nix: minor flake refactor; provide GTK and QT theme packages

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I136253e0d928e71e61824bc3f3b5a0726a6a6964

lib.nix

@@ -0,0 +1,63 @@
+{lib}: let
+  requiredBaseKeys = [
+    "base00"
+    "base01"
+    "base02"
+    "base03"
+    "base04"
+    "base05"
+    "base06"
+    "base07"
+    "base08"
+    "base09"
+    "base0A"
+    "base0B"
+    "base0C"
+    "base0D"
+    "base0E"
+    "base0F"
+  ];
+
+  sanitizeSlug = slug:
+    lib.strings.sanitizeDerivationName
+    (lib.strings.toLower (toString slug));
+
+  normalizeHex = color:
+    lib.strings.toLower
+    (lib.removePrefix "#" (toString color));
+
+  missingBaseKeys = palette:
+    builtins.filter (key: !(builtins.hasAttr key palette)) requiredBaseKeys;
+
+  validatePalette = {
+    slug,
+    palette,
+  }: let
+    missing = missingBaseKeys palette;
+  in
+    if missing != []
+    then throw "Basix theme generation failed for `${slug}`: missing palette keys ${lib.concatStringsSep ", " missing} (required: base00-base0F)"
+    else palette;
+
+  mkThemeName = slug: "Basix-${sanitizeSlug slug}";
+
+  evalSchemeData = lib.flip lib.pipe [
+    builtins.unsafeDiscardStringContext
+    lib.filesystem.listFilesRecursive
+    (builtins.filter (lib.hasSuffix ".json"))
+    (map (n: {
+      name = lib.removePrefix ((dirOf n) + "/") (lib.removeSuffix ".json" n);
+      value = lib.importJSON n;
+    }))
+    lib.listToAttrs
+  ];
+in {
+  inherit
+    evalSchemeData
+    mkThemeName
+    normalizeHex
+    requiredBaseKeys
+    sanitizeSlug
+    validatePalette
+    ;
+}