import { parse, toDate, getHours } from 'date-fns';
import { format, utcToZonedTime } from 'date-fns-tz';
import humanizeDuration from 'humanize-duration';

export function isUndefined(val): boolean {
  return val === undefined || val === null;
}

export function formatPercent(value: number, decimals = 3): string {
  return !isUndefined(value) ? `${(value * 100).toFixed(decimals)}%` : '';
}

export function formatPrice(value: number, decimals = 8): string {
  return !isUndefined(value) ? value.toFixed(decimals) : '';
}

export function dateFromString(datestring: string, format: string): Date {
  return parse(datestring, format, 0);
}

let locTimeZone = 'UTC';

/**
 * Set global timezone to use by conversion functions
 * @param tz Timezone to set
 */
export function setTimezone(tz: string) {
  locTimeZone = tz;
}

function getTimeZone(tz?: string): string {
  return tz || locTimeZone;
}

/**
 *
 * @param ts Convert timestamp or Date to datetime (in correct timezone)
 * @param timezone timezone to use
 * @returns Date object (in timezone)
 */
function convertToDate(ts: number | Date, timezone?: string): Date {
  const date = toDate(ts);
  const currentTz = Intl.DateTimeFormat().resolvedOptions().timeZone;
  if (getTimeZone(timezone) === 'UTC') {
    return utcToZonedTime(date, currentTz);
  }
  return date;
}

/**
 * Convert a timestamp / Date object to String
 * @param ts Timestamp as number or date (in utc!!)
 */
export function timestampms(ts: number | Date): string {
  return format(convertToDate(ts), 'yyyy-MM-dd HH:mm:ss', { timeZone: locTimeZone });
}

/**
 * Convert a timestamp / Date object to String
 * @param ts Timestamp as number or date (in utc!!)
 * @param timezone timezone to use
 * @returns formatted date in desired timezone (or globally configured timezone)
 */
export function timestampmsWithTimezone(ts: number | Date, timezone?: string): string {
  return format(convertToDate(ts, timezone), 'yyyy-MM-dd HH:mm:ss (z)', {
    timeZone: getTimeZone(timezone),
  });
}

/**
 * Converts timestamp or Date object to yyyy-MM-dd format.
 * @param ts
 */
export function timestampToDateString(ts: number | Date): string {
  return format(convertToDate(ts), 'yyyy-MM-dd');
}

/**
 * Converts a String of the format yyyy-MM-dd to YYYYMMDD. To be used as timerange.
 * @param datestring Input string (in the format yyyy-MM-dd)
 */
export function dateStringToTimeRange(datestring: string): string {
  return datestring.replace(/-/g, '');
}

export function timestampHour(ts: number): number {
  return getHours(convertToDate(ts));
}

/**
 *  Get humanized Duration from seconds
 * @param duration Duration in seconds
 */
export function humanizeDurationFromSeconds(duration: number): string {
  return humanizeDuration(duration * 1000);
}

export default {
  formatPrice,
  formatPercent,
  timestampms,
  timestampmsWithTimezone,
  timestampToDateString,
  dateStringToTimeRange,
  setTimezone,
};