first commit

packages/@n8n/nodes-langchain/nodes/mcp/McpTrigger/protocol/MessageParser.ts

@@ -0,0 +1,76 @@
+import {
+	JSONRPCMessageSchema,
+	ListToolsRequestSchema,
+	CallToolRequestSchema,
+} from '@modelcontextprotocol/sdk/types.js';
+import type { JSONRPCMessage } from '@modelcontextprotocol/sdk/types.js';
+
+import type { McpToolCallInfo } from './types';
+
+export class MessageParser {
+	static parse(body: string): JSONRPCMessage | undefined {
+		try {
+			const message: unknown = JSON.parse(body);
+			return JSONRPCMessageSchema.parse(message);
+		} catch {
+			return undefined;
+		}
+	}
+
+	static isToolCall(body: string): boolean {
+		const message = this.parse(body);
+		if (!message) return false;
+		return (
+			'method' in message &&
+			'id' in message &&
+			message.method === CallToolRequestSchema.shape.method.value
+		);
+	}
+
+	static isListToolsRequest(body: string): boolean {
+		const message = this.parse(body);
+		if (!message) return false;
+		return (
+			'method' in message &&
+			'id' in message &&
+			message.method === ListToolsRequestSchema.shape.method.value
+		);
+	}
+
+	static getRequestId(message: unknown): string | undefined {
+		try {
+			const parsed = JSONRPCMessageSchema.parse(message);
+			return 'id' in parsed ? String(parsed.id) : undefined;
+		} catch {
+			return undefined;
+		}
+	}
+
+	static extractToolCallInfo(body: string): McpToolCallInfo | undefined {
+		const message = this.parse(body);
+		if (!message) return undefined;
+
+		if (
+			'method' in message &&
+			'params' in message &&
+			message.method === CallToolRequestSchema.shape.method.value
+		) {
+			const params = message.params;
+			if (
+				typeof params === 'object' &&
+				params !== null &&
+				'name' in params &&
+				typeof params.name === 'string' &&
+				'arguments' in params &&
+				typeof params.arguments === 'object' &&
+				params.arguments !== null
+			) {
+				return {
+					toolName: params.name,
+					arguments: params.arguments as Record<string, unknown>,
+				};
+			}
+		}
+		return undefined;
+	}
+}