reccurence pattern

import * as moment from 'moment';

import { RecurrenceType, Recurrence } from '../../models/report/recurrence.model';

export class RecurrencePatternCalculator {
    public static calculateNextRecurrenceDate(recurrenceOptions: Recurrence): Date {

        switch (recurrenceOptions.recurrenceType) {
            case RecurrenceType.Daily:
                return RecurrencePatternCalculator.getDailyNextReccurenceOccurenceDate(recurrenceOptions);
            case RecurrenceType.Monthly:
                return RecurrencePatternCalculator.getMonthlyNextReccurenceOccurenceDate(recurrenceOptions);
            case RecurrenceType.Yearly:
                return RecurrencePatternCalculator.getYearlyNextReccurenceOccurenceDate(recurrenceOptions);
            default:
                throw new Error();
        }
    }

    private static getDailyNextReccurenceOccurenceDate(recurrenceOptions: Recurrence): Date {
        const startDate: Date = recurrenceOptions.startDate;
        const now: number = moment.now();

        let nextRecurrenceDate: any = startDate;
        const interval: number = recurrenceOptions.interval;
        do {
            nextRecurrenceDate = moment(nextRecurrenceDate).add(interval, 'days');
        } while (!moment(nextRecurrenceDate).isAfter(now) && interval > 0);

        return nextRecurrenceDate.toDate();
    }

    private static getMonthlyNextReccurenceOccurenceDate(recurrenceOptions: Recurrence): Date {
        const startDate: Date = recurrenceOptions.startDate;
        const startDateMoment: moment.Moment = moment(startDate);
        const now: number = moment.now();

        const dayOfMonth: number = recurrenceOptions.dayOfMonth;
        const interval: number = recurrenceOptions.interval;

        let nextDate: moment.Moment = moment(new Date(startDateMoment.year(), startDateMoment.month(), dayOfMonth));

        if (nextDate.date() > startDateMoment.date() && moment(nextDate).isAfter(now)) {
            return nextDate.toDate();
        }

        do {
            nextDate = moment(nextDate).add(interval, 'months');
        } while (!moment(nextDate).isAfter(now) && interval > 0);

        return nextDate.toDate();
    }

    private static getYearlyNextReccurenceOccurenceDate(recurrenceOptions: Recurrence): Date {
        const startDate: Date = recurrenceOptions.startDate;
        const startDateMoment: moment.Moment = moment(startDate);
        const now: number = moment.now();

        const dayOfMonth: number = recurrenceOptions.dayOfMonth;
        const interval: number = recurrenceOptions.interval;

        let nextDate: moment.Moment = moment(new Date(startDateMoment.year(), recurrenceOptions.month, dayOfMonth));

        if (moment(nextDate).isAfter(now)) {
            if (moment(nextDate).isAfter(startDateMoment)) {
                return nextDate.toDate();
            } else {
                nextDate = nextDate.add(1, 'years');
                return nextDate.toDate();
            }
        }

        do {

            nextDate = moment(nextDate).add(interval, 'years');
        } while (!moment(nextDate).isAfter(now) && interval > 0);

        return nextDate.toDate();
    }
}