Add UTC support to date add/subtract utilities

This commit update all date addition/subtraction utilities to optionally
support perfoming the calculation with UTC dates, which ignores
Daylight Saving Time.

app/assets/javascripts/lib/utils/datetime_utility.js

@@ -676,69 +676,127 @@ export const secondsToHours = (offset) => {
 };
 
 /**
- * Returns the date n days after the date provided
+ * Returns the date `n` days after the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfDays number of days after
- * @return {Date} the date following the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
+ * @return {Date} A `Date` object `n` days after the provided `Date`
  */
-export const nDaysAfter = (date, numberOfDays) =>
-  new Date(newDate(date)).setDate(date.getDate() + numberOfDays);
+export const nDaysAfter = (date, numberOfDays, { utc = false } = {}) => {
+  const clone = newDate(date);
+
+  const cloneValue = utc
+    ? clone.setUTCDate(date.getUTCDate() + numberOfDays)
+    : clone.setDate(date.getDate() + numberOfDays);
+
+  return new Date(cloneValue);
+};
 
 /**
- * Returns the date n days before the date provided
+ * Returns the date `n` days before the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfDays number of days before
- * @return {Date} the date preceding the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ * @return {Date} A `Date` object `n` days before the provided `Date`
  */
-export const nDaysBefore = (date, numberOfDays) => nDaysAfter(date, -numberOfDays);
+export const nDaysBefore = (date, numberOfDays, options) =>
+  nDaysAfter(date, -numberOfDays, options);
 
 /**
- * Returns the date n weeks after the date provided
+ * Returns the date `n` weeks after the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfWeeks number of weeks after
- * @return {Date} the date following the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
+ * @return {Date} A `Date` object `n` weeks after the provided `Date`
  */
-export const nWeeksAfter = (date, numberOfWeeks) =>
-  new Date(newDate(date)).setDate(date.getDate() + DAYS_IN_WEEK * numberOfWeeks);
+export const nWeeksAfter = (date, numberOfWeeks, options) =>
+  nDaysAfter(date, DAYS_IN_WEEK * numberOfWeeks, options);
 
 /**
- * Returns the date n weeks before the date provided
+ * Returns the date `n` weeks before the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfWeeks number of weeks before
- * @return {Date} the date following the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
+ * @return {Date} A `Date` object `n` weeks before the provided `Date`
  */
-export const nWeeksBefore = (date, numberOfWeeks) => nWeeksAfter(date, -numberOfWeeks);
+export const nWeeksBefore = (date, numberOfWeeks, options) =>
+  nWeeksAfter(date, -numberOfWeeks, options);
 
 /**
- * Returns the date n months after the date provided
+ * Returns the date `n` months after the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfMonths number of months after
- * @return {Date} the date following the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
+ * @return {Date} A `Date` object `n` months after the provided `Date`
  */
-export const nMonthsAfter = (date, numberOfMonths) =>
-  new Date(newDate(date)).setMonth(date.getMonth() + numberOfMonths);
+export const nMonthsAfter = (date, numberOfMonths, { utc = false } = {}) => {
+  const clone = newDate(date);
+
+  const cloneValue = utc
+    ? clone.setUTCMonth(date.getUTCMonth() + numberOfMonths)
+    : clone.setMonth(date.getMonth() + numberOfMonths);
+
+  return new Date(cloneValue);
+};
 
 /**
- * Returns the date n months before the date provided
+ * Returns the date `n` months before the date provided
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfMonths number of months before
- * @return {Date} the date preceding the date provided
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
+ * @return {Date} A `Date` object `n` months before the provided `Date`
  */
-export const nMonthsBefore = (date, numberOfMonths) => nMonthsAfter(date, -numberOfMonths);
+export const nMonthsBefore = (date, numberOfMonths, options) =>
+  nMonthsAfter(date, -numberOfMonths, options);
 
 /**
  * Returns the date after the date provided
  *
  * @param {Date} date the initial date
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC dates.
+ * This will cause Daylight Saving Time to be ignored. Defaults to `false`
+ * if not provided, which causes the calculation to be performed in the
+ * user's timezone.
+ *
  * @return {Date} the date following the date provided
  */
-export const dayAfter = (date) => new Date(newDate(date).setDate(date.getDate() + 1));
+export const dayAfter = (date, options) => nDaysAfter(date, 1, options);
 
 /**
  * Mimics the behaviour of the rails distance_of_time_in_words function
@@ -933,3 +991,22 @@ export const isToday = (date) => {
     date.getFullYear() === today.getFullYear()
   );
 };
+
+/**
+ * Returns the start of the provided day
+ *
+ * @param {Object} [options={}] Additional options for this calculation
+ * @param {boolean} [options.utc=false] Perform the calculation using UTC time.
+ * If `true`, the time returned will be midnight UTC. If `false` (the default)
+ * the time returned will be midnight in the user's local time.
+ *
+ * @returns {Date} A new `Date` object that represents the start of the day
+ * of the provided date
+ */
+export const getStartOfDay = (date, { utc = false } = {}) => {
+  const clone = newDate(date);
+
+  const cloneValue = utc ? clone.setUTCHours(0, 0, 0, 0) : clone.setHours(0, 0, 0, 0);
+
+  return new Date(cloneValue);
+};

ee/app/assets/javascripts/oncall_schedules/components/oncall_schedule.vue

@@ -76,7 +76,7 @@ export default {
       query: getShiftsForRotations,
       variables() {
         const startsAt = this.timeframeStartDate;
-        const endsAt = new Date(nWeeksAfter(startsAt, 2));
+        const endsAt = nWeeksAfter(startsAt, 2);
 
         return {
           projectPath: this.projectPath,
@@ -116,7 +116,7 @@ export default {
         case PRESET_TYPES.WEEKS: {
           const firstDayOfTheLastWeek = this.timeframe[this.timeframe.length - 1];
           const firstDayOfTheNextTimeframe = nWeeksAfter(firstDayOfTheLastWeek, 1);
-          const lastDayOfTimeframe = nDaysBefore(new Date(firstDayOfTheNextTimeframe), 1);
+          const lastDayOfTimeframe = nDaysBefore(firstDayOfTheNextTimeframe, 1);
 
           return `${formatDate(this.timeframe[0], 'mmmm d')} - ${formatDate(
             lastDayOfTimeframe,
@@ -142,10 +142,10 @@ export default {
     updateToViewPreviousTimeframe() {
       switch (this.presetType) {
         case PRESET_TYPES.DAYS:
-          this.timeframeStartDate = new Date(nDaysBefore(this.timeframeStartDate, 1));
+          this.timeframeStartDate = nDaysBefore(this.timeframeStartDate, 1);
           break;
         case PRESET_TYPES.WEEKS:
-          this.timeframeStartDate = new Date(nWeeksBefore(this.timeframeStartDate, 2));
+          this.timeframeStartDate = nWeeksBefore(this.timeframeStartDate, 2);
           break;
         default:
           break;
@@ -154,10 +154,10 @@ export default {
     updateToViewNextTimeframe() {
       switch (this.presetType) {
         case PRESET_TYPES.DAYS:
-          this.timeframeStartDate = new Date(nDaysAfter(this.timeframeStartDate, 1));
+          this.timeframeStartDate = nDaysAfter(this.timeframeStartDate, 1);
           break;
         case PRESET_TYPES.WEEKS:
-          this.timeframeStartDate = new Date(nWeeksAfter(this.timeframeStartDate, 2));
+          this.timeframeStartDate = nWeeksAfter(this.timeframeStartDate, 2);
           break;
         default:
           break;

ee/app/assets/javascripts/oncall_schedules/components/schedule/components/shifts/components/days_schedule_shift.vue

@@ -35,7 +35,7 @@ export default {
   },
   computed: {
     currentTimeframeEndsAt() {
-      return new Date(nDaysAfter(this.timeframeItem, 1));
+      return nDaysAfter(this.timeframeItem, 1);
     },
     hoursUntilEndOfTimeFrame() {
       return HOURS_IN_DAY - new Date(this.shiftRangeOverlap.overlapStartDate).getHours();

ee/app/assets/javascripts/oncall_schedules/components/schedule/components/shifts/components/weeks_schedule_shift.vue

@@ -35,7 +35,7 @@ export default {
   },
   computed: {
     currentTimeframeEndsAt() {
-      return new Date(nDaysAfter(this.timeframeItem, DAYS_IN_DATE_WEEK));
+      return nDaysAfter(this.timeframeItem, DAYS_IN_DATE_WEEK);
     },
     daysUntilEndOfTimeFrame() {
       return (

ee/app/assets/javascripts/projects/pipelines/charts/components/static_data.js

@@ -6,9 +6,9 @@ import { LAST_WEEK, LAST_MONTH, LAST_90_DAYS } from './constants';
 
 // Compute all relative dates based on the _beginning_ of today
 const startOfToday = new Date(new Date().setHours(0, 0, 0, 0));
-const lastWeek = new Date(nDaysBefore(startOfToday, 7));
-const lastMonth = new Date(nMonthsBefore(startOfToday, 1));
-const last90Days = new Date(nDaysBefore(startOfToday, 90));
+const lastWeek = nDaysBefore(startOfToday, 7);
+const lastMonth = nMonthsBefore(startOfToday, 1);
+const last90Days = nDaysBefore(startOfToday, 90);
 const apiDateFormatString = 'isoDateTime';
 const titleDateFormatString = 'mmm d';
 const sharedRequestParams = {