{ lib, pkgs }:

rec {

  modules2options = modules': let
    eval = lib.evalModules {
      modules = [{ _module.check = false; }] ++ modules';
    };
    options = lib.optionAttrSetToDocList eval.options;
  in builtins.filter (x: x.visible && !x.internal) options;

  mkHTML = name: source: modules: let
    options = modules2options modules;
    declarations = lib.pipe options [
      (builtins.map (option: option.declarations))
      lib.flatten
    ];
  in pkgs.runCommand "${name}-html" {
    nativeBuildInputs = with pkgs; [ aha bat j2cli ];
    passAsFile = [ "jsonData" ];
    jsonData = builtins.toJSON { inherit name options source; };
  } (''
    mkdir $out
    j2 --customize ${./j2_environ.py} -f json ${./template.html.j2} $jsonDataPath > $out/index.html
    # ${source} # just here to make declarations available
  '' + lib.concatStrings (lib.forEach declarations (declaration: with lib; ''
    BASE="$(basename ${lib.escapeShellArg declaration})"
    DIR="$(dirname ${lib.escapeShellArg declaration} | cut -d/ -f5-)"
    mkdir -p $out/sources/"$DIR"
    bat --color always --style plain ${escapeShellArg declaration} | aha --black --title "$BASE" > $out/sources/"$DIR"/"$BASE".html
  '')));

}