@burglekitt/gmt/dist/plain/calculate/diffDateTime.js

Temporal-based date and time utilities with timezone support and polyfill integration

import { Temporal } from "@js-temporal/polyfill";
import { isValidDateTime, isValidDateTimeDurationUnit } from "../validate/index.js";
import { getLargestDateTimeDurationUnit } from "./getLargestDateTimeDurationUnit.js";
/**
 * Return the difference between two PlainDateTime values in the requested unit.
 *
 * - Returns `null` for invalid inputs (negative diffs are valid).
 * - Uses Temporal.PlainDateTime.until and extracts the requested unit.
 *
 * `smallestUnit`, `roundingIncrement`, and `roundingMode` control optional rounding of the result,
 * per Temporal's DifferenceOptions — e.g. `{ smallestUnit: "hour", roundingMode: "halfExpand" }`
 * rounds the difference to the nearest hour before extracting the requested unit.
 * - When `units` is an array, `smallestUnit` must not be coarser than the largest unit in the
 *   array (e.g. `["day", "hour"]` with `smallestUnit: "week"`) — this combination is rejected by
 *   Temporal and returns null, same as other invalid input.
 *
 * @param dateTime1 ISO PlainDateTime string for the start
 * @param dateTime2 ISO PlainDateTime string for the end
 * @param units DateTimeDurationUnit | DateTimeDurationUnit[] to measure the difference
 * @param options optional: smallestUnit, roundingIncrement, roundingMode (Temporal.DifferenceOptions rounding controls)
 * @returns numeric difference in the requested unit, or null on invalid input
 *
 * @example diffDateTime("2024-03-10T12:00:00", "2024-03-15T12:00:00", "day") // 5
 * @example diffDateTime("invalid", "2024-03-15T12:00:00", "day") // null
 */
export function diffDateTime(dateTime1, dateTime2, units, options) {
    const validDateTimes = isValidDateTime(dateTime1) && isValidDateTime(dateTime2);
    const isSingleUnit = !Array.isArray(units);
    const validUnits = isSingleUnit
        ? isValidDateTimeDurationUnit(units)
        : units.every(isValidDateTimeDurationUnit);
    //
    if (!validDateTimes || !validUnits) {
        return null;
    }
    try {
        const dt1 = Temporal.PlainDateTime.from(dateTime1);
        const dt2 = Temporal.PlainDateTime.from(dateTime2);
        const duration = dt1.until(dt2, {
            largestUnit: isSingleUnit ? units : getLargestDateTimeDurationUnit(units),
            smallestUnit: options?.smallestUnit,
            roundingIncrement: options?.roundingIncrement,
            roundingMode: options?.roundingMode,
        });
        if (isSingleUnit) {
            return duration[units] ?? 0;
        }
        // craft record for units passed
        return units.reduce((result, unit) => {
            result[unit] = duration[unit] ?? 0;
            return result;
        }, {});
    }
    catch {
        return null;
    }
}