Initial commit

src/mcpdotnet/Utils/Json/JsonRpcMessageConverter.cs

@@ -0,0 +1,86 @@
+// Utils/Json/JsonRpcMessageConverter.cs (continued)
+namespace McpDotNet.Utils.Json;
+
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using global::McpDotNet.Protocol.Messages;
+
+/// <summary>
+/// JSON converter for IJsonRpcMessage that handles polymorphic deserialization of different message types.
+/// </summary>
+public class JsonRpcMessageConverter : JsonConverter<IJsonRpcMessage>
+{
+    public override IJsonRpcMessage? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType != JsonTokenType.StartObject)
+        {
+            throw new JsonException("Expected StartObject token");
+        }
+
+        using var doc = JsonDocument.ParseValue(ref reader);
+        var root = doc.RootElement;
+
+        // All JSON-RPC messages must have a jsonrpc property with value "2.0"
+        if (!root.TryGetProperty("jsonrpc", out var versionProperty) ||
+            versionProperty.GetString() != "2.0")
+        {
+            throw new JsonException("Invalid or missing jsonrpc version");
+        }
+
+        // Determine the message type based on the presence of id, method, and error properties
+        bool hasId = root.TryGetProperty("id", out _);
+        bool hasMethod = root.TryGetProperty("method", out _);
+        bool hasError = root.TryGetProperty("error", out _);
+
+        var rawText = root.GetRawText();
+
+        // Messages with an id but no method are responses
+        if (hasId && !hasMethod)
+        {
+            // Messages with an error property are error responses
+            if (hasError)
+            {
+                return JsonSerializer.Deserialize<JsonRpcError>(rawText, options);
+            }
+            // Messages with a result property are success responses
+            else if (root.TryGetProperty("result", out _))
+            {
+                return JsonSerializer.Deserialize<JsonRpcResponse>(rawText, options);
+            }
+            throw new JsonException("Response must have either result or error");
+        }
+        // Messages with a method but no id are notifications
+        else if (hasMethod && !hasId)
+        {
+            return JsonSerializer.Deserialize<JsonRpcNotification>(rawText, options);
+        }
+        // Messages with both method and id are requests
+        else if (hasMethod && hasId)
+        {
+            return JsonSerializer.Deserialize<JsonRpcRequest>(rawText, options);
+        }
+
+        throw new JsonException("Invalid JSON-RPC message format");
+    }
+
+    public override void Write(Utf8JsonWriter writer, IJsonRpcMessage value, JsonSerializerOptions options)
+    {
+        switch (value)
+        {
+            case JsonRpcRequest request:
+                JsonSerializer.Serialize(writer, request, options);
+                break;
+            case JsonRpcNotification notification:
+                JsonSerializer.Serialize(writer, notification, options);
+                break;
+            case JsonRpcResponse response:
+                JsonSerializer.Serialize(writer, response, options);
+                break;
+            case JsonRpcError error:
+                JsonSerializer.Serialize(writer, error, options);
+                break;
+            default:
+                throw new JsonException($"Unknown JSON-RPC message type: {value.GetType()}");
+        }
+    }
+}