From d8e1285c3d20bc6052090afeb462243c2594f3a2 Mon Sep 17 00:00:00 2001
From: Kim Peeters <kim@xs3.nl>
Date: Thu, 13 Jun 2024 12:22:46 +0200
Subject: [PATCH] Allowing BC era timestamps in fromAbsolute (#6541)

---
 packages/@internationalized/date/src/conversion.ts        | 2 +-
 packages/@internationalized/date/tests/conversion.test.js | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/packages/@internationalized/date/src/conversion.ts b/packages/@internationalized/date/src/conversion.ts
index ea18f334065..538015c18b6 100644
--- a/packages/@internationalized/date/src/conversion.ts
+++ b/packages/@internationalized/date/src/conversion.ts
@@ -187,7 +187,7 @@ export function fromAbsolute(ms: number, timeZone: string): ZonedDateTime {
   let second = date.getUTCSeconds();
   let millisecond = date.getUTCMilliseconds();
 
-  return new ZonedDateTime(year, month, day, timeZone, offset, hour, minute, second, millisecond);
+  return new ZonedDateTime(year < 1 ? 'BC' : 'AD', year < 0 ? Math.abs(year) + 1 : year, month, day, timeZone, offset, hour, minute, second, millisecond);
 }
 
 /**
diff --git a/packages/@internationalized/date/tests/conversion.test.js b/packages/@internationalized/date/tests/conversion.test.js
index 6d38a6aa627..27040d2c75b 100644
--- a/packages/@internationalized/date/tests/conversion.test.js
+++ b/packages/@internationalized/date/tests/conversion.test.js
@@ -136,6 +136,14 @@ describe('CalendarDate conversion', function () {
       date = fromAbsolute(new Date('2020-02-03T10:00Z').getTime(), 'America/New_York');
       expect(date).toEqual(new ZonedDateTime(2020, 2, 3, 'America/New_York', -18000000, 5));
     });
+
+    it('should convert a date from absolute in the BC era', function () {
+      let date = fromAbsolute(new Date('0000-01-01T00:00:00.000Z').getTime(), 'UTC');
+      expect(date).toEqual(new ZonedDateTime('BC', 1, 1, 1, 'UTC', 0, 0, 0, 0));
+
+      date = fromAbsolute(new Date('-000009-01-01T00:00:00.000Z').getTime(), 'UTC');
+      expect(date).toEqual(new ZonedDateTime('BC', 10, 1, 1, 'UTC', 0, 0, 0, 0));
+    });
   });
 
   describe('toCalendar', function () {