import { ExceptionBase } from '@mobicoop/ddd-library';
import { DateInterval } from './candidate.types';

export class CalendarTools {
  /**
   * Returns the first date corresponding to a week day (0 based monday)
   * within a date range
   */
  static firstDate = (weekDay: number, dateInterval: DateInterval): Date => {
    if (weekDay < 0 || weekDay > 6)
      throw new CalendarToolsException(
        new Error('weekDay must be between 0 and 6'),
      );
    const lowerDateAsDate: Date = new Date(dateInterval.lowerDate);
    const higherDateAsDate: Date = new Date(dateInterval.higherDate);
    if (lowerDateAsDate.getUTCDay() == weekDay) return lowerDateAsDate;
    const nextDate: Date = new Date(lowerDateAsDate);
    nextDate.setUTCDate(
      lowerDateAsDate.getUTCDate() +
        (7 - (lowerDateAsDate.getUTCDay() - weekDay)),
    );
    if (lowerDateAsDate.getUTCDay() < weekDay) {
      nextDate.setUTCMonth(lowerDateAsDate.getUTCMonth());
      nextDate.setUTCFullYear(lowerDateAsDate.getUTCFullYear());
      nextDate.setUTCDate(
        lowerDateAsDate.getUTCDate() + (weekDay - lowerDateAsDate.getUTCDay()),
      );
    }
    if (nextDate <= higherDateAsDate) return nextDate;
    throw new CalendarToolsException(
      new Error('no available day for the given date range'),
    );
  };

  /**
   * Returns the last date corresponding to a week day (0 based monday)
   * within a date range
   */
  static lastDate = (weekDay: number, dateInterval: DateInterval): Date => {
    if (weekDay < 0 || weekDay > 6)
      throw new CalendarToolsException(
        new Error('weekDay must be between 0 and 6'),
      );
    const lowerDateAsDate: Date = new Date(dateInterval.lowerDate);
    const higherDateAsDate: Date = new Date(dateInterval.higherDate);
    if (higherDateAsDate.getUTCDay() == weekDay) return higherDateAsDate;
    const previousDate: Date = new Date(higherDateAsDate);
    previousDate.setUTCDate(
      higherDateAsDate.getUTCDate() - (higherDateAsDate.getUTCDay() - weekDay),
    );
    if (higherDateAsDate.getUTCDay() < weekDay) {
      previousDate.setUTCMonth(higherDateAsDate.getUTCMonth());
      previousDate.setUTCFullYear(higherDateAsDate.getUTCFullYear());
      previousDate.setUTCDate(
        higherDateAsDate.getUTCDate() -
          (7 + (higherDateAsDate.getUTCDay() - weekDay)),
      );
    }
    if (previousDate >= lowerDateAsDate) return previousDate;
    throw new CalendarToolsException(
      new Error('no available day for the given date range'),
    );
  };

  /**
   * Returns a date from a date (as a date) and a time (as a string), adding optional seconds
   */
  static datetimeWithSeconds = (
    date: Date,
    time: string,
    additionalSeconds = 0,
  ): Date => {
    const datetime: Date = new Date(date);
    datetime.setUTCHours(parseInt(time.split(':')[0]));
    datetime.setUTCMinutes(parseInt(time.split(':')[1]));
    datetime.setUTCSeconds(additionalSeconds);
    return datetime;
  };

  /**
   * Returns dates from a day and time based on unix epoch day
   * (1970-01-01 is day 4)
   * The method returns an array of dates because for edges (day 0 and 6)
   * we need to return 2 possibilities : one for the previous week, one for the next week
   */
  static epochDaysFromTime = (weekDay: number, time: string): Date[] => {
    if (weekDay < 0 || weekDay > 6)
      throw new CalendarToolsException(
        new Error('weekDay must be between 0 and 6'),
      );
    switch (weekDay) {
      case 0:
        return [
          new Date(`1969-12-28T${time}:00Z`),
          new Date(`1970-01-04T${time}:00Z`),
        ];
      case 1:
        return [new Date(`1969-12-29T${time}:00Z`)];
      case 2:
        return [new Date(`1969-12-30T${time}:00Z`)];
      case 3:
        return [new Date(`1969-12-31T${time}:00Z`)];
      case 5:
        return [new Date(`1970-01-02T${time}:00Z`)];
      case 6:
        return [
          new Date(`1969-12-27T${time}:00Z`),
          new Date(`1970-01-03T${time}:00Z`),
        ];
      case 4:
      default:
        return [new Date(`1970-01-01T${time}:00Z`)];
    }
  };
}

export class CalendarToolsException extends ExceptionBase {
  static readonly message = 'Calendar tools error';

  public readonly code = 'CALENDAR.TOOLS';

  constructor(cause?: Error, metadata?: unknown) {
    super(CalendarToolsException.message, cause, metadata);
  }
}