function cmd::peer::run() {
  local subcmd="${1:-help}"
  shift || true
  case "$subcmd" in
    update-dns)    cmd::peer::update_dns    "$@" ;;
    update-tunnel) cmd::peer::update_tunnel "$@" ;;
    help)          cmd::peer::help               ;;
    *)
      log::error "Unknown subcommand: '${subcmd}'"
      cmd::peer::help
      return 1
      ;;
  esac
}

# ============================================
# Update DNS
# ============================================

function cmd::peer::update_dns() {
  local name="" type="" all=false
  local dns="" fallback_dns=""

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --name)         name="$2";         shift 2 ;;
      --type)         type="$2";         shift 2 ;;
      --all)          all=true;          shift   ;;
      --dns)          dns="$2";          shift 2 ;;
      --fallback-dns) fallback_dns="$2"; shift 2 ;;
      --help)         cmd::peer::help;   return  ;;
      *) log::error "Unknown flag: $1";  return 1 ;;
    esac
  done

  [[ -z "$name" && "$all" == "false" ]] && \
    log::error "Specify --name or --all" && return 1

  # Resolve DNS string
  local primary="${dns:-$(config::dns)}"
  local fallback="${fallback_dns:-$(config::dns_fallback)}"
  local dns_string
  if [[ -n "$fallback" ]]; then
    dns_string="${primary}, ${fallback}"
  else
    dns_string="$primary"
  fi

  # Collect target peers
  local peers=()
  if $all; then
    while IFS= read -r conf; do
      peers+=("$(basename "$conf" .conf)")
    done < <(find "$(ctx::clients)" -name "*.conf" 2>/dev/null)
  else
    name=$(peers::resolve_and_require "$name" "$type") || return 1
    peers=("$name")
  fi

  local updated=0
  for peer_name in "${peers[@]}"; do
    local conf
    conf="$(ctx::clients)/${peer_name}.conf"
    [[ ! -f "$conf" ]] && continue

    # Replace DNS line in-place
    if grep -q "^DNS" "$conf"; then
      sed -i "s|^DNS = .*|DNS = ${dns_string}|" "$conf"
    else
      # Add DNS line after Address line
      sed -i "/^Address/a DNS = ${dns_string}" "$conf"
    fi
    (( updated++ )) || true
    log::debug "Updated DNS for: ${peer_name}"
  done

  log::wg_success "Updated DNS to '${dns_string}' for ${updated} peer(s)"
}