_service_name="dell-xps-touchpad-haptics.service"
_default_level="high"
_env_path="/etc/dell-xps-touchpad-haptics.env"
_legacy_env_path="/etc/omarchy-dell-haptic-touchpad.env"
_legacy_override_dir="/etc/systemd/system/dell-xps-haptic-touchpad.service.d"

_existing_home() {
  local line value

  [[ -f $_env_path ]] || return 0

  while IFS= read -r line; do
    line=${line#${line%%[![:space:]]*}}
    line=${line%${line##*[![:space:]]}}
    [[ -z $line || ${line:0:1} == "#" || $line != *=* ]] && continue

    if [[ ${line%%=*} == "DELL_XPS_TOUCHPAD_HAPTICS_HOME" ]]; then
      value=${line#*=}
      value=${value#${value%%[![:space:]]*}}
      value=${value%${value##*[![:space:]]}}
      printf '%s\n' "$value"
      return 0
    fi
  done < "$_env_path"
}

_resolve_target_user() {
  if [[ -n ${OMARCHY_HAPTIC_USER:-} && ${OMARCHY_HAPTIC_USER} != "root" ]]; then
    printf '%s\n' "$OMARCHY_HAPTIC_USER"
    return 0
  fi

  if [[ -n ${SUDO_USER:-} && ${SUDO_USER} != "root" ]]; then
    printf '%s\n' "$SUDO_USER"
    return 0
  fi

  if command -v logname >/dev/null 2>&1; then
    local login_name
    login_name=$(logname 2>/dev/null || true)
    if [[ -n $login_name && $login_name != "root" ]]; then
      printf '%s\n' "$login_name"
      return 0
    fi
  fi

  if command -v loginctl >/dev/null 2>&1; then
    local active_user
    active_user=$(loginctl list-users --no-legend 2>/dev/null | awk '$2 != "root" && $4 == "active" { print $2; exit }')
    if [[ -n $active_user ]]; then
      printf '%s\n' "$active_user"
      return 0
    fi
  fi

  getent passwd | awk -F: '$3 >= 1000 && $1 != "nobody" && $7 !~ /(nologin|false)$/ { print $1; exit }'
}

_user_home() {
  getent passwd "$1" | cut -d: -f6
}

_debug_value() {
  local line value

  [[ -f $_env_path ]] || return 0

  while IFS= read -r line; do
    line=${line#${line%%[![:space:]]*}}
    line=${line%${line##*[![:space:]]}}
    [[ -z $line || ${line:0:1} == "#" || $line != *=* ]] && continue

    if [[ ${line%%=*} == "DELL_XPS_TOUCHPAD_HAPTICS_DEBUG" ]]; then
      value=${line#*=}
      value=${value#${value%%[![:space:]]*}}
      value=${value%${value##*[![:space:]]}}
      printf '%s\n' "$value"
      return 0
    fi
  done < "$_env_path"
}

_write_env_file() {
  local home=$1
  local debug_value=$2
  local tmpfile

  tmpfile=$(mktemp)
  printf 'DELL_XPS_TOUCHPAD_HAPTICS_HOME=%s\n' "$home" >"$tmpfile"
  if [[ -n $debug_value ]]; then
    printf 'DELL_XPS_TOUCHPAD_HAPTICS_DEBUG=%s\n' "$debug_value" >>"$tmpfile"
  fi
  install -D -m 644 "$tmpfile" "$_env_path"
  rm -f "$tmpfile"
}

_systemd_runtime_available() {
  [[ -d /run/systemd/system ]]
}

_udev_runtime_available() {
  [[ -S /run/udev/control ]]
}

_service_unit_present() {
  [[ -f /usr/lib/systemd/system/$_service_name ]]
}

_reload_runtime_state() {
  if _systemd_runtime_available && ! systemctl daemon-reload; then
    echo ":: Failed to reload the systemd manager for ${_service_name}." >&2
    return 1
  fi

  if _udev_runtime_available && ! udevadm control --reload-rules; then
    echo ":: Failed to reload udev rules for ${_service_name}." >&2
    return 1
  fi
}

_ensure_user_config() {
  local user=$1
  local home=$2
  local config_dir="$home/.config/omarchy"
  local config_path="$config_dir/dell-haptic.conf"

  if [[ ! -f $config_path ]] && ! env HOME="$home" USER="$user" LOGNAME="$user" \
    /usr/bin/dell-xps-touchpad-haptics set "$_default_level"; then
    echo ":: Failed to create ${config_path} for user '$user'." >&2
    return 1
  fi

  if [[ -f $config_path ]]; then
    chown "$user:$user" "$home/.config" 2>/dev/null || true
    chown "$user:$user" "$config_dir" 2>/dev/null || true
    chown "$user:$user" "$config_path" 2>/dev/null || true
  fi

  return 0
}

_reset_trackpad() {
  if command -v omarchy-restart-trackpad >/dev/null 2>&1; then
    omarchy-restart-trackpad 2>/dev/null || true
  fi
}

_cleanup_legacy_state() {
  rm -f "$_legacy_env_path" "$_legacy_override_dir/override.conf"
  rmdir "$_legacy_override_dir" 2>/dev/null || true
}

_enable_service() {
  if ! systemctl enable "$_service_name" >/dev/null; then
    echo ":: Failed to enable ${_service_name}." >&2
    return 1
  fi
}

_start_service_if_possible() {
  if ! _systemd_runtime_available; then
    echo ":: ${_service_name} enabled; it will start on next boot."
    return 0
  fi

  if ! systemctl restart "$_service_name" >/dev/null; then
    echo ":: Failed to start ${_service_name}." >&2
    return 1
  fi
}

_configure_package() {
  local user=""
  local home=""
  local debug_value
  local config_path=""

  _cleanup_legacy_state

  if ! _service_unit_present; then
    echo ":: Required unit file for ${_service_name} was not installed." >&2
    return 1
  fi

  if ! _reload_runtime_state; then
    return 1
  fi

  user=$(_resolve_target_user)
  if [[ -n $user ]]; then
    home=$(_user_home "$user")
  fi

  if [[ -z $home || ! -d $home ]]; then
    home=$(_existing_home)
  fi

  if [[ -z $home || ! -d $home ]]; then
    echo ":: Could not determine a usable home directory for ${_service_name}." >&2
    echo ":: Reinstall the package after logging in as your desktop user to finish setup." >&2
    return 1
  fi

  debug_value=$(_debug_value)
  _write_env_file "$home" "$debug_value"

  if [[ -n $user ]]; then
    if ! _ensure_user_config "$user" "$home"; then
      return 1
    fi
  else
    config_path="$home/.config/omarchy/dell-haptic.conf"
    if [[ ! -f $config_path ]]; then
      echo ":: Could not seed ${config_path} because no desktop user could be identified." >&2
      return 1
    fi
  fi

  if ! _enable_service; then
    return 1
  fi

  _reset_trackpad

  if ! _start_service_if_possible; then
    return 1
  fi

  return 0
}

post_install() {
  _configure_package
}

post_upgrade() {
  _configure_package
}

pre_remove() {
  systemctl disable "$_service_name" 2>/dev/null || true
  systemctl stop "$_service_name" 2>/dev/null || true
}

post_remove() {
  rm -f "$_env_path"
  _reload_runtime_state || true
}