frequency.ts

import { addMinutes, addHours, addDays } from "date-fns";

export enum EFrequency {
  EVERY_10_MINUTES = 'EVERY_10_MINUTES',
  EVERY_HOUR = 'EVERY_HOUR',
  EVERY_DAY = 'EVERY_DAY'
}

export class Frequency {
  public frequencyType: EFrequency;
  public time: string | number;

  constructor(frequencyType: EFrequency, time: Date| number) {
    this.frequencyType = frequencyType;
    this.time = time;
  }
}

class Task {
  public frequency: Frequency;
  public action: any;
  
  getScheduleTime(currentTime = new Date()): Date {
    const year = currentTime.getFullYear();
    const month = currentTime.getMonth();
    const date = currentTime.getDate();
    let hour, minutes;
    switch(this.frequency.frequencyType) {
      case EFrequencyType.EVERY_10_MINUTES:
        minutes = currentTime.getMinutes();
        const rest = minutes % 10;
        return addMinutes(new Date(
          year, month, date,
          currentTime.getHours(),
          currentTime.getMinutes(),
          0
        ), (10 - rest));

      case EFrequencyType.EVERY_HOUR:
        minutes = this.frequency.time;
        hour = currentTime.getHours(); 
        const dt =  new Date(
          year, month, date,
          hour,
          minutes,
          0
        );

        return minutes > currentTime.getMinutes() ? dt:  addHours(dt, 1);

      case EFrequencyType.EVERY_DAY:
        const timeArray = this.frequency.time.toString().split(":");
        hour = + timeArray[0]
        minutes = +timeArray[1];
        const frequencyDate = new Date(
          year, month, date,
          hour,
          minutes,
          0
        )
        
        return currentTime > frequencyDate ? addDays(frequencyDate, 1) : frequencyDate;
    }
  } 
}