feat: handle player drawing blackjack at the start of the game

backend/src/main/java/de/szut/casino/blackjack/BlackJackService.java

@@ -5,6 +5,7 @@ import de.szut.casino.user.UserRepository;
 import org.springframework.stereotype.Service;
 
 import java.math.BigDecimal;
+import java.util.List;
 import java.util.Random;
 
 @Service
@@ -23,7 +24,6 @@ public class BlackJackService {
         BlackJackGameEntity game = new BlackJackGameEntity();
         game.setUser(user);
         game.setBet(betAmount);
-        game.setState(getState(game));
         initializeDeck(game);
 
         for (int i = 0; i < 2; i++) {
@@ -34,6 +34,7 @@ public class BlackJackService {
         CardEntity dealerCard = drawCardFromDeck(game);
         game.getDealerCards().add(dealerCard);
 
+        game.setState(getState(game));
         user.setBalance(user.getBalance().subtract(betAmount));
 
         userRepository.save(user);
@@ -65,6 +66,30 @@ public class BlackJackService {
     }
 
     private BlackJackState getState(BlackJackGameEntity game) {
+        int playerHandValue = calculateHandValue(game.getPlayerCards());
+
+        if (playerHandValue == 21) {
+            return BlackJackState.PLAYER_WON;
+        }
+
         return BlackJackState.IN_PROGRESS;
     }
+
+    public int calculateHandValue(List<CardEntity> hand) {
+        int sum = 0;
+        int aceCount = 0;
+        for (CardEntity card : hand) {
+            sum += card.getRank().getValue();
+            if (card.getRank() == Rank.ACE) {
+                aceCount++;
+            }
+        }
+
+        while (sum > 21 && aceCount > 0) {
+            sum -= 10;
+            aceCount--;
+        }
+
+        return sum;
+    }
 }