1 files changed, 78 insertions, 0 deletions
diff --git a/services/sync/modules/stages/declined.sys.mjs b/services/sync/modules/stages/declined.sys.mjs
new file mode 100644
index 0000000000..2c74aab117
--- /dev/null
+++ b/services/sync/modules/stages/declined.sys.mjs
@@ -0,0 +1,78 @@
+/* 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/. */
+
+/**
+ * This file contains code for maintaining the set of declined engines,
+ * in conjunction with EngineManager.
+ */
+
+import { Log } from "resource://gre/modules/Log.sys.mjs";
+
+import { CommonUtils } from "resource://services-common/utils.sys.mjs";
+import { Observers } from "resource://services-common/observers.sys.mjs";
+
+export var DeclinedEngines = function (service) {
+  this._log = Log.repository.getLogger("Sync.Declined");
+  this._log.manageLevelFromPref("services.sync.log.logger.declined");
+
+  this.service = service;
+};
+
+DeclinedEngines.prototype = {
+  updateDeclined(meta, engineManager = this.service.engineManager) {
+    let enabled = new Set(engineManager.getEnabled().map(e => e.name));
+    let known = new Set(engineManager.getAll().map(e => e.name));
+    let remoteDeclined = new Set(meta.payload.declined || []);
+    let localDeclined = new Set(engineManager.getDeclined());
+
+    this._log.debug(
+      "Handling remote declined: " + JSON.stringify([...remoteDeclined])
+    );
+    this._log.debug(
+      "Handling local declined: " + JSON.stringify([...localDeclined])
+    );
+
+    // Any engines that are locally enabled should be removed from the remote
+    // declined list.
+    //
+    // Any engines that are locally declined should be added to the remote
+    // declined list.
+    let newDeclined = CommonUtils.union(
+      localDeclined,
+      CommonUtils.difference(remoteDeclined, enabled)
+    );
+
+    // If our declined set has changed, put it into the meta object and mark
+    // it as changed.
+    let declinedChanged = !CommonUtils.setEqual(newDeclined, remoteDeclined);
+    this._log.debug("Declined changed? " + declinedChanged);
+    if (declinedChanged) {
+      meta.changed = true;
+      meta.payload.declined = [...newDeclined];
+    }
+
+    // Update the engine manager regardless.
+    engineManager.setDeclined(newDeclined);
+
+    // Any engines that are locally known, locally disabled, and not remotely
+    // or locally declined, are candidates for enablement.
+    let undecided = CommonUtils.difference(
+      CommonUtils.difference(known, enabled),
+      newDeclined
+    );
+    if (undecided.size) {
+      let subject = {
+        declined: newDeclined,
+        enabled,
+        known,
+        undecided,
+      };
+      CommonUtils.nextTick(() => {
+        Observers.notify("weave:engines:notdeclined", subject);
+      });
+    }
+
+    return declinedChanged;
+  },
+};