#!/usr/bin/env -S deno run --allow-all

const ttyProc = await Deno.run({
  cmd: ["tput", "cols"],
  stdout: "piped",
  stderr: "piped",
});
const ttyOutput = new TextDecoder().decode(await ttyProc.output()).trim();
const terminalWidth = parseInt(ttyOutput) || 120;

const netstatProc = await Deno.run({
  cmd: ["netstat", "-an"],
  stdout: "piped",
  stderr: "piped",
});

const output = await netstatProc.output();
const decoded = new TextDecoder().decode(output);
const lines = decoded.split("\n");

const localWidth = 20;

console.log("Active Internet connections (only servers)");
console.log(`Proto Recv-Q Send-Q Local Address${" ".repeat(localWidth - 13)}Foreign Address         State       PID/Program name`);

const listeningLines = lines.filter((line) => line.includes("LISTEN"));

const seen = new Set<string>();
for (const line of listeningLines) {
  const parts = line.trim().split(/\s+/);
  if (parts.length < 5) continue;

  const proto = parts[0];
  const localAddr = parts[3];
  const state = parts[4];

  const key = `${proto}:${localAddr}`;
  if (seen.has(key)) continue;
  seen.add(key);

  const port = localAddr.includes(".")
    ? localAddr.split(".").pop()
    : localAddr.split(":").pop();

  const pidCmd = await Deno.run({
    cmd: ["lsof", "-i", `:${port}`, "-t"],
    stdout: "piped",
    stderr: "piped",
  });
  const pidOutput = new TextDecoder().decode(await pidCmd.output()).trim();
  let pidInfo = "-";
  if (pidOutput) {
    const pid = pidOutput.split("\n")[0];
    const nameCmd = await Deno.run({
      cmd: ["ps", "-p", pid, "-o", "args="],
      stdout: "piped",
      stderr: "piped",
    });
    const nameOutput = new TextDecoder().decode(await nameCmd.output()).trim();
    pidInfo = nameOutput;
  }

  const displayState = state === "*.*" ? "LISTEN" : state;
  const localFormatted = localAddr.padEnd(localWidth);
  const recvQ = "0".padStart(3);
  const sendQ = "0".padStart(6);
  console.log(
    `${proto.padEnd(8)} ${recvQ} ${sendQ} ${localFormatted} ${"0.0.0.0:*".padEnd(22)} ${displayState.padEnd(11)} ${pidInfo}`
  );
}