feat(home-manager): add support for fish (#46)

Signed-off-by: Sefa Eyeoglu <contact@scrumplex.net>

modules/home-manager/default.nix

@@ -15,6 +15,7 @@ in
         ./bat.nix
         ./bottom.nix
         ./btop.nix
+        ./fish.nix
         ./kitty.nix
         ./lazygit.nix
         ./starship.nix

modules/home-manager/fish.nix

@@ -0,0 +1,32 @@
+{ config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) ctp mkIf;
+  cfg = config.programs.fish.catppuccin;
+  enable = cfg.enable && config.programs.fish.enable;
+
+  theme = pkgs.fetchFromGitHub
+    {
+      owner = "catppuccin";
+      repo = "fish";
+      rev = "91e6d6721362be05a5c62e235ed8517d90c567c9";
+      sha256 = "sha256-l9V7YMfJWhKDL65dNbxaddhaM6GJ0CFZ6z+4R6MJwBA=";
+    };
+  themeName = "Catppuccin ${ctp.mkUpper cfg.flavour}";
+in
+{
+  options.programs.fish.catppuccin = lib.ctp.mkCatppuccinOpt "fish" config;
+
+  # xdg is required for this to work
+  config = mkIf enable {
+    xdg.enable = lib.mkForce true;
+
+    programs.fish.shellInit = ''
+      fish_config theme choose "${themeName}"
+    '';
+    xdg.configFile."fish/themes/${themeName}.theme".source = "${theme}/themes/${themeName}.theme";
+  };
+}