nixos: add programs.kdeconnect option

nixos/modules/module-list.nix

@@ -112,6 +112,7 @@
   ./programs/iftop.nix
   ./programs/iotop.nix
   ./programs/java.nix
+  ./programs/kdeconnect.nix
   ./programs/kbdlight.nix
   ./programs/less.nix
   ./programs/light.nix

nixos/modules/programs/kdeconnect.nix

@@ -0,0 +1,35 @@
+{ config, pkgs, lib, ... }:
+with lib;
+{
+  options.programs.kdeconnect = {
+    enable = mkEnableOption ''
+      kdeconnect.
+
+      Note that it will open the TCP and UDP port from
+      1714 to 1764 as they are needed for it to function properly.
+      You can use the <option>package</option> to use
+      <code>gnomeExtensions.gsconnect</code> as an alternative
+      implementation if you use Gnome.
+    '';
+    package = mkOption {
+      default = pkgs.kdeconnect;
+      defaultText = "pkgs.kdeconnect";
+      type = types.package;
+      example = literalExample "pkgs.gnomeExtensions.gsconnect";
+      description = ''
+        The package providing the implementation for kdeconnect.
+      '';
+    };
+  };
+  config =
+    let
+      cfg = config.programs.kdeconnect;
+    in
+      mkIf cfg.enable {
+        environment.systemPackages = [ cfg.package ];
+        networking.firewall = rec {
+          allowedTCPPortRanges = [ { from = 1714; to = 1764; } ];
+          allowedUDPPortRanges = allowedTCPPortRanges;
+        };
+      };
+}