import * as plugins from './plugins.js';

interface IDnsServerOptions {
  httpsKey: string;
  httpsCert: string;
  httpsPort: number;
  udpPort: number;
}

class DnsServer {
  private udpServer: plugins.dgram.Socket;
  private httpsServer: plugins.https.Server;

  constructor(private options: IDnsServerOptions) {
    this.udpServer = plugins.dgram.createSocket('udp4');
    this.setupUdpServer();

    this.httpsServer = plugins.https.createServer(
      {
        key: plugins.fs.readFileSync(options.httpsKey),
        cert: plugins.fs.readFileSync(options.httpsCert)
      },
      this.handleHttpsRequest.bind(this)
    );
  }

  private setupUdpServer(): void {
    this.udpServer.on('message', (msg, rinfo) => {
      const request = plugins.dnsPacket.decode(msg);
      const response = {
        type: 'response' as const,
        id: request.id,
        flags: plugins.dnsPacket.RECURSION_DESIRED | plugins.dnsPacket.RECURSION_AVAILABLE,
        questions: request.questions,
        answers: [] as plugins.dnsPacket.Answer[]
      };

      const question = request.questions[0];
      console.log(`UDP query for ${question.name} of type ${question.type}`);

      if (question.type === 'A') {
        response.answers.push({
          name: question.name,
          type: 'A',
          class: 'IN',
          ttl: 300,
          data: '127.0.0.1'
        });
      }

      const responseData = plugins.dnsPacket.encode(response);
      this.udpServer.send(responseData, rinfo.port, rinfo.address);
    });

    this.udpServer.on('error', (err) => {
      console.error(`UDP Server error:\n${err.stack}`);
      this.udpServer.close();
    });

    this.udpServer.bind(this.options.udpPort, '0.0.0.0', () => {
      console.log(`UDP DNS server running on port ${this.options.udpPort}`);
    });
  }

  private handleHttpsRequest(req: plugins.http.IncomingMessage, res: plugins.http.ServerResponse): void {
    if (req.method === 'POST' && req.url === '/dns-query') {
      let body: Buffer[] = [];

      req.on('data', chunk => {
        body.push(chunk);
      }).on('end', () => {
        const msg = Buffer.concat(body);
        const request = plugins.dnsPacket.decode(msg);
        const response = {
          type: 'response' as const,
          id: request.id,
          flags: plugins.dnsPacket.RECURSION_DESIRED | plugins.dnsPacket.RECURSION_AVAILABLE,
          questions: request.questions,
          answers: [] as plugins.dnsPacket.Answer[]
        };

        const question = request.questions[0];
        console.log(`DoH query for ${question.name} of type ${question.type}`);

        if (question.type === 'A') {
          response.answers.push({
            name: question.name,
            type: 'A',
            class: 'IN',
            ttl: 300,
            data: '127.0.0.1'
          });
        }

        const responseData = plugins.dnsPacket.encode(response);
        res.writeHead(200, { 'Content-Type': 'application/dns-message' });
        res.end(responseData);
      });
    } else {
      res.writeHead(404);
      res.end();
    }
  }

  public start(): void {
    this.httpsServer.listen(this.options.httpsPort, () => {
      console.log(`DoH server running on port ${this.options.httpsPort}`);
    });
  }

  public stop(): void {
    this.udpServer.close(() => {
      console.log('UDP DNS server stopped');
    });

    this.httpsServer.close(() => {
      console.log('HTTPS DNS server stopped');
    });
  }
}