{pkgs, config, lib, ...}: let
  inherit (lib.options) mkOption mkEnableOption;
  inherit (lib.modules) mkIf mkMerge mkAfter mkOptionDefault;
  inherit (lib.strings) hasPrefix;
  inherit (lib.attrsets) mapAttrsToList;
  inherit (config.services.nginx) lua;
  cfg = lua;
  enabled = cfg.http.enable || cfg.upstream.enable;
  luaPkgPath = pkg: "${pkg.lib or pkg}/lib/lua/${pkgs.luajit_openresty.luaversion}/?.lua";
  luaModule = {config, ...}: let
    cfg = config.lua;
    mkSetBy = var: value:
      if hasPrefix "/" "${value}" then "set_by_lua_file \$${var} ${value};"
      else ''
        set_by_lua_block ''$${var} {
          ${value}
        }
      '';
  in {
    options.lua = with lib.types; {
      access = {
        block = mkOption {
          type = lines;
          default = "";
        };
        files = mkOption {
          type = listOf path;
          default = [ ];
        };
      };
      set = mkOption {
        type = attrsOf (either path lines);
        default = { };
      };
    };
    config = {
      extraConfig = mkMerge [
        (mkIf (cfg.access.block != "") (assert lua.http.enable; ''
          access_by_lua_block {
            ${cfg.access.block}
          }
        ''))
        (mkIf (cfg.access.files != [ ]) (assert lua.http.enable; mkMerge (
          map (file: "access_by_lua_file ${file};") cfg.access.files
        )))
        (mkIf (cfg.set != { }) (assert lua.http.enable && lua.ndk.enable; mkMerge (
          mapAttrsToList mkSetBy cfg.set
        )))
      ];
    };
  };
  locationModule = {config, ...}: {
    imports = [ luaModule ];
  };
  hostModule = {config, ...}: {
    imports = [ luaModule ];

    options = with lib.types; {
      locations = mkOption {
        type = attrsOf (submoduleWith {
          modules = [ locationModule ];
          shorthandOnlyDefinesConfig = true;
        });
      };
    };
  };
in {
  options.services.nginx = with lib.types; {
    lua = {
      ndk.enable = mkEnableOption "ngx_devel_kit";
      http.enable = mkEnableOption "ngx_http_lua_module";
      upstream.enable = mkEnableOption "ngx_http_lua_upstream";
      luaPackage = mkOption {
        type = package;
        default = pkgs.luajit_openresty;
        readOnly = true;
      };
      modules = mkOption {
        type = listOf package;
      };
      luaPath = mkOption {
        type = separatedString ";";
      };
    };
    virtualHosts = mkOption {
      type = attrsOf (submoduleWith {
        modules = [ hostModule ];
        shorthandOnlyDefinesConfig = true;
      });
    };
  };
  config = {
    services.nginx = {
      lua = {
        modules = [
          cfg.luaPackage.pkgs.lua-resty-core
        ] ++ cfg.luaPackage.pkgs.lua-resty-core.propagatedBuildInputs;
        luaPath = mkMerge (
          map luaPkgPath cfg.modules
          ++ [ (mkAfter ";") ]
        );
      };
      additionalModules = mkMerge [
        (mkIf cfg.ndk.enable [ pkgs.nginxModules.develkit ])
        (mkIf cfg.http.enable [ pkgs.nginxModules.lua ])
        (mkIf cfg.upstream.enable [ pkgs.nginxModules.lua-upstream ])
      ];
    };
    systemd.services.nginx = mkIf config.services.nginx.enable {
      environment.LUA_PATH = mkIf enabled (mkOptionDefault cfg.luaPath);
    };
  };
}