import _flatten from 'lodash/flatten.js'
import _isNumber from 'lodash/isNumber.js'
import _intersectionWith from 'lodash/intersectionWith.js'
import _intersection from 'lodash/intersection.js'

export class DateTimeHelper {
  /**
   * if now is 2002 12 31 14:22, this return 20021231.
   * @param date
   * @returns
   */
  static getCurrentYearMonthDayString(date?: Date): string {
    if (!date) date = new Date()

    let ret = date.getFullYear().toString() + (date.getMonth() + 1).toString().padStart(2, '0') + date.getDate().toString().padStart(2, '0')

    return ret
  }

  /**
   * if now is 14:22, this return 1422.
   * 9:40AM ==> 0940
   * 16:03 (PM) ==> 1603
   * @param {Date} date
   * @returns {string}
   */
  static getCurrentHoursMinutesString(date?: Date): string {
    if (!date) date = new Date()

    let currentHoursMinutesString = date.getHours().toString().padStart(2, '0') + '' + date.getMinutes().toString().padStart(2, '0')

    return currentHoursMinutesString
  }

  /**
   * if now is 14:22:59, this return 142259.
   * 9:40AM ==> 094000
   * 16:03 (PM) ==> 160300
   */
  static getCurrentHoursMinutesSecondsString(date?: Date) {
    if (!date) date = new Date()

    let ret = this.getCurrentHoursMinutesString(date) + date.getSeconds().toString().padStart(2, '0')

    return ret
  }

  /**
   *
   * @returns string the Date string in format yyyyMMdd (in UTC timezone)
   */
  static getCurrentYearMonthDayStringUTC(date?: Date) {
    if (!date) date = new Date()

    return date.toISOString().substring(0, 10).replace(/-/g, '')
  }

  /**
   *
   * @returns string the Time string in format HHmm (in UTC timezone)
   */
  static getCurrentHoursMinutesStringUTC(date?: Date) {
    if (!date) date = new Date()

    return date.toISOString().substring(11, 16).replace(/:/g, '')
  }
  /**
   *
   * @returns string the Time string in format HHmmss (in UTC timezone)
   */
  static getCurrentHoursMinutesSecondsStringUTC(date?: Date) {
    if (!date) date = new Date()

    return date.toISOString().substring(11, 19).replace(/:/g, '')
  }

  /** full yearmonthdaytime string in UTC timezone, without ":" char (safe for file naming) */
  static getCurrentISOStringUTC() {
    return new Date().toISOString().replace(/:/g, '')
  }

  /**
   * return current date time in full format, in specific culture (language) and timezone.
   * new Date().toLocaleString("vi-VN", { timezone: "Asia/Saigon", hour12: false })
   * @param {*} culture
   * @param {*} timezone
   * @returns
   */
  static getDatetimeNowString(culture = 'vi-VN', timezone = 'Asia/Saigon') {
    return new Intl.DateTimeFormat(culture, {
      //
      timeZone: timezone,
      dateStyle: 'full',
      timeStyle: 'long',
      hour12: false,
    } as any).format(new Date())
  }

  /** return the DateTime object like it was get with `new Date()` in a host computer in expected timezone */
  static getTimeInGMTTimezone(gmtHour = 7) {
    const now = new Date()

    // Adjust for user's local time zone offset
    const utcOffset =
      // when calling this in GMT+7, it return -420 minutes
      now.getTimezoneOffset() *
      // Convert minutes to milliseconds
      60000

    const timeInExpectedGMTTimezone = new Date(now.getTime() + utcOffset + gmtHour * 60 * 60000) // gmtHour = 7, Add 7 hours for GMT+7
    return timeInExpectedGMTTimezone
  }
}