import { exec } from 'node:child_process';
import { promisify } from 'node:util';
import { env } from '@/config/env';
import type { DiscoveryResult, DiscoveryTarget, Scanner } from '../types';

const execAsync = promisify(exec);

/**
 * Lit la table ARP locale via `ip neigh` (Linux) ou `arp -a` (fallback).
 * Ne scanne pas activement : retourne ce que le kernel a déjà vu.
 * Pour forcer la résolution, il faut ping-sweeper d'abord (voir discovery.service).
 */
export const arpScanner: Scanner = {
  kind: 'arp',
  label: 'Table ARP locale',
  enabled: env.DISCOVERY_ENABLE_ARP,

  async run(_target: DiscoveryTarget): Promise<DiscoveryResult[]> {
    const { stdout } = await execAsync('ip neigh show').catch(() => ({ stdout: '' }));
    if (stdout) return parseIpNeigh(stdout);

    const { stdout: arpOut } = await execAsync('arp -a').catch(() => ({ stdout: '' }));
    return parseArpA(arpOut);
  },
};

function parseIpNeigh(output: string): DiscoveryResult[] {
  // Exemple : 192.168.1.10 dev eth0 lladdr aa:bb:cc:dd:ee:ff REACHABLE
  return output
    .split('\n')
    .map((line) => line.trim())
    .filter(Boolean)
    .map((line) => {
      const ipMatch = line.match(/^(\d{1,3}(?:\.\d{1,3}){3})/);
      const macMatch = line.match(/lladdr\s+([0-9a-fA-F:]{17})/);
      if (!ipMatch) return null;
      return {
        ipAddress: ipMatch[1],
        macAddress: macMatch?.[1],
      } satisfies DiscoveryResult;
    })
    .filter((r): r is DiscoveryResult => r !== null);
}

function parseArpA(output: string): DiscoveryResult[] {
  // Exemple : ? (192.168.1.10) at aa:bb:cc:dd:ee:ff [ether] on eth0
  return output
    .split('\n')
    .map((line) => line.trim())
    .filter(Boolean)
    .map((line) => {
      const ipMatch = line.match(/\((\d{1,3}(?:\.\d{1,3}){3})\)/);
      const macMatch = line.match(/([0-9a-fA-F]{2}(:[0-9a-fA-F]{2}){5})/);
      if (!ipMatch) return null;
      return {
        ipAddress: ipMatch[1],
        macAddress: macMatch?.[1],
      } satisfies DiscoveryResult;
    })
    .filter((r): r is DiscoveryResult => r !== null);
}