plugins/nixd: automatically add nixpkgs-fmt if needed

plugins/lsp/language-servers/default.nix

@@ -351,47 +351,6 @@ with lib; let
       description = "Enable nixd, for Nix";
       package = pkgs.nixd;
       settings = cfg: {nixd = cfg;};
-      settingsOptions = {
-        # The evaluation section, provide auto completion for dynamic bindings.
-        eval = {
-          target = {
-            args = helpers.defaultNullOpts.mkNullable (with types; listOf str) "[]" ''
-              Accept args as "nix eval".
-            '';
-
-            installable = helpers.defaultNullOpts.mkStr "" ''
-              "nix eval"
-            '';
-          };
-
-          depth = helpers.defaultNullOpts.mkInt 0 "Extra depth for evaluation";
-
-          workers = helpers.defaultNullOpts.mkInt 3 "The number of workers for evaluation task.";
-        };
-
-        formatting = {
-          command = helpers.defaultNullOpts.mkStr "nixpkgs-fmt" ''
-            Which command you would like to do formatting
-          '';
-        };
-
-        options = {
-          enable = helpers.defaultNullOpts.mkBool true ''
-            Enable option completion task.
-            If you are writting a package, disable this
-          '';
-
-          target = {
-            args = helpers.defaultNullOpts.mkNullable (with types; listOf str) "[]" ''
-              Accept args as "nix eval".
-            '';
-
-            installable = helpers.defaultNullOpts.mkStr "" ''
-              "nix eval"
-            '';
-          };
-        };
-      };
     }
     {
       name = "omnisharp";
@@ -541,8 +500,9 @@ in {
     lib.lists.map lspHelpers.mkLsp servers
     ++ [
       ./ccls.nix
+      ./efmls-configs.nix
+      ./nixd.nix
       ./pylsp.nix
       ./svelte.nix
-      ./efmls-configs.nix
     ];
 }

plugins/lsp/language-servers/nixd.nix

@@ -0,0 +1,64 @@
+{
+  lib,
+  config,
+  pkgs,
+  ...
+}:
+with lib; let
+  helpers = import ../../helpers.nix {inherit lib;};
+  cfg = config.plugins.lsp.servers.nixd;
+in {
+  # Options: https://github.com/nix-community/nixd/blob/main/docs/user-guide.md#configuration
+  options.plugins.lsp.servers.nixd.settings = {
+    # The evaluation section, provide auto completion for dynamic bindings.
+    eval = {
+      target = {
+        args = helpers.defaultNullOpts.mkNullable (with types; listOf str) "[]" ''
+          Accept args as "nix eval".
+        '';
+
+        installable = helpers.defaultNullOpts.mkStr "" ''
+          "nix eval"
+        '';
+      };
+
+      depth = helpers.defaultNullOpts.mkInt 0 "Extra depth for evaluation";
+
+      workers = helpers.defaultNullOpts.mkInt 3 "The number of workers for evaluation task.";
+    };
+
+    formatting = {
+      command = helpers.defaultNullOpts.mkStr "nixpkgs-fmt" ''
+        Which command you would like to do formatting.
+        Explicitly set to `"nixpkgs-fmt"` will automatically add `pkgs.nixpkgs-fmt` to the nixvim
+        environment.
+      '';
+    };
+
+    options = {
+      enable = helpers.defaultNullOpts.mkBool true ''
+        Enable option completion task.
+        If you are writting a package, disable this
+      '';
+
+      target = {
+        args = helpers.defaultNullOpts.mkNullable (with types; listOf str) "[]" ''
+          Accept args as "nix eval".
+        '';
+
+        installable = helpers.defaultNullOpts.mkStr "" ''
+          "nix eval"
+        '';
+      };
+    };
+  };
+
+  config =
+    mkIf cfg.enable
+    {
+      extraPackages =
+        optional
+        (cfg.settings.formatting.command == "nixpkgs-fmt")
+        pkgs.nixpkgs-fmt;
+    };
+}