From 2ef0b81743a9840220888020157064a2b76539b6 Mon Sep 17 00:00:00 2001
From: Carlos Valente <carlosvalente@pm.me>
Date: Tue, 3 Mar 2026 20:44:36 +0100
Subject: [PATCH] refactor: extract midnight cross rules

---
 .../src/services/__tests__/timerUtils.test.ts | 22 ++++++++++++++++++-
 apps/server/src/services/timerUtils.ts        | 11 +++++++++-
 apps/server/src/stores/runtimeState.ts        |  5 +++--
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/apps/server/src/services/__tests__/timerUtils.test.ts b/apps/server/src/services/__tests__/timerUtils.test.ts
index 7b6d37c04..792cd3021 100644
--- a/apps/server/src/services/__tests__/timerUtils.test.ts
+++ b/apps/server/src/services/__tests__/timerUtils.test.ts
@@ -1,5 +1,5 @@
 import { dayInMs, MILLIS_PER_HOUR, MILLIS_PER_MINUTE, MILLIS_PER_SECOND, millisToString } from 'ontime-utils';
-import { EndAction, Playback, TimeStrategy, TimerPhase, TimerType } from 'ontime-types';
+import { EndAction, Playback, TimeOfDay, TimeStrategy, TimerPhase, TimerType } from 'ontime-types';
 
 import {
   findDayOffset,
@@ -7,6 +7,7 @@ import {
   getExpectedFinish,
   getRuntimeOffset,
   getTimerPhase,
+  hasCrossedMidnight,
   normaliseEndTime,
   skippedOutOfEvent,
 } from '../timerUtils.js';
@@ -537,6 +538,25 @@ describe('getExpectedFinish() and getCurrentTime() combined', () => {
   });
 });
 
+describe('hasCrossedMidnight()', () => {
+  it('returns true when clock wraps from late to early', () => {
+    const previous = (23 * MILLIS_PER_HOUR + 59 * MILLIS_PER_MINUTE) as TimeOfDay; // 23:59
+    const current = (1 * MILLIS_PER_MINUTE) as TimeOfDay; // 00:01
+    expect(hasCrossedMidnight(previous, current)).toBe(true);
+  });
+
+  it('returns false when clock moves forward on the same day', () => {
+    const previous = (10 * MILLIS_PER_HOUR) as TimeOfDay; // 10:00
+    const current = (10 * MILLIS_PER_HOUR + 5 * MILLIS_PER_MINUTE) as TimeOfDay; // 10:05
+    expect(hasCrossedMidnight(previous, current)).toBe(false);
+  });
+
+  it('returns false when clock value is unchanged', () => {
+    const time = (15 * MILLIS_PER_HOUR) as TimeOfDay; // 15:00
+    expect(hasCrossedMidnight(time, time)).toBe(false);
+  });
+});
+
 describe('skippedOutOfEvent()', () => {
   const testSkipLimit = 32;
   it('does not consider an event end as a skip', () => {
diff --git a/apps/server/src/services/timerUtils.ts b/apps/server/src/services/timerUtils.ts
index cf4ba87e2..aae618d1b 100644
--- a/apps/server/src/services/timerUtils.ts
+++ b/apps/server/src/services/timerUtils.ts
@@ -1,4 +1,4 @@
-import { Day, MaybeNumber, TimerPhase } from 'ontime-types';
+import { Day, MaybeNumber, TimeOfDay, TimerPhase } from 'ontime-types';
 import { checkIsNow, dayInMs, isPlaybackActive, MILLIS_PER_HOUR } from 'ontime-utils';
 
 import type { RuntimeState } from '../stores/runtimeState.js';
@@ -8,6 +8,15 @@ import type { RuntimeState } from '../stores/runtimeState.js';
  */
 export const normaliseEndTime = (start: number, end: number) => (end < start ? end + dayInMs : end);
 
+/**
+ * Checks whether the local wall clock wrapped into a new day
+ * This currently uses a simple wrap heuristic and is centralized
+ * so day-boundary behavior can be evolved in one place later.
+ */
+export function hasCrossedMidnight(previous: TimeOfDay, current: TimeOfDay): boolean {
+  return previous > current;
+}
+
 /**
  * Calculates expected finish time of a running timer
  * @param {RuntimeState} state runtime state
diff --git a/apps/server/src/stores/runtimeState.ts b/apps/server/src/stores/runtimeState.ts
index 9775b28d4..26ac65fa1 100644
--- a/apps/server/src/stores/runtimeState.ts
+++ b/apps/server/src/stores/runtimeState.ts
@@ -35,6 +35,7 @@ import {
   getExpectedFinish,
   getRuntimeOffset,
   getTimerPhase,
+  hasCrossedMidnight,
 } from '../services/timerUtils.js';
 import { loadRoll, normaliseRollStart } from '../services/rollUtils.js';
 import { timerConfig } from '../setup/config.js';
@@ -555,8 +556,8 @@ export function update(): UpdateResult {
 
   // 2. are we waiting to roll?
   if (runtimeState.timer.playback === Playback.Roll && runtimeState.timer.secondaryTimer !== null) {
-    const hasCrossedMidnight = previousClock > now;
-    return updateIfWaitingToRoll(hasCrossedMidnight);
+    const clockHasCrossedMidnight = hasCrossedMidnight(previousClock, now);
+    return updateIfWaitingToRoll(clockHasCrossedMidnight);
   }
 
   // 3. at this point we know that we are playing an event