nix-darwin/modules/services/nix-gc/default.nix

# Based off: https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/misc/nix-gc.nix
# When making changes please try to keep it in sync.
{ config, lib, ... }:

with lib;

let
  cfg = config.nix.gc;
  launchdTypes = import ../../launchd/types.nix { inherit config lib; };
in

{
  imports = [
    (mkRemovedOptionModule [ "nix" "gc" "dates" ] "Use `nix.gc.interval` instead.")
    (mkRemovedOptionModule [ "nix" "gc" "randomizedDelaySec" ] "No `nix-darwin` equivalent to this NixOS option.")
    (mkRemovedOptionModule [ "nix" "gc" "persistent" ] "No `nix-darwin` equivalent to this NixOS option.")
    (mkRemovedOptionModule [ "nix" "gc" "user" ] "The garbage collection service now always runs as `root`.")
  ];

  ###### interface

  options = {

    nix.gc = {

      automatic = mkOption {
        default = false;
        type = types.bool;
        description = "Automatically run the garbage collector at a specific time.";
      };

      interval = mkOption {
        type = launchdTypes.StartCalendarInterval;
        default = [{ Weekday = 7; Hour = 3; Minute = 15; }];
        description = ''
          The calendar interval at which the garbage collector will run.
          See the {option}`serviceConfig.StartCalendarInterval` option of
          the {option}`launchd` module for more info.
        '';
      };

      options = mkOption {
        default = "";
        example = "--max-freed $((64 * 1024**3))";
        type = types.str;
        description = ''
          Options given to {file}`nix-collect-garbage` when the
          garbage collector is run automatically.
        '';
      };

    };

  };


  ###### implementation

  config = {
    assertions = [
      {
        assertion = cfg.automatic -> config.nix.enable;
        message = ''nix.gc.automatic requires nix.enable'';
      }
    ];

    launchd.daemons.nix-gc = mkIf cfg.automatic {
      command = "${config.nix.package}/bin/nix-collect-garbage ${cfg.options}";
      serviceConfig.RunAtLoad = false;
      serviceConfig.StartCalendarInterval = cfg.interval;
    };
  };
}