1 files changed, 174 insertions, 0 deletions
diff --git a/browser/components/newtab/lib/MomentsPageHub.jsm b/browser/components/newtab/lib/MomentsPageHub.jsm
new file mode 100644
index 0000000000..e37d1df8b1
--- /dev/null
+++ b/browser/components/newtab/lib/MomentsPageHub.jsm
@@ -0,0 +1,174 @@
+/* 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 lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  setInterval: "resource://gre/modules/Timer.sys.mjs",
+  clearInterval: "resource://gre/modules/Timer.sys.mjs",
+});
+
+// Frequency at which to check for new messages
+const SYSTEM_TICK_INTERVAL = 5 * 60 * 1000;
+const HOMEPAGE_OVERRIDE_PREF = "browser.startup.homepage_override.once";
+
+// For the "reach" event of Messaging Experiments
+const REACH_EVENT_CATEGORY = "messaging_experiments";
+const REACH_EVENT_METHOD = "reach";
+// Note it's not "moments-page" as Telemetry Events only accepts understores
+// for the event `object`
+const REACH_EVENT_OBJECT = "moments_page";
+
+class _MomentsPageHub {
+  constructor() {
+    this.id = "moments-page-hub";
+    this.state = {};
+    this.checkHomepageOverridePref = this.checkHomepageOverridePref.bind(this);
+    this._initialized = false;
+  }
+
+  async init(
+    waitForInitialized,
+    { handleMessageRequest, addImpression, blockMessageById, sendTelemetry }
+  ) {
+    if (this._initialized) {
+      return;
+    }
+
+    this._initialized = true;
+    this._handleMessageRequest = handleMessageRequest;
+    this._addImpression = addImpression;
+    this._blockMessageById = blockMessageById;
+    this._sendTelemetry = sendTelemetry;
+
+    // Need to wait for ASRouter to initialize before trying to fetch messages
+    await waitForInitialized;
+
+    this.messageRequest({
+      triggerId: "momentsUpdate",
+      template: "update_action",
+    });
+
+    const _intervalId = lazy.setInterval(
+      () => this.checkHomepageOverridePref(),
+      SYSTEM_TICK_INTERVAL
+    );
+    this.state = { _intervalId };
+  }
+
+  _sendPing(ping) {
+    this._sendTelemetry({
+      type: "MOMENTS_PAGE_TELEMETRY",
+      data: { action: "moments_user_event", ...ping },
+    });
+  }
+
+  sendUserEventTelemetry(message) {
+    this._sendPing({
+      message_id: message.id,
+      bucket_id: message.id,
+      event: "MOMENTS_PAGE_SET",
+    });
+  }
+
+  /**
+   * If we don't have `expire` defined with the message it could be because
+   * it depends on user dependent parameters. Since the message matched
+   * targeting we calculate `expire` based on the current timestamp and the
+   * `expireDelta` which defines for how long it should be available.
+   * @param expireDelta {number} - Offset in milliseconds from the current date
+   */
+  getExpirationDate(expireDelta) {
+    return Date.now() + expireDelta;
+  }
+
+  executeAction(message) {
+    const { id, data } = message.content.action;
+    switch (id) {
+      case "moments-wnp":
+        const { url, expireDelta } = data;
+        let { expire } = data;
+        if (!expire) {
+          expire = this.getExpirationDate(expireDelta);
+        }
+        // In order to reset this action we can dispatch a new message that
+        // will overwrite the prev value with an expiration date from the past.
+        Services.prefs.setStringPref(
+          HOMEPAGE_OVERRIDE_PREF,
+          JSON.stringify({ message_id: message.id, url, expire })
+        );
+        // Add impression and block immediately after taking the action
+        this.sendUserEventTelemetry(message);
+        this._addImpression(message);
+        this._blockMessageById(message.id);
+        break;
+    }
+  }
+
+  _recordReachEvent(message) {
+    const extra = { branches: message.branchSlug };
+    Services.telemetry.recordEvent(
+      REACH_EVENT_CATEGORY,
+      REACH_EVENT_METHOD,
+      REACH_EVENT_OBJECT,
+      message.experimentSlug,
+      extra
+    );
+  }
+
+  async messageRequest({ triggerId, template }) {
+    const telemetryObject = { triggerId };
+    TelemetryStopwatch.start("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
+    const messages = await this._handleMessageRequest({
+      triggerId,
+      template,
+      returnAll: true,
+    });
+    TelemetryStopwatch.finish("MS_MESSAGE_REQUEST_TIME_MS", telemetryObject);
+
+    // Record the "reach" event for all the messages with `forReachEvent`,
+    // only execute action for the first message without forReachEvent.
+    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) {
+      this.executeAction(nonReachMessages[0]);
+    }
+  }
+
+  /**
+   * Pref is set via Remote Settings message. We want to continously
+   * monitor new messages that come in to ensure the one with the
+   * highest priority is set.
+   */
+  checkHomepageOverridePref() {
+    this.messageRequest({
+      triggerId: "momentsUpdate",
+      template: "update_action",
+    });
+  }
+
+  uninit() {
+    lazy.clearInterval(this.state._intervalId);
+    this.state = {};
+    this._initialized = false;
+  }
+}
+
+/**
+ * ToolbarBadgeHub - singleton instance of _ToolbarBadgeHub that can initiate
+ * message requests and render messages.
+ */
+const MomentsPageHub = new _MomentsPageHub();
+
+const EXPORTED_SYMBOLS = ["_MomentsPageHub", "MomentsPageHub"];