import React, { useState, useEffect } from 'react';

export type CountdownLocale = 'ru' | 'ru-passive' | 'en';
export type CountdownFormat = 's' | 'ss' | 'mm ss' | 'm:s' | 'm' | 'mm';


export const puralize = (amount: number, locale: CountdownLocale): string => {
  switch (locale) {
    case ('ru'):
    case ('ru-passive'):
      switch (amount % 10) {
        case (1):
          return locale === 'ru-passive' ? 'у' : 'а';
        case (2):
        case (3):
        case (4):
          return 'ы';
        default:
          return '';
      }
    case ('en'):
    default:
      switch (amount) {
        case (1):
          return '';
        default:
          return 's';
      }
  }
};

export const formatTime = (seconds: number, format: CountdownFormat, locale: CountdownLocale): string => {
  const fullMminutesLeft = Math.floor(seconds / 60);
  const secondsLeft = seconds % 60;
  const minutesLeft = Math.ceil(seconds / 60);

  switch (format) {
    case ('m:s'):
      return `${fullMminutesLeft >= 10 ? '' : '0'}${fullMminutesLeft}:${secondsLeft >= 10 ? '' : '0'}${secondsLeft}`;
    case ('mm ss'):
      switch (locale) {
        case ('ru'):
        case ('ru-passive'):
          return `${fullMminutesLeft > 0 ? `${fullMminutesLeft} минут${puralize(fullMminutesLeft, 'ru')} ` : ''
          }${secondsLeft} секунд${puralize(secondsLeft, locale)}`;
        case ('en'):
        default:
          return `${fullMminutesLeft > 0 ? `${fullMminutesLeft} minute${puralize(fullMminutesLeft, locale)} ` : ''
          }${secondsLeft} second${puralize(secondsLeft, locale)}`;
      }
    case ('ss'):
      switch (locale) {
        case ('ru'):
        case ('ru-passive'):
          return `${seconds} секунд${puralize(seconds, locale)}`;
        case ('en'):
        default:
          return `${seconds} second${puralize(seconds, locale)}`;
      }
    case ('mm'):
      switch (locale) {
        case ('ru'):
        case ('ru-passive'):
          return `${minutesLeft} минут${puralize(minutesLeft, locale)}`;
        case ('en'):
        default:
          return `${minutesLeft} minute${puralize(minutesLeft, locale)}`;
      }
    case ('m'):
      return `${Math.ceil(seconds / 60)}`;
    case ('s'):
    default:
      return `${seconds}`;
  }
};

export type CountdownProps =  {
  seconds: number;
  pause?: boolean;
  format?: CountdownFormat;
  onExpire?: () => void;
  onChange?: (seconds: number) => void;
  locale?: CountdownLocale;
}

export const Countdown = ({
  seconds,
  pause = false,
  format = 'm:s',
  onExpire,
  onChange,
  locale = 'en',
}: CountdownProps) => {
  const [startAt, setStartAt] = useState(Date.now());
  const [timeLeft, setTimeLeft] = useState(seconds);

  useEffect(() => {
    setStartAt(Date.now());
    setTimeLeft(seconds);
  }, [seconds]);

  useEffect(() => {
    if (timeLeft <= 0) {
      if (onExpire) {
        onExpire();
      }
      return () => undefined;
    }

    const interval = setInterval(() => {
      const currentTime = seconds - Math.ceil((Date.now() - startAt) / 1000);
      if (currentTime !== timeLeft) {
        if (!pause) {
          setTimeLeft(currentTime);
          if (onChange) {
            onChange(currentTime);
          }
        } else {
          setStartAt(v => v + 1000);
        }
      }
    }, 100);
    return () => clearInterval(interval);
  }, [pause, timeLeft, startAt]);
  return (
    <>{formatTime(timeLeft, format, locale)}</>
  );
};

export default Countdown;