style: Split out and fixes

hm/brightness/default.nix

@@ -0,0 +1,36 @@
+# Light theme during the day, dark theme during the night (not automatic)
+{ pkgs, lib, config, ... }:
+let
+  phases = [
+    { command = "jour"; polarity = "light"; }
+    { command = "crepuscule"; polarity = "dark"; }
+    { command = "nuit"; polarity = "dark"; }
+  ];
+  phasesBrightness = config.frogeye.desktop.phasesBrightness;
+in
+{
+  config = {
+    home.packages = map
+      (phase: (pkgs.writeShellApplication {
+        name = "${phase.command}";
+        runtimeInputs = [ pkgs.brightnessctl ];
+        text = (lib.optionalString phasesBrightness.enable ''
+          brightnessctl set ${builtins.getAttr phase.command phasesBrightness}
+        '') + ''
+          switch="/nix/var/nix/profiles/system/specialisation/${phase.polarity}/bin/switch-to-configuration"
+          if [ -x "$switch" ]
+          then
+              # In two steps to get the visual changes slightly earlier
+              sudo "$switch" test
+              sudo "$switch" boot
+          fi
+        '';
+      })
+      )
+      phases;
+    xsession.windowManager.i3.config.keybindings = {
+      "XF86MonBrightnessUp" = "exec ${pkgs.brightnessctl}/bin/brightnessctl set +5%";
+      "XF86MonBrightnessDown" = "exec ${pkgs.brightnessctl}/bin/brightnessctl set 5%-";
+    };
+  };
+}