1 files changed, 20 insertions, 0 deletions
diff --git a/modules/office/khal/assertions.nix b/modules/office/khal/assertions.nix
new file mode 100644
index 0000000..bda7797
--- /dev/null
+++ b/modules/office/khal/assertions.nix
@@ -0,0 +1,20 @@
+# Validates the configured khal calendars.
+{ config, lib, ... }:
+let
+  cfg = config.office.khal;
+  primaryCalendars = builtins.filter (calendar: calendar.primary) (builtins.attrValues cfg.calendars);
+in
+{
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = cfg.calendars != { };
+        message = "office.khal.enable requires at least one office.khal.calendars entry.";
+      }
+      {
+        assertion = builtins.length primaryCalendars == 1;
+        message = "Exactly one office.khal.calendars entry must set primary = true.";
+      }
+    ];
+  };
+}