Refactor card stack into own class

src/edu/kit/informatik/cardgame/model/CardGame.java

@@ -18,13 +18,9 @@ import java.util.stream.Collectors;
  */
 public class CardGame {
     /**
-     * Copy of the card stack used to start the game.
+     * Card stack used.
      */
-    private Deque<Card> cardStack;
-    /**
-     * Currently active card stack.
-     */
-    private Deque<Card> currentCardStack;
+    private CardStack cardStack;
     /**
      * Resources collected by the player. Obviously only contains {@link CardCategory#RESOURCE resource} cards.
      */
@@ -57,7 +53,7 @@ public class CardGame {
                  .allMatch(card -> Collections.frequency(cardStack, card) == card.requiredAmount())) {
             throw new LogicException("invalid deck: missing or surplus cards");
         }
-        this.cardStack = new ArrayDeque<>(cardStack);
+        this.cardStack = new CardStack(cardStack);
         reset();
         return true;
     }
@@ -70,12 +66,12 @@ public class CardGame {
      * @throws LogicException if no card to draw exists or phase is not scavenge
      */
     public Card draw() throws LogicException {
-        if (currentCardStack == null || currentCardStack.isEmpty()) {
+        if (cardStack == null) {
             throw new LogicException("no card to draw exists");
         } else if (phase != Phase.SCAVENGE) {
             throw new LogicException("can only draw cards in scavenge phase");
         }
-        final Card card = currentCardStack.removeFirst();
+        final Card card = cardStack.draw().orElseThrow(() -> new LogicException("no card to draw exists"));
         switch (card.category()) {
             case RESOURCE:
                 resources.add(card);
@@ -245,7 +241,7 @@ public class CardGame {
      */
     private void checkLost() {
         // can not draw new cards
-        if (currentCardStack != null && currentCardStack.isEmpty()
+        if (cardStack != null && cardStack.isEmpty()
                 // can not roll dice
                 && phase != Phase.ENCOUNTER && phase != Phase.ENDEAVOR
                 // can not build item
@@ -312,7 +308,7 @@ public class CardGame {
      * End the current game, deleting the active card stack.
      */
     private void endGame() {
-        currentCardStack = null;
+        cardStack.clearActiveStack();
     }
 
     /**
@@ -324,7 +320,7 @@ public class CardGame {
         if (cardStack == null) {
             throw new LogicException("can not reset a game that is not started!");
         } else {
-            this.currentCardStack = new ArrayDeque<>(cardStack);
+            this.cardStack.reset();
         }
         this.resources.clear();
         this.items.clear();

src/edu/kit/informatik/cardgame/model/CardStack.java

@@ -0,0 +1,38 @@
+package edu.kit.informatik.cardgame.model;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Optional;
+
+public class CardStack {
+    /**
+     * Copy of the card stack used to initialize the stack.
+     */
+    private final Deque<Card> stack;
+    /**
+     * Currently active card stack.
+     */
+    private Deque<Card> activeStack;
+
+    public CardStack(Deque<Card> cards) {
+        // copy stack to avoid modifications
+        this.stack = new ArrayDeque<>(cards);
+        reset();
+    }
+
+    public Optional<Card> draw() {
+        return Optional.ofNullable(activeStack.pollFirst());
+    }
+
+    public void clearActiveStack() {
+        activeStack.clear();
+    }
+
+    public void reset() {
+        activeStack = new ArrayDeque<>(stack);
+    }
+
+    public boolean isEmpty() {
+        return activeStack.isEmpty();
+    }
+}