import { DateTime } from 'luxon';

const DEFAULT_TIMEZONE = 'Etc/UTC';

const TimeEnumInSeconds = {
  SECOND: 1,
  MINUTE: 60,
  HOUR: 3600,
  DAY: 86400,
};

const TimeEnumInMiliseconds = {
  SECOND: 1000,
  MINUTE: 60000,
  HOUR: 3600000,
  DAY: 86400000,
};

const NumericDateToShortString = {
  '01': 'Jan',
  '02': 'Feb',
  '03': 'Mar',
  '04': 'Apr',
  '05': 'May',
  '06': 'Jun',
  '07': 'Jul',
  '08': 'Aug',
  '09': 'Sep',
  10: 'Oct',
  11: 'Nov',
  12: 'Dec',
};

const currentBrowserTimezone = (): string => {
  return Intl.DateTimeFormat().resolvedOptions().timeZone;
};

const timezoneAbbreviation = (timezone = DEFAULT_TIMEZONE): string => {
  return DateTime.fromObject({ zone: timezone ?? DEFAULT_TIMEZONE }).offsetNameShort;
};

/**
 * Returns a signed integer representing the timezone offset in hours.
 */
const timezoneOffset = (timezone = DEFAULT_TIMEZONE): number => {
  return DateTime.fromObject({ zone: timezone ?? DEFAULT_TIMEZONE }).offset / TimeEnumInSeconds.MINUTE;
};

const formattedTimezoneWithOffset = (timezone = DEFAULT_TIMEZONE): string => {
  const offset = timezoneOffset(timezone);
  return `${timezoneAbbreviation(timezone)} ${offset >= 0 ? `(+${offset}:00)` : `(${offset}:00)`}`;
};

const now = (timezone: string = DEFAULT_TIMEZONE): number => {
  return DateTime.fromMillis(DateTime.now().toMillis(), { zone: timezone }).toMillis();
};

const fromNow = (millis: number | string, timezone = DEFAULT_TIMEZONE): number => {
  if (typeof millis === 'string') millis = Number(millis);
  return now(timezone) + millis;
};

const date = (millis: number | string, timezone = DEFAULT_TIMEZONE): DateTime => {
  if (typeof millis === 'string') millis = Number(millis);
  return DateTime.fromMillis(millis, { zone: timezone });
};

const dateFromIso = (isoDate: string, timezone = DEFAULT_TIMEZONE): DateTime => {
  return DateTime.fromISO(isoDate, { zone: timezone });
};

const dateToIso = (millis: number): string => {
  return DateTime.fromMillis(millis).toISO();
};

const dateToSeconds = (millis: number): number => {
  return Math.round(millis / 1000);
};

const dateToLocaleDateString = (millis: number): string => {
  const date = new Date(millis);
  return date.toLocaleDateString();
};

const is24HoursLater = (millis: number): boolean => {
  const now = new Date().getTime();
  const oneDayLater = millis + (1000 * 60 * 60 * 24);
  return now > oneDayLater;
};

/**
 * See https://moment.github.io/luxon/#/formatting?id=table-of-tokens
 * for formatting rules
 */
const format = (millis: number | string, format: string = 'DD', timezone: string = DEFAULT_TIMEZONE): string => {
  if (typeof millis === 'string') millis = Number(millis);
  return date(millis, timezone).toFormat(format);
};

const yearStart = function (year: number | undefined = undefined, timezone = DEFAULT_TIMEZONE): number {
  const rightNow = DateTime.fromMillis(now(), { zone: timezone });
  return DateTime.local(year ?? rightNow.year).toMillis();
};

const dayStart = function (millis: number, timezone = DEFAULT_TIMEZONE): number {
  const date = DateTime.fromMillis(millis, { zone: timezone });
  return DateTime.utc(date.year, date.month, date.day).toMillis();
};

export const formattedCountDown = (millisStart: number, millisEnd: number): string => {
  const totalSeconds = millisEnd - millisStart;
  const days = Math.floor(totalSeconds / 86400000);
  const hours = Math.floor((totalSeconds % 86400000) / 3600000);
  const minutes = Math.floor(((totalSeconds % 86400000) % 3600000) / 60000);
  const seconds = Math.floor((((totalSeconds % 86400000) % 3600000) % 60000) / 1000);

  if (minutes === 0 && hours === 0 && days === 0) return `${seconds}s`;
  if (hours === 0 && days === 0) return `${minutes}m ${seconds}s`;
  if (days === 0) return `${hours}h ${minutes}m ${seconds}s`;

  return `${days}d ${hours}h ${minutes}m ${seconds}s`;
};

const TimeUtil = {
  TimeEnumInSeconds,
  TimeEnumInMiliseconds,
  NumericDateToShortString,
  currentBrowserTimezone,
  timezoneAbbreviation,
  formattedTimezoneWithOffset,
  timezoneOffset,
  now,
  fromNow,
  date,
  dateFromIso,
  dateToIso,
  dateToSeconds,
  dateToLocaleDateString,
  format,
  yearStart,
  dayStart,
  formattedCountDown,
  is24HoursLater,
};

export default TimeUtil;