Add Timestamp support

Author: Havret

src/System.Text.Json.Protobuf/FieldInfo.cs

@@ -1,3 +1,4 @@
+using System.Text.Json.Protobuf.InternalConverters;
 using Google.Protobuf.Reflection;
 
 namespace System.Text.Json.Protobuf;

…tem.Text.Json.Protobuf/FieldConverter.cs …buf/InternalConverters/FieldConverter.cssrc/System.Text.Json.Protobuf/FieldConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/FieldConverter.cs src/System.Text.Json.Protobuf/FieldConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/FieldConverter.cs

@@ -2,7 +2,7 @@
 using Google.Protobuf;
 using Google.Protobuf.Reflection;
 
-namespace System.Text.Json.Protobuf;
+namespace System.Text.Json.Protobuf.InternalConverters;
 
 internal class FieldConverter<T> : InternalConverter
 {

….Text.Json.Protobuf/InternalConverter.cs …/InternalConverters/InternalConverter.cssrc/System.Text.Json.Protobuf/InternalConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/InternalConverter.cs src/System.Text.Json.Protobuf/InternalConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/InternalConverter.cs

@@ -1,7 +1,7 @@
 using Google.Protobuf;
 using Google.Protobuf.Reflection;
 
-namespace System.Text.Json.Protobuf;
+namespace System.Text.Json.Protobuf.InternalConverters;
 
 internal abstract class InternalConverter
 {

…son.Protobuf/InternalConverterFactory.cs …alConverters/InternalConverterFactory.cssrc/System.Text.Json.Protobuf/InternalConverterFactory.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/InternalConverterFactory.cs src/System.Text.Json.Protobuf/InternalConverterFactory.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/InternalConverterFactory.cs

@@ -1,4 +1,4 @@
-namespace System.Text.Json.Protobuf;
+namespace System.Text.Json.Protobuf.InternalConverters;
 
 internal class InternalConverterFactory
 {

….Json.Protobuf/RepeatedFieldConverter.cs …rnalConverters/RepeatedFieldConverter.cssrc/System.Text.Json.Protobuf/RepeatedFieldConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/RepeatedFieldConverter.cs src/System.Text.Json.Protobuf/RepeatedFieldConverter.cs renamed to src/System.Text.Json.Protobuf/InternalConverters/RepeatedFieldConverter.cs

@@ -3,7 +3,7 @@
 using Google.Protobuf.Collections;
 using Google.Protobuf.Reflection;
 
-namespace System.Text.Json.Protobuf;
+namespace System.Text.Json.Protobuf.InternalConverters;
 
 internal class RepeatedFieldConverter<T> : InternalConverter
 {

src/System.Text.Json.Protobuf/JsonSerializerOptionsExtensions.cs

@@ -7,6 +7,7 @@ public static class JsonSerializerOptionsExtensions
 {
     public static void AddProtobufSupport(this JsonSerializerOptions options)
     {
+        options.Converters.Add(new TimestampConverter());
         options.Converters.Add(new ProtobufJsonConverterFactory());
     }
 }

src/System.Text.Json.Protobuf/ProtobufConverter.cs

@@ -1,4 +1,5 @@
 using System.Reflection;
+using System.Text.Json.Protobuf.InternalConverters;
 using System.Text.Json.Serialization;
 using Google.Protobuf;
 using Google.Protobuf.Reflection;

src/System.Text.Json.Protobuf/TimestampConverter.cs

@@ -0,0 +1,29 @@
+using System.Text.Json.Serialization;
+using Google.Protobuf.WellKnownTypes;
+
+namespace System.Text.Json.Protobuf;
+
+public class TimestampConverter : JsonConverter<Timestamp?>
+{
+    private JsonConverter<DateTime>? _converter;
+
+    public override Timestamp? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TryGetDateTime(out var dateTime))
+        {
+            return dateTime.ToTimestamp();
+        }
+
+        return null;
+    }
+
+    public override void Write(Utf8JsonWriter writer, Timestamp? value, JsonSerializerOptions options)
+    {
+        if (value != null)
+        {
+            var dateTime = value.ToDateTime();
+            _converter ??= (JsonConverter<DateTime>) options.GetConverter(typeof(DateTime));
+            _converter.Write(writer, dateTime, options);
+        }
+    }
+}

test/System.Text.Json.Protobuf.Tests/MessageWithTimestampTests.Should_serialize_message_with_timestamp.approved.json

@@ -0,0 +1,3 @@
+{
+  "timestampProperty": "1991-01-25T00:00:00Z"
+}

test/System.Text.Json.Protobuf.Tests/MessageWithTimestampTests.Should_serialize_message_with_timestamp_when_value_not_set.approved.json

@@ -0,0 +1 @@
+{}