import net from "node:net";
import IpToAsn from "ip-to-asn";

import {
  getASFromCache,
  updateAS,
  isASBanned,
  incrementRejected,
  incrementAccepted,
} from "./db.mjs";

const asClient = new IpToAsn();

// Create a server
const server = net.createServer((socket) => {
  // console.log(`Policy server connection established`);

  socket.on("data", async (data) => {
    const lines = data.toString().trim();

    let response = "dunno"; // Default response

    try {
      const command = lines.split(/[\r\n]/).reduce((acc, i) => {
        const [key, value] = i.split("=");
        return { ...acc, [key]: value };
      }, {});

      const { client_address, client_name, sender, recipient } = command;

      console.log(
        `Incoming email from "${client_name}[${client_address}]. ${sender} -> ${recipient}`,
      );

      // check if IP belongs to previously cached AS records
      let as = getASFromCache(client_address);

      if (!as) {
        // console.log(`Fetching AS for ${client_address}`);
        const result = await query(client_address);
        if (result) {
          const { range, ASN, description } = result;
          as = ASN;
          updateAS(as, range, description);
        }
      }

      const reason = isASBanned(as);
      if (reason) {
        // console.log(`AS ${as} is banned`);
        response = `reject ${reason.reason}`;
        incrementRejected(as);
      } else {
        incrementAccepted(as);
      }
      // Check if AS is in the ban list
    } catch (err) {
      console.error("Error processing command:", err);
    }

    console.log(`Verdict: ${response}`);
    socket.write(`${response}\r\n`);
  });

  socket.on("end", () => {
    console.log("Policy server connection ended");
  });

  socket.on("error", (err) => {
    console.error("Policy server socket error:", err);
  });
});

// Start the server
server.listen(12346, "127.0.0.1", () => {
  console.log(`Policy server running`);
});

function query(...ip) {
  return new Promise((resolve, reject) => {
    asClient.query(ip, (err, result) => {
      if (err) {
        return reject(err);
      }

      resolve(result[ip[0]]);
    });
  });
}