import net from 'node:net';
import fs from 'node:fs';
import path from 'node:path';
import { mkdir, rm } from 'node:fs/promises';

const MAX_LINE = 64 * 1024;

export async function createEventSocket({ socketPath, onMessage }) {
  await mkdir(path.dirname(socketPath), { recursive: true });
  try { await rm(socketPath, { force: true }); } catch {}
  const server = net.createServer((socket) => {
    let buffer = '';
    socket.setEncoding('utf8');
    socket.on('data', (chunk) => {
      buffer += chunk;
      if (buffer.length > MAX_LINE * 2) { socket.destroy(new Error('IPC buffer too large')); return; }
      let index;
      while ((index = buffer.indexOf('\n')) >= 0) {
        const line = buffer.slice(0, index); buffer = buffer.slice(index + 1);
        if (line.length > MAX_LINE) { socket.destroy(new Error('IPC message too large')); return; }
        try { onMessage?.(JSON.parse(line), socket); } catch { socket.write(JSON.stringify({ error: 'invalid IPC message' }) + '\n'); }
      }
    });
  });
  await new Promise((resolve, reject) => { server.once('error', reject); server.listen(socketPath, resolve); });
  return { server, socketPath, close: () => new Promise((resolve) => server.close(() => fs.unlink(socketPath, () => resolve()))) };
}

export function sendEvent(socket, event, payload = {}) {
  const message = JSON.stringify({ event, ...payload });
  if (Buffer.byteLength(message) > MAX_LINE) throw new Error('IPC event too large; use a file path for bulk data');
  socket.write(`${message}\n`);
}

export { MAX_LINE };