--- /dev/null
+import { TestBed } from '@angular/core/testing';
+
+import { configureTestBed } from '../../../testing/unit-test-helper';
+import { TimeDiffService } from './time-diff.service';
+
+describe('TimeDiffService', () => {
+ let service: TimeDiffService;
+ const baseTime = new Date('2022-02-22T00:00:00');
+
+ configureTestBed({
+ providers: [TimeDiffService]
+ });
+
+ beforeEach(() => {
+ service = TestBed.get(TimeDiffService);
+ });
+
+ it('should be created', () => {
+ expect(service).toBeTruthy();
+ });
+
+ it('calculates a new date that happens after the given date', () => {
+ expect(service.calculateDate(new Date('2022-02-28T04:05:00'), '2h')).toEqual(
+ new Date('2022-02-28T06:05:00')
+ );
+ expect(service.calculateDate(baseTime, '15m')).toEqual(new Date('2022-02-22T00:15'));
+ expect(service.calculateDate(baseTime, '5d 23h')).toEqual(new Date('2022-02-27T23:00'));
+ });
+
+ it('calculates a new date that happens before the given date', () => {
+ expect(service.calculateDate(new Date('2022-02-22T02:00:00'), '2h', true)).toEqual(baseTime);
+ });
+
+ it('calculates the difference of two dates', () => {
+ expect(
+ service.calculateDuration(new Date('2022-02-22T00:45:00'), new Date('2022-02-22T02:00:00'))
+ ).toBe('1h 15m');
+ expect(service.calculateDuration(baseTime, new Date('2022-02-28T04:05:00'))).toBe('6d 4h 5m');
+ });
+
+ describe('testing duration calculation in detail', () => {
+ const minutes = 60 * 1000;
+ const hours = 60 * minutes;
+ const days = 24 * hours;
+
+ it('should allow different writings', () => {
+ const expectDurationToBeMs = (duration, ms) =>
+ expect(service['getDurationMs'](duration)).toBe(ms);
+ expectDurationToBeMs('2h', 2 * hours);
+ expectDurationToBeMs('4 Days', 4 * days);
+ expectDurationToBeMs('3 minutes', 3 * minutes);
+ expectDurationToBeMs('4 Days 2h 3 minutes', 4 * days + 2 * hours + 3 * minutes);
+ expectDurationToBeMs('5d3h120m', 5 * days + 5 * hours);
+ });
+
+ it('should create duration string from ms', () => {
+ const expectMsToBeDuration = (ms, duration) =>
+ expect(service['getDuration'](ms)).toBe(duration);
+ expectMsToBeDuration(2 * hours, '2h');
+ expectMsToBeDuration(4 * days, '4d');
+ expectMsToBeDuration(3 * minutes, '3m');
+ expectMsToBeDuration(4 * days + 2 * hours + 3 * minutes, '4d 2h 3m');
+ expectMsToBeDuration(service['getDurationMs']('5d3h120m'), '5d 5h');
+ });
+ });
+});
--- /dev/null
+import { Injectable } from '@angular/core';
+
+import * as _ from 'lodash';
+
+@Injectable({
+ providedIn: 'root'
+})
+export class TimeDiffService {
+ constructor() {}
+
+ calculateDuration(startDate: Date, endDate: Date): string {
+ const startTime = +startDate;
+ const endTime = +endDate;
+ const duration = this.getDuration(Math.abs(startTime - endTime));
+ if (startTime > endTime) {
+ return '-' + duration;
+ }
+ return duration;
+ }
+
+ private getDuration(ms: number): string {
+ const date = new Date(ms);
+ const h = date.getUTCHours();
+ const m = date.getUTCMinutes();
+ const d = Math.floor(ms / (24 * 3600 * 1000));
+
+ const format = (n, s) => (n ? n + s : n);
+ return [format(d, 'd'), format(h, 'h'), format(m, 'm')].filter((x) => x).join(' ');
+ }
+
+ calculateDate(date: Date, duration: string, reverse?: boolean): Date {
+ const time = +date;
+ if (_.isNaN(time)) {
+ return;
+ }
+ const diff = this.getDurationMs(duration) * (reverse ? -1 : 1);
+ return new Date(time + diff);
+ }
+
+ private getDurationMs(duration: string): number {
+ const d = this.getNumbersFromString(duration, 'd');
+ const h = this.getNumbersFromString(duration, 'h');
+ const m = this.getNumbersFromString(duration, 'm');
+ return ((d * 24 + h) * 60 + m) * 60000;
+ }
+
+ private getNumbersFromString(duration, prefix): number {
+ const match = duration.match(new RegExp(`[0-9 ]+${prefix}`, 'i'));
+ return match ? parseInt(match, 10) : 0;
+ }
+}