{ config, pkgs, ... }:

let
  batteryNotify = pkgs.writeShellScript "battery-notify" ''
    BAT="/sys/class/power_supply/BAT1"
    LEVEL=$(cat "$BAT/capacity")
    STATUS=$(cat "$BAT/status")
    ID=9991

    if [ "$STATUS" = "Discharging" ] && [ "$LEVEL" -lt 20 ]; then
      ${pkgs.dunst}/bin/dunstify \
        -r "$ID" -t 0 \
        -u critical \
        "Battery Low" \
        "Battery is at ''${LEVEL}%"
    else
      ${pkgs.dunst}/bin/dunstify \
        -C "$ID" 2>/dev/null || true
    fi
  '';
in
{
  systemd.services.battery-notify = {
    description = "Low battery notification";
    serviceConfig = {
      Type = "oneshot";
      ExecStart = batteryNotify;
    };
  };

  systemd.timers.battery-notify = {
    description = "Check battery level every 20 seconds";
    wantedBy = [ "timers.target" ];

    timerConfig = {
      OnBootSec = "20s";
      OnUnitActiveSec = "20s";
    };
  };
}