feat(core): add outsideOfficeHours

README.md

@@ -22,10 +22,14 @@ npm install --save is-office-hours
 
 ## :memo: Usage
 
-Always `false` on Saturday and Sunday, `true` from 9:00am until 4:59pm weekdays.
-Does not take into account public holidays.
+### isOfficeHours
+
+Returns `true` if the provided `Date` falls within Monday to Friday 9:00am to
+4:59pm.
 
 ```js
+import { isOfficeHours } from 'is-office-hours';
+
 isOfficeHours(new Date('2019-03-04T08:59:59.000Z'));
 // false
 isOfficeHours(new Date('2019-03-04T09:00:00.000Z'));
@@ -39,3 +43,32 @@ isOfficeHours(new Date('2019-03-04T17:00:00.000Z'));
 isOfficeHours(new Date('2019-03-04T17:01:00.000Z'));
 // false
 ```
+
+### outsideOfficeHours
+
+If the provided date falls within Office Hours, a new date is returned with the
+time adjusted to fall outside Office Hours. If the provided date falls outside
+Office Hours, it is returned unchanged.
+
+The provided date is never mutated.
+
+```js
+import { outsideOfficeHours } from 'is-office-hours';
+
+outsideOfficeHours(new Date('2019-03-04T09:00:00.000Z'));
+// Date(2019-03-04T18:00:00.000Z)
+outsideOfficeHours(new Date('2019-03-04T10:00:00.000Z'));
+// Date(2019-03-04T18:37:29.000Z)
+outsideOfficeHours(new Date('2019-03-04T11:00:00.000Z'));
+// Date(2019-03-04T19:14:59.000Z)
+outsideOfficeHours(new Date('2019-03-04T12:00:00.000Z'));
+// Date(2019-03-04T19:52:29.000Z)
+outsideOfficeHours(new Date('2019-03-04T13:00:00.000Z'));
+// Date(2019-03-04T20:29:59.000Z)
+outsideOfficeHours(new Date('2019-03-04T14:00:00.000Z'));
+// Date(2019-03-04T21:07:29.000Z)
+outsideOfficeHours(new Date('2019-03-04T15:00:00.000Z'));
+// Date(2019-03-04T21:44:59.000Z)
+outsideOfficeHours(new Date('2019-03-04T16:00:00.000Z'));
+// Date(2019-03-04T22:22:29.000Z)
+```

src/index.ts

@@ -1,4 +1,2 @@
-const isWorkingDay = (date: Date) => date.getDay() >= 1 && date.getDay() <= 5;
-
-export const isOfficeHours = (date: Date): boolean =>
-  isWorkingDay(date) && date.getHours() >= 9 && date.getHours() < 17;
+export { isOfficeHours } from './is-office-hours';
+export { outsideOfficeHours } from './outside-office-hours';

src/index.spec.ts → src/is-office-hours.spec.ts

@@ -29,17 +29,11 @@ const checkDate = (isoDate: string, isoTime: string) =>
 
 [['Saturday', '2019-03-09'], ['Sunday', '2019-03-10']].forEach(
   ([restDay, isoDate]) => {
-    it(`Returns false until 9:00am  ${restDay}`, () => {
+    it(`Returns false on ${restDay}`, () => {
       expect(checkDate(isoDate, '08:59:59')).toBeFalse();
-    });
-
-    it(`Returns false between 9:00am and 4:59pm ${restDay}`, () => {
       expect(checkDate(isoDate, '09:00:00')).toBeFalse();
       expect(checkDate(isoDate, '09:01:00')).toBeFalse();
       expect(checkDate(isoDate, '16:59:59')).toBeFalse();
-    });
-
-    it(`Returns false from 5:00pm  ${restDay}`, () => {
       expect(checkDate(isoDate, '17:00:00')).toBeFalse();
       expect(checkDate(isoDate, '17:01:00')).toBeFalse();
     });

src/is-office-hours.ts

@@ -0,0 +1,16 @@
+const isWorkingDay = (day: number) => day >= 1 && day <= 5;
+
+/** @member hour @member minute @member second */
+export type Time = [number, number, number];
+
+export const stintStart: Time = [9, 0, 0];
+export const stintEnd: Time = [16, 59, 59];
+
+/**
+ * Returns `true` if the provided `Date` falls within Monday to Friday 9:00am to
+ * 4:59pm.
+ */
+export const isOfficeHours = (date: Date): boolean =>
+  isWorkingDay(date.getDay()) &&
+  date.getHours() >= stintStart[0] &&
+  date.getHours() <= stintEnd[0];

src/lib/pad.ts

@@ -0,0 +1 @@
+export const pad = (n: number) => (n < 10 ? `0${n}` : `${n}`);

src/lib/range.ts

@@ -0,0 +1,7 @@
+export const range = (floor: number, ceiling: number) => {
+  const array = [];
+  while (floor <= ceiling) {
+    array.push(floor++);
+  }
+  return array;
+};

src/outside-office-hours.spec.ts

@@ -0,0 +1,41 @@
+import 'expect-more-jest';
+import { outsideOfficeHours } from './';
+import { pad } from './lib/pad';
+import { range } from './lib/range';
+
+describe('Dates during office hours', () => {
+  range(9, 16).forEach((hour) => {
+    range(0, 59).forEach((minute) => {
+      const eveStart = new Date('2019-03-04T18:00:00.000Z');
+      const eveEnd = new Date('2019-03-04T22:59:59.000Z');
+      const iso8601 = `2019-03-04T${pad(hour)}:${pad(minute)}:00.000Z`;
+      const date = new Date(iso8601);
+      const epoch = date.getTime();
+      const nextDate = outsideOfficeHours(date);
+
+      it(`Moves ${iso8601}`, () => {
+        expect(nextDate.getTime()).toBeLessThanOrEqual(eveEnd.getTime());
+        expect(nextDate.getTime()).toBeGreaterThanOrEqual(eveStart.getTime());
+      });
+
+      it('Does not mutate the original Date', () => {
+        expect(date.getTime()).toEqual(epoch);
+      });
+    });
+  });
+});
+
+describe('Dates outside office hours', () => {
+  range(0, 8)
+    .concat(range(17, 23))
+    .forEach((hour) => {
+      range(0, 59).forEach((minute) => {
+        const iso8601 = `2019-03-04T${pad(hour)}:${pad(minute)}:00.000Z`;
+        const date = new Date(iso8601);
+
+        it(`Leaves ${iso8601} untouched`, () => {
+          expect(outsideOfficeHours(date)).toBe(date);
+        });
+      });
+    });
+});

src/outside-office-hours.ts

@@ -0,0 +1,61 @@
+import { isOfficeHours, stintEnd, stintStart, Time } from './is-office-hours';
+
+const getPercentOfPart = (part: number, whole: number) => (part / whole) * 100;
+
+const getPartFromPercent = (percent: number, whole: number) =>
+  whole * (percent / 100);
+
+const getMsSinceMidnight = ([hours, minutes, seconds]: Time) => {
+  const date = new Date(0);
+  date.setHours(hours);
+  date.setMinutes(minutes);
+  date.setSeconds(seconds);
+  return date.getTime();
+};
+
+const getTimeFromDate = (date: Date): Time => [
+  date.getHours(),
+  date.getMinutes(),
+  date.getSeconds()
+];
+
+const getDateWithTime = (date: Date, [hours, minutes, seconds]: Time) => {
+  const nextDate = new Date(date.getTime());
+  nextDate.setHours(hours);
+  nextDate.setMinutes(minutes);
+  nextDate.setSeconds(seconds);
+  return nextDate;
+};
+
+const getMsBetween = (start: Time, end: Time) =>
+  getMsSinceMidnight(end) - getMsSinceMidnight(start);
+
+const eveningStart: Time = [18, 0, 0];
+const eveningEnd: Time = [22, 59, 59];
+const eveningLength = getMsBetween(eveningStart, eveningEnd);
+const stintLength = getMsBetween(stintStart, stintEnd);
+const eveningStartMs = getMsSinceMidnight(eveningStart);
+const stintStartMs = getMsSinceMidnight(stintStart);
+
+/**
+ * If the provided `Date` falls within Office Hours, a new `Date` is returned
+ * with the time adjusted to fall outside Office Hours. If the provided `Date`
+ * falls outside Office Hours, it is returned unchanged.
+ *
+ * The provided `Date` is never mutated.
+ */
+export const outsideOfficeHours = (date: Date): Date => {
+  if (isOfficeHours(date)) {
+    const eventTime = getTimeFromDate(date);
+    const eventStartMs = getMsSinceMidnight(eventTime);
+    const eventDistance = eventStartMs - stintStartMs;
+    if (eventDistance === 0) {
+      return getDateWithTime(date, eveningStart);
+    }
+    const eventPercent = getPercentOfPart(eventDistance, stintLength);
+    const eveningDistance = getPartFromPercent(eventPercent, eveningLength);
+    const nextDate = new Date(eveningDistance + eveningStartMs);
+    return getDateWithTime(date, getTimeFromDate(nextDate));
+  }
+  return date;
+};