funky-framadate-front/src/app/features/old-stuff/config/DateUtilities.ts

import { Injectable } from '@angular/core';

@Injectable({
	providedIn: 'root',
})
export class DateUtilities {
	/**
	 * add some days to a date, to compute intervals
	 * @param days
	 * @param date
	 */
	addDaysToDate(days: number, date: Date) {
		date = new Date(date.valueOf());
		date.setDate(date.getDate() + days);
		return date;
	}

	/**
	 *
	 * @param d1
	 * @param d2
	 * @param interval
	 */
	getDatesInRange(d1: Date, d2: Date, interval: number) {
		d1 = new Date(d1);
		d2 = new Date(d2);
		const dates = [];
		while (+d1 < +d2) {
			dates.push({
				literal: this.formateDate(d1),
				date_object: d1,
			});
			d1.setDate(d1.getDate() + interval);
		}
		return [...dates];
	}

	/**
	 * get the number of days between two dates
	 * @param d1
	 * @param d2
	 */
	dayDiff(d1: Date, d2: Date): number {
		return Number(d2.getTime() - d1.getTime() / 31536000000);
	}

	/**
	 * format a date object to the date format used by the inputs of type date
	 * YYYY-MM-DD
	 * @param date
	 */
	formateDate(date) {
		return [
			date.getFullYear(),
			this.getDoubleDigits(date.getMonth() + 1),
			this.getDoubleDigits(date.getDate()),
		].join('-');
	}

	getDoubleDigits(str) {
		return ('00' + str).slice(-2);
	}

	countDays(startDateInterval: Date, endDateInterval: Date): number {
		// compute the number of days in the date interval
		if (endDateInterval && startDateInterval) {
			return this.dayDiff(endDateInterval, startDateInterval);
		}
		return 0;
	}
}