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

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

import { Temporal } from "@js-temporal/polyfill";
import { calendarOfAllDateValues, formatDateInCalendar, parseCalendarDateValue, } from "../../internal/index.js";
import { isValidCalendarDate } from "../validate/index.js";
/**
 * Return the symmetric difference of two date intervals — time covered by exactly one interval.
 *
 * - Uses `Temporal.PlainDate.compare` for comparison.
 * - Returns `[]` when intervals are identical or both invalid.
 * - Returns `[{ start, end }]` when one interval fully contains the other.
 * - Returns `[{ start, end }, { start, end }]` when intervals partially overlap (two non-overlapping pieces).
 * - Returns `[]` if either interval is invalid (`start > end`).
 * - Returns `[]` on invalid input (wrong type, malformed strings).
 * - Accepts GMT calendar-annotated PlainDate strings — E5 (issue #78). Since the result is
 *   date *values*, all four arguments must carry the *same* calendar tag (or all be bare ISO);
 *   a mismatch returns `[]` (E5 decision of record D4). Each output piece's tag is re-derived,
 *   never copied from an input.
 *
 * @param aStart ISO 8601 date string for the first interval start, optionally calendar-annotated
 * @param aEnd ISO 8601 date string for the first interval end, optionally calendar-annotated
 * @param bStart ISO 8601 date string for the second interval start, optionally calendar-annotated
 * @param bEnd ISO 8601 date string for the second interval end, optionally calendar-annotated
 * @returns array of `{ start, end }` records representing the symmetric difference, or `[]` on invalid input / mismatched calendars
 *
 * @example intervalXorDate("2024-01-01", "2024-06-30", "2024-04-01", "2024-12-31") // [{ start: "2024-01-01", end: "2024-03-31" }, { start: "2024-07-01", end: "2024-12-31" }]
 * @example intervalXorDate("2024-01-01", "2024-12-31", "2024-04-01", "2024-06-30") // [{ start: "2024-01-01", end: "2024-03-31" }, { start: "2024-07-01", end: "2024-12-31" }]
 * @example intervalXorDate("2024-01-01", "2024-12-31", "2024-01-01", "2024-12-31") // []
 * @example intervalXorDate("2024-01-01", "2024-06-30", "2024-07-01", "2024-12-31") // [{ start: "2024-01-01", end: "2024-06-30" }, { start: "2024-07-01", end: "2024-12-31" }]
 * @example intervalXorDate("invalid", "2024-06-30", "2024-07-01", "2024-12-31") // []
 */
export function intervalXorDate(aStart, aEnd, bStart, bEnd) {
    if (typeof aStart !== "string" ||
        typeof aEnd !== "string" ||
        typeof bStart !== "string" ||
        typeof bEnd !== "string") {
        return [];
    }
    if (!isValidCalendarDate(aStart) ||
        !isValidCalendarDate(aEnd) ||
        !isValidCalendarDate(bStart) ||
        !isValidCalendarDate(bEnd)) {
        return [];
    }
    const calendar = calendarOfAllDateValues([aStart, aEnd, bStart, bEnd]);
    if (!calendar) {
        return [];
    }
    try {
        const aS = parseCalendarDateValue(aStart);
        const aE = parseCalendarDateValue(aEnd);
        const bS = parseCalendarDateValue(bStart);
        const bE = parseCalendarDateValue(bEnd);
        if (Temporal.PlainDate.compare(aS, aE) > 0) {
            return [];
        }
        if (Temporal.PlainDate.compare(bS, bE) > 0) {
            return [];
        }
        const result = [];
        // If intervals don't overlap, return both as-is
        if (Temporal.PlainDate.compare(aE, bS) < 0 ||
            Temporal.PlainDate.compare(bE, aS) < 0) {
            return [
                {
                    start: formatDateInCalendar(aS, calendar),
                    end: formatDateInCalendar(aE, calendar),
                },
                {
                    start: formatDateInCalendar(bS, calendar),
                    end: formatDateInCalendar(bE, calendar),
                },
            ];
        }
        // Left piece: A before B starts
        if (Temporal.PlainDate.compare(aS, bS) < 0) {
            result.push({
                start: formatDateInCalendar(aS, calendar),
                end: formatDateInCalendar(bS.subtract({ days: 1 }), calendar),
            });
        }
        // Right piece: A after B ends
        if (Temporal.PlainDate.compare(aE, bE) > 0) {
            result.push({
                start: formatDateInCalendar(bE.add({ days: 1 }), calendar),
                end: formatDateInCalendar(aE, calendar),
            });
        }
        // Left piece: B before A starts
        if (Temporal.PlainDate.compare(bS, aS) < 0) {
            result.push({
                start: formatDateInCalendar(bS, calendar),
                end: formatDateInCalendar(aS.subtract({ days: 1 }), calendar),
            });
        }
        // Right piece: B after A ends
        if (Temporal.PlainDate.compare(bE, aE) > 0) {
            result.push({
                start: formatDateInCalendar(aE.add({ days: 1 }), calendar),
                end: formatDateInCalendar(bE, calendar),
            });
        }
        return result;
    }
    catch {
        return [];
    }
}