kitty: remove IFD

With this change the theme check happens at activation time. An
integration test is also added to verify the functionality.

Fixes #5110

modules/programs/kitty.nix

@@ -3,7 +3,6 @@
 with lib;
 
 let
-
   cfg = config.programs.kitty;
 
   eitherStrBoolInt = with types; either str (either bool int);
@@ -57,6 +56,26 @@ let
     '';
   };
 in {
+  imports = [
+    (mkChangedOptionModule [ "programs" "kitty" "theme" ] [
+      "programs"
+      "kitty"
+      "themeFile"
+    ] (config:
+      let value = getAttrFromPath [ "programs" "kitty" "theme" ] config;
+      in if value != null then
+        (let
+          matching = filter (x: x.name == value) (builtins.fromJSON
+            (builtins.readFile
+              "${pkgs.kitty-themes}/share/kitty-themes/themes.json"));
+        in throwIf (length matching == 0)
+        "kitty-themes does not contain a theme named ${value}"
+        strings.removeSuffix ".conf"
+        (strings.removePrefix "themes/" (head matching).file))
+      else
+        null))
+  ];
+
   options.programs.kitty = {
     enable = mkEnableOption "Kitty terminal emulator";
 
@@ -100,16 +119,16 @@ in {
       '';
     };
 
-    theme = mkOption {
+    themeFile = mkOption {
       type = types.nullOr types.str;
       default = null;
       description = ''
-        Apply a Kitty color theme. This option takes the friendly name of
-        any theme given by the command {command}`kitty +kitten themes`.
-        See <https://github.com/kovidgoyal/kitty-themes>
-        for more details.
+        Apply a Kitty color theme. This option takes the file name of a theme
+        in `kitty-themes`, without the `.conf` suffix. See
+        <https://github.com/kovidgoyal/kitty-themes/tree/master/themes> for a
+        list of themes.
       '';
-      example = "Space Gray Eighties";
+      example = "SpaceGray_Eighties";
     };
 
     font = mkOption {
@@ -146,11 +165,11 @@ in {
         type = types.str;
         default = "no-rc";
         example = "no-cursor";
-        apply = (o:
+        apply = o:
           let
             modes = splitString " " o;
             filtered = filter (m: m != "no-rc") modes;
-          in concatStringsSep " " (concatLists [ [ "no-rc" ] filtered ]));
+          in concatStringsSep " " (concatLists [ [ "no-rc" ] filtered ]);
         description = ''
           Set the mode of the shell integration. This accepts the same options
           as the `shell_integration` option of Kitty. Note that
@@ -184,24 +203,15 @@ in {
       text = ''
         # Generated by Home Manager.
         # See https://sw.kovidgoyal.net/kitty/conf.html
-      '' + concatStringsSep "\n" ([
-
+      '' + concatStringsSep "\n" [
         (optionalString (cfg.font != null) ''
           font_family ${cfg.font.name}
           ${optionalString (cfg.font.size != null)
           "font_size ${toString cfg.font.size}"}
         '')
 
-        (optionalString (cfg.theme != null) ''
-          include ${pkgs.kitty-themes}/share/kitty-themes/${
-            let
-              matching = filter (x: x.name == cfg.theme) (builtins.fromJSON
-                (builtins.readFile
-                  "${pkgs.kitty-themes}/share/kitty-themes/themes.json"));
-            in throwIf (length matching == 0)
-            "kitty-themes does not contain a theme named ${cfg.theme}"
-            (head matching).file
-          }
+        (optionalString (cfg.themeFile != null) ''
+          include ${pkgs.kitty-themes}/share/kitty-themes/themes/${cfg.themeFile}.conf
         '')
         ''
           # Shell integration is sourced and configured manually
@@ -211,13 +221,23 @@ in {
         (toKittyKeybindings cfg.keybindings)
         (toKittyEnv cfg.environment)
         cfg.extraConfig
-      ]);
+      ];
     } // optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
       onChange = ''
         ${pkgs.procps}/bin/pkill -USR1 -u $USER kitty || true
       '';
     };
 
+    home.activation.checkKittyTheme = mkIf (cfg.themeFile != null) (let
+      themePath =
+        "${pkgs.kitty-themes}/share/kitty-themes/themes/${cfg.themeFile}.conf";
+    in hm.dag.entryBefore [ "writeBoundary" ] ''
+      if [[ ! -f "${themePath}" ]]; then
+        errorEcho "kitty-themes does not contain the theme file ${themePath}!"
+        exit 1
+      fi
+    '');
+
     xdg.configFile."kitty/macos-launch-services-cmdline" = mkIf
       (cfg.darwinLaunchOptions != null && pkgs.stdenv.hostPlatform.isDarwin) {
         text = concatStringsSep " " cfg.darwinLaunchOptions;