add indentation options to kate

modules/apps/default.nix

@@ -0,0 +1,7 @@
+{ ... }:
+
+{
+  imports = [
+	./kate.nix
+  ];
+}

modules/apps/kate.nix

@@ -0,0 +1,89 @@
+{ config, lib, ... }:
+
+let
+  # compute kate's magic TabHandlingMode
+  boolToInt = b: if b then 1 else 0;
+  t = boolToInt config.programs.kate.editor.indent.tabFromEverywhere;
+  s = boolToInt config.programs.kate.editor.indent.undoByShiftTab;
+  tabHandlingMode = t + 2 * s - 1;
+in
+{
+  options.programs.kate.editor = {
+    tabWidth = lib.mkOption {
+      description = "The width of a single tab (\\t) sign (in number of spaces).";
+      default = 4;
+      type = lib.types.int;
+    };
+
+    indent.showLines = lib.mkOption {
+      description = "Whether to show the vertical lines that mark each indentation level.";
+      default = true;
+      type = lib.types.bool;
+    };
+
+    indent.width = lib.mkOption {
+      description = "The width of each indent level (in number of spaces).";
+      default = config.programs.kate.editor.tabWidth;
+      type = lib.types.int;
+    };
+
+    indent.autodetect = lib.mkOption {
+      description = "Whether kate should try to detect indentation for each given file and not impose default indentation settings.";
+      default = true;
+      type = lib.types.bool;
+    };
+
+    indent.keepExtraSpaces = lib.mkOption {
+      description = "Whether additional spaces that do not match the indent should be kept when adding/removing indentation level. If these are kept (option to true) then indenting 1 space further (with a default of 4 spaces) will be set to 5 spaces.";
+      default = false;
+      type = lib.types.bool;
+    };
+
+    indent.replaceWithSpaces = lib.mkOption {
+      description = "Whether all indentation should be automatically converted to spaces.";
+      default = false;
+      type = lib.types.bool;
+    };
+
+    indent.backspaceDecreaseIndent = lib.mkOption {
+      description = "Whether the backspace key in the indentation should decrease indentation by a full level always.";
+      default = true;
+      type = lib.types.bool;
+    };
+
+    indent.tabFromEverywhere = lib.mkOption {
+      description = "Whether the tabulator key increases intendation independent from the current cursor position.";
+      default = false;
+      type = lib.types.bool;
+    };
+
+    indent.undoByShiftTab = lib.mkOption {
+      description = "Whether to unindent the current line by one level with the shortcut Shift+Tab";
+      default = true;
+      type = lib.types.bool;
+    };
+  };
+
+  config.assertions = [
+    {
+      assertion = tabHandlingMode >= -1;
+      message = "Either 'undeByShiftTab' or 'tabFromEverywhere' needs to be enabled!";
+      # kate does not seem to support disabling both.
+    }
+  ];
+
+  config.programs.plasma.configFile."katerc" = {
+    "KTextEditor Document" = {
+      "Auto Detect Indent" = config.programs.kate.editor.indent.autodetect;
+      "Indentation Width" = config.programs.kate.editor.indent.width;
+      "Tab Handling" = tabHandlingMode;
+      "Tab Width" = config.programs.kate.editor.tabWidth;
+      "Keep Extra Spaces" = config.programs.kate.editor.indent.keepExtraSpaces;
+      "ReplaceTabsDyn" = config.programs.kate.editor.indent.replaceWithSpaces;
+    };
+
+    "KTextEditor Renderer" = {
+      "Show Indentation Lines" = config.programs.kate.editor.indent.showLines;
+    };
+  };
+}

modules/default.nix

@@ -11,6 +11,7 @@
     ./kwin.nix
     ./startup.nix
     ./panels.nix
+    ./apps
   ];
 
   options.programs.plasma.enable = lib.mkEnableOption ''