refactor: share jst helpers

static/shared/broadcast.ts

@@ -0,0 +1,88 @@
+export interface ParsedClockTime {
+  hour: number;
+  minute: number;
+}
+
+export interface LocalClockTime {
+  dayIndex: number;
+  hour: number;
+  minute: number;
+  totalMinutes: number;
+}
+
+const jstOffsetMinutes = 9 * 60;
+
+const weekdayIndexes: Record<string, number> = {
+  sun: 0,
+  sunday: 0,
+  mon: 1,
+  monday: 1,
+  tue: 2,
+  tues: 2,
+  tuesday: 2,
+  wed: 3,
+  wednesday: 3,
+  thu: 4,
+  thur: 4,
+  thurs: 4,
+  thursday: 4,
+  fri: 5,
+  friday: 5,
+  sat: 6,
+  saturday: 6,
+};
+
+export const normalizeWeekday = (value: string | null): number | null => {
+  if (!value) return null;
+  const key = value.trim().toLowerCase().replace(/s$/, "");
+  const dayIndex = weekdayIndexes[key];
+  return typeof dayIndex === "number" ? dayIndex : null;
+};
+
+export const parseHHMM = (value: string | null): ParsedClockTime | null => {
+  if (!value) return null;
+  const match = value.trim().match(/^(\d{1,2}):(\d{2})$/);
+  if (!match) return null;
+  const hour = Number.parseInt(match[1], 10);
+  const minute = Number.parseInt(match[2], 10);
+  if (
+    Number.isNaN(hour) ||
+    Number.isNaN(minute) ||
+    hour < 0 ||
+    hour > 23 ||
+    minute < 0 ||
+    minute > 59
+  ) {
+    return null;
+  }
+  return { hour, minute };
+};
+
+export const isJstTimezone = (value: string | null): boolean => {
+  const normalized = (value ?? "").trim().toLowerCase();
+  if (!normalized) return true;
+  return normalized === "asia/tokyo" || normalized === "jst";
+};
+
+export const convertJstToLocalTime = (
+  dayIndex: number,
+  hour: number,
+  minute: number,
+  localOffsetMinutes: number,
+): LocalClockTime => {
+  const sourceMinutes = hour * 60 + minute;
+  const diff = jstOffsetMinutes - localOffsetMinutes;
+  const localTotal = sourceMinutes - diff;
+
+  const dayShift = Math.floor(localTotal / 1440);
+  const normalizedMinutes = ((localTotal % 1440) + 1440) % 1440;
+  const localHour = Math.floor(normalizedMinutes / 60);
+  const localMinute = normalizedMinutes % 60;
+
+  return {
+    dayIndex: (((dayIndex + dayShift) % 7) + 7) % 7,
+    hour: localHour,
+    minute: localMinute,
+    totalMinutes: localHour * 60 + localMinute,
+  };
+};