@burglekitt/gmt/dist/plain/interval/intervalDifferenceTime.js

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

import { Temporal } from "@js-temporal/polyfill";
import { plainTime } from "../../regex/index.js";
/**
 * Return the portion(s) of interval A not covered by interval B.
 *
 * - Uses `Temporal.PlainTime.compare` for comparison.
 * - Returns `[]` when B fully covers A.
 * - Returns `[{ start, end }]` when B overlaps one edge of A (or equals A).
 * - Returns `[{ start, end }, { start, end }]` when B is fully inside A with gaps on both sides.
 * - Returns `[]` if either interval is invalid (`start > end`).
 * - Returns `[]` on invalid input (wrong type, malformed strings).
 *
 * @param aStart ISO 8601 time string for the first interval start
 * @param aEnd ISO 8601 time string for the first interval end
 * @param bStart ISO 8601 time string for the second interval start
 * @param bEnd ISO 8601 time string for the second interval end
 * @returns array of `{ start, end }` records representing A minus B, or `[]` on invalid input
 *
 * @example intervalDifferenceTime("09:00:00", "17:00:00", "12:00:00", "13:00:00") // [{ start: "09:00:00", end: "11:59:59" }, { start: "13:00:01", end: "17:00:00" }]
 * @example intervalDifferenceTime("09:00:00", "17:00:00", "09:00:00", "17:00:00") // []
 * @example intervalDifferenceTime("09:00:00", "17:00:00", "12:00:00", "17:00:00") // [{ start: "09:00:00", end: "11:59:59" }]
 * @example intervalDifferenceTime("invalid", "17:00:00", "12:00:00", "13:00:00") // []
 */
export function intervalDifferenceTime(aStart, aEnd, bStart, bEnd) {
    if (typeof aStart !== "string" ||
        typeof aEnd !== "string" ||
        typeof bStart !== "string" ||
        typeof bEnd !== "string") {
        return [];
    }
    if (!plainTime.test(aStart) ||
        !plainTime.test(aEnd) ||
        !plainTime.test(bStart) ||
        !plainTime.test(bEnd)) {
        return [];
    }
    try {
        const aS = Temporal.PlainTime.from(aStart);
        const aE = Temporal.PlainTime.from(aEnd);
        const bS = Temporal.PlainTime.from(bStart);
        const bE = Temporal.PlainTime.from(bEnd);
        if (Temporal.PlainTime.compare(aS, aE) > 0) {
            return [];
        }
        if (Temporal.PlainTime.compare(bS, bE) > 0) {
            return [];
        }
        const result = [];
        // Left piece: A before B starts
        if (Temporal.PlainTime.compare(aS, bS) < 0) {
            const leftEnd = Temporal.PlainTime.compare(aE, bS) < 0
                ? aE
                : bS.subtract({ nanoseconds: 1 });
            if (Temporal.PlainTime.compare(leftEnd, aS) >= 0) {
                result.push({ start: aS.toString(), end: leftEnd.toString() });
            }
        }
        // Right piece: A after B ends
        if (Temporal.PlainTime.compare(aE, bE) > 0) {
            result.push({
                start: bE.add({ nanoseconds: 1 }).toString(),
                end: aE.toString(),
            });
        }
        return result;
    }
    catch {
        return [];
    }
}