From cdb6130345a52797c36eb3008e2bff968a538359 Mon Sep 17 00:00:00 2001
From: Sam Becker <sam@sambecker.com>
Date: Thu, 12 Mar 2026 09:08:10 -0500
Subject: [PATCH] Extract date utility logic

---
 src/components/DateTimePicker.tsx | 19 +++++++++----------
 src/utility/date.ts               |  9 ++++++++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/components/DateTimePicker.tsx b/src/components/DateTimePicker.tsx
index 0fc0357a..a5080092 100644
--- a/src/components/DateTimePicker.tsx
+++ b/src/components/DateTimePicker.tsx
@@ -24,17 +24,16 @@ import { clsx } from 'clsx/lite';
 import useClickInsideOutside from '@/utility/useClickInsideOutside';
 import { useFormStatus } from 'react-dom';
 import { TbCalendar, TbChevronLeft, TbChevronRight } from 'react-icons/tb';
+import {
+  DATE_FORMAT_POSTGRES,
+  DAY_NAMES,
+  getLocalTimeZoneLabel,
+} from '@/utility/date';
 
-const FORMAT_NAIVE = 'yyyy-MM-dd HH:mm:ss';
-const DAY_NAMES = ['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa'];
-
-export type DateTimePickerType = 'utc' | 'naive';
+type DateTimePickerType = 'utc' | 'naive';
 type DisplayMode = 'utc' | 'local';
 
-// Get short local timezone label, e.g. "EST", "PST", "UTC+5"
-const LOCAL_TZ_LABEL =
-  new Date().toLocaleTimeString('en-US', { timeZoneName: 'short' })
-    .split(' ').at(-1) ?? 'LOCAL';
+const LOCAL_TZ_LABEL = getLocalTimeZoneLabel() ?? 'LOCAL';
 
 function parseValue(
   value: string,
@@ -60,7 +59,7 @@ function parseValue(
         utcDate.getUTCSeconds(),
       );
     } else {
-      const d = parse(value, FORMAT_NAIVE, new Date());
+      const d = parse(value, DATE_FORMAT_POSTGRES, new Date());
       return isValid(d) ? d : null;
     }
   } catch {
@@ -95,7 +94,7 @@ function formatValue(
       displayDate.getSeconds(),
     )).toISOString();
   }
-  return format(displayDate, FORMAT_NAIVE);
+  return format(displayDate, DATE_FORMAT_POSTGRES);
 }
 
 export default function DateTimePicker({
diff --git a/src/utility/date.ts b/src/utility/date.ts
index b8b9294a..96c14049 100644
--- a/src/utility/date.ts
+++ b/src/utility/date.ts
@@ -20,11 +20,13 @@ const DATE_FORMAT_LONG_PLACEHOLDER       = '00 000 0000 00:0000';
 const DATE_FORMAT_RSS                    = 'EEE, dd LLL yyyy HH:mm:ss xx';
 const DATE_FORMAT_RSS_PLACEHOLDER        = '000, 00 000 0000 00:00:00 00';
 
-const DATE_FORMAT_POSTGRES               = 'yyyy-MM-dd HH:mm:ss';
+export const DATE_FORMAT_POSTGRES               = 'yyyy-MM-dd HH:mm:ss';
 
 export const VALIDATION_EXAMPLE_POSTGRES        = '2025-01-03T21:00:44.000Z';
 export const VALIDATION_EXAMPLE_POSTGRES_NAIVE  = '2025-01-03 16:00:44';
 
+export const DAY_NAMES = ['Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa'];
+
 type AmbiguousTimestamp = number | string;
 
 type Length = 'tiny' | 'short' | 'medium' | 'long' | 'rss';
@@ -158,3 +160,8 @@ export const validationMessageNaivePostgresDateString = (date = '') =>
   validateNaivePostgresDateString(date)
     ? undefined
     : `Invalid format (${VALIDATION_EXAMPLE_POSTGRES_NAIVE})`;
+
+// Short local timezone label, e.g. "EST", "PST", "UTC+5"
+export const getLocalTimeZoneLabel = () =>
+  new Date().toLocaleTimeString('en-US', { timeZoneName: 'short' })
+    .split(' ').at(-1);