#!/bin/sh
set -eu

KARLDNS_INSTALL_MODE="${KARLDNS_INSTALL_MODE:-auto}"
KARLDNS_DELETE_CONFIG="${KARLDNS_DELETE_CONFIG:-0}"

usage() {
  cat <<'EOF'
KarlDNS Linux uninstaller

Usage:
  uninstall-linux.sh [options]

Options:
  --mode MODE       auto, system, or user. Default: auto
  --delete-config   Also delete saved private URLs and the last-IP cache
  -h, --help        Show this help
EOF
}

while [ "$#" -gt 0 ]; do
  case "$1" in
    --mode) KARLDNS_INSTALL_MODE="${2:?missing value for --mode}"; shift 2 ;;
    --delete-config) KARLDNS_DELETE_CONFIG=1; shift ;;
    -h|--help) usage; exit 0 ;;
    *) echo "KarlDNS uninstaller: unknown option: $1" >&2; usage >&2; exit 1 ;;
  esac
done

remove_user() {
  config_dir="${XDG_CONFIG_HOME:-$HOME/.config}/karldns"
  cache_dir="${XDG_CACHE_HOME:-$HOME/.cache}/karldns"
  updater_path="${HOME}/.local/bin/karldns-update"
  cron_file="$(mktemp)"

  if command -v crontab >/dev/null 2>&1; then
    crontab -l 2>/dev/null | awk '
      $0 == "# karldns-update start" {skip = 1; next}
      $0 == "# karldns-update end" {skip = 0; next}
      skip != 1 {print}
    ' > "$cron_file" || true
    crontab "$cron_file"
  fi
  rm -f "$cron_file" "$updater_path"

  if [ "$KARLDNS_DELETE_CONFIG" = "1" ]; then
    rm -rf "$config_dir" "$cache_dir"
  fi
}

remove_marked_crontab_file() {
  cron_file="$1"
  [ -f "$cron_file" ] || return 0
  tmp_file="$(mktemp)"
  awk '
    $0 == "# karldns-update start" {skip = 1; next}
    $0 == "# karldns-update end" {skip = 0; next}
    skip != 1 {print}
  ' "$cron_file" > "$tmp_file"
  cat "$tmp_file" > "$cron_file"
  rm -f "$tmp_file"
}

remove_marked_root_crontab() {
  if ! command -v crontab >/dev/null 2>&1; then
    return 0
  fi
  tmp_file="$(mktemp)"
  crontab -l 2>/dev/null | awk '
    $0 == "# karldns-update start" {skip = 1; next}
    $0 == "# karldns-update end" {skip = 0; next}
    skip != 1 {print}
  ' > "$tmp_file" || true
  crontab "$tmp_file"
  rm -f "$tmp_file"
}

remove_system() {
  if [ "$(id -u)" -ne 0 ]; then
    echo "System uninstall needs root. Re-run with sudo or set --mode user." >&2
    exit 1
  fi

  rm -f /etc/cron.d/karldns-updater /usr/local/bin/karldns-update
  remove_marked_crontab_file /etc/crontabs/root
  remove_marked_root_crontab
  if [ "$KARLDNS_DELETE_CONFIG" = "1" ]; then
    rm -rf /etc/karldns /var/cache/karldns
  fi
}

case "$KARLDNS_INSTALL_MODE" in
  auto)
    if [ "$(id -u)" -eq 0 ]; then
      KARLDNS_INSTALL_MODE="system"
    else
      KARLDNS_INSTALL_MODE="user"
    fi
    ;;
  user|system) ;;
  *) echo "KARLDNS_INSTALL_MODE must be auto, user, or system" >&2; exit 1 ;;
esac

if [ "$KARLDNS_INSTALL_MODE" = "system" ]; then
  remove_system
else
  remove_user
fi

echo "KarlDNS uninstalled from $KARLDNS_INSTALL_MODE mode."
if [ "$KARLDNS_DELETE_CONFIG" = "0" ]; then
  echo "Saved private URLs were kept. Re-run with --delete-config to remove them."
fi