func()

in plugins/golang-filter/mcp-session/common/server.go [241:442]

• 194 lines of code
• 32 McCabe index (conditional complexity)

func (s *MCPServer) HandleMessage(
	ctx context.Context,
	message json.RawMessage,
) mcp.JSONRPCMessage {
	// Add server to context

	ctx = context.WithValue(ctx, serverKey{}, s)

	var baseMessage struct {
		JSONRPC string      `json:"jsonrpc"`
		Method  string      `json:"method"`
		ID      interface{} `json:"id,omitempty"`
	}

	if err := json.Unmarshal(message, &baseMessage); err != nil {
		return createErrorResponse(
			nil,
			mcp.PARSE_ERROR,
			"Failed to parse message",
		)
	}

	// Check for valid JSONRPC version
	if baseMessage.JSONRPC != mcp.JSONRPC_VERSION {
		return createErrorResponse(
			baseMessage.ID,
			mcp.INVALID_REQUEST,
			"Invalid JSON-RPC version",
		)
	}

	if baseMessage.ID == nil {
		var notification mcp.JSONRPCNotification
		if err := json.Unmarshal(message, &notification); err != nil {
			return createErrorResponse(
				nil,
				mcp.PARSE_ERROR,
				"Failed to parse notification",
			)
		}
		s.handleNotification(ctx, notification)
		return nil // Return nil for notifications
	}

	switch baseMessage.Method {
	case "initialize":
		var request mcp.InitializeRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid initialize request",
			)
		}
		return s.handleInitialize(ctx, baseMessage.ID, request)
	case "ping":
		var request mcp.PingRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid ping request",
			)
		}
		return s.handlePing(ctx, baseMessage.ID, request)
	case "resources/list":
		if s.capabilities.resources == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Resources not supported",
			)
		}
		var request mcp.ListResourcesRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid list resources request",
			)
		}
		return s.handleListResources(ctx, baseMessage.ID, request)
	case "resources/templates/list":
		if s.capabilities.resources == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Resources not supported",
			)
		}
		var request mcp.ListResourceTemplatesRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid list resource templates request",
			)
		}
		return s.handleListResourceTemplates(ctx, baseMessage.ID, request)
	case "resources/read":
		if s.capabilities.resources == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Resources not supported",
			)
		}
		var request mcp.ReadResourceRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid read resource request",
			)
		}
		return s.handleReadResource(ctx, baseMessage.ID, request)
	case "prompts/list":
		if s.capabilities.prompts == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Prompts not supported",
			)
		}
		var request mcp.ListPromptsRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid list prompts request",
			)
		}
		return s.handleListPrompts(ctx, baseMessage.ID, request)
	case "prompts/get":
		if s.capabilities.prompts == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Prompts not supported",
			)
		}
		var request mcp.GetPromptRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid get prompt request",
			)
		}
		return s.handleGetPrompt(ctx, baseMessage.ID, request)
	case "tools/list":
		if s.capabilities.tools == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Tools not supported",
			)
		}
		var request mcp.ListToolsRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid list tools request",
			)
		}
		return s.handleListTools(ctx, baseMessage.ID, request)
	case "tools/call":
		if s.capabilities.tools == nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.METHOD_NOT_FOUND,
				"Tools not supported",
			)
		}
		var request mcp.CallToolRequest
		if err := json.Unmarshal(message, &request); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid call tool request",
			)
		}
		return s.handleToolCall(ctx, baseMessage.ID, request)
	case "":
		var response mcp.JSONRPCResponse
		if err := json.Unmarshal(message, &response); err != nil {
			return createErrorResponse(
				baseMessage.ID,
				mcp.INVALID_REQUEST,
				"Invalid message format",
			)
		}
		return nil
	default:
		return createErrorResponse(
			baseMessage.ID,
			mcp.METHOD_NOT_FOUND,
			fmt.Sprintf("Method %s not found", baseMessage.Method),
		)
	}
}