1 files changed, 97 insertions, 0 deletions
diff --git a/krebs/3modules/power-action.nix b/krebs/3modules/power-action.nix
new file mode 100644
index 000000000..4c2533eb7
--- /dev/null
+++ b/krebs/3modules/power-action.nix
@@ -0,0 +1,97 @@
+{ config, lib, pkgs, ... }:
+
+with config.krebs.lib;
+
+let
+  cfg = config.krebs.power-action;
+
+  out = {
+    options.krebs.power-action = api;
+    config = lib.mkIf cfg.enable imp;
+  };
+
+  api = {
+    enable = mkEnableOption "power-action";
+    battery = mkOption {
+      type = types.str;
+      default = "BAT0";
+    };
+    user = mkOption {
+      type = types.user;
+      default = {
+        name = "power-action";
+      };
+    };
+    startAt = mkOption {
+      type = types.str;
+      default = "*:0/1";
+    };
+    plans = mkOption {
+      type = with types; attrsOf (submodule {
+        options = {
+          charging = mkOption {
+            type = nullOr bool;
+            default = null;
+            description = ''
+              check for charging status.
+              null = don't care
+              true = only if system is charging
+              false = only if system is discharging
+            '';
+          };
+          upperLimit = mkOption {
+            type = int;
+          };
+          lowerLimit = mkOption {
+            type = int;
+          };
+          action = mkOption {
+            type = path;
+          };
+        };
+      });
+    };
+  };
+
+  imp = {
+    systemd.services.power-action = {
+      serviceConfig = rec {
+        ExecStart = startScript;
+        User = cfg.user.name;
+      };
+      startAt = cfg.startAt;
+    };
+    users.users.${cfg.user.name} = {
+      inherit (cfg.user) name uid;
+    };
+  };
+
+  startScript = pkgs.writeDash "power-action" ''
+    set -euf
+
+    power="$(${powerlvl})"
+    state="$(${state})"
+    ${concatStringsSep "\n" (mapAttrsToList writeRule cfg.plans)}
+  '';
+  charging_check = plan:
+    if (plan.charging == null) then "" else
+      if plan.charging
+        then ''&& [ "$state" = "true" ]''
+        else ''&& ! [ "$state" = "true" ]''
+    ;
+
+  writeRule = _: plan:
+    "if [ $power -ge ${toString plan.lowerLimit} ] && [ $power -le ${toString plan.upperLimit} ] ${charging_check plan}; then ${plan.action}; fi";
+
+  powerlvl = pkgs.writeDash "powerlvl" ''
+    cat /sys/class/power_supply/${cfg.battery}/capacity
+  '';
+
+  state = pkgs.writeDash "state" ''
+    if [ "$(cat /sys/class/power_supply/${cfg.battery}/status)" = "Discharging" ]
+      then echo "false"
+      else echo "true"
+    fi
+  '';
+
+in out