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

with lib;

let

  xcfg = config.services.xserver;
  cfg = xcfg.desktopManager.kde5;
  xorg = pkgs.xorg;

  kde5 = pkgs.kde5;

in

{
  options = {

    services.xserver.desktopManager.kde5 = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = "Enable the Plasma 5 (KDE 5) desktop environment.";
      };

    };

  };


  config = mkIf (xcfg.enable && cfg.enable) {

    warnings = optional config.services.xserver.desktopManager.kde4.enable
      "KDE 4 should not be enabled at the same time as KDE 5";

    services.xserver.desktopManager.session = singleton {
      name = "kde5";
      bgSupport = true;
      start = ''
        # Load PulseAudio module for routing support.
        # See http://colin.guthr.ie/2009/10/so-how-does-the-kde-pulseaudio-support-work-anyway/
        ${optionalString config.hardware.pulseaudio.enable ''
          ${getBin config.hardware.pulseaudio.package}/bin/pactl load-module module-device-manager "do_routing=1"
        ''}

        exec "${kde5.startkde}"

      '';
    };

    security.setuidOwners = [
      {
        program = "kcheckpass";
        source = "${kde5.plasma-workspace.out}/lib/libexec/kcheckpass";
        owner = "root";
        setuid = true;
      }
      {
        program = "start_kdeinit";
        source = "${kde5.kinit.out}/lib/libexec/kf5/start_kdeinit";
        owner = "root";
        setuid = true;
      }
    ];

    environment.systemPackages =
      [
        kde5.frameworkintegration
        kde5.kactivities
        kde5.kauth
        kde5.kcmutils
        kde5.kconfig
        kde5.kconfigwidgets
        kde5.kcoreaddons
        kde5.kdbusaddons
        kde5.kdeclarative
        kde5.kded
        kde5.kdesu
        kde5.kdnssd
        kde5.kemoticons
        kde5.kfilemetadata
        kde5.kglobalaccel
        kde5.kguiaddons
        kde5.kiconthemes
        kde5.kidletime
        kde5.kimageformats
        kde5.kinit
        kde5.kio
        kde5.kjobwidgets
        kde5.knewstuff
        kde5.knotifications
        kde5.knotifyconfig
        kde5.kpackage
        kde5.kparts
        kde5.kpeople
        kde5.krunner
        kde5.kservice
        kde5.ktextwidgets
        kde5.kwallet
        kde5.kwayland
        kde5.kwidgetsaddons
        kde5.kxmlgui
        kde5.kxmlrpcclient
        kde5.plasma-framework
        kde5.solid
        kde5.sonnet
        kde5.threadweaver

        kde5.breeze
        kde5.kactivitymanagerd
        kde5.kde-cli-tools
        kde5.kdecoration
        kde5.kdeplasma-addons
        kde5.kgamma5
        kde5.khelpcenter
        kde5.khotkeys
        kde5.kinfocenter
        kde5.kmenuedit
        kde5.kscreen
        kde5.kscreenlocker
        kde5.ksysguard
        kde5.kwayland
        kde5.kwin
        kde5.kwrited
        kde5.libkscreen
        kde5.libksysguard
        kde5.milou
        kde5.oxygen
        kde5.plasma-integration
        kde5.polkit-kde-agent
        kde5.systemsettings

        kde5.plasma-desktop
        kde5.plasma-workspace
        kde5.plasma-workspace-wallpapers

        kde5.dolphin
        kde5.dolphin-plugins
        kde5.ffmpegthumbs
        kde5.kdegraphics-thumbnailers
        kde5.kio-extras
        kde5.konsole
        kde5.print-manager

        # Oxygen icons moved to KDE Frameworks 5.16 and later.
        (kde5.oxygen-icons or kde5.oxygen-icons5)
        pkgs.hicolor_icon_theme

        kde5.kde-gtk-config

        pkgs.phonon-backend-gstreamer
        pkgs.qt5.phonon-backend-gstreamer
      ]

      # Plasma 5.5 and later has a Breeze GTK theme.
      # If it is not available, Orion is very similar to Breeze.
      ++ lib.optional (!(lib.hasAttr "breeze-gtk" kde5)) pkgs.orion

      # Install Breeze icons if available
      ++ lib.optional (lib.hasAttr "breeze-icons" kde5) kde5.breeze-icons

      # Install activity manager if available
      ++ lib.optional (lib.hasAttr "kactivitymanagerd" kde5) kde5.kactivitymanagerd

      # frameworkintegration was split with plasma-integration in Plasma 5.6
      ++ lib.optional (lib.hasAttr "plasma-integration" kde5) kde5.plasma-integration

      # Optional hardware support features
      ++ lib.optional config.hardware.bluetooth.enable kde5.bluedevil
      ++ lib.optional config.networking.networkmanager.enable kde5.plasma-nm
      ++ lib.optional config.hardware.pulseaudio.enable kde5.plasma-pa
      ++ lib.optional config.powerManagement.enable kde5.powerdevil
      ++ lib.optional config.services.colord.enable pkgs.colord-kde
      ++ lib.optionals config.services.samba.enable [ kde5.kdenetwork-filesharing pkgs.samba ];

    environment.pathsToLink = [ "/share" ];

    environment.etc = singleton {
      source = "${pkgs.xkeyboard_config}/etc/X11/xkb";
      target = "X11/xkb";
    };

    # Enable GTK applications to load SVG icons
    environment.variables =
      {
        GST_PLUGIN_SYSTEM_PATH_1_0 =
          lib.makeSearchPath "/lib/gstreamer-1.0"
          (builtins.map (pkg: pkg.out) (with pkgs.gst_all_1; [
            gstreamer
            gst-plugins-base
            gst-plugins-good
            gst-plugins-ugly
            gst-plugins-bad
            gst-libav # for mp3 playback
          ]));
      }
      // (if (lib.hasAttr "breeze-icons" kde5)
          then { GDK_PIXBUF_MODULE_FILE = "${pkgs.librsvg.out}/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache"; }
          else { });

    fonts.fonts = [ (kde5.oxygen-fonts or pkgs.noto-fonts) ];

    programs.ssh.askPassword = "${kde5.ksshaskpass.out}/bin/ksshaskpass";

    # Enable helpful DBus services.
    services.udisks2.enable = true;
    services.upower.enable = config.powerManagement.enable;

    # Extra UDEV rules used by Solid
    services.udev.packages = [
      pkgs.libmtp
      pkgs.media-player-info
    ];

    services.xserver.displayManager.sddm = {
      theme = "breeze";
      themes = [
        kde5.ecm # for the setup-hook
        kde5.plasma-workspace
        kde5.breeze-icons
        (kde5.oxygen-icons or kde5.oxygen-icons5)
      ];
    };

    security.pam.services.kde = { allowNullPassword = true; };

  };

}