{ config, lib, ... }:

let
  cfg = config.my.zram;
in {
  options.my.zram = {
    enable = lib.mkEnableOption null // {
      default = !config.my.fs.swapPartition;
    };
    writebackDevice = lib.mkOption {
      default = null;
      type = with lib.types; nullOr path;
    };
  };

  config = lib.mkIf cfg.enable {
    zramSwap = {
      enable = true;
      algorithm = "zstd";
      memoryPercent = 90;
      inherit (cfg) writebackDevice;
    };

    boot.kernel.sysctl = {
      "vm.swappiness" = 180;
      "vm.watermark_boost_factor" = 0;
      "vm.watermark_scale_factor" = 125;
      "vm.page-cluster" = 1;
    };
  };
}