fairnesscoop / permacoop

import { Injectable } from '@nestjs/common';

import {

  format as fnsFormat,

  isWeekend as fnsIsWeekend,

  getDaysInMonth as fnsGetDaysInMonth,

  eachDayOfInterval,

  addDays

} from 'date-fns';

import { IDateUtils } from 'src/Application/IDateUtils';

@Injectable()

export class DateUtilsAdapter implements IDateUtils {

  constructor(private readonly date: Date = new Date()) {}

  public format(date: Date, format: string): string {

    return fnsFormat(date, format);

  }

  public getDaysInMonth(date: Date): number {

    return fnsGetDaysInMonth(date);

  }

  public isWeekend(date: Date): boolean {

    return fnsIsWeekend(date);

  }

  public getCurrentDate(): Date {

    return this.date;

  }

  public getCurrentDateToISOString(): string {

    return this.date.toISOString();

  }

  public addDaysToDate(date: Date, days: number): Date {

    return addDays(date, days);

  }

  public getWorkedDaysDuringAPeriod(start: Date, end: Date): Date[] {

    const dates: Date[] = [];

    const workedFreeDays: Date[] = [];

    for (let year = start.getFullYear(); year <= end.getFullYear(); year++) {

      workedFreeDays.push(...this.getWorkedFreeDays(year));

    }

    for (const day of eachDayOfInterval({ start, end })) {

      if (

        this.isWeekend(day) ||

        workedFreeDays.filter(d => d.toISOString() === day.toISOString())

          .length > 0

      ) {

        continue;

      }

      dates.push(day);

    }

    return dates;

  }

  public getWorkedFreeDays(year: number): Date[] {

    const fixedDays: Date[] = [

      new Date(`${year}-01-01`), // New Year's Day

      new Date(`${year}-05-01`), // Labour Day

      new Date(`${year}-05-08`), // Victory in 1945

      new Date(`${year}-07-14`), // National Day

      new Date(`${year}-08-15`), // Assumption

      new Date(`${year}-11-01`), // All Saints' Day

      new Date(`${year}-11-11`), // The Armistice

      new Date(`${year}-12-25`) // Christmas

    ];

    const easterDate = this.getEasterDate(year);

    const easterDays: Date[] = [

      addDays(easterDate, 1), // Easter Monday

      addDays(easterDate, 39) // Ascension

    ];

    return [...fixedDays, ...easterDays];

  }

  public getEasterDate(year: number): Date {

    const a = year % 19;

    const b = Math.floor(year / 100);

    const c = year % 100;

    const d = Math.floor(b / 4);

    const e = b % 4;

    const f = Math.floor((b + 8) / 25);

    const g = Math.floor((b - f + 1) / 3);

    const h = (19 * a + b - d - g + 15) % 30;

    const i = Math.floor(c / 4);

    const k = c % 4;

    const l = (32 + 2 * e + 2 * i - h - k) % 7;

    const m = Math.floor((a + 11 * h + 22 * l) / 451);

    const n0 = h + l + 7 * m + 114;

    const n = Math.floor(n0 / 31) - 1;

    const p = (n0 % 31) + 1;

    return new Date(year, n, p);

  }

  public getLeaveDuration(startDate: string, isStartsAllDay: boolean, endDate: string, isEndsAllDay: boolean): number {

    let duration = this.getWorkedDaysDuringAPeriod(

      new Date(startDate),

      new Date(endDate)

    ).length;

    if (false === isStartsAllDay) {

      duration -= 0.5;

    }

    if (false === isEndsAllDay && duration > 0.5) {

      duration -= 0.5;

    }

    return duration;

  }

}