neovim-flake/modules/languages/lua.nix

{
  pkgs,
  config,
  lib,
  ...
}: let
  inherit (lib) isList nvim mkEnableOption mkOption types mkIf mkMerge optionalString getExe;

  cfg = config.vim.languages.lua;
in {
  options.vim.languages.lua = {
    enable = mkEnableOption "Lua language support";
    treesitter = {
      enable = mkEnableOption "Lua Treesitter support" // {default = config.vim.languages.enableTreesitter;};
      package = nvim.types.mkGrammarOption pkgs "lua";
    };
    lsp = {
      enable = mkEnableOption "Lua LSP support via LuaLS" // {default = config.vim.languages.enableLSP;};

      package = mkOption {
        description = "LuaLS package, or the command to run as a list of strings";
        type = with types; either package (listOf str);
        default = pkgs.lua-language-server;
      };

      neodev.enable = mkEnableOption "neodev.nvim integration, useful for neovim plugin developers";
    };
  };

  config = mkIf cfg.enable (mkMerge [
    (mkIf cfg.treesitter.enable {
      vim.treesitter.enable = true;
      vim.treesitter.grammars = [cfg.treesitter.package];
    })

    (mkIf cfg.lsp.enable {
      vim.lsp.lspconfig.enable = true;
      vim.lsp.lspconfig.sources.lua-lsp = ''
        lspconfig.lua_ls.setup {
          capabilities = capabilities;
          on_attach = default_on_attach;
          ${optionalString cfg.lsp.neodev.enable "before_init = require('neodev.lsp').before_init;"}
          cmd = ${
          if isList cfg.lsp.package
          then nvim.lua.expToLua cfg.lsp.package
          else ''{"${getExe cfg.lsp.package}"}''
        };
        }
      '';
    })

    (mkIf cfg.lsp.neodev.enable {
      vim.startPlugins = ["neodev-nvim"];
      vim.luaConfigRC.neodev = nvim.dag.entryBefore ["lua-lsp"] ''
        require("neodev").setup({})
      '';
    })
  ]);
}