[#90] added freebusy (#618)

src/utils/extractCalendarHrefs.ts

@@ -0,0 +1,15 @@
+export function extractCalendarHrefs(data: unknown): string[] {
+  try {
+    const calendars = (
+      data as {
+        _embedded: { "dav:calendar": { _links: { self: { href: string } } }[] };
+      }
+    )._embedded["dav:calendar"];
+
+    return Array.isArray(calendars)
+      ? calendars.map((cal) => cal?._links?.self?.href ?? "").filter(Boolean)
+      : [];
+  } catch {
+    return [];
+  }
+}