazy.ASRouterPreferences.getUserPreference(p.id) !== false
        ),
      ].map(async _provider => {
        // make a copy so we don't modify the source of the pref
        const provider = { ..._provider };

        if (provider.type === "local" && !provider.messages) {
          // Get the messages from the local message provider
          const localProvider = this._localProviders[provider.localProvider];
          provider.messages = [];
          if (localProvider) {
            provider.messages = await localProvider.getMessages();
          }
        }
        if (provider.type === "remote" && provider.url) {
          provider.url = provider.url.replace(
            /%STARTPAGE_VERSION%/g,
            STARTPAGE_VERSION
          );
          provider.url = Services.urlFormatter.formatURL(provider.url);
        }
        if (provider.id === "messaging-experiments") {
          // By default, the messaging-experiments provider lacks a featureIds
          // property, so fall back to the list of default features.
          if (!provider.featureIds) {
            provider.featureIds = MESSAGING_EXPERIMENTS_DEFAULT_FEATURES;
          }
        }
        // Reset provider update timestamp to force message refresh
        provider.lastUpdated = undefined;
        return provider;
      })
    );

    const providerIDs = providers.map(p => p.id);
    let invalidProviders = [];

    // Clear old messages for providers that are no longer enabled
    for (const prevProvider of previousProviders) {
      if (!providerIDs.includes(prevProvider.id)) {
        invalidProviders.push(prevProvider.id);
      }
    }

    {
      // If the feature IDs of the messaging-experiments provider has changed,
      // then we need to update which features for which we are listening to
      // changes.
      const prevExpts = previousProviders.find(
        p => p.id === "messaging-experiments"
      );
      const expts = providers.find(p => p.id === "messaging-experiments");

      this._onFeatureListChanged(
        prevExpts?.enabled ? prevExpts.featureIds : [],
        expts?.enabled ? expts.featureIds : []
      );
    }

    return this.setState(prevState => ({
      providers,
      // Clear any messages from removed providers
      messages: [
        ...prevState.messages.filter(message =>
          providerIDs.includes(message.provider)
        ),
      ],
    })).then(() => invalidProviders);
  }

  get state() {
    return this._state;
  }

  set state(value) {
    throw new Error(
      "Do not modify this.state directy. Instead, call this.setState(newState)"
    );
  }

  /**
   * _resetInitialization - adds the following to the instance:
   *  .initialized {bool}            Has AS Router been initialized?
   *  .waitForInitialized {Promise}  A promise that resolves when initializion is complete
   *  ._finishInitializing {func}    A function that, when called, resolves the .waitForInitialized
   *                                 promise and sets .initialized to true.
   * @memberof _ASRouter
   */
  _resetInitialization() {
    this.initialized = false;
    this.initializing = false;
    this.waitForInitialized = new Promise(resolve => {
      this._finishInitializing = () => {
        this.initialized = true;
        this.initializing = false;
        resolve();
      };
    });
  }

  /**
   * Check all provided groups are enabled.
   * @param groups Set of groups to verify
   * @returns bool
   */
  hasGroupsEnabled(groups = []) {
    return this.state.groups
      .filter(({ id }) => groups.includes(id))
      .every(({ enabled }) => enabled);
  }

  /**
   * Verify that the provider block the message through the `exclude` field
   * @param message Message to verify
   * @returns bool
   */
  isExcludedByProvider(message) {
    // preview snippets are never excluded
    if (message.provider === "preview") {
      return false;
    }
    const provider = this.state.providers.find(p => p.id === message.provider);
    if (!provider) {
      return true;
    }
    if (provider.exclude) {
      return provider.exclude.includes(message.id);
    }
    return false;
  }

  /**
   * Takes a group and sets the correct `enabled` state based on message config
   * and user preferences
   *
   * @param {GroupConfig} group
   * @returns {GroupConfig}
   */
  _checkGroupEnabled(group) {
    return {
      ...group,
      enabled:
        group.enabled &&
        // And if defined user preferences are true. If multiple prefs are
        // defined then at least one has to be enabled.
        (Array.isArray(group.userPreferences)
          ? group.userPreferences.some(pref =>
              lazy.ASRouterPreferences.getUserPreference(pref)
            )
          : true),
    };
  }

  /**
   * Fetch all message groups and update Router.state.groups.
   * There are two cases to consider:
   * 1. The provider needs to update as determined by the update cycle
   * 2. Some pref change occured which could invalidate one of the existing
   *    groups.
   */
  async loadAllMessageGroups() {
    const provider = this.state.providers.find(
      p =>
        p.id === "message-groups" && MessageLoaderUtils.shouldProviderUpdate(p)
    );
    let remoteMessages = null;
    if (provider) {
      const { messages } = await MessageLoaderUtils._loadDataForProvider(
        provider,
        {
          storage: this._storage,
          dispatchCFRAction: this.dispatchCFRAction,
        }
      );
      remoteMessages = messages;
    }
    await this.setState(state => ({
      // If fetching remote messages fails we default to existing state.groups.
      groups: (remoteMessages || state.groups).map(this._checkGroupEnabled),
    }));
  }

  /**
   * loadMessagesFromAllProviders - Loads messages from all providers if they require updates.
   *                                Checks the .lastUpdated field on each provider to see if updates are needed
   * @param toUpdate  An optional list of providers to update. This overrides
   *                  the checks to determine which providers to update.
   * @memberof _ASRouter
   */
  async loadMessagesFromAllProviders(toUpdate = undefined) {
    const needsUpdate = Array.isArray(toUpdate)
      ? toUpdate
      : this.state.providers.filter(provider =>
          MessageLoaderUtils.shouldProviderUpdate(provider)
        );
    lazy.ASRouterPreferences.console.debug(
      "entering loadMessagesFromAllProviders"
    );

    await this.loadAllMessageGroups();
    // Don't do extra work if we don't need any updates
    if (needsUpdate.length) {
      let newState = { messages: [], providers: [] };
      for (const provider of this.state.providers) {
        if (needsUpdate.includes(provider)) {
          const {
            messages,
            lastUpdated,
            errors,
          } = await MessageLoaderUtils.loadMessagesForProvider(provider, {
            storage: this._storage,
            dispatchCFRAction: this.dispatchCFRAction,
          });
          newState.providers.push({ ...provider, lastUpdated, errors });
          newState.messages = [...newState.messages, ...messages];
        } else {
          // Skip updating this provider's messages if no update is required
          let messages = this.state.messages.filter(
            msg => msg.provider === provider.id
          );
          newState.providers.push(provider);
          newState.messages = [...newState.messages, ...messages];
        }
      }

      // Some messages have triggers that require us to initalise trigger listeners
      const unseenListeners = new Set(lazy.ASRouterTriggerListeners.keys());
      for (const { trigger } of newState.messages) {
        if (trigger && lazy.ASRouterTriggerListeners.has(trigger.id)) {
          lazy.ASRouterTriggerListeners.get(trigger.id).init(
            this._triggerHandler,
            trigger.params,
            trigger.patterns
          );
          unseenListeners.delete(trigger.id);
        }
      }
      // We don't need these listeners, but they may have previously been
      // initialised, so uninitialise them
      for (const triggerID of unseenListeners) {
        lazy.ASRouterTriggerListeners.get(triggerID).uninit();
      }

      // We don't want to cache preview endpoints, remove them after messages are fetched
      await this.setState(this._removePreviewEndpoint(newState));
      await this.cleanupImpressions();
    }
    return this.state;
  }

  async _maybeUpdateL10nAttachment() {
    const { localeInUse } = this.state.localeInUse;
    const newLocale = Services.locale.appLocaleAsBCP47;
    if (newLocale !== localeInUse) {
      const providers = [...this.state.providers];
      let needsUpdate = false;
      providers.forEach(provider => {
        if (RS_PROVIDERS_WITH_L10N.includes(provider.id)) {
          // Force to refresh the messages as well as the attachment.
          provider.lastUpdated = undefined;
          needsUpdate = true;
        }
      });
      if (needsUpdate) {
        await this.setState({
          localeInUse: newLocale,
          providers,
        });
        await this.loadMessagesFromAllProviders();
      }
    }
    return this.state;
  }

  async _onLocaleChanged(subject, topic, data) {
    await this._maybeUpdateL10nAttachment();
  }

  observe(aSubject, aTopic, aPrefName) {
    switch (aPrefName) {
      case USE_REMOTE_L10N_PREF:
        CFRPageActions.reloadL10n();
        break;
    }
  }

  toWaitForInitFunc(func) {
    return (...args) => this.waitForInitialized.then(() => func(...args));
  }

  /**
   * init - Initializes the MessageRouter.
   *
   * @param {obj} parameters parameters to initialize ASRouter
   * @memberof _ASRouter
   */
  async init({
    storage,
    sendTelemetry,
    clearChildMessages,
    clearChildProviders,
    updateAdminState,
    dispatchCFRAction,
  }) {
    if (this.initializing || this.initialized) {
      return null;
    }
    this.initializing = true;
    this._storage = storage;
    this.ALLOWLIST_HOSTS = this._loadSnippetsAllowHosts();
    this.clearChildMessages = this.toWaitForInitFunc(clearChildMessages);
    this.clearChildProviders = this.toWaitForInitFunc(clearChildProviders);
    // NOTE: This is only necessary to sync devtools and snippets when devtools is active.
    this.updateAdminState = this.toWaitForInitFunc(updateAdminState);
    this.sendTelemetry = sendTelemetry;
    this.dispatchCFRAction = this.toWaitForInitFunc(dispatchCFRAction);

    lazy.ASRouterPreferences.init();
    lazy.ASRouterPreferences.addListener(this.onPrefChange);
    lazy.ToolbarBadgeHub.init(this.waitForInitialized, {
      handleMessageRequest: this.handleMessageRequest,
      addImpression: this.addImpression,
      blockMessageById: this.blockMessageById,
      unblockMessageById: this.unblockMessageById,
      sendTelemetry: this.sendTelemetry,
    });
    lazy.ToolbarPanelHub.init(this.waitForInitialized, {
      getMessages: this.handleMessageRequest,
      sendTelemetry: this.sendTelemetry,
    });
    lazy.MomentsPageHub.init(this.waitForInitialized, {
      handleMessageRequest: this.handleMessageRequest,
      addImpression: this.addImpression,
      blockMessageById: this.blockMessageById,
      sendTelemetry: this.sendTelemetry,
    });

    this._loadLocalProviders();

    const messageBlockList =
      (await this._storage.get("messageBlockList")) || [];
    const messageImpressions =
      (await this._storage.get("messageImpressions")) || {};
    const groupImpressions =
      (await this._storage.get("groupImpressions")) || {};
    const previousSessionEnd =
      (await this._storage.get("previousSessionEnd")) || 0;

    await this.setState({
      messageBlockList,
      groupImpressions,
      messageImpressions,
      previousSessionEnd,
      ...(lazy.ASRouterPreferences.specialConditions || {}),
      initialized: false,
    });
    await this._updateMessageProviders();
    await this.loadMessagesFromAllProviders();
    await MessageLoaderUtils.cleanupCache(this.state.providers, storage);

    lazy.SpecialMessageActions.blockMessageById = this.blockMessageById;
    Services.obs.addObserver(this._onLocaleChanged, TOPIC_INTL_LOCALE_CHANGED);
    Services.obs.addObserver(
      this._onExperimentForceEnrolled,
      TOPIC_EXPERIMENT_FORCE_ENROLLED
    );
    Services.prefs.addObserver(USE_REMOTE_L10N_PREF, this);
    // sets .initialized to true and resolves .waitForInitialized promise
    this._finishInitializing();
    return this.state;
  }

  uninit() {
    this._storage.set("previousSessionEnd", Date.now());

    this.clearChildMessages = null;
    this.clearChildProviders = null;
    this.updateAdminState = null;
    this.sendTelemetry = null;
    this.dispatchCFRAction = null;

    lazy.ASRouterPreferences.removeListener(this.onPrefChange);
    lazy.ASRouterPreferences.uninit();
    lazy.ToolbarPanelHub.uninit();
    lazy.ToolbarBadgeHub.uninit();
    lazy.MomentsPageHub.uninit();

    // Uninitialise all trigger listeners
    for (const listener of lazy.ASRouterTriggerListeners.values()) {
      listener.uninit();
    }
    Services.obs.removeObserver(
      this._onLocaleChanged,
      TOPIC_INTL_LOCALE_CHANGED
    );
    Services.obs.removeObserver(
      this._onExperimentForceEnrolled,
      TOPIC_EXPERIMENT_FORCE_ENROLLED
    );
    Services.prefs.removeObserver(USE_REMOTE_L10N_PREF, this);
    // If we added any CFR recommendations, they need to be removed
    CFRPageActions.clearRecommendations();
    this._resetInitialization();
  }

  setState(callbackOrObj) {
    lazy.ASRouterPreferences.console.debug(
      "in setState, callbackOrObj = ",
      callbackOrObj
    );
    lazy.ASRouterPreferences.console.trace();
    const newState =
      typeof callbackOrObj === "function"
        ? callbackOrObj(this.state)
        : callbackOrObj;
    this._state = {
      ...this.state,
      ...newState,
    };
    if (lazy.ASRouterPreferences.devtoolsEnabled) {
      return this.updateTargetingParameters().then(state => {
        this.updateAdminState(state);
        return state;
      });
    }
    return Promise.resolve(this.state);
  }

  updateTargetingParameters() {
    return this.getTargetingParameters(
      lazy.ASRouterTargeting.Environment,
      this._getMessagesContext()
    ).then(targetingParameters => ({
      ...this.state,
      providerPrefs: lazy.ASRouterPreferences.providers,
      userPrefs: lazy.ASRouterPreferences.getAllUserPreferences(),
      targetingParameters,
      errors: this.errors,
    }));
  }

  getMessageById(id) {
    return this.state.messages.find(message => message.id === id);
  }

  _loadLocalProviders() {
    // If we're in ASR debug mode add the local test providers
    if (lazy.ASRouterPreferences.devtoolsEnabled) {
      this._localProviders = {
        ...this._localProviders,
        SnippetsTestMessageProvider: lazy.SnippetsTestMessageProvider,
        PanelTestProvider: lazy.PanelTestProvider,
      };
    }
  }

  /**
   * Used by ASRouter Admin returns all ASRouterTargeting.Environment
   * and ASRouter._getMessagesContext parameters and values
   */
  async getTargetingParameters(environment, localContext) {
    const targetingParameters = {};
    for (const param of Object.keys(environment)) {
      targetingParameters[param] = await environment[param];
    }
    for (const param of Object.keys(localContext)) {
      targetingParameters[param] = await localContext[param];
    }

    return targetingParameters;
  }

  _handleTargetingError(error, message) {
    console.error(error);
    this.dispatchCFRAction(
      ac.ASRouterUserEvent({
        message_id: message.id,
        action: "asrouter_undesired_event",
        event: "TARGETING_EXPRESSION_ERROR",
        event_context: {},
      })
    );
  }

  // Return an object containing targeting parameters used to select messages
  _getMessagesContext() {
    const { messageImpressions, previousSessionEnd } = this.state;

    return {
      get messageImpressions() {
        return messageImpressions;
      },
      get previousSessionEnd() {
        return previousSessionEnd;
      },
    };
  }

  async evaluateExpression({ expression, context }) {
    const targetingContext = new lazy.TargetingContext(context);
    let evaluationStatus;
    try {
      evaluationStatus = {
        result: await targetingContext.evalWithDefault(expression),
        success: true,
      };
    } catch (e) {
      evaluationStatus = { result: e.message, success: false };
    }
    return Promise.resolve({ evaluationStatus });
  }

  unblockAll() {
    return this.setState({ messageBlockList: [] });
  }

  isUnblockedMessage(message) {
    const { state } = this;
    return (
      !state.messageBlockList.includes(message.id) &&
      (!message.campaign ||
        !state.messageBlockList.includes(message.campaign)) &&
      this.hasGroupsEnabled(message.groups) &&
      !this.isExcludedByProvider(message)
    );
  }

  // Work out if a message can be shown based on its and its provider's frequency caps.
  isBelowFrequencyCaps(message) {
    const { messageImpressions, groupImpressions } = this.state;
    const impressionsForMessage = messageImpressions[message.id];

    const _belowItemFrequencyCap = this._isBelowItemFrequencyCap(
      message,
      impressionsForMessage,
      MAX_MESSAGE_LIFETIME_CAP
    );
    if (!_belowItemFrequencyCap) {
      lazy.ASRouterPreferences.console.debug(
        `isBelowFrequencyCaps: capped by item: `,
        message,
        "impressions =",
        impressionsForMessage
      );
    }

    const _belowGroupFrequencyCaps = message.groups.every(messageGroup => {
      const belowThisGroupCap = this._isBelowItemFrequencyCap(
        this.state.groups.find(({ id }) => id === messageGroup),
        groupImpressions[messageGroup]
      );

      if (!belowThisGroupCap) {
        lazy.ASRouterPreferences.console.debug(
          `isBelowFrequencyCaps: ${message.id} capped by group ${messageGroup}`
        );
      } else {
        lazy.ASRouterPreferences.console.debug(
          `isBelowFrequencyCaps: ${message.id} allowed by group ${messageGroup}, groupImpressions = `,
          groupImpressions
        );
      }

      return belowThisGroupCap;
    });

    return _belowItemFrequencyCap && _belowGroupFrequencyCaps;
  }

  // Helper for isBelowFrecencyCaps - work out if the frequency cap for the given
  //                                  item has been exceeded or not
  _isBelowItemFrequencyCap(item, impressions, maxLifetimeCap = Infinity) {
    if (item && item.frequency && impressions && impressions.length) {
      if (
        item.frequency.lifetime &&
        impressions.length >= Math.min(item.frequency.lifetime, maxLifetimeCap)
      ) {
        lazy.ASRouterPreferences.console.debug(
          `${item.id} capped by lifetime (${item.frequency.lifetime})`
        );

        return false;
      }
      if (item.frequency.custom) {
        const now = Date.now();
        for (const setting of item.frequency.custom) {
          let { period } = setting;
          const impressionsInPeriod = impressions.filter(t => now - t < period);
          if (impressionsInPeriod.length >= setting.cap) {
            lazy.ASRouterPreferences.console.debug(
              `${item.id} capped by impressions (${impressionsInPeriod.length}) in period (${period}) >= ${setting.cap}`
            );
            return false;
          }
        }
      }
    }
    return true;
  }

  async _extraTemplateStrings(originalMessage) {
    let extraTemplateStrings;
    let localProvider = this._findProvider(originalMessage.provider);
    if (localProvider && localProvider.getExtraAttributes) {
      extraTemplateStrings = await localProvider.getExtraAttributes();
    }

    return extraTemplateStrings;
  }

  _findProvider(providerID) {
    return this._localProviders[
      this.state.providers.find(i => i.id === providerID).localProvider
    ];
  }

  routeCFRMessage(message, browser, trigger, force = false) {
    if (!message) {
      return { message: {} };
    }

    switch (message.template) {
      case "whatsnew_panel_message":
        if (force) {
          lazy.ToolbarPanelHub.forceShowMessage(browser, message);
        }
        break;
      case "cfr_doorhanger":
      case "milestone_message":
        if (force) {
          CFRPageActions.forceRecommendation(
            browser,
            message,
            this.dispatchCFRAction
          );
        } else {
          CFRPageActions.addRecommendation(
            browser,
            trigger.param && trigger.param.host,
            message,
            this.dispatchCFRAction
          );
        }
        break;
      case "cfr_urlbar_chiclet":
        if (force) {
          CFRPageActions.forceRecommendation(
            browser,
            message,
            this.dispatchCFRAction
          );
        } else {
          CFRPageActions.addRecommendation(
            browser,
            null,
            message,
            this.dispatchCFRAction
          );
        }
        break;
      case "toolbar_badge":
        lazy.ToolbarBadgeHub.registerBadgeNotificationListener(message, {
          force,
        });
        break;
      case "update_action":
        lazy.MomentsPageHub.executeAction(message);
        break;
      case "infobar":
        lazy.InfoBar.showInfoBarMessage(
          browser,
          message,
          this.dispatchCFRAction
        );
        break;
      case "spotlight":
        lazy.Spotlight.showSpotlightDialog(
          browser,
          message,
          this.dispatchCFRAction
        );
        break;
      case "toast_notification":
        lazy.ToastNotification.showToastNotification(
          message,
          this.dispatchCFRAction
        );
        break;
    }

    return { message };
  }

  addImpression(message) {
    lazy.ASRouterPreferences.console.debug(
      `entering addImpression for ${message.id}`
    );

    const groupsWithFrequency = this.state.groups.filter(
      ({ frequency, id }) => frequency && message.groups.includes(id)
    );
    // We only need to store impressions for messages that have frequency, or
    // that have providers that have frequency
    if (message.frequency || groupsWithFrequency.length) {
      const time = Date.now();
      return this.setState(state => {
        const messageImpressions = this._addImpressionForItem(
          state.messageImpressions,
          message,
          "messageImpressions",
          time
        );
        // Initialize this with state.groupImpressions, and then assign the
        // newly-updated copy to it during each iteration so that
        // all the changes get captured and either returned or passed into the
        // _addImpressionsForItem call on the next iteration.
        let { groupImpressions } = state;
        for (const group of groupsWithFrequency) {
          groupImpressions = this._addImpressionForItem(
            groupImpressions,
            group,
            "groupImpressions",
            time
          );
        }

        return { messageImpressions, groupImpressions };
      });
    }
    return Promise.resolve();
  }

  // Helper for addImpression - calculate the updated impressions object for the given
  //                            item, then store it and return it
  _addImpressionForItem(currentImpressions, item, impressionsString, time) {
    // The destructuring here is to avoid mutating passed parameters
    // (see https://redux.js.org/recipes/structuring-reducers/prerequisite-concepts#immutable-data-management)
    const impressions = { ...currentImpressions };
    if (item.frequency) {
      impressions[item.id] = impressions[item.id]
        ? [...impressions[item.id]]
        : [];
      impressions[item.id].push(time);
      lazy.ASRouterPreferences.console.debug(
        item.id,
        "impression added, impressions[item.id]: ",
        impressions[item.id]
      );

      this._storage.set(impressionsString, impressions);
    }
    return impressions;
  }

  /**
   * getLongestPeriod
   *
   * @param {obj} item Either an ASRouter message or an ASRouter provider
   * @returns {int|null} if the item has custom frequency caps, the longest period found in the list of caps.
                         if the item has no custom frequency caps, null
   * @memberof _ASRouter
   */
  getLongestPeriod(item) {
    if (!item.frequency || !item.frequency.custom) {
      return null;
    }
    return item.frequency.custom.sort((a, b) => b.period - a.period)[0].period;
  }

  /**
   * cleanupImpressions - this function cleans up obsolete impressions whenever
   * messages are refreshed or fetched. It will likely need to be more sophisticated in the future,
   * but the current behaviour for when both message impressions and provider impressions are
   * cleared is as follows (where `item` is either `message` or `provider`):
   *
   * 1. If the item id for a list of item impressions no longer exists in the ASRouter state, it
   *    will be cleared.
   * 2. If the item has time-bound frequency caps but no lifetime cap, any item impressions older
   *    than the longest time period will be cleared.
   */
  cleanupImpressions() {
    return this.setState(state => {
      const messageImpressions = this._cleanupImpressionsForItems(
        state,
        state.messages,
        "messageImpressions"
      );
      const groupImpressions = this._cleanupImpressionsForItems(
        state,
        state.groups,
        "groupImpressions"
      );
      return { messageImpressions, groupImpressions };
    });
  }

  /** _cleanupImpressionsForItems - Helper for cleanupImpressions - calculate the updated
  /*                                impressions object for the given items, then store it and return it
   *
   * @param {obj} state Reference to ASRouter internal state
   * @param {array} items Can be messages, providers or groups that we count impressions for
   * @param {string} impressionsString Key name for entry in state where impressions are stored
   */
  _cleanupImpressionsForItems(state, items, impressionsString) {
    const impressions = { ...state[impressionsString] };
    let needsUpdate = false;
    Object.keys(impressions).forEach(id => {
      const [item] = items.filter(x => x.id === id);
      // Don't keep impressions for items that no longer exist
      if (!item || !item.frequency || !Array.isArray(impressions[id])) {
        lazy.ASRouterPreferences.console.debug(
          "_cleanupImpressionsForItem: removing impressions for deleted or changed item: ",
          item
        );
        lazy.ASRouterPreferences.console.trace();
        delete impressions[id];
        needsUpdate = true;
        return;
      }
      if (!impressions[id].length) {
        return;
      }
      // If we don't want to store impressions older than the longest period
      if (item.frequency.custom && !item.frequency.lifetime) {
        lazy.ASRouterPreferences.console.debug(
          "_cleanupImpressionsForItem: removing impressions older than longest period for item: ",
          item
        );
        const now = Date.now();
        impressions[id] = impressions[id].filter(
          t => now - t < this.getLongestPeriod(item)
        );
        needsUpdate = true;
      }
    });
    if (needsUpdate) {
      this._storage.set(impressionsString, impressions);
    }
    return impressions;
  }

  handleMessageRequest({
    messages: candidates,
    triggerId,
    triggerParam,
    triggerContext,
    template,
    provider,
    ordered = false,
    returnAll = false,
  }) {
    let shouldCache;
    lazy.ASRouterPreferences.console.debug(
      "in handleMessageRequest, arguments = ",
      Array.from(arguments) // eslint-disable-line prefer-rest-params
    );
    lazy.ASRouterPreferences.console.trace();
    const messages =
      candidates ||
      this.state.messages.filter(m => {
        if (provider && m.provider !== provider) {
          lazy.ASRouterPreferences.console.debug(m.id, " filtered by provider");
          return false;
        }
        if (template && m.template !== template) {
          lazy.ASRouterPreferences.console.debug(m.id, " filtered by template");
          return false;
        }
        if (triggerId && !m.trigger) {
          lazy.ASRouterPreferences.console.debug(m.id, " filtered by trigger");
          return false;
        }
        if (triggerId && m.trigger.id !== triggerId) {
          lazy.ASRouterPreferences.console.debug(
            m.id,
            " filtered by triggerId"
          );
          return false;
        }
        if (!this.isUnblockedMessage(m)) {
          lazy.ASRouterPreferences.console.debug(
            m.id,
            " filtered because blocked"
          );
          return false;
        }
        if (!this.isBelowFrequencyCaps(m)) {
          lazy.ASRouterPreferences.console.debug(
            m.id,
            " filtered because capped"
          );
          return false;
        }

        if (shouldCache !== false) {
          shouldCache = JEXL_PROVIDER_CACHE.has(m.provider);
        }

        return true;
      });

    if (!messages.length) {
      return returnAll ? messages : null;
    }

    const context = this._getMessagesContext();

    // Find a message that matches the targeting context as well as the trigger context (if one is provided)
    // If no trigger is provided, we should find a message WITHOUT a trigger property defined.
    return lazy.ASRouterTargeting.findMatchingMessage({
      messages,
      trigger: triggerId && {
        id: triggerId,
        param: triggerParam,
        context: triggerContext,
      },
      context,
      onError: this._handleTargetingError,
      ordered,
      shouldCache,
      returnAll,
    });
  }

  setMessageById({ id, ...data }, force, browser) {
    return this.routeCFRMessage(this.getMessageById(id), browser, data, force);
  }

  blockMessageById(idOrIds) {
    lazy.ASRouterPreferences.console.debug(
      "blockMessageById called, idOrIds = ",
      idOrIds
    );
    lazy.ASRouterPreferences.console.trace();

    const idsToBlock = Array.isArray(idOrIds) ? idOrIds : [idOrIds];

    return this.setState(state => {
      const messageBlockList = [...state.messageBlockList];
      const messageImpressions = { ...state.messageImpressions };

      idsToBlock.forEach(id => {
        const message = state.messages.find(m => m.id === id);
        const idToBlock = message && message.campaign ? message.campaign : id;
        if (!messageBlockList.includes(idToBlock)) {
          messageBlockList.push(idToBlock);
        }

        // When a message is blocked, its impressions should be cleared as well
        delete messageImpressions[id];
      });

      this._storage.set("messageBlockList", messageBlockList);
      this._storage.set("messageImpressions", messageImpressions);
      return { messageBlockList, messageImpressions };
    });
  }

  unblockMessageById(idOrIds) {
    const idsToUnblock = Array.isArray(idOrIds) ? idOrIds : [idOrIds];

    return this.setState(state => {
      const messageBlockList = [...state.messageBlockList];
      idsToUnblock
        .map(id => state.messages.find(m => m.id === id))
        // Remove all `id`s (or `campaign`s for snippets) from the message
        // block list
        .forEach(message => {
          const idToUnblock =
            message && message.campaign ? message.campaign : message.id;
          messageBlockList.splice(messageBlockList.indexOf(idToUnblock), 1);
        });

      this._storage.set("messageBlockList", messageBlockList);
      return { messageBlockList };
    });
  }

  resetGroupsState() {
    const newGroupImpressions = {};
    for (let { id } of this.state.groups) {
      newGroupImpressions[id] = [];
    }
    // Update storage
    this._storage.set("groupImpressions", newGroupImpressions);
    return this.setState(({ groups }) => ({
      groupImpressions: newGroupImpressions,
    }));
  }

  resetMessageState() {
    const newMessageImpressions = {};
    for (let { id } of this.state.messages) {
      newMessageImpressions[id] = [];
    }
    // Update storage
    this._storage.set("messageImpressions", newMessageImpressions);
    return this.setState(() => ({
      messageImpressions: newMessageImpressions,
    }));
  }

  _validPreviewEndpoint(url) {
    try {
      const endpoint = new URL(url);
      if (!this.ALLOWLIST_HOSTS[endpoint.host]) {
        console.error(
          `The preview URL host ${endpoint.host} is not in the list of allowed hosts.`
        );
      }
      if (endpoint.protocol !== "https:") {
        console.error("The URL protocol is not https.");
      }
      return (
        endpoint.protocol === "https:" && this.ALLOWLIST_HOSTS[endpoint.host]
      );
    } catch (e) {
      return false;
    }
  }

  // Ensure we switch to the Onboarding message after RTAMO addon was installed
  _updateOnboardingState() {
    let addonInstallObs = (subject, topic) => {
      Services.obs.removeObserver(
        addonInstallObs,
        "webextension-install-notify"
      );
    };
    Services.obs.addObserver(addonInstallObs, "webextension-install-notify");
  }

  _loadSnippetsAllowHosts() {
    let additionalHosts = [];
    const allowPrefValue = Services.prefs.getStringPref(
      SNIPPETS_ENDPOINT_ALLOWLIST,
      ""
    );
    try {
      additionalHosts = JSON.parse(allowPrefValue);
    } catch (e) {
      if (allowPrefValue) {
        console.error(
          `Pref ${SNIPPETS_ENDPOINT_ALLOWLIST} value is not valid JSON`
        );
      }
    }

    if (!additionalHosts.length) {
      return DEFAULT_ALLOWLIST_HOSTS;
    }

    // If there are additional hosts we want to allow, add them as
    // `preview` so that the updateCycle is 0
    return additionalHosts.reduce(
      (allow_hosts, host) => {
        allow_hosts[host] = "preview";
        Services.console.logStringMessage(
          `Adding ${host} to list of allowed hosts.`
        );
        return allow_hosts;
      },
      { ...DEFAULT_ALLOWLIST_HOSTS }
    );
  }

  // To be passed to ASRouterTriggerListeners
  _triggerHandler(browser, trigger) {
    // Disable ASRouterTriggerListeners in kiosk mode.
    if (lazy.BrowserHandler.kiosk) {
      return Promise.resolve();
    }
    return this.sendTriggerMessage({ ...trigger, browser });
  }

  _removePreviewEndpoint(state) {
    state.providers = state.providers.filter(p => p.id !== "preview");
    return state;
  }

  addPreviewEndpoint(url, browser) {
    const providers = [...this.state.providers];
    if (
      this._validPreviewEndpoint(url) &&
      !providers.find(p => p.url === url)
    ) {
      // When you view a preview snippet we want to hide all real content -
      // sending EnterSnippetsPreviewMode puts this browser tab in that state.
      browser.sendMessageToActor("EnterSnippetsPreviewMode", {}, "ASRouter");
      providers.push({
        id: "preview",
        type: "remote",
        enabled: true,
        url,
        updateCycleInMs: 0,
      });
      return this.setState({ providers });
    }
    return Promise.resolve();
  }

  /**
   * forceAttribution - this function should only be called from within about:newtab#asrouter.
   * It forces the browser attribution to be set to something specified in asrouter admin
   * tools, and reloads the providers in order to get messages that are dependant on this
   * attribution data (see Return to AMO flow in bug 1475354 for example). Note - OSX and Windows only
   * @param {data} Object an object containing the attribtion data that came from asrouter admin page
   */
  async forceAttribution(data) {
    // Extract the parameters from data that will make up the referrer url
    const attributionData = AttributionCode.allowedCodeKeys
      .map(key => `${key}=${encodeURIComponent(data[key] || "")}`)
      .join("&");
    if (AppConstants.platform === "win") {
      // The whole attribution data is encoded (again) for windows
      await AttributionCode.writeAttributionFile(
        encodeURIComponent(attributionData)
      );
    } else if (AppConstants.platform === "macosx") {
      let appPath = lazy.MacAttribution.applicationPath;
      let attributionSvc = Cc["@mozilla.org/mac-attribution;1"].getService(
        Ci.nsIMacAttributionService
      );

      // The attribution data is treated as a url query for mac
      let referrer = `https://www.mozilla.org/anything/?${attributionData}`;

      // This sets the Attribution to be the referrer
      attributionSvc.setReferrerUrl(appPath, referrer, true);

      // Delete attribution data file
      await AttributionCode.deleteFileAsync();
    }

    // Clear cache call is only possible in a testing environment
    Services.env.set("XPCSHELL_TEST_PROFILE_DIR", "testing");

    // Clear and refresh Attribution, and then fetch the messages again to update
    AttributionCode._clearCache();
    await AttributionCode.getAttrDataAsync();
    await this._updateMessageProviders();
    return this.loadMessagesFromAllProviders();
  }

  async sendPBNewTabMessage({ tabId, hideDefault }) {
    let message = null;
    const PromoInfo = {
      FOCUS: { enabledPref: "browser.promo.focus.enabled" },
      VPN: { enabledPref: "browser.vpn_promo.enabled" },
      PIN: { enabledPref: "browser.promo.pin.enabled" },
    };
    await this.loadMessagesFromAllProviders();

    // If message has hideDefault property set to true
    // remove from state all pb_newtab messages with type default
    if (hideDefault) {
      await this.setState(state => ({
        messages: state.messages.filter(
          m => !(m.template === "pb_newtab" && m.type === "default")
        ),
      }));
    }

    // Remove from state pb_newtab messages with PromoType disabled
    await this.setState(state => ({
      messages: state.messages.filter(
        m =>
          !(
            m.template === "pb_newtab" &&
            !Services.prefs.getBoolPref(
              PromoInfo[m.content?.promoType]?.enabledPref,
              true
            )
          )
      ),
    }));

    const telemetryObject = { tabId };
    TelemetryStopwatch.start("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
    message = await this.handleMessageRequest({
      template: "pb_newtab",
    });
    TelemetryStopwatch.finish("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);

    // Format urls if any are defined
    ["infoLinkUrl"].forEach(key => {
      if (message?.content?.[key]) {
        message.content[key] = Services.urlFormatter.formatURL(
          message.content[key]
        );
      }
    });

    return { message };
  }

  async sendNewTabMessage({ endpoint, tabId, browser }) {
    let message;

    // Load preview endpoint for snippets if one is sent
    if (endpoint) {
      await this.addPreviewEndpoint(endpoint.url, browser);
    }

    // Load all messages
    await this.loadMessagesFromAllProviders();

    if (endpoint) {
      message = await this.handleMessageRequest({ provider: "preview" });

      // We don't want to cache preview messages, remove them after we selected the message to show
      if (message) {
        await this.setState(state => ({
          messages: state.messages.filter(m => m.id !== message.id),
        }));
      }
    } else {
      const telemetryObject = { tabId };
      TelemetryStopwatch.start("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
      message = await this.handleMessageRequest({ provider: "snippets" });
      TelemetryStopwatch.finish("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
    }

    return this.routeCFRMessage(message, browser, undefined, false);
  }

  _recordReachEvent(message) {
    const messageGroup = message.forReachEvent.group;
    // Events telemetry only accepts understores for the event `object`
    const underscored = messageGroup.split("-").join("_");
    const extra = { branches: message.branchSlug };
    Services.telemetry.recordEvent(
      REACH_EVENT_CATEGORY,
      REACH_EVENT_METHOD,
      underscored,
      message.experimentSlug,
      extra
    );
  }

  async sendTriggerMessage({ tabId, browser, ...trigger }) {
    await this.loadMessagesFromAllProviders();

    const telemetryObject = { tabId };
    TelemetryStopwatch.start("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
    // Return all the messages so that it can record the Reach event
    const messages =
      (await this.handleMessageRequest({
        triggerId: trigger.id,
        triggerParam: trigger.param,
        triggerContext: trigger.context,
        returnAll: true,
      })) || [];
    TelemetryStopwatch.finish("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);

    // Record the Reach event for all the messages with `forReachEvent`,
    // only send the first message without forReachEvent to the target
    const nonReachMessages = [];
    for (const message of messages) {
      if (message.forReachEvent) {
        if (!message.forReachEvent.sent) {
          this._recordReachEvent(message);
          message.forReachEvent.sent = true;
        }
      } else {
        nonReachMessages.push(message);
      }
    }

    if (nonReachMessages.length) {
      let featureId = nonReachMessages[0]._nimbusFeature;
      if (featureId) {
        lazy.NimbusFeatures[featureId].recordExposureEvent({ once: true });
      }
    }

    return this.routeCFRMessage(
      nonReachMessages[0] || null,
      browser,
      trigger,
      false
    );
  }

  async forceWNPanel(browser) {
    let win = browser.ownerGlobal;
    await lazy.ToolbarPanelHub.enableToolbarButton();

    win.PanelUI.showSubView(
      "PanelUI-whatsNew",
      win.document.getElementById("whats-new-menu-button")
    );

    let panel = win.document.getElementById("customizationui-widget-panel");
    // Set the attribute to keep the panel open
    panel.setAttribute("noautohide", true);
  }

  async closeWNPanel(browser) {
    let win = browser.ownerGlobal;
    let panel = win.document.getElementById("customizationui-widget-panel");
    // Set the attribute to allow the panel to close
    panel.setAttribute("noautohide", false);
    // Removing the button is enough to close the panel.
    await lazy.ToolbarPanelHub._hideToolbarButton(win);
  }

  async _onExperimentForceEnrolled(subject, topic, slug) {
    const experimentProvider = this.state.providers.find(
      p => p.id === "messaging-experiments"
    );
    if (!experimentProvider.enabled) {
      return;
    }

    const branch = lazy.ExperimentAPI.getActiveBranch({ slug });
    const features = branch.features ?? [branch.feature];
    const featureIds = features.map(feature => feature.featureId);

    this._onFeaturesUpdated(...featureIds);

    await this.loadMessagesFromAllProviders([experimentProvider]);
  }

  /**
   * Handle a change to the list of featureIds that the messaging-experiments
   * provider is watching.
   *
   * This normally occurs when ASRouter update message providers, which happens
   * every startup and when the messaging-experiment provider pref changes.
   *
   * On startup, |oldFeatures| will be an empty array and we will subscribe to
   * everything in |newFeatures|.
   *
   * When the pref changes, we unsubscribe from |oldFeatures - newFeatures| and
   * subscribe to |newFeatures - oldFeatures|. Features that are listed in both
   * sets do not have their subscription status changed. Pref changes are mostly
   * during unit tests.
   *
   * @param {string[]} oldFeatures The list of feature IDs we were previously
   *                               listening to for new experiments.
   * @param {string[]} newFeatures The list of feature IDs we are now listening
   *                               to for new experiments.
   */
  _onFeatureListChanged(oldFeatures, newFeatures) {
    for (const featureId of oldFeatures) {
      if (!newFeatures.includes(featureId)) {
        const listener = this._experimentChangedListeners.get(featureId);
        this._experimentChangedListeners.delete(featureId);
        lazy.NimbusFeatures[featureId].off(listener);
      }
    }

    const newlySubscribed = [];

    for (const featureId of newFeatures) {
      if (!oldFeatures.includes(featureId)) {
        const listener = () => this._onFeaturesUpdated(featureId);
        this._experimentChangedListeners.set(featureId, listener);
        lazy.NimbusFeatures[featureId].onUpdate(listener);

        newlySubscribed.push(featureId);
      }
    }

    // Check for any messages present in the newly subscribed to Nimbus features
    // so we can prefetch their remote images (if any).
    this._onFeaturesUpdated(...newlySubscribed);
  }

  /**
   * Handle updated experiment features.
   *
   * If there are messages for the feature, RemoteImages will prefetch any
   * images.
   *
   * @param {string[]} featureIds The feature IDs that have been updated.
   */
  _onFeaturesUpdated(...featureIds) {
    const messages = [];

    for (const featureId of featureIds) {
      const featureAPI = lazy.NimbusFeatures[featureId];
      // If there is no active experiment for the feature, this will return
      // null.
      if (lazy.ExperimentAPI.getExperimentMetaData({ featureId })) {
        // Otherwise, getAllVariables() will return the JSON blob for the
        // message.
        messages.push(featureAPI.getAllVariables());
      }
    }

    // We are not awaiting this because we want these images to load in the
    // background.
    if (messages.length) {
      lazy.RemoteImages.prefetchImagesFor(messages);
    }
  }

  async forcePBWindow(browser, msg) {
    const privateBrowserOpener = await new Promise((
      resolveOnContentBrowserCreated // wrap this in a promise to give back the right browser
    ) =>
      browser.ownerGlobal.openTrustedLinkIn(
        "about:privatebrowsing?debug",
        "window",
        {
          private: true,
          triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(
            {}
          ),
          csp: null,
          resolveOnContentBrowserCreated,
          opener: "devtools",
        }
      )
    );

    lazy.setTimeout(() => {
      // setTimeout is necessary to make sure the private browsing window has a chance to open before the message is sent
      privateBrowserOpener.browsingContext.currentWindowGlobal
        .getActor("AboutPrivateBrowsing")
        .sendAsyncMessage("ShowDevToolsMessage", msg);
    }, 100);

    return privateBrowserOpener;
  }
}

/**
 * ASRouter - singleton instance of _ASRouter that controls all messages
 * in the new tab page.
 */
const ASRouter = new _ASRouter();

const EXPORTED_SYMBOLS = ["_ASRouter", "ASRouter", "MessageLoaderUtils"];