From 636d1a09d8a4fc2306aee0c8a33dac21bd9e201a Mon Sep 17 00:00:00 2001
From: Maxime Daffis <maxime.daffis@gmail.com>
Date: Tue, 2 Jul 2024 14:22:37 +0200
Subject: [PATCH] (feature) Add swapLeftCtrlAndFn

Use this and never find yourself again hitting fn because of muscle
memory! (you can even physically swap the keycaps, at least on M series)

Keycodes have been pulled from https://hidutil-generator.netlify.app/
and the hex value has been converted to a base 10 int.
---
 modules/system/keyboard.nix       | 14 ++++++++++++++
 tests/system-keyboard-mapping.nix |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/modules/system/keyboard.nix b/modules/system/keyboard.nix
index 01e25256..f4f64060 100644
--- a/modules/system/keyboard.nix
+++ b/modules/system/keyboard.nix
@@ -38,6 +38,12 @@ in
       description = "Whether to swap the left Command key and left Alt key.";
     };
 
+    system.keyboard.swapLeftCtrlAndFn = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether to swap the left Control key and Fn (Globe) key.";
+    };
+
     system.keyboard.userKeyMapping = mkOption {
       internal = true;
       type = types.listOf (types.attrsOf types.int);
@@ -66,6 +72,14 @@ in
         HIDKeyboardModifierMappingSrc = 30064771298;
         HIDKeyboardModifierMappingDst = 30064771299;
       })
+      (mkIf cfg.swapLeftCtrlAndFn {
+        HIDKeyboardModifierMappingSrc = 30064771296;
+        HIDKeyboardModifierMappingDst = 1095216660483;
+      })
+      (mkIf cfg.swapLeftCtrlAndFn {
+        HIDKeyboardModifierMappingSrc = 1095216660483;
+        HIDKeyboardModifierMappingDst = 30064771296;
+      })
     ];
 
     system.activationScripts.keyboard.text = optionalString cfg.enableKeyMapping ''
diff --git a/tests/system-keyboard-mapping.nix b/tests/system-keyboard-mapping.nix
index b75efbd3..654ca0c9 100644
--- a/tests/system-keyboard-mapping.nix
+++ b/tests/system-keyboard-mapping.nix
@@ -6,6 +6,7 @@
   system.keyboard.remapCapsLockToEscape = true;
   system.keyboard.nonUS.remapTilde = true;
   system.keyboard.swapLeftCommandAndLeftAlt = true;
+  system.keyboard.swapLeftCtrlAndFn = true;
 
   test = ''
     echo checking keyboard mappings in /activate >&2
@@ -17,5 +18,7 @@
     grep "\"HIDKeyboardModifierMappingDst\":30064771296" ${config.out}/activate
     grep "\"HIDKeyboardModifierMappingDst\":30064771298" ${config.out}/activate
     grep "\"HIDKeyboardModifierMappingDst\":30064771299" ${config.out}/activate
+    grep "\"HIDKeyboardModifierMappingDst\":30064771296" ${config.out}/activate
+    grep "\"HIDKeyboardModifierMappingDst\":1095216660483" ${config.out}/activate
   '';
 }