@iflow-mcp/chess-mcp/dist/src/lib/mcp/middleware.js

A Model Context Protocol (MCP) server that provides an interactive chess game experience using MCP-UI. This server exposes chess game functionality through MCP tools and provides a web-based chessboard interface for playing games.

import express, {} from "express";
import { randomUUID } from "node:crypto";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { isInitializeRequest } from "@modelcontextprotocol/sdk/types.js";
import header from "./header";
import { validUUID } from "./uuid";
export function Middleware(newServer) {
    const middleware = new McpServerMiddleware(newServer);
    return middleware.middleware;
}
class McpServerMiddleware {
    transports = {};
    app = express();
    newServer;
    get middleware() {
        return this.app;
    }
    constructor(newServer) {
        this.newServer = newServer;
        this.setup();
    }
    setup = () => {
        this.app.use(express.json());
        this.app.post("/", this.post);
        this.app.get("/", this.post);
        this.app.delete("/", this.getDelete);
    };
    newTransport = async (sessionId, req, res) => {
        let transport;
        if (sessionId) {
            transport = new StreamableHTTPServerTransport({
                sessionIdGenerator: undefined,
            });
            transport.sessionId = sessionId;
            this.transports[sessionId] = transport;
            transport.onclose = () => {
                if (transport.sessionId) {
                    delete this.transports[transport.sessionId];
                }
            };
        }
        else {
            transport = new StreamableHTTPServerTransport({
                sessionIdGenerator: () => randomUUID(),
                onsessioninitialized: (sessionId) => {
                    this.transports[sessionId] = transport;
                },
            });
        }
        transport.onclose = () => {
            if (transport.sessionId) {
                delete this.transports[transport.sessionId];
            }
        };
        const server = await this.newServer(req, res, transport);
        await server.connect(transport);
        return transport;
    };
    post = async (req, res) => {
        const sessionId = header(req.headers, "mcp-session-id");
        let transport;
        if (sessionId && this.transports[sessionId]) {
            transport = this.transports[sessionId];
        }
        else if ((!sessionId && isInitializeRequest(req.body)) ||
            validUUID(sessionId)) {
            transport = await this.newTransport(sessionId, req, res);
        }
        else {
            res.status(404).json({
                jsonrpc: "2.0",
                error: {
                    code: -32000,
                    message: "Bad Request: No valid session ID provided",
                },
                id: null,
            });
            return;
        }
        await transport.handleRequest(req, res, req.body);
    };
    getDelete = async (req, res) => {
        const sessionId = header(req.headers, "mcp-session-id");
        const transport = sessionId && this.transports[sessionId];
        if (!transport) {
            res
                .status(400)
                .send(`Invalid or missing session ID: ${sessionId ? sessionId.slice(0, 8) : "none"}`);
            return;
        }
        await transport.handleRequest(req, res);
    };
}