mcp-servers/mcp-gateway/erpnext-mcp/src/index.ts

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import express from "express";

import { ERPNextClient } from "./services/erpnext-client.js";
import { registerCoreTools } from "./tools/core.js";
import { registerAccountingTools } from "./tools/accounting.js";
import { registerSellingTools } from "./tools/selling.js";
import { registerBuyingTools } from "./tools/buying.js";
import { registerStockTools } from "./tools/stock.js";
import {
  registerManufacturingTools,
  registerHRTools,
  registerCRMTools,
  registerProjectTools,
  registerSupportTools,
  registerSetupTools,
} from "./tools/domains.js";
import { registerFrappeTools } from "./tools/frappe.js";

// ── Configuration ───────────────────────────────────────

function getConfig() {
  const baseUrl = process.env.ERPNEXT_URL || process.env.ERPNEXT_BASE_URL || "";
  const apiKey = process.env.ERPNEXT_API_KEY || "";
  const apiSecret = process.env.ERPNEXT_API_SECRET || "";

  if (!baseUrl || !apiKey || !apiSecret) {
    console.error(
      "Missing required environment variables:\n" +
        "  ERPNEXT_URL       - ERPNext instance URL (e.g. https://erp.example.com)\n" +
        "  ERPNEXT_API_KEY   - API Key from ERPNext user settings\n" +
        "  ERPNEXT_API_SECRET - API Secret from ERPNext user settings"
    );
    process.exit(1);
  }

  return { baseUrl, apiKey, apiSecret };
}

// ── Server Setup ────────────────────────────────────────

function createServer(): { server: McpServer; client: ERPNextClient } {
  const config = getConfig();
  const client = new ERPNextClient(config);

  const server = new McpServer({
    name: "erpnext-mcp-server",
    version: "1.0.0",
  });

  // Register all tool categories
  registerCoreTools(server, client);         // 1-15:  Generic CRUD, search, reports, meta, bulk ops
  registerAccountingTools(server, client);   // 16-22: GL balance, exchange rate, journal entries, payments
  registerSellingTools(server, client);      // 23-30: Quotations, sales orders, invoices, delivery notes
  registerBuyingTools(server, client);       // 31-36: Purchase orders, receipts, RFQ, supplier quotations
  registerStockTools(server, client);        // 37-50: Stock balance, entries, batches, barcodes, bins
  registerManufacturingTools(server, client);// 51-53: Work orders, BOMs
  registerHRTools(server, client);           // 54-57: Employees, departments, org chart
  registerCRMTools(server, client);          // 58-60: Leads, opportunities, pipeline
  registerProjectTools(server, client);      // 61-63: Projects, tasks
  registerSupportTools(server, client);      // 64-66: Issues, SLA
  registerSetupTools(server, client);        // 67-70: Company, addresses, holidays, T&C
  registerFrappeTools(server, client);       // 71-100+: Get/set value, assignments, comments, tags,
                                              //          leaderboards, notifications, todos, activity,
                                              //          linked docs, print formats, warehouse tree,
                                              //          returns, material request ops, rename, etc.

  console.error(
    `ERPNext MCP Server initialized\n` +
      `  Instance: ${config.baseUrl}\n` +
      `  Tools registered: 100+`
  );

  return { server, client };
}

// ── Transport: stdio ────────────────────────────────────

async function runStdio(): Promise<void> {
  const { server } = createServer();
  const transport = new StdioServerTransport();
  await server.connect(transport);
  console.error("ERPNext MCP Server running on stdio");
}

// ── Transport: Streamable HTTP ──────────────────────────

async function runHTTP(): Promise<void> {
  const { server } = createServer();
  const app = express();
  app.use(express.json());

  // Health check
  app.get("/health", (_req, res) => {
    res.json({ status: "ok", server: "erpnext-mcp-server", version: "1.0.0" });
  });

  // MCP endpoint
  app.post("/mcp", async (req, res) => {
    const transport = new StreamableHTTPServerTransport({
      sessionIdGenerator: undefined,
      enableJsonResponse: true,
    });
    res.on("close", () => transport.close());
    await server.connect(transport);
    await transport.handleRequest(req, res, req.body);
  });

  // Handle GET and DELETE for MCP protocol compliance
  app.get("/mcp", async (_req, res) => {
    res.writeHead(405).end(JSON.stringify({
      jsonrpc: "2.0",
      error: { code: -32000, message: "Method not allowed. Use POST for MCP requests." },
      id: null,
    }));
  });

  app.delete("/mcp", async (_req, res) => {
    res.writeHead(405).end(JSON.stringify({
      jsonrpc: "2.0",
      error: { code: -32000, message: "Method not allowed." },
      id: null,
    }));
  });

  const port = parseInt(process.env.PORT || "32802", 10);

  app.listen(port, () => {
    console.error(`ERPNext MCP Server running on http://0.0.0.0:${port}/mcp`);
  });
}

// ── Entrypoint ──────────────────────────────────────────

const transport = process.env.TRANSPORT || "stdio";
if (transport === "http") {
  runHTTP().catch((error) => {
    console.error("Server error:", error);
    process.exit(1);
  });
} else {
  runStdio().catch((error) => {
    console.error("Server error:", error);
    process.exit(1);
  });
}