{ config, lib, ... }:

let
  options = import ./vim/options.nix { inherit lib; };

  bufferOpts = { name, config, ... }: {
    options = with lib; {
      filetypes = mkOption {
        type = types.extCommas;
        description = "File types for which the buffer is enabled";
      };
      opt = options.buffer;
    };
    config = {
      filetypes = lib.mkDefault name;
    };
  };

  mkFiletypeBuffer = name: cfg:
    lib.nameValuePair
      "buffer-${name}"
      {
        event = "FileType";
        pattern = cfg.filetypes;
        callback = with lib; with nix2lua; lambda ["ev"] (lib.flatten [
          (flip mapAttrsToList cfg.opt (k: v: if v == null then null else set "vim.opt.${k}" v))
        ]);
      };
in
{
  options.buffer = lib.mkOption {
    type = with lib.types; attrsOf (submodule bufferOpts);
    default = { };
  };

  config = {
    vim.augroup = lib.mkIf (config.buffer != {}) (lib.listToAttrs (lib.mapAttrsToList mkFiletypeBuffer config.buffer));
  };
}