From 17fd3edb94a581fc571f5775ee8240a8b3518b93 Mon Sep 17 00:00:00 2001
From: bernhard <Bernhard.Schmalhofer@gmx.de>
Date: Wed, 19 Aug 2020 16:40:41 +0200
Subject: [PATCH] Issue #238: implement the UTC-workaround for
 PreviousEventGet()

Just like in NextEventGet()
---
 Kernel/System/CronEvent.pm | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/Kernel/System/CronEvent.pm b/Kernel/System/CronEvent.pm
index b28e2ae70c..fa356e220f 100644
--- a/Kernel/System/CronEvent.pm
+++ b/Kernel/System/CronEvent.pm
@@ -84,6 +84,7 @@ sub NextEventGet {
     }
 
     my $StartDateTime = $Param{StartDateTime} || $Kernel::OM->Create('Kernel::System::DateTime');
+
     return if !$StartDateTime;
 
     # Calculations are only made in UTC time zone to prevent errors with times that
@@ -106,6 +107,7 @@ sub NextEventGet {
     );
 
     return if !$CronObject;
+
     my ( $Sec, $Min, $Hour, $Day, $Month, $Year ) = $CronObject->nextEvent();
 
     my $EventDateTime = $Kernel::OM->Create(
@@ -162,6 +164,7 @@ sub NextEventList {
     }
 
     my $StartDateTime = $Param{StartDateTime} || $Kernel::OM->Create('Kernel::System::DateTime');
+
     return if !$StartDateTime;
 
     if ( $StartDateTime > $Param{StopDateTime} ) {
@@ -239,8 +242,22 @@ sub PreviousEventGet {
     }
 
     my $StartDateTime = $Param{StartDateTime} || $Kernel::OM->Create('Kernel::System::DateTime');
+
     return if !$StartDateTime;
 
+    # Calculations are only made in UTC time zone to prevent errors with times that
+    # would not exist in the given time zone (e. g. on/around daylight saving time switch).
+    # CPAN DateTime fails if trying to create a object of a non-existing
+    # time in the given time zone. Converting it to UTC and back has the desired effect.
+    my $OTOBOTimeZone = $StartDateTime->OTOBOTimeZoneGet();
+    my $TimeZoneChanged;
+    if ( $OTOBOTimeZone ne 'UTC' ) {
+        $StartDateTime->ToTimeZone(
+            TimeZone => 'UTC'
+        );
+        $TimeZoneChanged = 1;
+    }
+
     # init cron object
     my $CronObject = $Self->_Init(
         Schedule      => $Param{Schedule},
@@ -254,15 +271,22 @@ sub PreviousEventGet {
     my $EventDateTime = $Kernel::OM->Create(
         'Kernel::System::DateTime',
         ObjectParams => {
-            Year   => $Year + 1900,
-            Month  => $Month + 1,
-            Day    => $Day,
-            Hour   => $Hour,
-            Minute => $Min,
-            Second => $Sec,
+            Year     => $Year + 1900,
+            Month    => $Month + 1,
+            Day      => $Day,
+            Hour     => $Hour,
+            Minute   => $Min,
+            Second   => $Sec,
+            TimeZone => 'UTC'
         },
     );
 
+    if ($TimeZoneChanged) {
+        $EventDateTime->ToTimeZone(
+            TimeZone => $OTOBOTimeZone
+        );
+    }
+
     return $EventDateTime->ToString();
 }