[QtUtils] Add Debouncer helper (#7623)

* [QtUtils] Add Debouncer helper

* Extract long message to variable before confirm() call

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_utility/CMakeLists.txt

@@ -21,6 +21,7 @@ set(UTILITY_HEADERS
     libcockatrice/utility/card_ref.h
     libcockatrice/utility/color.h
     libcockatrice/utility/cryptoutil.h
+    libcockatrice/utility/debouncer.h
     libcockatrice/utility/expression.h
     libcockatrice/utility/levenshtein.h
     libcockatrice/utility/local_server_name.h

libcockatrice_utility/libcockatrice/utility/debouncer.h

@@ -0,0 +1,62 @@
+#ifndef COCKATRICE_DEBOUNCER_H
+#define COCKATRICE_DEBOUNCER_H
+
+#include <QObject>
+#include <QTimer>
+#include <functional>
+#include <utility>
+
+namespace QtUtils
+{
+/**
+ * @brief Runs the most recent call() after a period without further calls.
+ *
+ * Typical use is coalescing rapid model or editor updates into one refresh:
+ *
+ *     debouncer.call([this] { refresh(); });
+ *
+ * The pending callback is owned by the debouncer and replaced when call() is invoked
+ * again. The debouncer must outlive any callback it schedules; parenting it to the
+ * owning widget is usually enough.
+ */
+class Debouncer : public QObject
+{
+public:
+    explicit Debouncer(int intervalMs, QObject *parent = nullptr) : QObject(parent)
+    {
+        timer.setSingleShot(true);
+        timer.setInterval(intervalMs);
+        connect(&timer, &QTimer::timeout, this, [this] {
+            if (callback) {
+                auto pending = std::move(callback);
+                callback = nullptr;
+                pending();
+            }
+        });
+    }
+
+    /**
+     * @brief Schedules @p newCallback, replacing any callback not run yet.
+     */
+    void call(std::function<void()> newCallback)
+    {
+        callback = std::move(newCallback);
+        timer.start();
+    }
+
+    /**
+     * @brief Drops the pending callback and stops the timer.
+     */
+    void cancel()
+    {
+        timer.stop();
+        callback = nullptr;
+    }
+
+private:
+    QTimer timer;
+    std::function<void()> callback;
+};
+} // namespace QtUtils
+
+#endif // COCKATRICE_DEBOUNCER_H