@burglekitt/gmt/dist/utc/format/formatRelativeUtc.js

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

import { Temporal } from "@js-temporal/polyfill";
import { normalizeDateTime } from "../../internal/normalizeDateTime.js";
import { normalizeTimeZone } from "../../internal/normalizeTimeZone.js";
import { resolveRelativeRounding } from "../../internal/resolveRelativeRounding.js";
import { toInstantFromUtc } from "../../internal/toInstantFromUtc.js";
import { isValidUtc } from "../validate/index.js";
const AUTO_UNITS = [
    { unit: "second", maxSeconds: 60 },
    { unit: "minute", maxSeconds: 3_600 },
    { unit: "hour", maxSeconds: 86_400 },
    { unit: "day", maxSeconds: Infinity },
];
/**
 * Format the relative time between a UTC ISO string and a reference instant.
 *
 * - Auto-picks the display unit (second through year) based on the distance, unless
 *   `largestUnit` forces one.
 * - `roundingMethod` controls how the distance rounds to the display unit.
 *
 * @param value UTC ISO string to format
 * @param locale optional: BCP 47 locale tag
 * @param options optional: { style, numeric, largestUnit, roundingMethod, reference, timeZone }
 * @returns the formatted relative-time string, or "" on invalid input
 *
 * @example formatRelativeUtc("2024-03-17T14:30:45+00:00[UTC]", "en-US") // "2 years ago"
 * @example formatRelativeUtc(value, "en-US", { roundingMethod: "floor" }) // rounds toward the earlier boundary
 * @example formatRelativeUtc("not-a-date") // ""
 */
export function formatRelativeUtc(value, locale, options = {}) {
    if (!isValidUtc(value))
        return "";
    if (options.reference !== undefined && !isValidUtc(options.reference))
        return "";
    const target = toInstantFromUtc(value);
    if (target === null)
        return "";
    let reference;
    if (options.reference) {
        const ref = toInstantFromUtc(options.reference);
        if (ref === null)
            return "";
        reference = ref;
    }
    else {
        try {
            reference = Temporal.Now.instant();
        }
        catch {
            return "";
        }
    }
    try {
        const diff = target.since(reference);
        const absSeconds = Math.abs(diff.total("second"));
        const unit = options.largestUnit ??
            AUTO_UNITS.find((t) => absSeconds < t.maxSeconds)?.unit ??
            "day";
        let amount;
        try {
            amount = resolveRelativeRounding(diff.total(unit), options.roundingMethod);
        }
        catch {
            // month/year are calendrical and need a relativeTo anchor.
            // Defer timezone normalization until we know we need it.
            const tz = normalizeTimeZone(options.timeZone);
            amount = resolveRelativeRounding(diff.total({ unit, relativeTo: reference.toZonedDateTimeISO(tz) }), options.roundingMethod);
        }
        return normalizeDateTime(new Intl.RelativeTimeFormat(locale, {
            numeric: options.numeric ?? "auto",
            style: options.style ?? "long",
        }).format(amount, unit));
    }
    catch {
        return "";
    }
}