// The per-box Linux user. Terminal sessions and agent turns exec as this user
// instead of root (Claude Code refuses some operations as root, and a real
// machine has a named user); sudo is passwordless until the user stores a
// password, after which wheel membership makes sudo prompt for it.

export const BOX_UID = 1000;

const shellQuote = (value: string) => `'${value.replaceAll("'", "'\\''")}'`;

// Linux-safe username derived from the Spoon username. The home path keeps
// the Spoon username everywhere; only the passwd entry uses this.
export const linuxUsername = (spoonUsername: string): string => {
  const cleaned = spoonUsername
    .toLowerCase()
    .replaceAll(/[^a-z0-9_-]/g, '-')
    .slice(0, 32);
  if (!cleaned) return 'spoon';
  return /^[a-z_]/.test(cleaned) ? cleaned : `u${cleaned}`.slice(0, 32);
};

// Idempotent root init: create the user at the (already mounted) home, grant
// wheel, and chown the home ONCE (marker-guarded — later host-side writes are
// repaired by targeted chowns, so a big home is never re-walked). `-o` allows
// the uid even if the image ever gains a uid-1000 user; `-M` skips skeleton
// copy since the mounted home persists across containers.
export const buildBoxInitScript = (args: {
  username: string;
  home: string;
}): string => {
  const user = shellQuote(args.username);
  const home = shellQuote(args.home);
  const marker = shellQuote(`${args.home}/.spoon/chown-v1`);
  return [
    'set -e',
    `if ! id -u ${user} >/dev/null 2>&1; then`,
    `  useradd -u ${BOX_UID} -o -M -d ${home} -s /bin/bash ${user}`,
    'fi',
    `usermod -aG wheel ${user}`,
    `if [ ! -f ${marker} ]; then`,
    `  chown -R ${BOX_UID}:${BOX_UID} ${home}`,
    `  mkdir -p "$(dirname ${marker})" && touch ${marker} && chown ${BOX_UID}:${BOX_UID} ${marker}`,
    'fi',
  ].join('\n');
};

// Sudo policy: NOPASSWD drop-in only while no password is stored; with a
// password, wheel membership makes sudo prompt for it. The drop-in is staged
// to a temp file and checked with `visudo -c` before install so a bad write
// can never brick sudo.
export const buildSudoPolicyScript = (args: {
  username: string;
  passwordSet: boolean;
}): string => {
  if (args.passwordSet) {
    return 'rm -f /etc/sudoers.d/spoon-box';
  }
  const line = `${args.username} ALL=(ALL) NOPASSWD:ALL`;
  return [
    'set -e',
    `printf '%s\\n' ${shellQuote(line)} > /etc/sudoers.d/spoon-box.tmp`,
    'visudo -c -f /etc/sudoers.d/spoon-box.tmp',
    'chmod 0440 /etc/sudoers.d/spoon-box.tmp',
    'mv /etc/sudoers.d/spoon-box.tmp /etc/sudoers.d/spoon-box',
  ].join('\n');
};

// `chpasswd` reads `user:password` from stdin, so the password never appears
// in argv (visible in `ps`) or in a shell script body.
export const CHPASSWD_COMMAND = ['chpasswd'];

export const buildClearPasswordCommand = (username: string): string[] => [
  'passwd',
  '-d',
  username,
];