Fix #1125 NatsJetStreamMetaData timestamp timezone (#1126)

src/main/java/io/nats/client/impl/NatsJetStreamMetaData.java

@@ -13,18 +13,14 @@
 
 package io.nats.client.impl;
 
-import java.time.LocalDateTime;
-import java.time.OffsetDateTime;
-import java.time.ZoneId;
+import io.nats.client.support.DateTimeUtils;
 import java.time.ZonedDateTime;
 
 /**
  * Jetstream meta data about a message, when applicable.
  */
 public class NatsJetStreamMetaData {
 
-    private static final long NANO_FACTOR = 10_00_000_000;
-
     private final String prefix;
     private final String domain;
     private final String accountHash;
@@ -99,15 +95,8 @@ else if (parts.length >= 11) {
             delivered = Long.parseLong(parts[streamIndex + 2]);
             streamSeq = Long.parseLong(parts[streamIndex + 3]);
             consumerSeq = Long.parseLong(parts[streamIndex + 4]);
-
-            // not so clever way to separate nanos from seconds
-            long tsi = Long.parseLong(parts[streamIndex + 5]);
-            long seconds = tsi / NANO_FACTOR;
-            int nanos = (int) (tsi - ((tsi / NANO_FACTOR) * NANO_FACTOR));
-            LocalDateTime ltd = LocalDateTime.ofEpochSecond(seconds, nanos, OffsetDateTime.now().getOffset());
-            timestamp = ZonedDateTime.of(ltd, ZoneId.systemDefault()); // I think this is safe b/c the zone should match local
-
-            this.pending = hasPending ? Long.parseLong(parts[streamIndex + 6]) : -1L;
+            timestamp = DateTimeUtils.parseDateTimeNanos(parts[streamIndex + 5]);
+            pending = hasPending ? Long.parseLong(parts[streamIndex + 6]) : -1L;
         }
         catch (Exception e) {
             throw new IllegalArgumentException(notAJetStreamMessage(natsMessage.getReplyTo()));

src/main/java/io/nats/client/support/DateTimeUtils.java

@@ -15,7 +15,9 @@
 
 import java.time.Duration;
 import java.time.Instant;
+import java.time.OffsetDateTime;
 import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeParseException;
@@ -29,7 +31,8 @@ private DateTimeUtils() {}  /* ensures cannot be constructed */
     public static final ZoneId ZONE_ID_GMT = ZoneId.of("GMT");
     public static final ZonedDateTime DEFAULT_TIME = ZonedDateTime.of(1, 1, 1, 0, 0, 0, 0, ZONE_ID_GMT);
     public static final DateTimeFormatter RFC3339_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.nnnnnnnnn'Z'");
-
+    private static final long NANO_FACTOR = 1_000_000_000;
+
     public static ZonedDateTime toGmt(ZonedDateTime zonedDateTime) {
         return zonedDateTime.withZoneSameInstant(ZONE_ID_GMT);
     }
@@ -69,6 +72,34 @@ public static ZonedDateTime parseDateTime(String dateTime, ZonedDateTime dflt) {
     public static ZonedDateTime parseDateTimeThrowParseError(String dateTime) {
         return toGmt(ZonedDateTime.parse(dateTime));
     }
+
+    /**
+     * Parses a long timestamp with nano precission in epoch UTC to the system 
+     * default time-zone date time
+     * 
+     * @param timestampNanos String timestamp
+     * @return a local Zoned Date time.
+     */
+    public static ZonedDateTime parseDateTimeNanos(String timestampNanos) {
+        return parseDateTimeNanos(timestampNanos, ZoneId.systemDefault());
+    }
+
+    /**
+     * Parses a long timestamp with nano precission in epoch UTC to a Zoned date 
+     * time
+     * 
+     * @param timestampNanos String timestamp
+     * @param zoneId ZoneId
+     * @return a Zoned Date time.
+     */
+    public static ZonedDateTime parseDateTimeNanos(String timestampNanos, ZoneId zoneId) {
+        long ts = Long.parseLong(timestampNanos);
+        long seconds = ts / NANO_FACTOR;
+        long nanos = ts % NANO_FACTOR;
+        Instant utcInstant = Instant.ofEpochSecond(seconds, nanos);
+        OffsetDateTime utcOffsetDT = OffsetDateTime.ofInstant(utcInstant, ZoneOffset.UTC);
+        return utcOffsetDT.atZoneSameInstant(zoneId);
+    }
 
     public static ZonedDateTime fromNow(long millis) {
         return ZonedDateTime.ofInstant(Instant.now().plusMillis(millis), ZONE_ID_GMT);

src/test/java/io/nats/client/impl/NatsJetStreamMetaDataTests.java

@@ -14,6 +14,8 @@
 package io.nats.client.impl;
 
 import io.nats.client.Message;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -52,9 +54,13 @@ private void validateMeta(boolean hasPending, boolean hasDomainHashToken, NatsJe
         assertEquals(2, meta.streamSequence());
         assertEquals(3, meta.consumerSequence());
 
-        assertEquals(2020, meta.timestamp().getYear());
-        assertEquals(6, meta.timestamp().getMinute());
-        assertEquals(113260000, meta.timestamp().getNano());
+        ZonedDateTime localTs = meta.timestamp();
+        assertEquals(2020, localTs.getYear());
+        assertEquals(6, localTs.getMinute());
+        assertEquals(113260000, localTs.getNano());
+
+        ZonedDateTime utcTs = localTs.withZoneSameInstant(ZoneId.of("UTC"));
+        assertEquals(0, utcTs.getHour());
 
         assertEquals(hasPending ? 4L : -1L, meta.pendingCount());
 

src/test/java/io/nats/client/support/DateTimeUtilsTests.java

@@ -23,6 +23,12 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 public final class DateTimeUtilsTests {
+
+    @Test
+    public void testParseDateTimeNanos() {
+       assertEquals(1605139610, DateTimeUtils.parseDateTimeNanos("1605139610113260000").toEpochSecond());
+       assertEquals(113261234, DateTimeUtils.parseDateTimeNanos("1605139610113261234").toInstant().getNano());
+    }
 
     @Test
     public void testParseDateTime() {