Add calendar configuration

Use vdirsyncer to sync with xandikos server. Add khal for calendar
management.

system/home/desktop.nix

@@ -7,6 +7,7 @@
     ./browser/default.nix
     ./zathura/default.nix
     ./services/email/default.nix
+    ./services/calendar/default.nix
   ];
   home.packages = with pkgs; [
     webcord
@@ -18,7 +19,7 @@
   programs.mpv.enable = true;
   gtk = {
     enable = true;
-    gtk2.configLocation = "${config.xdg.configHome}/gtk-2.0/gtkrc";
+    gtk2.configLocation = "${config.xdg.configHome}/gtk-2.0/dummyrc"; # Stop clashing with KDE
     iconTheme = {
       package = pkgs.papirus-icon-theme;
       name = "Papirus";

system/home/services/calendar/default.nix

@@ -0,0 +1,66 @@
+{ config, pkgs, ... }:
+{
+  home.packages = [
+    (pkgs.writeShellScriptBin "vdirsyncer-ensure-pass" (builtins.readFile ./vdirsyncer-ensure-pass.sh))
+  ];
+  programs = {
+    vdirsyncer.enable = true;
+    khal = {
+      enable = true;
+      locale = {
+        timeformat = "%H:%M";
+        dateformat = "%Y-%m-%d";
+        longdateformat = "%Y-%m-%d %a";
+        datetimeformat = "%Y-%m-%d %H:%M";
+        longdatetimeformat = "%Y-%m-%d %H:%M";
+      };
+    };
+  };
+  services.vdirsyncer.enable = true;
+  accounts.calendar = {
+    basePath = "Calendar";
+    accounts = {
+      personal =
+        let
+          url = "dav.xenia.me.uk";
+        in
+        {
+          primary = true;
+          primaryCollection = "calendar";
+          local = {
+            type = "filesystem";
+            fileExt = ".ics";
+          };
+          remote = {
+            url = "https://${url}";
+            type = "caldav";
+            userName = "pixelifytica";
+            passwordCommand = [
+              "${pkgs.libsecret}/bin/secret-tool"
+              "lookup"
+              "url"
+              "${url}"
+            ];
+          };
+          vdirsyncer = {
+            inherit (config.programs.vdirsyncer) enable;
+            auth = "basic";
+            collections = [ "from a" ];
+            metadata = [
+              "color"
+              "displayname"
+            ];
+            timeRange = {
+              start = "datetime.now() - timedelta(days=365)";
+              end = "datetime.now() + timedelta(days=365)";
+            };
+          };
+          khal = {
+            inherit (config.programs.khal) enable;
+            type = "discover";
+            addresses = with config.accounts.email.accounts.proton; [ address ] ++ aliases;
+          };
+        };
+    };
+  };
+}

system/home/services/calendar/vdirsyncer-ensure-pass.sh

@@ -0,0 +1,5 @@
+URL="dav.xenia.me.uk"
+secret-tool lookup url "$URL" >/dev/null || (
+    echo "Setup calendar password"
+    secret-tool store --label="Calendar vdirsyncer" url "$URL"
+)