nix-community.nixvim/modules/lsp/on-attach.nix

{ lib, config, ... }:
let
  cfg = config.lsp;
in
{
  options.lsp = {
    onAttach = lib.mkOption {
      type = lib.types.lines;
      description = ''
        Lines of lua to be run when a language server is attached.

        > [!TIP]
        > The variables `client` and `bufnr` are made available in scope.

        This is a global equivialent to the per-server `on_attach` callback,
        which can be defined via `lsp.servers.<name>.settings.on_attach`.

        Unlike the per-server callback, which should be defined as a lua
        callback function, this option should be defined as the function body.
      '';
      default = "";
    };
  };

  config = lib.mkIf (cfg.onAttach != "") {
    autoGroups.nixvim_lsp_on_attach.clear = false;

    autoCmd = [
      {
        event = "LspAttach";
        group = "nixvim_lsp_on_attach";
        callback = lib.nixvim.mkRaw ''
          function(args)
            do
              -- client and bufnr are supplied to the builtin `on_attach` callback,
              -- so make them available in scope for our global `onAttach` impl
              local client = vim.lsp.get_client_by_id(args.data.client_id)
              local bufnr = args.bufnr

              ${cfg.onAttach}
            end
          end
        '';
        desc = "Run LSP onAttach";
      }
    ];
  };
}