patch: Feature/ygo set selection (#16)

ui_wx/include/ccm/ui/CardEditModalGuard.hpp

@@ -0,0 +1,34 @@
+#pragma once
+
+// Tracks when a modal Add/Edit card dialog is on screen so a second one
+// cannot be stacked (toolbar + list activation, or rare re-entrant cases).
+
+#include <atomic>
+
+namespace ccm::ui {
+
+// User-visible hint when Add/Edit is requested while a card dialog is already modal.
+inline constexpr const char* kCardEditModalBlockedUtf8 =
+    "Close the open card dialog (save or cancel) before opening another card.";
+
+[[nodiscard]] inline std::atomic<int>& cardEditModalDepthRef() noexcept {
+    static std::atomic<int> depth{0};
+    return depth;
+}
+
+[[nodiscard]] inline bool cardEditModalIsActive() noexcept {
+    return cardEditModalDepthRef().load(std::memory_order_relaxed) > 0;
+}
+
+struct CardEditModalGuard {
+    CardEditModalGuard() {
+        cardEditModalDepthRef().fetch_add(1, std::memory_order_relaxed);
+    }
+    ~CardEditModalGuard() {
+        cardEditModalDepthRef().fetch_sub(1, std::memory_order_relaxed);
+    }
+    CardEditModalGuard(const CardEditModalGuard&)            = delete;
+    CardEditModalGuard& operator=(const CardEditModalGuard&) = delete;
+};
+
+}  // namespace ccm::ui