import express from "express";
import {
  ResourceTemplate,
  McpServer,
} from "@modelcontextprotocol/sdk/server/mcp.js";
import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
import { z } from "zod";

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

server.resource(
  "echo",
  new ResourceTemplate("echo://{message}", { list: undefined }),
  async (uri, { message }) => ({
    contents: [
      {
        uri: uri.href,
        text: `Resource echo: ${message}`,
      },
    ],
  })
);

server.tool("echo", { message: z.string() }, async ({ message }) => ({
  content: [{ type: "text", text: `Tool echo: ${message}` }],
}));

server.prompt("echo", { message: z.string() }, ({ message }) => ({
  messages: [
    {
      role: "user",
      content: {
        type: "text",
        text: `Please process this message: ${message}`,
      },
    },
  ],
}));

const app = express();
let transport
app.get("/sse", async (req, res) => {
  transport = new SSEServerTransport("/messages", res);
  await server.connect(transport);
});

app.post("/messages", async (req, res) => {
  // Note: to support multiple simultaneous connections, these messages will
  // need to be routed to a specific matching transport. (This logic isn't
  // implemented here, for simplicity.)
  await transport.handlePostMessage(req, res);
});

app.listen(3001);
console.log("Server running on http://localhost:3001");