lightline

URL: https://github.com/itchyny/lightline.vim/

Example of defining your own component_function

plugins.lightline = {
   enable = true;
   settings.component_function = {
     readonly = "LightlineReadonly";
   };

   luaConfig.pre = ''
     function LightlineReadonly()
       local is_readonly = vim.bo.readonly == 1
       local filetype = vim.bo.filetype

       if is_readonly and filetype ~= "help" then
         return "RO"
       else
         return ""
       end
     end
   '';
 };