Bring legacy CultNet into the schema-v0 fold

src/GameCult.Networking/CultNetSchemaMessageSerialization.cs

@@ -0,0 +1,63 @@
+using System;
+using MessagePack;
+
+namespace GameCult.Networking
+{
+    /// <summary>
+    /// Serializes and deserializes the explicit modern CultNet schema-v0 message family.
+    /// </summary>
+    public static class CultNetSchemaMessageSerialization
+    {
+        public static readonly MessagePackSerializerOptions Options =
+            MessagePackSerializerOptions.Standard.WithSecurity(MessagePackSecurity.UntrustedData);
+
+        public static byte[] Serialize<T>(T message) where T : ICultNetSchemaMessage
+        {
+            if (message == null) throw new ArgumentNullException(nameof(message));
+            return MessagePackSerializer.Serialize(message, Options);
+        }
+
+        public static T Deserialize<T>(byte[] payload) where T : ICultNetSchemaMessage
+        {
+            if (payload == null) throw new ArgumentNullException(nameof(payload));
+            return MessagePackSerializer.Deserialize<T>(payload, Options);
+        }
+
+        public static ICultNetSchemaMessage Deserialize(byte[] payload)
+        {
+            if (payload == null) throw new ArgumentNullException(nameof(payload));
+
+            var header = MessagePackSerializer.Deserialize<CultNetSchemaHeader>(payload, Options);
+            if (header == null || string.IsNullOrWhiteSpace(header.SchemaVersion))
+            {
+                throw new MessagePackSerializationException("CultNet schema-v0 payload is missing schemaVersion.");
+            }
+
+            return header.SchemaVersion switch
+            {
+                CultNetSchemaVersions.Hello => Deserialize<CultNetHelloMessage>(payload),
+                CultNetSchemaVersions.Login => Deserialize<CultNetLoginMessage>(payload),
+                CultNetSchemaVersions.Register => Deserialize<CultNetRegisterMessage>(payload),
+                CultNetSchemaVersions.Verify => Deserialize<CultNetVerifyMessage>(payload),
+                CultNetSchemaVersions.LoginSuccess => Deserialize<CultNetLoginSuccessMessage>(payload),
+                CultNetSchemaVersions.Error => Deserialize<CultNetErrorMessage>(payload),
+                CultNetSchemaVersions.SampleChangeName => Deserialize<CultNetSampleChangeNameMessage>(payload),
+                CultNetSchemaVersions.SampleChat => Deserialize<CultNetSampleChatMessage>(payload),
+                CultNetSchemaVersions.DocumentDelete => Deserialize<CultNetDocumentDeleteMessage>(payload),
+                CultNetSchemaVersions.DocumentPutRaw => Deserialize<CultNetDocumentPutRawMessage>(payload),
+                CultNetSchemaVersions.SnapshotRequest => Deserialize<CultNetSnapshotRequestMessage>(payload),
+                CultNetSchemaVersions.SnapshotResponseRaw => Deserialize<CultNetSnapshotResponseRawMessage>(payload),
+                CultNetSchemaVersions.SchemaCatalogRequest => Deserialize<CultNetSchemaCatalogRequestMessage>(payload),
+                CultNetSchemaVersions.SchemaCatalogResponse => Deserialize<CultNetSchemaCatalogResponseMessage>(payload),
+                _ => throw new MessagePackSerializationException(
+                    $"Unsupported CultNet schema-v0 message \"{header.SchemaVersion}\".")
+            };
+        }
+
+        [MessagePackObject]
+        internal sealed class CultNetSchemaHeader
+        {
+            [Key("schemaVersion")] public string SchemaVersion { get; set; } = string.Empty;
+        }
+    }
+}