Refactor: use ExactCard to represent specific printings (#6049)

* Create new class

* Update CardInfo and CardDatabase

* Use new class instead of CardInfoPtr

* fix cmake

cockatrice/src/game/cards/exact_card.cpp

@@ -0,0 +1,79 @@
+#include "exact_card.h"
+
+/**
+ * Default constructor.
+ * This will set the CardInfoPtr to null.
+ * The printing will be the default-constructed PrintingInfo.
+ */
+ExactCard::ExactCard()
+{
+}
+
+/**
+ * @param _card The card. Can be null.
+ * @param _printing The printing. Can be empty.
+ */
+ExactCard::ExactCard(const CardInfoPtr &_card, const PrintingInfo &_printing) : card(_card), printing(_printing)
+{
+}
+
+bool ExactCard::operator==(const ExactCard &other) const
+{
+    return this->card == other.card && this->printing == other.printing;
+}
+
+/**
+ * Convenience method to safely get the card's name.
+ * @return The name in the CardInfo, or an empty string if card is null
+ */
+QString ExactCard::getName() const
+{
+    return card.isNull() ? "" : card->getName();
+}
+
+/**
+ * Gets a view of the underlying cardInfoPtr.
+ * @return A const reference to the CardInfo, or an empty CardInfo if card is null
+ */
+const CardInfo &ExactCard::getInfo() const
+{
+    if (card.isNull()) {
+        static CardInfoPtr emptyCard = CardInfo::newInstance("");
+        return *emptyCard;
+    }
+    return *card;
+}
+
+/**
+ * The key used to identify this exact printing in the cache
+ */
+QString ExactCard::getPixmapCacheKey() const
+{
+    QString uuid = printing.getUuid();
+    QString suffix = uuid.isEmpty() ? "" : "_" + uuid;
+    return QLatin1String("card_") + card->getName() + suffix;
+}
+
+/**
+ * Checks if the card is null or empty.
+ */
+bool ExactCard::isEmpty() const
+{
+    return card.isNull() || card->getName().isEmpty();
+}
+
+/**
+ * Returns true if isEmpty() is false
+ */
+ExactCard::operator bool() const
+{
+    return !isEmpty();
+}
+
+/**
+ * Gets the CardInfo to emit the pixmapUpdated signal
+ */
+void ExactCard::emitPixmapUpdated() const
+{
+    emit card->pixmapUpdated(printing);
+}