@burglekitt/gmt/dist/utc/interval/intervalsOverlapUtc.js

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

import { Temporal } from "@js-temporal/polyfill";
import { isLeapSecond } from "../../plain/validate/isLeapSecond.js";
import { utcDateTime } from "../../regex/utc-date-time.js";
/**
 * Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
 *
 * - Uses `Temporal.Instant.compare` for comparison (same instant semantics).
 * - Adjacent intervals (e.g. `aEnd === bStart`) do NOT overlap — returns `false`.
 * - Returns `false` if either interval is invalid (`start > end`).
 * - Returns `false` on invalid input (wrong type, malformed strings, leap seconds).
 *
 * @param aStart ISO 8601 UTC datetime string for the first interval start
 * @param aEnd ISO 8601 UTC datetime string for the first interval end
 * @param bStart ISO 8601 UTC datetime string for the second interval start
 * @param bEnd ISO 8601 UTC datetime string for the second interval end
 * @returns true if intervals overlap, or false on invalid input
 *
 * @example intervalsOverlapUtc("2024-01-01T00:00:00Z", "2024-06-30T23:59:59Z", "2024-04-01T00:00:00Z", "2024-12-31T23:59:59Z") // true
 * @example intervalsOverlapUtc("2024-01-01T00:00:00Z", "2024-06-30T23:59:59Z", "2024-07-01T00:00:00Z", "2024-12-31T23:59:59Z") // false (adjacent)
 * @example intervalsOverlapUtc("2024-01-01T00:00:00Z", "2024-06-30T23:59:59Z", "2024-07-02T00:00:00Z", "2024-12-31T23:59:59Z") // false (disjoint)
 * @example intervalsOverlapUtc("invalid", "2024-06-30T23:59:59Z", "2024-04-01T00:00:00Z", "2024-12-31T23:59:59Z") // false
 */
export function intervalsOverlapUtc(aStart, aEnd, bStart, bEnd) {
    if (typeof aStart !== "string" ||
        typeof aEnd !== "string" ||
        typeof bStart !== "string" ||
        typeof bEnd !== "string") {
        return false;
    }
    if (!utcDateTime.test(aStart) ||
        !utcDateTime.test(aEnd) ||
        !utcDateTime.test(bStart) ||
        !utcDateTime.test(bEnd)) {
        return false;
    }
    if (isLeapSecond(aStart) ||
        isLeapSecond(aEnd) ||
        isLeapSecond(bStart) ||
        isLeapSecond(bEnd)) {
        return false;
    }
    try {
        const aSI = Temporal.Instant.from(aStart);
        const aEI = Temporal.Instant.from(aEnd);
        const bSI = Temporal.Instant.from(bStart);
        const bEI = Temporal.Instant.from(bEnd);
        if (Temporal.Instant.compare(aSI, aEI) > 0) {
            return false;
        }
        if (Temporal.Instant.compare(bSI, bEI) > 0) {
            return false;
        }
        return (Temporal.Instant.compare(aEI, bSI) >= 0 &&
            Temporal.Instant.compare(bEI, aSI) >= 0);
    }
    catch {
        return false;
    }
}