modules: add suspend

common/suspend.nix

@@ -0,0 +1,70 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+with lib; let
+  cfg = config.services.batteryNotifier;
+in {
+  options = {
+    services.batteryNotifier = {
+      enable = mkOption {
+        default = false;
+        description = ''
+          Whether to enable battery notifier.
+        '';
+      };
+      device = mkOption {
+        default = "BAT0";
+        description = ''
+          Device to monitor.
+        '';
+      };
+      notifyCapacity = mkOption {
+        default = 10;
+        description = ''
+          Battery level at which a notification shall be sent.
+        '';
+      };
+      suspendCapacity = mkOption {
+        default = 5;
+        description = ''
+          Battery level at which a suspend unless connected shall be sent.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.user.timers."lowbatt" = {
+      description = "check battery level";
+      timerConfig.OnBootSec = "1m";
+      timerConfig.OnUnitInactiveSec = "1m";
+      timerConfig.Unit = "lowbatt.service";
+      wantedBy = ["timers.target"];
+    };
+    systemd.user.services."lowbatt" = {
+      description = "battery level notifier";
+      serviceConfig.PassEnvironment = "DISPLAY";
+      script = ''
+        export battery_capacity=$(${pkgs.coreutils}/bin/cat /sys/class/power_supply/${cfg.device}/capacity)
+        export battery_status=$(${pkgs.coreutils}/bin/cat /sys/class/power_supply/${cfg.device}/status)
+
+        if [[ $battery_capacity -le ${builtins.toString cfg.notifyCapacity} && $battery_status = "Discharging" ]]; then
+            ${pkgs.libnotify}/bin/notify-send --urgency=critical --hint=int:transient:1 --icon=battery_empty "Battery Low" "You should probably plug-in."
+        fi
+
+        if [[ $battery_capacity -le ${builtins.toString cfg.suspendCapacity} && $battery_status = "Discharging" ]]; then
+            ${pkgs.libnotify}/bin/notify-send --urgency=critical --hint=int:transient:1 --icon=battery_empty "Battery Critically Low" "Computer will suspend in 60 seconds."
+            sleep 60s
+
+            battery_status=$(${pkgs.coreutils}/bin/cat /sys/class/power_supply/${cfg.device}/status)
+            if [[ $battery_status = "Discharging" ]]; then
+                systemctl suspend
+            fi
+        fi
+      '';
+    };
+  };
+}