@kalender/core/src/event/handlers.ts

calendar core library

import {
  daysBetween,
  daysOfMonth,
  daysRemainOfMonth,
  diffTime,
  eraseTime,
  extract,
  getDefault,
  getWeekDay,
  isDefined,
  isNthWeekDay,
  perfectDate,
  theNthWeekDay,
  toPositiveInt,
  WeekDays,
  weekDaysBetween,
  weeksBetween,
} from 'date-tools';
import { RepeatTypes } from './definition';
import { registerHandler } from './repeat';

export function setupHandlers() {
    registerHandler(RepeatTypes.Interval, (date, option) => {
        const interval = toPositiveInt(getDefault(option.interval, 1));
        const days = daysBetween(eraseTime(option.start), eraseTime(date));
        if ((days - 1) % interval !== 0) {
            return false;
        }
        if (isDefined(option.times)) {
            return days <= interval * option.times;
        }
        return true;
    });

    registerHandler(RepeatTypes.DayOfWeek, (date, option) => {
        const interval = toPositiveInt(getDefault(option.interval, 1));
        const days = getDefault(option.days, WeekDays);
        if (!days.includes(getWeekDay(date))) {
            return false;
        }

        const weeks = weeksBetween(option.start, date);

        if ((weeks - 1) % interval !== 0) return false;

        if (isDefined(option.weeks) && weeks > option.weeks * interval)
            return false;

        if (isDefined(option.times)) {
            let weekDays = weekDaysBetween(
                eraseTime(option.start),
                eraseTime(date),
                days
            );

            weekDays -= ((weeks - 1) / interval) * (interval - 1) * days.length;

            return weekDays <= option.times;
        }

        return true;
    });

    registerHandler(RepeatTypes.DayOfMonth, (date, option) => {
        const { day, month, year } = extract(date);
        // support days counting from end of month:
        const maxDay = daysOfMonth(year, month);
        const endDays = option.days
          .filter((x) => x < 0)
          .map((x) => x + maxDay + 1);

        if (!option.days.includes(day) && !endDays.includes(day)) return false;
        if (isDefined(option.months) && !option.months.includes(month))
            return false;
        if (isDefined(option.times)) {
            console.log('times option for [DayOfMonth] is not supported now');
        }

        return true;
    });

    registerHandler(RepeatTypes.DayOfYear, () => {
      throw new Error('Handler not implemented');
    });

    registerHandler(RepeatTypes.MonthDay, (date, option) => {
      // support days counting from end of month:
      const daysRemain = daysRemainOfMonth(date);

      if (option.day < 0) {
          if(Math.abs(option.day + 1) !== daysRemain) return false;
      } else {
        if(option.day !== date.getDate()) {
            return false;
        }
      }

      const thatDay = perfectDate(
        option.start.getFullYear(),
        option.month,
        option.day
      );

      const { year, month } = diffTime(thatDay, eraseTime(date));
      if (month !== 0) return false;
      if (
        isDefined(option.interval) &&
        (year - (thatDay < eraseTime(option.start) ? 1 : 0)) %
          option.interval !==
          0
      )
        return false;
      if (
        isDefined(option.times) &&
        year + (thatDay < eraseTime(option.start) ? 0 : 1) >
          getDefault(option.interval, 1) * option.times
      )
        return false;
      return true;
    });

    registerHandler(RepeatTypes.NthWeekDayOfIntervalMonth, (date, option) => {
        if (isDefined(option.times)) {
            console.log(
                'times option for [NthWeekDayOfIntervalMonth] is not supported now'
            );
        }

        if (isDefined(option.rank) && option.rank > 3) {
            console.log('rank should be [0-3] or -1');
            return false;
        }

        const { year, month } = extract(option.start);

        const nth = theNthWeekDay(
            year,
            month,
            option.weekDay,
            getDefault(option.rank, 0)
        );

        let start: Date;

        if (nth >= option.start) {
            start = nth;
        } else {
            start = theNthWeekDay(
                year,
                month + 1,
                option.weekDay,
                getDefault(option.rank, 0)
            );
        }

        const diff = diffTime(start, eraseTime(date));

        if (
            isDefined(option.interval) &&
            (diff.year * 12 + diff.month) % option.interval !== 0
        )
            return false;

        return isNthWeekDay(date, option.weekDay, getDefault(option.rank, 0));
    });

    registerHandler(RepeatTypes.NthWeekDayOfSpecifiedMonth, (date, option) => {
        if (isDefined(option.times)) {
            console.log(
                'times option for [NthWeekDayOfIntervalMonth] is not supported now'
            );
        }

        if (isDefined(option.rank) && option.rank > 3) {
            console.log('rank should be [0-3] or -1');
            return false;
        }

        if (!isNthWeekDay(date, option.weekDay, getDefault(option.rank, 0))) {
            return false;
        }

        const { year } = extract(option.start);

        let start = theNthWeekDay(
            year,
            option.month,
            option.weekDay,
            getDefault(option.rank, 0)
        );

        if (start.valueOf() < eraseTime(option.start).valueOf()) {
            start = theNthWeekDay(
                year + 1,
                option.month,
                option.weekDay,
                getDefault(option.rank, 0)
            );
        }

        const diff = diffTime(start, date);

        return (
            diff.month === 0 && diff.year % getDefault(option.interval, 1) === 0
        );
    });
}