extract active maintenance window check

server/src/utils/maintenanceWindow.ts

@@ -0,0 +1,28 @@
+import type { MaintenanceWindow } from "@/types/index.js";
+
+export const isWindowActive = (window: MaintenanceWindow, now: Date = new Date()): boolean => {
+	if (!window.active) {
+		return false;
+	}
+
+	const start = new Date(window.start);
+	const end = new Date(window.end);
+	const repeatInterval = window.repeat || 0;
+
+	if (start <= now && end >= now) {
+		return true;
+	}
+
+	// For a recurring window whose first occurrence is in the past,
+	// advance start/end by the repeat interval until we either catch
+	// an occurrence covering `now` or move past it.
+	while (start < now && repeatInterval !== 0) {
+		start.setTime(start.getTime() + repeatInterval);
+		end.setTime(end.getTime() + repeatInterval);
+		if (start <= now && end >= now) {
+			return true;
+		}
+	}
+
+	return false;
+};