// Auto-installs the FlyWithLua companion scripts into X-Plane on bridge start.
//
// The web cockpit needs three .lua helpers running INSIDE X-Plane (they have the
// FMS / scenery SDK the Web API lacks — see plugins/*.lua). Rather than make the
// user copy files by hand, the bridge drops them into the sim's FlyWithLua
// Scripts folder on startup and keeps them up to date (content-compare, so a new
// build self-updates the installed copy; unchanged files are left alone).
//
// Everything degrades gracefully: no X-Plane found, no FlyWithLua installed, or
// the script sources missing → we log a hint and carry on. We never create the
// FlyWithLua folder ourselves (its absence means the user must install
// FlyWithLua NG+ first; making an empty folder would only hide that).

import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));

// The companion scripts to install, in load-independent order.
const SCRIPTS = ['fms-sync.lua', 'ui-sync.lua', 'terrain-probe.lua'];

// Where do the canonical .lua sources live? plugins/ sits next to server/ in the
// repo; in the packaged desktop app it's bundled as a Tauri resource. Probe a
// few locations so both `node server/bridge.js` and the compiled sidecar work.
function sourceDir() {
  const candidates = [
    process.env.LUA_SRC_DIR,
    path.join(__dirname, '..', 'plugins'),          // repo: server/ -> ../plugins
    path.join(process.cwd(), 'plugins'),            // run from repo root
    path.join(path.dirname(process.execPath), 'plugins'),
    path.join(path.dirname(process.execPath), '..', 'Resources', 'plugins'),
  ].filter(Boolean);
  for (const dir of candidates) {
    try {
      if (fs.existsSync(path.join(dir, SCRIPTS[0]))) return dir;
    } catch { /* ignore */ }
  }
  return null;
}

// Install / update the scripts under <root>. Returns a report object; never throws.
export function installLuaScripts(root, log = console.log) {
  if (!root) {
    return { ok: false, reason: 'no-xplane', installed: [], updated: [], unchanged: [] };
  }
  const fwl = path.join(root, 'Resources', 'plugins', 'FlyWithLua');
  if (!fs.existsSync(fwl)) {
    log('lua-install: FlyWithLua not found — install FlyWithLua NG+ into ' +
        `${path.join(root, 'Resources', 'plugins')} to enable FMS/terrain sync`);
    return { ok: false, reason: 'no-flywithlua', installed: [], updated: [], unchanged: [] };
  }
  const src = sourceDir();
  if (!src) {
    log('lua-install: companion script sources not found (set LUA_SRC_DIR)');
    return { ok: false, reason: 'no-source', installed: [], updated: [], unchanged: [] };
  }

  const dest = path.join(fwl, 'Scripts');
  const report = { ok: true, reason: 'ok', dir: dest, installed: [], updated: [], unchanged: [], failed: [] };
  try { fs.mkdirSync(dest, { recursive: true }); } catch { /* ignore */ }

  for (const name of SCRIPTS) {
    const from = path.join(src, name);
    const to = path.join(dest, name);
    try {
      if (!fs.existsSync(from)) { report.failed.push(name); continue; }
      const want = fs.readFileSync(from, 'utf8');
      const have = fs.existsSync(to) ? fs.readFileSync(to, 'utf8') : null;
      if (have === null) { fs.writeFileSync(to, want); report.installed.push(name); }
      else if (have !== want) { fs.writeFileSync(to, want); report.updated.push(name); }
      else { report.unchanged.push(name); }
    } catch (e) {
      report.failed.push(name);
      log(`lua-install: ${name} failed: ${e.message}`);
    }
  }

  const parts = [];
  if (report.installed.length) parts.push(`installed ${report.installed.join(', ')}`);
  if (report.updated.length) parts.push(`updated ${report.updated.join(', ')}`);
  if (report.unchanged.length) parts.push(`${report.unchanged.length} up to date`);
  log(`lua-install: ${parts.join('; ') || 'nothing to do'} → ${dest}`);
  if (report.installed.length || report.updated.length) {
    log('lua-install: reload in X-Plane — "FlyWithLua > Reload all Lua script files" (or restart)');
  }
  return report;
}