nixdots/system/roles/laptop/power/power-profiles-daemon/default.nix

{
  pkgs,
  lib,
  config,
  ...
}: let
  inherit (lib) mkIf;
  inherit (lib.modules) mkForce;
  inherit (lib.strings) makeBinPath;
  deviceType = config.myOptions.device.roles.type;
  acceptedTypes = ["laptop"];
in {
  config = mkIf (builtins.elem deviceType acceptedTypes) {
    # allows changing system behavior based upon user-selected power profiles
    # (with `powerprofilesctl` command)
    services.power-profiles-daemon.enable = true;

    # Power state monitor. Switches power profiles based on charging state.
    # Plugged in - performance (if available, falls back to balance)
    # Unplugged - balanced, until below 50%, then power-saver
    systemd.services."power-monitor" = let
      dependencies = with pkgs; [
        coreutils
        gnugrep
        power-profiles-daemon
        inotify-tools
        jaq
      ];
    in {
      description = "Power Monitoring Service";
      environment.PATH = mkForce "/run/wrappers/bin:${makeBinPath dependencies}";
      script = builtins.readFile ./power_monitor.sh;

      serviceConfig = {
        Type = "simple";
        Restart = "on-failure";
      };

      wants = ["power-profiles-daemon.service"];
      wantedBy = ["default.target"];
    };
  };
}