feat: next occurance utils

packages/common/src/core/index.ts

@@ -14,6 +14,7 @@ export * from "./shareEntityWithGroups";
 export * from "./unshareEntityWithGroups";
 export * from "./getEntityGroups";
 export * from "./getEntityThumbnailUrl";
+export * from "./nextOccuranceUtils";
 
 // For sme reason, if these are exported here,
 // they are not actually exported in the final package.

packages/common/src/core/nextOccuranceUtils.ts

@@ -0,0 +1,220 @@
+import { IHubSchedule } from "./types";
+
+// IHubSchedule utils
+
+/**
+ * Get the next daily occurance of the specified hour in the specified timezone
+ * @param hour takes an hour of the day between 0 and 23
+ * @param timezone takes a timezone string
+ * @returns a Date object representing the next daily occurance of the specified hour
+ */
+const getNextDailyOccurance = (hour: number, timezone: string): Date => {
+  validateHour(hour);
+
+  // Get the time in the specified timezone
+  const targetTime = getInitialTargetTime(timezone, "en-US");
+
+  if (targetTime.getHours() < hour) {
+    targetTime.setHours(hour, 0, 0, 0);
+  } else {
+    targetTime.setDate(targetTime.getDate() + 1);
+    targetTime.setHours(hour, 0, 0, 0);
+  }
+
+  return targetTime;
+};
+
+/**
+ * Get the next weekly occurance of the specified hour in the specified timezone
+ * @param hour takes an hour of the day between 0 and 23
+ * @param timezone takes a timezone string
+ * @param dayOfWeek takes a day of the week between 0 (Sunday) and 6 (Saturday)
+ * @returns a Date object representing the next weekly occurance of the specified hour
+ */
+const getNextWeeklyOccurance = (
+  hour: number,
+  timezone: string,
+  dayOfWeek: number
+): Date => {
+  validateHour(hour);
+  validateDayOfWeek(dayOfWeek);
+
+  // Get the time in the specified timezone
+  const targetTime = getInitialTargetTime(timezone, "en-US");
+
+  // Calculate the difference in days between today and the next occurrence of the specified day of the week
+  const currentDayOfWeek = targetTime.getDay();
+  let daysUntilNextEvent = (dayOfWeek - currentDayOfWeek + 7) % 7;
+
+  // If the event is today but the hour has already passed, schedule it for next week
+  if (daysUntilNextEvent === 0 && targetTime.getHours() >= hour) {
+    daysUntilNextEvent = 7;
+  }
+
+  // Set the event time to the next occurrence of the specified day at the given hour
+  targetTime.setDate(targetTime.getDate() + daysUntilNextEvent);
+  targetTime.setHours(hour, 0, 0, 0);
+
+  // Convert the event time to an ISO string
+  return targetTime;
+};
+
+/**
+ * Get the next monthly occurance of the specified hour in the specified timezone
+ * @param hour takes an hour of the day between 0 and 23
+ * @param timezone takes a timezone string
+ * @param dayOfMonth takes a day of the week between 1 and 28
+ * @returns a Date object representing the next monthly occurance of the specified hour
+ */
+const getNextMonthlyOccurance = (
+  hour: number,
+  timezone: string,
+  dayOfMonth: number
+): Date => {
+  validateHour(hour);
+  validateDayOfMonth(dayOfMonth);
+
+  // Get the time in the specified timezone
+  const targetTime = getInitialTargetTime(timezone, "en-US");
+
+  // Calculate the difference in days between today and the next occurrence of the specified day of the month
+  const currentDayOfMonth = targetTime.getDate();
+  let daysUntilNextEvent = dayOfMonth - currentDayOfMonth;
+
+  // If the event is today but the hour has already passed, schedule it for next month
+  if (daysUntilNextEvent === 0 && targetTime.getHours() >= hour) {
+    daysUntilNextEvent = 0;
+    targetTime.setMonth(targetTime.getMonth() + 1);
+  } else if (daysUntilNextEvent < 0) {
+    // If the day of the month has already passed, schedule it for next month
+    targetTime.setMonth(targetTime.getMonth() + 1);
+    targetTime.setDate(dayOfMonth);
+  } else {
+    // Set the event time to the next occurrence of the specified day at the given hour
+    targetTime.setDate(dayOfMonth);
+  }
+
+  targetTime.setHours(hour, 0, 0, 0);
+
+  // Convert the event time to an ISO string
+  return targetTime;
+};
+
+/**
+ * Get the next yearly occurance of the specified hour in the specified timezone
+ * @param hour takes an hour of the day between 0 and 23
+ * @param timezone takes a timezone string
+ * @param dayOfMonth takes a day of the week between 1 and 28
+ * @param month takes a month of the year between 0 and 11
+ * @returns a Date object representing the next yearly occurance of the specified hour
+ */
+const getNextYearlyOccurance = (
+  hour: number,
+  timezone: string,
+  dayOfMonth: number,
+  month: number
+): Date => {
+  validateHour(hour);
+  validateDayOfMonth(dayOfMonth);
+  validateMonth(month);
+
+  // Get the time in the specified timezone
+  const targetTime = getInitialTargetTime(timezone, "en-US");
+
+  // Calculate the next occurrence of the specified month and day
+  const currentMonth = targetTime.getMonth();
+  const currentDayOfMonth = targetTime.getDate();
+  const currentYear = targetTime.getFullYear();
+
+  if (
+    currentMonth > month ||
+    (currentMonth === month &&
+      (currentDayOfMonth > dayOfMonth ||
+        (currentDayOfMonth === dayOfMonth && targetTime.getHours() >= hour)))
+  ) {
+    // If the specified month and day have already passed this year, schedule it for next year
+    targetTime.setFullYear(currentYear + 1);
+  }
+  targetTime.setMonth(month);
+  targetTime.setDate(dayOfMonth);
+  targetTime.setHours(hour, 0, 0, 0);
+
+  // Convert the event time to an ISO string
+  return targetTime;
+};
+
+/**
+ * Get the next occurance of the specified schedule
+ * @param schedule takes an IHubSchedule object
+ * @returns a Date object representing the next occurance of the specified schedule
+ */
+export const getNextOccurance = (schedule: IHubSchedule): Date => {
+  if (schedule.mode === "scheduled") {
+    switch (schedule.cadence) {
+      case "daily":
+        return getNextDailyOccurance(schedule.hour, schedule.timezone);
+      case "weekly":
+        return getNextWeeklyOccurance(
+          schedule.hour,
+          schedule.timezone,
+          schedule.day
+        );
+      case "monthly":
+        return getNextMonthlyOccurance(
+          schedule.hour,
+          schedule.timezone,
+          schedule.date
+        );
+      case "yearly":
+        return getNextYearlyOccurance(
+          schedule.hour,
+          schedule.timezone,
+          schedule.date,
+          schedule.month
+        );
+      default:
+        throw new Error("Invalid cadence");
+    }
+  } else {
+    // If the schedule mode is not "scheduled", return undefined because it is either "automatic" or "manual"
+    return undefined;
+  }
+};
+
+/****** REPEATED CODE ******/
+const getInitialTargetTime = (timezone: string, locale: string): Date => {
+  const now = new Date();
+  const utcOffset = now.getTimezoneOffset() * 60000;
+  const localTime = new Date(now.getTime() + utcOffset);
+  const targetTime = new Date(
+    localTime.toLocaleString(locale, { timeZone: timezone })
+  );
+  return targetTime;
+};
+
+/****** VALIDATION ******/
+const validateHour = (hour: number): void => {
+  if (hour < 0 || hour > 23) {
+    throw new Error("Hour must be between 0 and 23");
+  }
+};
+
+const validateDayOfWeek = (dayOfWeek: number): void => {
+  if (dayOfWeek < 0 || dayOfWeek > 6) {
+    throw new Error(
+      "Day of the week must be between 0 (Sunday) and 6 (Saturday)"
+    );
+  }
+};
+
+const validateMonth = (month: number): void => {
+  if (month < 0 || month > 11) {
+    throw new Error("Month must be between 0 and 11");
+  }
+};
+
+const validateDayOfMonth = (dayOfMonth: number): void => {
+  if (dayOfMonth < 1 || dayOfMonth > 28) {
+    throw new Error("Day of the month must be between 1 and 28");
+  }
+};