Bug 1932183 – Pass followed sections to merino. r=home-newtab-reviewers,npypchenko

Differential Revision: https://phabricator.services.mozilla.com/D231758

browser/components/newtab/lib/ActivityStream.sys.mjs

@@ -488,6 +488,13 @@ export const PREFS_CONFIG = new Map([
       value: true,
     },
   ],
+  [
+    "discoverystream.sections.following",
+    {
+      title: "A comma-separated list of strings of followed section topics",
+      value: "",
+    },
+  ],
   [
     "discoverystream.spoc-positions",
     {

browser/components/newtab/lib/DiscoveryStreamFeed.sys.mjs

@@ -119,6 +119,7 @@ const PREF_CONTEXTUAL_CONTENT_FAKESPOT_CTA_URL =
   "discoverystream.contextualContent.fakespot.ctaUrl";
 
 const PREF_SECTIONS_ENABLED = "discoverystream.sections.enabled";
+const PREF_SECTIONS_FOLLOWING = "discoverystream.sections.following";
 
 let getHardcodedLayout;
 
@@ -1814,12 +1815,32 @@ export class DiscoveryStreamFeed {
         PREF_MERINO_FEED_EXPERIMENT
       );
 
+      // Raw string of followed topics, ex: "entertainment, news"
+      const followedSectionsString = prefs[PREF_SECTIONS_FOLLOWING];
+
+      // Format followed sections into desired JSON shape for merino:
+      // {
+      //   "sectionId": "business",
+      //   "isFollowed": true,
+      //   "isBlocked": false
+      // }
+      const followedSections = followedSectionsString
+        ? followedSectionsString.split(",").map(s => s.trim())
+        : [];
+
+      const sections = followedSections.map(section => ({
+        sectionId: section,
+        isFollowed: true,
+        isBlocked: false,
+      }));
+
       headers.append("content-type", "application/json");
       let body = {
         ...(prefMerinoFeedExperiment ? this.getExperimentInfo() : {}),
         locale: this.locale,
         region: this.region,
         topics,
+        sections,
       };
 
       const sectionsEnabled = prefs[PREF_SECTIONS_ENABLED];