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

with lib;

let
  cfg = config.services.xserver.desktopManager.xfce;
in

{

  meta = {
    maintainers = with maintainers; [ worldofpeace ];
  };

  imports = [
    # added 2019-08-18
    # needed to preserve some semblance of UI familarity
    # with original XFCE module
    (mkRenamedOptionModule
      [ "services" "xserver" "desktopManager" "xfce4-14" "extraSessionCommands" ]
      [ "services" "xserver" "displayManager" "sessionCommands" ])

    # added 2019-11-04
    # xfce4-14 module removed and promoted to xfce.
    # Needed for configs that used xfce4-14 module to migrate to this one.
    (mkRenamedOptionModule
      [ "services" "xserver" "desktopManager" "xfce4-14" "enable" ]
      [ "services" "xserver" "desktopManager" "xfce" "enable" ])
    (mkRenamedOptionModule
      [ "services" "xserver" "desktopManager" "xfce4-14" "noDesktop" ]
      [ "services" "xserver" "desktopManager" "xfce" "noDesktop" ])
    (mkRenamedOptionModule
      [ "services" "xserver" "desktopManager" "xfce4-14" "enableXfwm" ]
      [ "services" "xserver" "desktopManager" "xfce" "enableXfwm" ])
    (mkRenamedOptionModule
      [ "services" "xserver" "desktopManager" "xfce" "extraSessionCommands" ]
      [ "services" "xserver" "displayManager" "sessionCommands" ])
    (mkRemovedOptionModule [ "services" "xserver" "desktopManager" "xfce" "screenLock" ] "")
  ];

  options = {
    services.xserver.desktopManager.xfce = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = "Enable the Xfce desktop environment.";
      };

      thunarPlugins = mkOption {
        default = [];
        type = types.listOf types.package;
        example = literalExample "[ pkgs.xfce.thunar-archive-plugin ]";
        description = ''
          A list of plugin that should be installed with Thunar.
        '';
      };

      noDesktop = mkOption {
        type = types.bool;
        default = false;
        description = "Don't install XFCE desktop components (xfdesktop and panel).";
      };

      enableXfwm = mkOption {
        type = types.bool;
        default = true;
        description = "Enable the XFWM (default) window manager.";
      };
    };
  };

  config = mkIf cfg.enable {
    environment.systemPackages = with pkgs.xfce // pkgs; [
      glib # for gsettings
      gtk3.out # gtk-update-icon-cache

      gnome3.gnome-themes-extra
      gnome3.adwaita-icon-theme
      hicolor-icon-theme
      tango-icon-theme
      xfce4-icon-theme

      desktop-file-utils
      shared-mime-info # for update-mime-database

      # For a polkit authentication agent
      polkit_gnome

      # Needed by Xfce's xinitrc script
      xdg-user-dirs # Update user dirs as described in https://freedesktop.org/wiki/Software/xdg-user-dirs/

      exo
      garcon
      libxfce4ui
      xfconf

      mousepad
      parole
      ristretto
      xfce4-appfinder
      xfce4-notifyd
      xfce4-screenshooter
      xfce4-session
      xfce4-settings
      xfce4-taskmanager
      xfce4-terminal

      (thunar.override { thunarPlugins = cfg.thunarPlugins; })
    ] # TODO: NetworkManager doesn't belong here
      ++ optional config.networking.networkmanager.enable networkmanagerapplet
      ++ optional config.powerManagement.enable xfce4-power-manager
      ++ optionals config.hardware.pulseaudio.enable [
        pavucontrol
        # volume up/down keys support:
        # xfce4-pulseaudio-plugin includes all the functionalities of xfce4-volumed-pulse
        # but can only be used with xfce4-panel, so for no-desktop usage we still include
        # xfce4-volumed-pulse
        (if cfg.noDesktop then xfce4-volumed-pulse else xfce4-pulseaudio-plugin)
      ] ++ optionals cfg.enableXfwm [
        xfwm4
        xfwm4-themes
      ] ++ optionals (!cfg.noDesktop) [
        xfce4-panel
        xfdesktop
      ];

    environment.pathsToLink = [
      "/share/xfce4"
      "/lib/xfce4"
      "/share/gtksourceview-3.0"
      "/share/gtksourceview-4.0"
    ];

    services.xserver.desktopManager.session = [{
      name = "xfce";
      desktopNames = [ "XFCE" ];
      bgSupport = true;
      start = ''
        ${pkgs.runtimeShell} ${pkgs.xfce.xfce4-session.xinitrc} &
        waitPID=$!
      '';
    }];

    services.xserver.updateDbusEnvironment = true;
    services.xserver.gdk-pixbuf.modulePackages = [ pkgs.librsvg ];

    # Enable helpful DBus services.
    services.udisks2.enable = true;
    security.polkit.enable = true;
    services.accounts-daemon.enable = true;
    services.upower.enable = config.powerManagement.enable;
    services.gnome3.glib-networking.enable = true;
    services.gvfs.enable = true;
    services.gvfs.package = pkgs.xfce.gvfs;
    services.tumbler.enable = true;
    services.system-config-printer.enable = (mkIf config.services.printing.enable (mkDefault true));
    services.xserver.libinput.enable = mkDefault true; # used in xfce4-settings-manager

    # Enable default programs
    programs.dconf.enable = true;

    # Shell integration for VTE terminals
    programs.bash.vteIntegration = mkDefault true;
    programs.zsh.vteIntegration = mkDefault true;

    # Systemd services
    systemd.packages = with pkgs.xfce; [
      (thunar.override { thunarPlugins = cfg.thunarPlugins; })
      xfce4-notifyd
    ];

  };
}