@burglekitt/gmt/dist/utc/interval/splitIntervalByUnitUtc.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";
import { isValidUtc } from "../validate/isValidUtc.js";
import { resolveDurationUnit } from "../../internal/index.js";
/**
 * Split a UTC interval into sub-intervals of `amount × unit`.
 *
 * - Returns an array of `{ start, end }` records that tile the interval.
 * - The final sub-interval is trimmed so its `end` never exceeds the original `end`.
 * - Returns `[{ start, end }]` when `start === end` (zero-length interval).
 * - Returns `[]` on invalid input (unparseable start/end, unsupported unit, non-positive amount,
 *   leap-second strings).
 *
 * @param start ISO UTC datetime string for the interval start
 * @param end ISO UTC datetime string for the interval end
 * @param unit duration unit string — any `DateTimeDurationUnit`
 * @param amount positive number of units per step
 * @returns array of `{ start, end }` records, or [] on invalid input
 *
 * @example splitIntervalByUnitUtc("2024-01-01T00:00:00Z", "2024-01-02T00:00:00Z", "hour", 6) // [{ start: "2024-01-01T00:00:00Z", end: "2024-01-01T06:00:00Z" }, { start: "2024-01-01T06:00:00Z", end: "2024-01-01T12:00:00Z" }, { start: "2024-01-01T12:00:00Z", end: "2024-01-01T18:00:00Z" }, { start: "2024-01-01T18:00:00Z", end: "2024-01-02T00:00:00Z" }]
 * @example splitIntervalByUnitUtc("2024-01-01T00:00:00Z", "2024-01-01T01:30:00Z", "hour", 1) // [{ start: "2024-01-01T00:00:00Z", end: "2024-01-01T01:00:00Z" }, { start: "2024-01-01T01:00:00Z", end: "2024-01-01T01:30:00Z" }]
 * @example splitIntervalByUnitUtc("2024-01-01T00:00:00Z", "2024-01-01T00:00:00Z", "hour", 1) // [{ start: "2024-01-01T00:00:00Z", end: "2024-01-01T00:00:00Z" }]
 * @example splitIntervalByUnitUtc("2024-01-01T00:00:00Z", "2024-01-02T00:00:00Z", "hour", 0) // []
 * @example splitIntervalByUnitUtc("invalid", "2024-01-02T00:00:00Z", "hour", 1) // []
 */
export function splitIntervalByUnitUtc(start, end, unit, amount) {
    if (typeof start !== "string" || typeof end !== "string") {
        return [];
    }
    if (!utcDateTime.test(start) || !utcDateTime.test(end)) {
        return [];
    }
    if (isLeapSecond(start) || isLeapSecond(end)) {
        return [];
    }
    if (!isValidUtc(start) || !isValidUtc(end)) {
        return [];
    }
    if (typeof unit !== "string") {
        return [];
    }
    const resolvedUnit = resolveDurationUnit(unit);
    if (!resolvedUnit) {
        return [];
    }
    if (!Number.isFinite(amount) || amount <= 0) {
        return [];
    }
    try {
        const startInstant = Temporal.Instant.from(start);
        const endInstant = Temporal.Instant.from(end);
        if (Temporal.Instant.compare(startInstant, endInstant) > 0) {
            return [];
        }
        if (Temporal.Instant.compare(startInstant, endInstant) === 0) {
            return [{ start: startInstant.toString(), end: endInstant.toString() }];
        }
        const result = [];
        for (let currentInstant = startInstant; Temporal.Instant.compare(currentInstant, endInstant) < 0;) {
            const zoned = currentInstant.toZonedDateTimeISO("UTC");
            const next = zoned.add({ [resolvedUnit]: amount }).toInstant();
            if (Temporal.Instant.compare(next, currentInstant) === 0) {
                return [];
            }
            const sliceEnd = Temporal.Instant.compare(next, endInstant) > 0 ? endInstant : next;
            result.push({
                start: currentInstant.toString(),
                end: sliceEnd.toString(),
            });
            currentInstant = next;
        }
        return result;
    }
    catch {
        return [];
    }
}