{
  lib,
  config,
  pkgs,
  ...
}:
let
  inherit (lib)
    mkOption
    mkEnableOption
    mkIf
    types
    importJSON
    mapAttrs'
    mapAttrsToList
    removePrefix
    pathIsDirectory
    hasSuffix
    hasPrefix
    attrNames
    filter
    head
    ;
  inherit (lib.strings)
    sanitizeDerivationName
    ;
  yaml = pkgs.formats.yaml { };
  json = pkgs.formats.json { };
  cfg = config.services.extranix;

  module-eval =
    module-name: module:
    let
      ignored-eval = lib.evalModules {
        modules = module.ignored-modules;
        inherit (module) specialArgs;
      };
      ignored-opts-doc = pkgs.nixosOptionsDoc { inherit (ignored-eval) options; };
      ignored-opts = importJSON "${ignored-opts-doc.optionsJSON}/share/doc/nixos/options.json";
      eval = lib.evalModules {
        modules = module.paths ++ module.ignored-modules;
        inherit (module) specialArgs;
      };
      opts-doc = pkgs.nixosOptionsDoc { inherit (eval) options; };
      opts = importJSON "${opts-doc.optionsJSON}/share/doc/nixos/options.json";
      filtered-opts = removeAttrs opts (attrNames ignored-opts);
      path-translation =
        let
          translations = map (
            { base, url }:
            {
              url = "${url}${if hasSuffix "/" url then "" else "/"}";
              base =
                let
                  base1 = toString base;
                in
                base1 + (if hasSuffix "/" base1 then "" else "/");
            }
          ) module.path-translations;
        in
        path:
        let
          fullPath = path + (if pathIsDirectory path then "/default.nix" else "");
          fitting = filter ({ base, ... }: hasPrefix base fullPath) translations;
          translate-info = head (
            fitting ++ [ (throw "${fullPath} is not in any base path of ${module-name}") ]
          );
          innerPath = removePrefix translate-info.base fullPath;
        in
        {
          name = "<${innerPath}>";
          url = "${translate-info.url}${innerPath}";
        };
      result = json.generate "options-extranix.json" {
        last_update = "-/-";
        options = mapAttrsToList (title: val: {
          inherit title;
          inherit (val)
            type
            readOnly
            description
            loc
            ;
          example = val.example.text or "";
          default = val.default.text or "";
          declarations = map path-translation val.declarations;
        }) filtered-opts;
      };
    in
    result;

  options-files = mapAttrs' (name: value: {
    name = sanitizeDerivationName name;
    value = module-eval name value;
  }) cfg.modules;

  webroot = pkgs.callPackage ./webroot.nix {
    inherit options-files;
    inherit (cfg) static-data;
    settings = yaml.generate "config.yaml" cfg.settings;
    hugo-theme-extranix-options-search = pkgs.callPackage ./hugo-theme-extranix-options-search.nix { };
  };
in
{
  options.services.extranix = {
    enable = mkEnableOption "extranix documentation";
    modules = mkOption {
      type =
        let
          module-mod.options = {
            specialArgs = mkOption {
              type = types.attrs;
              default = { };
            };
            paths = mkOption {
              type = types.listOf types.path;
            };
            ignored-modules = mkOption {
              type = types.listOf types.deferredModule;
              default = [ ];
            };
            path-translations = mkOption {
              type =
                let
                  path-mod.options = {
                    base = mkOption {
                      type = types.path;
                    };
                    url = mkOption {
                      type = types.str;
                    };
                  };
                in
                types.listOf (types.submodule path-mod);
            };
          };
        in
        types.attrsOf (types.submodule module-mod);
    };
    settings = mkOption {
      type = yaml.type;
    };
    static-data = mkOption {
      type = types.path;
    };
    host = mkOption {
      type = types.str;
    };
  };
  config = mkIf cfg.enable {
    services = {
      extranix = {
        settings = {
          markup.goldmark.renderer.unsafe = true;
          theme = "extranix-options-search";
          params.releases = mapAttrsToList (name: _: {
            inherit name;
            value = sanitizeDerivationName name;
          }) cfg.modules;
        };
      };
      nginx = {
        enable = true;
        virtualHosts.${cfg.host}.locations."/".alias = "${webroot}/";
      };
    };
  };
}