From 3f5a4bd900028630f2b89b4ef94eaef74b044de1 Mon Sep 17 00:00:00 2001
From: Antonin Delpeuch <antonin@delpeuch.eu>
Date: Sun, 14 Nov 2021 10:29:46 +0100
Subject: [PATCH] Fix date parsing to avoid offsets due to DST. (#4295)

This pull request comes without tetsts because there is no clean way
to set the system timezone in a Java unit test:
https://stackoverflow.com/questions/23466218/setting-timezone-for-maven-unit-tests-on-java-8

The problem came from the fact that we were interpreting all dates with the current
zone *offset*, which varies during the year depending on DST, meaning that during the winter
we would interpret summer dates in a winter timezone, which does not make sense.
This changes the date conversion mechanism to only rely on the current zone, making sure
the correct offset is used depending on the value of the converted date.
---
 main/src/com/google/refine/util/ParsingUtilities.java | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/main/src/com/google/refine/util/ParsingUtilities.java b/main/src/com/google/refine/util/ParsingUtilities.java
index d5844c16c..3f84766b2 100644
--- a/main/src/com/google/refine/util/ParsingUtilities.java
+++ b/main/src/com/google/refine/util/ParsingUtilities.java
@@ -99,7 +99,7 @@ public class ParsingUtilities {
     public static final ObjectWriter defaultWriter = mapper.writerWithView(JsonViews.NonSaveMode.class).with(defaultFilters);
 
     public static final DateTimeFormatter ISO8601 = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'");
-    private static final ZoneOffset defaultTimeOffset = OffsetDateTime.now().getOffset();
+    private static final ZoneId defaultZone = ZoneId.systemDefault();
                 
     static public Properties parseUrlParameters(HttpServletRequest request) {
         Properties options = new Properties();
@@ -248,26 +248,26 @@ public class ParsingUtilities {
 
     /**
      * Converts an old-style Java Date to an OffsetDateTime,
-     * assuming the date is represented in the current default system timezone
+     * assuming the date is represented in the current default system zone
      * (which is what you get if the date was parsed using `Calendar.getDefault()`).
      * 
      * @param date
      * @return
      */
     public static OffsetDateTime toDate(Date date) {
-        return date.toInstant().atOffset(defaultTimeOffset);
+        return date.toInstant().atZone(defaultZone).toOffsetDateTime();
     }
 
     /**
      * Converts an old-style Java Calendar to an OffsetDateTime,
-     * assuming the date is represented in the current default system timezone
+     * assuming the date is represented in the current default system zone
      * (which is what you get if the date was parsed using `Calendar.getDefault()`).
      * 
      * @param date
      * @return
      */
     public static OffsetDateTime toDate(Calendar date) {
-        return date.toInstant().atOffset(defaultTimeOffset);
+        return date.toInstant().atZone(defaultZone).toOffsetDateTime();
     }
 
 	public static ObjectNode evaluateJsonStringToObjectNode(String optionsString) {