import express from "express";
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { PORT } from "../config/server-config.js";
import fs from 'fs';
import path from 'path';
// Create a logger that won't interfere with stdio transport
export const logger = {
_stdioMode: process.env.TRANSPORT === 'stdio',
_logFile: process.env.LOG_FILE || './mcp-server.log',
_writeToFile(message: string) {
try {
fs.appendFileSync(this._logFile, `${new Date().toISOString()} - ${message}\n`);
} catch (err) {
process.stderr.write(`${message}\n`);
}
},
log: (message: string) => {
if (logger._stdioMode) {
logger._writeToFile(`[LOG] ${message}`);
} else {
console.log(message);
}
},
info: (message: string) => {
if (logger._stdioMode) {
logger._writeToFile(`[INFO] ${message}`);
} else {
console.log(message);
}
},
warn: (message: string) => {
if (logger._stdioMode) {
logger._writeToFile(`[WARN] ${message}`);
} else {
console.warn(message);
}
},
error: (message: string, error?: unknown) => {
let errorMsg = message;
if (error instanceof Error) {
errorMsg += ` ${error.stack || error.message}`;
} else if (error !== undefined) {
errorMsg += ` ${String(error)}`;
}
if (logger._stdioMode) {
logger._writeToFile(`[ERROR] ${errorMsg}`);
} else {
console.error(errorMsg);
}
}
};
/**
* Setup stdio transport for command line usage
* @param server MCP server instance
*/
export function setupStdioTransport(server: McpServer): Promise<void> {
const transport = new StdioServerTransport();
return server.connect(transport).then(() => {
logger.info("Open Food Facts MCP Server started with stdio transport");
}).catch(error => {
logger.error("Error starting MCP server with stdio transport:", error);
process.exit(1);
});
}
/**
* Setup HTTP transport using StreamableHTTP for web-based clients
* @param server MCP server instance
* @param app Express application
*/
export function setupHttpTransport(server: McpServer, app: express.Application): Promise<void> {
return new Promise((resolve, reject) => {
try {
app.use(express.json());
// StreamableHTTP endpoint (modern MCP transport)
app.post("/mcp", async (req, res) => {
try {
// Create a new transport for each request to prevent request ID collisions
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: undefined,
enableJsonResponse: true
});
res.on('close', () => {
transport.close();
});
await server.connect(transport);
await transport.handleRequest(req, res, req.body);
} catch (error) {
logger.error('Error handling MCP request:', error);
if (!res.headersSent) {
res.status(500).json({
jsonrpc: '2.0',
error: {
code: -32603,
message: 'Internal server error'
},
id: null
});
}
}
});
app.get('/', (_, res) => {
res.send('Open Food Facts MCP Server is running');
});
app.get('/health', (_, res) => {
res.json({ status: 'UP', version: '1.0.0' });
});
app.listen(PORT, () => {
logger.info(`Open Food Facts MCP Server running on HTTP port ${PORT}`);
logger.info(`Use StreamableHTTP endpoint at http://localhost:${PORT}/mcp`);
resolve();
});
} catch (error) {
reject(error);
}
});
}
