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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.import { DAY, HOUR, MINUTE, SECOND, WEEK } from "./constants.ts";
export type Unit =  | "milliseconds"  | "seconds"  | "minutes"  | "hours"  | "days"  | "weeks"  | "months"  | "quarters"  | "years";
export type DifferenceFormat = Partial<Record<Unit, number>>;
export type DifferenceOptions = {  units?: Unit[];};
function calculateMonthsDifference(from: Date, to: Date): number {  let months = (from.getFullYear() - to.getFullYear()) * 12 +    (from.getMonth() - to.getMonth());  if (from.getDate() < to.getDate()) {    months--;  }  return months;}
/** * Returns the difference of the 2 given dates in the given units. If the units * are omitted, it returns the difference in the all available units. * * @example * ```ts * import { difference } from "https://deno.land/std@$STD_VERSION/datetime/difference.ts"; * * const date0 = new Date("2018-05-14"); * const date1 = new Date("2020-05-13"); * * difference(date0, date1, { units: ["days", "months", "years"] }); * // => returns { days: 730, months: 23, years: 1 } * * difference(date0, date1); * // => returns { * //   milliseconds: 63072000000, * //   seconds: 63072000, * //   minutes: 1051200, * //   hours: 17520, * //   days: 730, * //   weeks: 104, * //   months: 23, * //   quarters: 5, * //   years: 1 * // } * ``` * * @param from Year to calculate difference * @param to Year to calculate difference with * @param options Options for determining how to respond */export function difference(  from: Date,  to: Date,  options?: DifferenceOptions,): DifferenceFormat {  const uniqueUnits = options?.units ? [...new Set(options?.units)] : [    "milliseconds",    "seconds",    "minutes",    "hours",    "days",    "weeks",    "months",    "quarters",    "years",  ];
  const differenceInMs = Math.abs(from.getTime() - to.getTime());
  const differences: DifferenceFormat = {};
  for (const uniqueUnit of uniqueUnits) {    switch (uniqueUnit) {      case "milliseconds":        differences.milliseconds = 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(from, to);        break;      case "quarters":        differences.quarters = Math.floor(          (differences.months !== undefined && differences.months / 3) ||            calculateMonthsDifference(from, to) / 3,        );        break;      case "years":        differences.years = Math.floor(          (differences.months !== undefined && differences.months / 12) ||            calculateMonthsDifference(from, to) / 12,        );        break;    }  }
  return differences;}