hotkeys: Initial support for custom key shortcuts

example/home.nix

@@ -3,10 +3,15 @@
   programs.plasma = {
     enable = true;
 
-    # A high-level setting:
+    # Some high-level settings:
     workspace.clickItemTo = "select";
 
-    # A mid-level setting:
+    hotkeys.commands."Launch Konsole" = {
+      key = "Meta+Alt+K";
+      command = "konsole";
+    };
+
+    # Some mid-level settings:
     shortcuts = {
       ksmserver = {
         "Lock Session" = [ "Screensaver" "Meta+Ctrl+Alt+L" ];

modules/default.nix

@@ -3,6 +3,7 @@
 {
   imports = [
     ./files.nix
+    ./hotkeys.nix
     ./shortcuts.nix
     ./windows.nix
     ./workspace.nix

modules/hotkeys.nix

@@ -0,0 +1,108 @@
+# Global hotkeys (user-defined keyboard shortcuts):
+{ config, lib, ... }:
+let
+  cfg = config.programs.plasma;
+
+  commandType = { name, ... }: {
+    options = {
+      name = lib.mkOption {
+        type = lib.types.str;
+        default = name;
+        description = "Command hotkey name.";
+      };
+
+      comment = lib.mkOption {
+        type = lib.types.str;
+        default = name;
+        description = "Optional comment to display in the KDE settings UI.";
+      };
+
+      key = lib.mkOption {
+        type = lib.types.str;
+        description = "The key that triggers the action.";
+      };
+
+      command = lib.mkOption {
+        type = lib.types.str;
+        description = "The command to execute.";
+      };
+    };
+  };
+
+  # Create a hotkey attribute set from the given command.  The idx
+  # parameter is the index within the hotkey list for this command.
+  commandToHotkey = cmd: idx: {
+    inherit (cmd) name comment;
+
+    triggers = [{
+      Key = cmd.key;
+      Type = "SHORTCUT";
+      Uuid = "{" + builtins.hashString "sha256" (builtins.toString idx + cmd.name) + "}";
+    }];
+
+    actions = [{
+      CommandURL = cmd.command;
+      Type = "COMMAND_URL";
+    }];
+
+    conditions = [ ];
+  };
+
+  # Convert a hotkey to an attribute set that can be used with
+  # programs.plasma.files:
+  hotkeyToSettings = hotkey: idx:
+    let
+      prefix = "Data_${toString idx}";
+
+      toSection = name: items:
+        builtins.listToAttrs
+          (lib.imap0
+            (jdx: item: {
+              name = "${prefix}${name}${toString jdx}";
+              value = item;
+            })
+            items);
+    in
+    {
+      ${prefix} = {
+        Comment = hotkey.comment;
+        Enabled = true;
+        Name = hotkey.name;
+        Type = "SIMPLE_ACTION_DATA";
+      };
+
+      "${prefix}Conditions".ConditionsCount =
+        builtins.length (hotkey.conditions);
+
+      "${prefix}Actions".ActionsCount =
+        builtins.length (hotkey.actions);
+
+      "${prefix}Triggers".TriggersCount =
+        builtins.length (hotkey.triggers);
+    }
+    // toSection "Conditions" hotkey.conditions
+    // toSection "Actions" hotkey.actions
+    // toSection "Triggers" hotkey.triggers;
+
+  # Turn all options in this module into an attribute sets for
+  # programs.plasma.files.
+  hotkeys =
+    let items =
+      (map commandToHotkey (builtins.attrValues cfg.hotkeys.commands));
+    in
+    lib.foldr (a: b: a // b) { Data.DataCount = builtins.length items; }
+      (lib.imap1 (idx: hotkey: hotkeyToSettings (hotkey idx) idx) items);
+in
+{
+  options.programs.plasma.hotkeys = {
+    commands = lib.mkOption {
+      type = with lib.types; attrsOf (submodule commandType);
+      default = { };
+      description = "Commands triggered by a keyboard shortcut.";
+    };
+  };
+
+  config = lib.mkIf (cfg.enable && builtins.length (builtins.attrNames hotkeys) != 0) {
+    programs.plasma.files.khotkeysrc = hotkeys;
+  };
+}