From 37bda3f3fd8a02bd96557fdc00dc3d888738c2a6 Mon Sep 17 00:00:00 2001
From: Markus Poerschke <markus@poerschke.nrw>
Date: Tue, 17 Jan 2023 11:26:56 +0100
Subject: [PATCH] Fix formatting UTC date time (#482)

Rather than setting TZID=UTC, date times that are using UTC must end
with the Z letter.

Wrong: DTSTART;TZID=UTC:20220812T090000
Correct: DTSTART;20220812T090000Z

Fixes: #462
Fixes: #263
---
 CHANGELOG.md                                             | 4 ++++
 .../Component/Property/Value/DateTimeValue.php           | 4 ++++
 src/Presentation/Factory/DateTimeFactory.php             | 6 +++++-
 tests/Unit/Presentation/Factory/DateTimeFactoryTest.php  | 9 +++++++++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4740f6b2..1b79afa2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+-   Fix formatting date time property with UTC time zone [#482](https://github.com/markuspoerschke/iCal/pull/482)
+
 ## [2.9.0] - 2022-12-23
 
 ### Changed
diff --git a/src/Presentation/Component/Property/Value/DateTimeValue.php b/src/Presentation/Component/Property/Value/DateTimeValue.php
index 63b3e934..25766839 100644
--- a/src/Presentation/Component/Property/Value/DateTimeValue.php
+++ b/src/Presentation/Component/Property/Value/DateTimeValue.php
@@ -41,6 +41,10 @@ private function convertTimestampToString(Timestamp $timestamp): string
 
     private function convertDateTimeToString(DateTime $dateTime): string
     {
+        if ($dateTime->hasDateTimeZone() && $dateTime->getDateTimeZone()->getName() === 'UTC') {
+            return $dateTime->getDateTime()->format(self::FORMAT_UTC);
+        }
+
         return $dateTime->getDateTime()->format(self::FORMAT);
     }
 
diff --git a/src/Presentation/Factory/DateTimeFactory.php b/src/Presentation/Factory/DateTimeFactory.php
index efa9a30a..45abf67c 100644
--- a/src/Presentation/Factory/DateTimeFactory.php
+++ b/src/Presentation/Factory/DateTimeFactory.php
@@ -37,7 +37,11 @@ public function createProperty(string $propertyName, PointInTime $pointInTime):
      */
     private function getParameters(PointInTime $pointInTime): array
     {
-        if ($pointInTime instanceof DateTime && $pointInTime->hasDateTimeZone()) {
+        if (
+            $pointInTime instanceof DateTime
+            && $pointInTime->hasDateTimeZone()
+            && $pointInTime->getDateTimeZone()->getName() !== 'UTC'
+        ) {
             return [
                 new Property\Parameter('TZID', new TextValue($pointInTime->getDateTimeZone()->getName())),
             ];
diff --git a/tests/Unit/Presentation/Factory/DateTimeFactoryTest.php b/tests/Unit/Presentation/Factory/DateTimeFactoryTest.php
index cdff4001..a3d42978 100644
--- a/tests/Unit/Presentation/Factory/DateTimeFactoryTest.php
+++ b/tests/Unit/Presentation/Factory/DateTimeFactoryTest.php
@@ -27,4 +27,13 @@ public function testCreateProperty(): void
 
         self::assertSame('DTSTART;TZID=Europe/Berlin:20210122T111213', $property->__toString());
     }
+
+    public function testUtcTimeZone(): void
+    {
+        $dateTime = new DateTime(new PhpDateTimeImmutable('2022-12-25 23:29:00', new DateTimeZone('UTC')), true);
+
+        $property = (new DateTimeFactory())->createProperty('DTSTART', $dateTime);
+
+        self::assertSame('DTSTART:20221225T232900Z', $property->__toString());
+    }
 }