Implement Msg DateTime and Sequence only in JetStream

.editorconfig

@@ -13,6 +13,7 @@ generated_code = true
 
 [*.cs]
 indent_size = 4
+max_line_length = 300
 
 # changes from VS2019 defaults
 csharp_style_namespace_declarations = file_scoped

src/NATS.Client.Core/NatsMsg.cs

@@ -1,6 +1,5 @@
 using System.Buffers;
 using System.Diagnostics.CodeAnalysis;
-using NATS.Client.Core.Internal;
 
 namespace NATS.Client.Core;
 
@@ -25,8 +24,6 @@ namespace NATS.Client.Core;
 public readonly record struct NatsMsg(
     string Subject,
     string? ReplyTo,
-    long? Seq,
-    DateTimeOffset? DateTime,
     int Size,
     NatsHeaders? Headers,
     ReadOnlyMemory<byte> Data,
@@ -53,22 +50,12 @@ internal static NatsMsg Build(
             headers.SetReadOnly();
         }
 
-        long? seq = null;
-        DateTimeOffset? dateTime = null;
-
-        if (replyTo != null)
-        {
-            var dateTimeAndSeq = ReplyToDateTimeAndSeq.Parse(replyTo);
-            seq = dateTimeAndSeq.Seq;
-            dateTime = dateTimeAndSeq.DateTime;
-        }
-
         var size = subject.Length
                    + (replyTo?.Length ?? 0)
                    + (headersBuffer?.Length ?? 0)
                    + payloadBuffer.Length;
 
-        return new NatsMsg(subject, replyTo, seq, dateTime, (int) size, headers, payloadBuffer.ToArray(), connection);
+        return new NatsMsg(subject, replyTo, (int)size, headers, payloadBuffer.ToArray(), connection);
     }
 
     /// <summary>
@@ -142,8 +129,6 @@ private void CheckReplyPreconditions()
 public readonly record struct NatsMsg<T>(
     string Subject,
     string? ReplyTo,
-    long? Seq,
-    DateTimeOffset? DateTime,
     int Size,
     NatsHeaders? Headers,
     T? Data,
@@ -178,22 +163,12 @@ internal static NatsMsg<T> Build(
             headers.SetReadOnly();
         }
 
-        long? seq = null;
-        DateTimeOffset? dateTime = null;
-
-        if (replyTo != null)
-        {
-            var dateTimeAndSeq = ReplyToDateTimeAndSeq.Parse(replyTo);
-            seq = dateTimeAndSeq.Seq;
-            dateTime = dateTimeAndSeq.DateTime;
-        }
-
         var size = subject.Length
             + (replyTo?.Length ?? 0)
             + (headersBuffer?.Length ?? 0)
             + payloadBuffer.Length;
 
-        return new NatsMsg<T>(subject, replyTo, seq, dateTime, (int) size, headers, data, connection);
+        return new NatsMsg<T>(subject, replyTo, (int)size, headers, data, connection);
     }
 
     /// <summary>

src/NATS.Client.JetStream/Internal/ReplyToDateTimeAndSeq.cs

@@ -0,0 +1,28 @@
+namespace NATS.Client.JetStream.Internal;
+
+internal static class ReplyToDateTimeAndSeq
+{
+    internal static (DateTimeOffset? DateTime, long? Seq) Parse(string? reply)
+    {
+        if (reply == null)
+        {
+            return (null, null);
+        }
+
+        var ackSeperated = reply.Split(".");
+
+        // It must be seperated by 9 dots as defined in
+        // https://docs.nats.io/reference/reference-protocols/nats_api_reference#acknowledging-messages
+        if (ackSeperated.Length != 9)
+        {
+            return (null, null);
+        }
+
+        var timestamp = long.Parse(ackSeperated[^2]);
+        var offset = DateTimeOffset.FromUnixTimeMilliseconds(timestamp / 1000000);
+        var dateTime = new DateTimeOffset(offset.Ticks, TimeSpan.Zero);
+        var seq = long.Parse(ackSeperated[5]);
+
+        return (dateTime, seq);
+    }
+}

src/NATS.Client.JetStream/NatsJSMsg.cs

@@ -12,11 +12,13 @@ public readonly struct NatsJSMsg<T>
 {
     private readonly NatsJSContext _context;
     private readonly NatsMsg<T> _msg;
+    private readonly Lazy<(DateTimeOffset? DateTime, long? Sequence)> _replyToDateTimeAndSeq;
 
     internal NatsJSMsg(NatsMsg<T> msg, NatsJSContext context)
     {
         _msg = msg;
         _context = context;
+        _replyToDateTimeAndSeq = new Lazy<(DateTimeOffset? DateTime, long? Sequnce)>(() => ReplyToDateTimeAndSeq.Parse(msg.ReplyTo));
     }
 
     /// <summary>
@@ -53,12 +55,12 @@ internal NatsJSMsg(NatsMsg<T> msg, NatsJSContext context)
     /// <summary>
     /// The sequence number of the message.
     /// </summary>
-    public long? Sequence => _msg.Seq;
+    public long? Sequence => _replyToDateTimeAndSeq.Value.Sequence;
 
     /// <summary>
     /// The time of the message.
     /// </summary>
-    public DateTimeOffset? DateTime => _msg.DateTime;
+    public DateTimeOffset? DateTime => _replyToDateTimeAndSeq.Value.DateTime;
 
     /// <summary>
     /// Acknowledges the message was completely handled.
@@ -112,10 +114,7 @@ private ValueTask SendAckAsync(ReadOnlySequence<byte> payload, AckOpts opts = de
 
         return _msg.ReplyAsync(
             payload: payload,
-            opts: new NatsPubOpts
-            {
-                WaitUntilSent = opts.WaitUntilSent ?? _context.Opts.AckOpts.WaitUntilSent,
-            },
+            opts: new NatsPubOpts {WaitUntilSent = opts.WaitUntilSent ?? _context.Opts.AckOpts.WaitUntilSent,},
             cancellationToken: cancellationToken);
     }
 }

tests/NATS.Client.JetStream.Tests/Internal/ReplyToDateTimeAndSeqTest.cs

@@ -0,0 +1,33 @@
+using NATS.Client.JetStream.Internal;
+
+namespace NATS.Client.JetStream.Tests.Internal;
+
+public class ReplyToDateTimeAndSeqTest
+{
+    [Fact]
+    public void ShouldParseReplyToDateTimeAndSeq()
+    {
+        var (dateTime, seq) = ReplyToDateTimeAndSeq.Parse("$JS.ACK.UnitTest.GetEvents_0.1.100.1.1696023331771188000.0");
+
+        dateTime!.Value.ToString("O").Should().Be("2023-09-29T21:35:31.7710000+00:00");
+        seq.Should().Be(100);
+    }
+
+    [Fact]
+    public void ShouldSetNullForReturnWhenReplyToIsNull()
+    {
+        var (dateTime, seq) = ReplyToDateTimeAndSeq.Parse(null);
+
+        dateTime.Should().BeNull();
+        seq.Should().BeNull();
+    }
+
+    [Fact]
+    public void ShouldSetNullWhenReplyToIsASimpleReqResponse()
+    {
+        var (dateTime, seq) = ReplyToDateTimeAndSeq.Parse("_INBOX.1");
+
+        dateTime.Should().BeNull();
+        seq.Should().BeNull();
+    }
+}