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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.import { assert } from "../_util/assert.ts";
export type DateFormat = "mm-dd-yyyy" | "dd-mm-yyyy" | "yyyy-mm-dd";
export const SECOND = 1e3;export const MINUTE = SECOND * 60;export const HOUR = MINUTE * 60;export const DAY = HOUR * 24;export const WEEK = DAY * 7;const DAYS_PER_WEEK = 7;
enum Day {  Sun,  Mon,  Tue,  Wed,  Thu,  Fri,  Sat,}
function execForce(reg: RegExp, pat: string): RegExpExecArray {  const v = reg.exec(pat);  assert(v != null);  return v;}/** * Parse date from string using format string * @param dateStr Date string * @param format Format string * @return Parsed date */export function parseDate(dateStr: string, format: DateFormat): Date {  let m, d, y: string;  let datePattern: RegExp;
  switch (format) {    case "mm-dd-yyyy":      datePattern = /^(\d{2})-(\d{2})-(\d{4})$/;      [, m, d, y] = execForce(datePattern, dateStr);      break;    case "dd-mm-yyyy":      datePattern = /^(\d{2})-(\d{2})-(\d{4})$/;      [, d, m, y] = execForce(datePattern, dateStr);      break;    case "yyyy-mm-dd":      datePattern = /^(\d{4})-(\d{2})-(\d{2})$/;      [, y, m, d] = execForce(datePattern, dateStr);      break;    default:      throw new Error("Invalid date format!");  }
  return new Date(Number(y), Number(m) - 1, Number(d));}
export type DateTimeFormat =  | "mm-dd-yyyy hh:mm"  | "dd-mm-yyyy hh:mm"  | "yyyy-mm-dd hh:mm"  | "hh:mm mm-dd-yyyy"  | "hh:mm dd-mm-yyyy"  | "hh:mm yyyy-mm-dd";
/** * Parse date & time from string using format string * @param dateStr Date & time string * @param format Format string * @return Parsed date */export function parseDateTime(  datetimeStr: string,  format: DateTimeFormat,): Date {  let m, d, y, ho, mi: string;  let datePattern: RegExp;
  switch (format) {    case "mm-dd-yyyy hh:mm":      datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;      [, m, d, y, ho, mi] = execForce(datePattern, datetimeStr);      break;    case "dd-mm-yyyy hh:mm":      datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;      [, d, m, y, ho, mi] = execForce(datePattern, datetimeStr);      break;    case "yyyy-mm-dd hh:mm":      datePattern = /^(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})$/;      [, y, m, d, ho, mi] = execForce(datePattern, datetimeStr);      break;    case "hh:mm mm-dd-yyyy":      datePattern = /^(\d{2}):(\d{2}) (\d{2})-(\d{2})-(\d{4})$/;      [, ho, mi, m, d, y] = execForce(datePattern, datetimeStr);      break;    case "hh:mm dd-mm-yyyy":      datePattern = /^(\d{2}):(\d{2}) (\d{2})-(\d{2})-(\d{4})$/;      [, ho, mi, d, m, y] = execForce(datePattern, datetimeStr);      break;    case "hh:mm yyyy-mm-dd":      datePattern = /^(\d{2}):(\d{2}) (\d{4})-(\d{2})-(\d{2})$/;      [, ho, mi, y, m, d] = execForce(datePattern, datetimeStr);      break;    default:      throw new Error("Invalid datetime format!");  }
  return new Date(Number(y), Number(m) - 1, Number(d), Number(ho), Number(mi));}
/** * Get number of the day in the year * @return Number of the day in year */export function dayOfYear(date: Date): number {  const yearStart = new Date(date.getFullYear(), 0, 0);  const diff = date.getTime() -    yearStart.getTime() +    (yearStart.getTimezoneOffset() - date.getTimezoneOffset()) * 60 * 1000;  return Math.floor(diff / DAY);}
/** * Get number of current day in year * @return Number of current day in year */export function currentDayOfYear(): number {  return dayOfYear(new Date());}
/** * Get number of the week in the year (ISO-8601) * @return Number of the week in year */export function weekOfYear(date: Date): number {  const workingDate = new Date(    Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()),  );
  const day = workingDate.getUTCDay();
  const nearestThursday = workingDate.getUTCDate() +    Day.Thu -    (day === Day.Sun ? DAYS_PER_WEEK : day);
  workingDate.setUTCDate(nearestThursday);
  // Get first day of year  const yearStart = new Date(Date.UTC(workingDate.getUTCFullYear(), 0, 1));
  // return the calculated full weeks to nearest Thursday  return Math.ceil((workingDate.getTime() - yearStart.getTime() + DAY) / WEEK);}
/** * Parse a date to return a IMF formated string date * RFC: https://tools.ietf.org/html/rfc7231#section-7.1.1.1 * IMF is the time format to use when generating times in HTTP * headers. The time being formatted must be in UTC for Format to * generate the correct format. * @param date Date to parse * @return IMF date formated string */export function toIMF(date: Date): string {  function dtPad(v: string, lPad = 2): string {    return v.padStart(lPad, "0");  }  const d = dtPad(date.getUTCDate().toString());  const h = dtPad(date.getUTCHours().toString());  const min = dtPad(date.getUTCMinutes().toString());  const s = dtPad(date.getUTCSeconds().toString());  const y = date.getUTCFullYear();  const days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];  const months = [    "Jan",    "Feb",    "Mar",    "Apr",    "May",    "Jun",    "Jul",    "Aug",    "Sep",    "Oct",    "Nov",    "Dec",  ];  return `${days[date.getUTCDay()]}, ${d} ${    months[date.getUTCMonth()]  } ${y} ${h}:${min}:${s} GMT`;}
/** * Check given year is a leap year or not. * based on : https://docs.microsoft.com/en-us/office/troubleshoot/excel/determine-a-leap-year * @param year year in number or Date format */export function isLeap(year: Date | number): boolean {  const yearNumber = year instanceof Date ? year.getFullYear() : year;  return (    (yearNumber % 4 === 0 && yearNumber % 100 !== 0) || yearNumber % 400 === 0  );}
export type Unit =  | "miliseconds"  | "seconds"  | "minutes"  | "hours"  | "days"  | "weeks"  | "months"  | "quarters"  | "years";
export type DifferenceFormat = Partial<Record<Unit, number>>;
export type DifferenceOptions = {  units?: Unit[];};
/** * Calculate difference between two dates. * @param from Year to calculate difference * @param to Year to calculate difference with * @param options Options for determining how to respond * * example : * * ```typescript * datetime.difference(new Date("2020/1/1"),new Date("2020/2/2"),{ units : ["days","months"] }) * ``` */export function difference(  from: Date,  to: Date,  options?: DifferenceOptions,): DifferenceFormat {  const uniqueUnits = options?.units ? [...new Set(options?.units)] : [    "miliseconds",    "seconds",    "minutes",    "hours",    "days",    "weeks",    "months",    "quarters",    "years",  ];
  const bigger = Math.max(from.getTime(), to.getTime());  const smaller = Math.min(from.getTime(), to.getTime());  const differenceInMs = bigger - smaller;
  const differences: DifferenceFormat = {};
  for (const uniqueUnit of uniqueUnits) {    switch (uniqueUnit) {      case "miliseconds":        differences.miliseconds = differenceInMs;        break;      case "seconds":        differences.seconds = Math.floor(differenceInMs / SECOND);        break;      case "minutes":        differences.minutes = Math.floor(differenceInMs / MINUTE);        break;      case "hours":        differences.hours = Math.floor(differenceInMs / HOUR);        break;      case "days":        differences.days = Math.floor(differenceInMs / DAY);        break;      case "weeks":        differences.weeks = Math.floor(differenceInMs / WEEK);        break;      case "months":        differences.months = calculateMonthsDifference(bigger, smaller);        break;      case "quarters":        differences.quarters = Math.floor(          (typeof differences.months !== "undefined" &&            differences.months / 4) ||            calculateMonthsDifference(bigger, smaller) / 4,        );        break;      case "years":        differences.years = Math.floor(          (typeof differences.months !== "undefined" &&            differences.months / 12) ||            calculateMonthsDifference(bigger, smaller) / 12,        );        break;    }  }
  return differences;}
function calculateMonthsDifference(bigger: number, smaller: number): number {  const biggerDate = new Date(bigger);  const smallerDate = new Date(smaller);  const yearsDiff = biggerDate.getFullYear() - smallerDate.getFullYear();  const monthsDiff = biggerDate.getMonth() - smallerDate.getMonth();  const calendarDiffrences = Math.abs(yearsDiff * 12 + monthsDiff);  const compareResult = biggerDate > smallerDate ? 1 : -1;  biggerDate.setMonth(    biggerDate.getMonth() - compareResult * calendarDiffrences,  );  const isLastMonthNotFull = biggerDate > smallerDate    ? 1    : -1 === -compareResult    ? 1    : 0;  const months = compareResult * (calendarDiffrences - isLastMonthNotFull);  return months === 0 ? 0 : months;}