import { McpServer } from "@modelcontextprotocol/server";
import { serveStdio } from "@modelcontextprotocol/server/stdio";
import { NodeStreamableHTTPServerTransport } from "@modelcontextprotocol/node";
import { Command } from "commander";
import http from "node:http";
import crypto from "node:crypto";
import { registerAuthTools } from "./tools/auth.ts";
import { registerEmailTools } from "./tools/email.ts";
import { registerFolderTools } from "./tools/folders.ts";

const program = new Command()
  .name("exchange-mcp")
  .description("Exchange MCP Server — EWS integration via MCP")
  .option("--transport <type>", "Transport: stdio or sse", "stdio")
  .option("--token-hash <hash>", "SHA-256 hash of bearer token for HTTP transport auth")
  .option("--host <host>", "HTTP host", "127.0.0.1")
  .option("--port <port>", "HTTP port", "8000");

program.parse(process.argv);
const options = program.opts();

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

  registerAuthTools(server);
  registerEmailTools(server);
  registerFolderTools(server);

  return server;
}

async function main() {
  const transportType: string = options.transport;

  if (transportType === "stdio") {
    serveStdio(buildServer);
    return;
  }

  if (transportType === "sse") {
    const server = buildServer();

    const mcpTransport = new NodeStreamableHTTPServerTransport({
      sessionIdGenerator: () => crypto.randomUUID(),
    });

    await server.connect(mcpTransport);

    const httpServer = http.createServer(async (req, res) => {
      if (options.tokenHash) {
        const auth = req.headers.authorization || "";
        const token = auth.startsWith("Bearer ") ? auth.slice(7) : "";
        const hash = crypto.createHash("sha256").update(token).digest("hex");
        if (hash !== options.tokenHash) {
          res.writeHead(401, { "Content-Type": "text/plain" });
          res.end("Unauthorized");
          return;
        }
      }

      res.setHeader("Access-Control-Allow-Origin", "*");
      res.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
      res.setHeader("Access-Control-Allow-Headers", "Content-Type, Authorization");

      if (req.method === "OPTIONS") {
        res.writeHead(200);
        res.end();
        return;
      }

      await mcpTransport.handleRequest(req, res);
    });

    const port = Number(options.port);
    httpServer.listen(port, options.host);

    console.error(
      `Exchange MCP Server running via SSE on http://${options.host}:${port}`,
    );
    return;
  }

  console.error(`Unsupported transport: ${transportType}. Use "stdio" or "sse".`);
  process.exit(1);
}

main().catch((error) => {
  console.error("Fatal error:", error);
  process.exit(1);
});