{ pkgs, lib, config, ... }:
let

  unstable = import <nixpkgs-unstable> { };

  activeTasks = pkgs.writers.writeBash "active-tasks" ''
    ${pkgs.taskwarrior}/bin/task export +checklist status:pending +READY | \
    ${pkgs.jq}/bin/jq  \
      --raw-output '
      sort_by(.description) | reverse |
      .[] |
      "[ \( .id ) ] \( .description )"
    '
    echo
    ${pkgs.taskwarrior}/bin/task export  \
    +ACTIVE status:pending \
    | ${pkgs.jq}/bin/jq --raw-output '.[] | "⇒ \(.id) \(.description)"'
  '';

  userHighlight = map ({ user, ... }: user)
    (builtins.attrValues config.programs.custom.browser.configList);

  activeUsers = pkgs.writers.writeBash "active-users" ''
    ${pkgs.procps}/bin/ps -eo user \
     | ${pkgs.gnused}/bin/sed '1 d' \
     | ${pkgs.coreutils}/bin/sort  \
     | ${pkgs.coreutils}/bin/uniq \
     | ${pkgs.gnugrep}/bin/egrep --color=always '(${
       pkgs.lib.concatStringsSep "|" userHighlight
     })|$'
  '';

  # default settings
  wtfModule =
    args@{ height ? 1, width ? 1, top, left, enabled ? true, type, ... }:
    {
      enabled = enabled;
      focusable = false;
      position.top = top;
      position.left = left;
      position.height = height;
      position.width = width;
    } // (lib.filterAttrs
      (key: _: lib.all (x: x != key) [ "height" "width" "top" "left" ]) args);

  modules = {

    # command runner module
    cmdRunner = args@{ cmd, ... }:
      wtfModule ({
        type = "cmdrunner";
        focusable = false;
        refreshInterval = 300;
      } // args);

    digitalclock = args@{ top, left, ... }:
      wtfModule ({
        type = "digitalclock";
        title = "";
        color = "white";
        font = "bigfont";
        hourFormat = 24;
        refreshInterval = 1;
      } // args);

    clocks = args@{ top, left, ... }:
      wtfModule ({
        type = "clocks";
        title = "";
        border = false;
        colors.rows = {
          even = "white";
          odd = "white";
        };
        locations = {
          Berlin = "Europe/Berlin";
          Wellington = "Pacific/Auckland";
        };
        sort = "alphabetical";
        refreshInterval = 60;
      } // args);

    resourceusage = args@{ top, left, ... }:
      wtfModule ({
        type = "resourceusage";
        title = "";
        cpuCombined = false;
        refreshInterval = 5;
      } // args);

    power = args@{ top, left, ... }:
      wtfModule ({
        type = "power";
        title = "";
        refreshInterval = 100;
      } // args);

    prettyweather = args@{ top, left, ... }:
      wtfModule ({
        type = "prettyweather";
        title = "";
        city = "Wellington";
        unit = "m";
        view = 0;
        language = "en";
        refreshInterval = 3600;
      } // args);

  };

  qJson = {
    wtf = {

      term = "rxvt-unicode-256color";

      colors.border = {
        focusable = "darkslateblue";
        focused = "orange";
        normal = "green";
      };

      grid = {
        columns = [ 33 40 36 0 ];
        rows = [ 9 3 7 6 0 ];
      };

      refreshInterval = 1;

      mods = with modules; {

        digitalclock = digitalclock {
          top = 0;
          left = 0;
        };

        clocks = clocks {
          top = 1;
          left = 0;
        };

        top = resourceusage {
          top = 0;
          left = 1;
        };

        power = power {
          top = 2;
          left = 0;
        };

        rates = wtfModule {
          type = "exchangerates";
          top = 3;
          left = 0;
          title = "rates";
          rates.NZD = [ "EUR" ];
          rates.EUR = [ "NZD" ];
        };

        weather = prettyweather {
          top = 0;
          left = 2;
        };

        calendar = cmdRunner {
          title = "";
          args = [ "-3" "--monday" "--color=never" "-w" ];
          cmd = "cal";
          top = 1;
          left = 1;
          height = 2;
          width = 2;
          refreshInterval = 3600;
        };

        uptime = cmdRunner {
          title = "uptime";
          cmd = "uptime";
          top = 3;
          left = 1;
          height = 1;
          width = 2;
        };

        active-users = cmdRunner {
          title = "users";
          cmd = activeUsers;
          top = 0;
          left = 3;
          height = 4;
          width = 1;
          refreshInterval = 30;
        };

        active-tasks = cmdRunner {
          title = "active tasks";
          cmd = activeTasks;
          top = 4;
          left = 0;
          height = 1;
          width = 4;
          refreshInterval = 60;
        };
      };
    };
  };

  qConfig = pkgs.writeText "config.yml" (builtins.toJSON qJson);

  q = pkgs.writers.writeBashBin "q" ''
    ${unstable.wtf}/bin/wtfutil --config=${toString qConfig}
  '';
in {

  services.upower.enable = true;

  environment.systemPackages = [
    unstable.wtf
    q
    #activeUsers
    #activeTasks
    pkgs.upower
  ];

}