#!/usr/bin/env node
/**
 * Docker launcher — the container's entry point (see Dockerfile).
 *
 * `compose.yaml` publishes the port on the host's loopback, but Docker still
 * delivers the host's own browser to the container FROM the container
 * network's gateway address, never from 127.0.0.1. Provider Settings admits
 * loopback only, so without this the POWER UP panel refuses the very machine
 * running the container. This launcher reads the gateway out of the kernel
 * routing table and declares exactly that one address trusted, then starts
 * Vite the way scripts/pinokio-start.mjs does.
 */
import { accessSync, constants, readFileSync, realpathSync, statSync } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { isDirectInvocation } from './pinokio-install.mjs';
import { loadViteFromCanonicalRoot } from './pinokio-start.mjs';

const MODULE_PATH = fileURLToPath(import.meta.url);
const ROOT = realpathSync(path.resolve(path.dirname(MODULE_PATH), '..'));
const ROUTE_TABLE = '/proc/net/route';

/**
 * Extract the IPv4 default gateway from Linux `/proc/net/route` text. The
 * addresses there are little-endian hex and only the default route (a
 * destination of 00000000 on an interface flagged up) names a gateway.
 * Returns null when there is none — the `--network none` case, which must
 * never fabricate an address.
 * @param {string} text Raw routing-table contents.
 * @returns {string|null} Dotted-quad gateway, or null.
 */
export function defaultGatewayFromRouteTable(text) {
  const lines = String(text || '').split(/\r?\n/).slice(1);
  for (const line of lines) {
    const fields = line.trim().split(/\s+/);
    if (fields.length < 4) continue;
    const [, destination, gateway, flags] = fields;
    if (destination !== '00000000' || !/^[0-9a-f]{8}$/i.test(gateway)) continue;
    if ((Number.parseInt(flags, 16) & 0x1) === 0) continue; // RTF_UP
    const octets = [6, 4, 2, 0].map((offset) =>
      Number.parseInt(gateway.slice(offset, offset + 2), 16),
    );
    if (octets.every((octet) => octet === 0)) continue;
    return octets.join('.');
  }
  return null;
}

/**
 * Decide this launch's trusted-peer list. An operator value always wins, so a
 * compose override stays authoritative; otherwise the gateway alone is
 * trusted. No gateway trusts nothing and Provider Settings stays loopback-only,
 * exactly as under `npm run dev`.
 * @param {{env?: NodeJS.ProcessEnv, routeTable?: string}} input
 * @returns {string} Value for GEV_KEY_SETUP_TRUSTED_PEERS ('' trusts nothing).
 */
export function resolveTrustedPeers({ env = process.env, routeTable = '' } = {}) {
  const explicit = String(env.GEV_KEY_SETUP_TRUSTED_PEERS ?? '').trim();
  if (explicit) return explicit;
  return defaultGatewayFromRouteTable(routeTable) ?? '';
}

/**
 * A checkout the container cannot write fails quietly: Provider Settings
 * answers 500 and `.gev-cache` is never created, with nothing in the log. The
 * usual cause is a clone made as root on a NAS or Proxmox host while the
 * container runs as 1000:1000. Say so at start, naming both sets of ids.
 * @param {{root: string, writable: boolean, owner: {uid: number, gid: number}, runAs: {uid: number, gid: number}}} input
 * @returns {string|null} A warning, or null when the checkout is writable.
 */
export function unwritableRootWarning({ root, writable, owner, runAs }) {
  if (writable) return null;
  return (
    `[Docker] ${root} is owned by ${owner.uid}:${owner.gid} but the container runs as ` +
    `${runAs.uid}:${runAs.gid}, so saving keys and caching will fail. Either give ` +
    `the checkout to that user (chown -R ${runAs.uid}:${runAs.gid} on the host) or ` +
    `run as its owner (env UID=${owner.uid} GID=${owner.gid} docker compose up)`
  );
}

function readRouteTable() {
  try {
    return readFileSync(ROUTE_TABLE, 'utf8');
  } catch {
    return '';
  }
}

async function start() {
  let writable = true;
  try {
    accessSync(ROOT, constants.W_OK);
  } catch {
    writable = false;
  }
  if (!writable) {
    const { uid, gid } = statSync(ROOT);
    console.warn(
      unwritableRootWarning({
        root: ROOT,
        writable,
        owner: { uid, gid },
        runAs: { uid: process.getuid?.() ?? -1, gid: process.getgid?.() ?? -1 },
      }),
    );
  }

  const trustedPeers = resolveTrustedPeers({ routeTable: readRouteTable() });
  if (trustedPeers) {
    // Set before Vite is imported: the dev server snapshots process.env during
    // configuration, and the admission gate reads it per request.
    process.env.GEV_KEY_SETUP_TRUSTED_PEERS = trustedPeers;
    console.log(`[Docker] Provider Settings trusts the container gateway (${trustedPeers}).`);
  } else {
    console.log('[Docker] No default gateway; Provider Settings stays loopback-only.');
  }

  const port = Number.parseInt(process.env.PORT, 10) || 4173;
  const { createServer } = await loadViteFromCanonicalRoot(ROOT);
  const server = await createServer({
    root: ROOT,
    server: {
      // The container's own namespace. compose publishes this to the host's
      // 127.0.0.1 only; widening that mapping is the LAN opt-in.
      host: '0.0.0.0',
      port,
      strictPort: true,
    },
  });
  await server.listen();
  server.printUrls();
  console.log(`[Docker] Ready at http://localhost:${port}/`);

  for (const signal of ['SIGINT', 'SIGTERM']) {
    process.once(signal, async () => {
      await server.close();
      process.exit(0);
    });
  }
}

if (isDirectInvocation(process.argv[1], MODULE_PATH)) {
  start().catch((error) => {
    console.error(`[Docker] Start refused: ${error.message}`);
    process.exitCode = 1;
  });
}