gpt-engineer-app[bot]andrenee-png
be8229c39f
Co-authored-by: renee-png <262607627+renee-png@users.noreply.github.com>
33 lines
1.4 KiB
TypeScript
33 lines
1.4 KiB
TypeScript
import { fromZonedTime, toZonedTime, format as formatTz } from "date-fns-tz";
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/**
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* Firm timezone — all calendar entries are entered and displayed in EST/EDT
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* regardless of the browser's local timezone.
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*/
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export const FIRM_TZ = "America/New_York";
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/**
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* Convert a "wall clock" date + HH:mm string entered in EST into an ISO UTC
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* timestamp suitable for Postgres `timestamptz`. Handles DST automatically.
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*
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* Example: ("2024-07-04", "09:00") → "2024-07-04T13:00:00.000Z" (EDT, -04:00)
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* ("2024-01-15", "09:00") → "2024-01-15T14:00:00.000Z" (EST, -05:00)
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*/
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export function estWallTimeToUTC(dateStr: string, timeStr: string): string {
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// Build a naive local-style string and tell date-fns-tz to interpret it as EST.
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const naive = `${dateStr}T${timeStr.length === 5 ? `${timeStr}:00` : timeStr}`;
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return fromZonedTime(naive, FIRM_TZ).toISOString();
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}
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/** Format a UTC ISO timestamp in EST using a date-fns format token. */
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export function formatInEST(iso: string | Date, fmt: string): string {
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const d = typeof iso === "string" ? new Date(iso) : iso;
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return formatTz(toZonedTime(d, FIRM_TZ), fmt, { timeZone: FIRM_TZ });
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}
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/** Get a Date object representing the EST wall-clock for a UTC ISO. */
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export function toESTDate(iso: string | Date): Date {
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const d = typeof iso === "string" ? new Date(iso) : iso;
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return toZonedTime(d, FIRM_TZ);
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}
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