fix: add deterministic tiebreaker to RR host selection algorithm (calcom#28783)

* fix: add deterministic tiebreaker to RR host selection algorithm

* chore: cleanup comments

* Update packages/features/bookings/lib/getLuckyUser.integration-test.ts

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Sahitya Chandra <sahityajb@gmail.com>
Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: 3 people

packages/features/bookings/lib/getLuckyUser.integration-test.ts

@@ -441,7 +441,7 @@ describe("getOrderedListOfLuckyUsers Integration tests", () => {
     vi.setSystemTime("2024-11-14T00:00:13Z");
   });
 
-  it("should sort as per availableUsers if no other criteria like weight/priority/calibration (TODO: make it independent of availableUsers order)", async () => {
+  it("should sort by user id if no other criteria like weight/priority/calibration", async () => {
     const [host1, host2, host3] = await Promise.all([
       createHostWithBookings({
         user: { email: "test-user1@example.com" },
@@ -475,7 +475,9 @@ describe("getOrderedListOfLuckyUsers Integration tests", () => {
       routingFormResponse: null,
     });
 
-    expectLuckyUsers(luckyUsers, [user2, user1, user3]);
+    const expectedOrder = [user1, user2, user3].sort((a, b) => a.id - b.id)
+
+    expectLuckyUsers(luckyUsers, expectedOrder);
 
     const { users: luckyUsers2 } = await luckyUserService.getOrderedListOfLuckyUsers({
       availableUsers: [user3, user1, user2],
@@ -487,7 +489,7 @@ describe("getOrderedListOfLuckyUsers Integration tests", () => {
       allRRHosts: [],
       routingFormResponse: null,
     });
-    expectLuckyUsers(luckyUsers2, [user3, user1, user2]);
+    expectLuckyUsers(luckyUsers2, expectedOrder);
   });
 
   describe("should sort as per weights", () => {

packages/features/bookings/lib/getLuckyUser.ts

@@ -170,6 +170,7 @@ export class LuckyUserService implements ILuckyUserService {
     availableUsers,
     bookingsOfAvailableUsers,
     organizersWithLastCreated,
+    eventType,
   }: GetLuckyUserParams<T> & {
     bookingsOfAvailableUsers: PartialBooking[];
     organizersWithLastCreated: { id: number; bookings: { createdAt: Date }[] }[];
@@ -216,7 +217,7 @@ export class LuckyUserService implements ILuckyUserService {
     const leastRecentlyBookedUser = availableUsers.sort((a, b) => {
       if (userIdAndAtCreatedPair[a.id] > userIdAndAtCreatedPair[b.id]) return 1;
       else if (userIdAndAtCreatedPair[a.id] < userIdAndAtCreatedPair[b.id]) return -1;
-      else return 0;
+      else return eventType.isRRWeightsEnabled ? 0 : a.id - b.id;
     })[0];
 
     return leastRecentlyBookedUser;