add lsp server support to kate

modules/apps/kate/default.nix

@@ -26,6 +26,53 @@ let
     '';
 
   script = pkgs.writeScript "kate-check" (checkThemeName cfg.editor.theme.name);
+
+  supportedLspServers = {
+    # https://github.com/oxalica/nil?tab=readme-ov-file#kate-with-lsp-client-plugin
+    nil = {
+      name = "nix"; # the name in the settings file. no collisions in the end!
+      settings = {
+        command = [ "nil" ];
+        url = "https://github.com/oxalica/nil";
+        highlightingModeRegex = "^Nix$";
+      };
+      package = pkgs.nil;
+    };
+
+    marksman = {
+      #https://www.reddit.com/r/kde/comments/webug0/trying_to_get_marksman_markdown_lsp_to_work_in/
+      name = "markdown";
+      settings = {
+       command = [ "marksman" "server" ];
+        url = "https://github.com/artempyanykh/marksman";
+        highlightingModeRegex = "^Markdown$";
+      };
+      package = pkgs.marksman;
+    };
+  };
+
+  installedLspSettings =
+    cfg.lsp.extraSettings //
+    (
+      # rename the settings to the language name
+      lib.mapAttrs'
+      (name: value: lib.nameValuePair value.name value.settings)
+      (
+        # pick only the lspServers which the user chose
+        lib.filterAttrs
+        (n: v: builtins.elem n cfg.lsp.servers)
+        supportedLspServers
+      )
+    );
+
+  lspPackages =
+    lib.attrVals
+    cfg.lsp.servers
+    (
+      lib.mapAttrs
+      (name: value: value.package)
+      supportedLspServers
+    );
 in
 {
   options.programs.kate = {
@@ -175,7 +222,11 @@ in
     };
 
   config = {
-    home.packages = lib.mkIf (cfg.enable && cfg.package != null) [ cfg.package ];
+    home.packages = lib.mkIf cfg.enable
+      (
+        (lib.lists.optional (cfg.package != null) cfg.package)
+        ++ lspPackages
+      );
 
     # In case of using a custom theme, check that there is no name collision
     home.activation.checkKateTheme = lib.mkIf (cfg.enable && cfg.editor.theme.src != null) (lib.hm.dag.entryBefore [ "writeBoundary" ]
@@ -189,4 +240,28 @@ in
     # That's why there is no check for now
     # See also [the original PR](https://github.com/pjones/plasma-manager/pull/95#issue-2206192839)
   };
+
+
+  # ==================================
+  #     LSP Servers
+
+  options.programs.kate.lsp.servers = lib.mkOption {
+    default = [];
+    type = lib.types.listOf ( lib.types.enum (builtins.attrNames supportedLspServers) );
+    description = ''
+      List of all preconfigured LSP servers to use.
+    '';
+  };
+
+  options.programs.kate.lsp.extraSettings = lib.mkOption {
+    default = {};
+    type = lib.types.attrs;
+    description = ''
+      Add more lsp server settings here. Check out the format on the [KDE page](https://kate-editor.org/post/2019/2019-08-10-kate-lsp-more-languages-supported/).
+    '';
+  };
+
+  config.xdg.configFile."kate/lspclient/settings.json" = {
+    text = builtins.toJSON { servers = installedLspSettings; };
+  };
 }