Improved alternative cost from dynamic effects (it's like #5913 PR):

* Game: added multiple cards/effects support (old version supported only 1 effect per game);
 * Game: added combo support with split and adventure cards;
 * AI: computer can see and play cards with dynamic added alternative cost (like Bolas's Citadel);
 * UI: users can see playable cards with alternative cost.

Mage.Server.Plugins/Mage.Player.Human/src/mage/player/human/HumanPlayer.java

@@ -1742,7 +1742,7 @@ public class HumanPlayer extends PlayerImpl {
             if (ability instanceof PlayLandAbility) {
                 return true;
             }
-            if (!ability.getSourceId().equals(getCastSourceIdWithAlternateMana())
+            if (!getCastSourceIdWithAlternateMana().contains(ability.getSourceId())
                     && ability.getManaCostsToPay().convertedManaCost() > 0) {
                 return true;
             }

Mage.Tests/src/test/java/org/mage/test/player/TestPlayer.java

@@ -2374,20 +2374,25 @@ public class TestPlayer implements Player {
     }
 
     @Override
-    public UUID getCastSourceIdWithAlternateMana() {
+    public Set<UUID> getCastSourceIdWithAlternateMana() {
         return computerPlayer.getCastSourceIdWithAlternateMana();
     }
 
     @Override
-    public ManaCosts getCastSourceIdManaCosts() {
+    public Map<UUID, ManaCosts<ManaCost>> getCastSourceIdManaCosts() {
         return computerPlayer.getCastSourceIdManaCosts();
     }
 
     @Override
-    public Costs<Cost> getCastSourceIdCosts() {
+    public Map<UUID, Costs<Cost>> getCastSourceIdCosts() {
         return computerPlayer.getCastSourceIdCosts();
     }
 
+    @Override
+    public void clearCastSourceIdManaCosts() {
+        computerPlayer.clearCastSourceIdManaCosts();
+    }
+
     @Override
     public boolean isInPayManaMode() {
         return computerPlayer.isInPayManaMode();

Mage.Tests/src/test/java/org/mage/test/stub/PlayerStub.java

@@ -19,8 +19,8 @@ import mage.counters.Counter;
 import mage.counters.Counters;
 import mage.designations.Designation;
 import mage.designations.DesignationType;
-import mage.filter.FilterPermanent;
 import mage.filter.FilterMana;
+import mage.filter.FilterPermanent;
 import mage.game.Game;
 import mage.game.Graveyard;
 import mage.game.Table;
@@ -1208,7 +1208,7 @@ public class PlayerStub implements Player {
     }
 
     @Override
-    public UUID getCastSourceIdWithAlternateMana() {
+    public Set<UUID> getCastSourceIdWithAlternateMana() {
         return null;
     }
 
@@ -1218,15 +1218,20 @@ public class PlayerStub implements Player {
     }
 
     @Override
-    public ManaCosts getCastSourceIdManaCosts() {
+    public Map<UUID, Costs<Cost>> getCastSourceIdCosts() {
         return null;
     }
 
     @Override
-    public Costs<Cost> getCastSourceIdCosts() {
+    public Map<UUID, ManaCosts<ManaCost>> getCastSourceIdManaCosts() {
         return null;
     }
 
+    @Override
+    public void clearCastSourceIdManaCosts() {
+
+    }
+
     @Override
     public void addPermissionToShowHandCards(UUID watcherUserId) {
 

Mage/src/main/java/mage/abilities/SpellAbility.java

@@ -63,7 +63,7 @@ public class SpellAbility extends ActivatedAbilityImpl {
      */
     public boolean spellCanBeActivatedRegularlyNow(UUID playerId, Game game) {
         MageObject object = game.getObject(sourceId);
-        if ((Boolean) game.getState().getValue("CastFromExileEnabled" + object.getId()) != null) {
+        if (game.getState().getValue("CastFromExileEnabled" + object.getId()) != null) {
             return (Boolean) game.getState().getValue("CastFromExileEnabled" + object.getId());  // card like Chandra, Torch of Defiance +1 loyal ability)
         }
         return null != game.getContinuousEffects().asThough(sourceId, AsThoughEffectType.CAST_AS_INSTANT, this, playerId, game) // check this first to allow Offering in main phase
@@ -98,7 +98,7 @@ public class SpellAbility extends ActivatedAbilityImpl {
             if (getSpellAbilityType() == SpellAbilityType.BASE_ALTERNATE) {
                 Player player = game.getPlayer(playerId);
                 if (player != null
-                        && getSourceId().equals(player.getCastSourceIdWithAlternateMana())) {
+                        && player.getCastSourceIdWithAlternateMana().contains(getSourceId())) {
                     return ActivationStatus.getFalse();
                 }
             }

Mage/src/main/java/mage/players/Player.java

@@ -20,8 +20,8 @@ import mage.counters.Counter;
 import mage.counters.Counters;
 import mage.designations.Designation;
 import mage.designations.DesignationType;
-import mage.filter.FilterPermanent;
 import mage.filter.FilterMana;
+import mage.filter.FilterPermanent;
 import mage.game.Game;
 import mage.game.Graveyard;
 import mage.game.Table;
@@ -851,11 +851,13 @@ public interface Player extends MageItem, Copyable<Player> {
      */
     void setCastSourceIdWithAlternateMana(UUID sourceId, ManaCosts<ManaCost> manaCosts, Costs<Cost> costs);
 
-    UUID getCastSourceIdWithAlternateMana();
+    Set<UUID> getCastSourceIdWithAlternateMana();
 
-    ManaCosts<ManaCost> getCastSourceIdManaCosts();
+    Map<UUID, ManaCosts<ManaCost>> getCastSourceIdManaCosts();
 
-    Costs<Cost> getCastSourceIdCosts();
+    Map<UUID, Costs<Cost>> getCastSourceIdCosts();
+
+    void clearCastSourceIdManaCosts();
 
     // permission handling to show hand cards
     void addPermissionToShowHandCards(UUID watcherUserId);

Mage/src/main/java/mage/players/PlayerImpl.java

@@ -32,8 +32,8 @@ import mage.counters.Counters;
 import mage.designations.Designation;
 import mage.designations.DesignationType;
 import mage.filter.FilterCard;
-import mage.filter.FilterPermanent;
 import mage.filter.FilterMana;
+import mage.filter.FilterPermanent;
 import mage.filter.common.FilterControlledPermanent;
 import mage.filter.common.FilterCreatureForCombat;
 import mage.filter.common.FilterCreatureForCombatBlock;
@@ -160,9 +160,10 @@ public abstract class PlayerImpl implements Player, Serializable {
     protected boolean reachedNextTurnAfterLeaving = false;
 
     // indicates that the spell with the set sourceId can be cast with an alternate mana costs (can also be no mana costs)
-    protected UUID castSourceIdWithAlternateMana;
-    protected ManaCosts<ManaCost> castSourceIdManaCosts;
-    protected Costs<Cost> castSourceIdCosts;
+    // support multiple cards with alternative mana cost
+    protected Set<UUID> castSourceIdWithAlternateMana = new HashSet<>();
+    protected Map<UUID, ManaCosts<ManaCost>> castSourceIdManaCosts = new HashMap<>();
+    protected Map<UUID, Costs<Cost>> castSourceIdCosts = new HashMap<>();
 
     // indicates that the player is in mana payment phase
     protected boolean payManaMode = false;
@@ -271,9 +272,10 @@ public abstract class PlayerImpl implements Player, Serializable {
         this.priorityTimeLeft = player.getPriorityTimeLeft();
         this.reachedNextTurnAfterLeaving = player.reachedNextTurnAfterLeaving;
 
-        this.castSourceIdWithAlternateMana = player.castSourceIdWithAlternateMana;
-        this.castSourceIdManaCosts = player.castSourceIdManaCosts;
-        this.castSourceIdCosts = player.castSourceIdCosts;
+        this.castSourceIdWithAlternateMana.addAll(player.castSourceIdWithAlternateMana);
+        this.castSourceIdManaCosts.putAll(player.castSourceIdManaCosts);
+        this.castSourceIdCosts.putAll(player.castSourceIdCosts);
+
         this.payManaMode = player.payManaMode;
         this.phyrexianColors = player.phyrexianColors.copy();
 
@@ -340,9 +342,12 @@ public abstract class PlayerImpl implements Player, Serializable {
         this.turnControllers.clear();
         this.turnControllers.addAll(player.getTurnControllers());
         this.reachedNextTurnAfterLeaving = player.hasReachedNextTurnAfterLeaving();
-        this.castSourceIdWithAlternateMana = player.getCastSourceIdWithAlternateMana();
-        this.castSourceIdManaCosts = player.getCastSourceIdManaCosts();
-        this.castSourceIdCosts = player.getCastSourceIdCosts();
+
+        this.clearCastSourceIdManaCosts();
+        this.castSourceIdWithAlternateMana.addAll(player.getCastSourceIdWithAlternateMana());
+        this.castSourceIdManaCosts.putAll(player.getCastSourceIdManaCosts());
+        this.castSourceIdCosts.putAll(player.getCastSourceIdCosts());
+
         this.phyrexianColors = player.getPhyrexianColors().copy();
 
         this.designations.clear();
@@ -417,9 +422,8 @@ public abstract class PlayerImpl implements Player, Serializable {
         this.setLife(game.getLife(), game, (UUID) null);
         this.setReachedNextTurnAfterLeaving(false);
 
-        this.castSourceIdWithAlternateMana = null;
-        this.castSourceIdManaCosts = null;
-        this.castSourceIdCosts = null;
+        this.clearCastSourceIdManaCosts();
+
         this.getManaPool().init(); // needed to remove mana that not empties on step change from previous game if left
         this.phyrexianColors = new FilterMana();
 
@@ -444,9 +448,7 @@ public abstract class PlayerImpl implements Player, Serializable {
         this.canPlayCardsFromGraveyard = false;
         this.topCardRevealed = false;
         this.alternativeSourceCosts.clear();
-        this.castSourceIdWithAlternateMana = null;
-        this.castSourceIdManaCosts = null;
-        this.castSourceIdCosts = null;
+        this.clearCastSourceIdManaCosts();
         this.getManaPool().clearEmptyManaPoolRules();
         this.phyrexianColors = new FilterMana();
     }
@@ -1061,26 +1063,33 @@ public abstract class PlayerImpl implements Player, Serializable {
 
     @Override
     public void setCastSourceIdWithAlternateMana(UUID sourceId, ManaCosts<ManaCost> manaCosts, Costs<Cost> costs) {
-        castSourceIdWithAlternateMana = sourceId;
-        castSourceIdManaCosts = manaCosts;
-        castSourceIdCosts = costs;
+        castSourceIdWithAlternateMana.add(sourceId);
+        castSourceIdManaCosts.put(sourceId, manaCosts);
+        castSourceIdCosts.put(sourceId, costs);
     }
 
     @Override
-    public UUID getCastSourceIdWithAlternateMana() {
+    public Set<UUID> getCastSourceIdWithAlternateMana() {
         return castSourceIdWithAlternateMana;
     }
 
     @Override
-    public Costs<Cost> getCastSourceIdCosts() {
+    public Map<UUID, Costs<Cost>> getCastSourceIdCosts() {
         return castSourceIdCosts;
     }
 
     @Override
-    public ManaCosts getCastSourceIdManaCosts() {
+    public Map<UUID, ManaCosts<ManaCost>> getCastSourceIdManaCosts() {
         return castSourceIdManaCosts;
     }
 
+    @Override
+    public void clearCastSourceIdManaCosts() {
+        this.castSourceIdCosts.clear();
+        this.castSourceIdManaCosts.clear();
+        this.castSourceIdWithAlternateMana.clear();
+    }
+
     @Override
     public void setPayManaMode(boolean payManaMode) {
         this.payManaMode = payManaMode;
@@ -1144,11 +1153,13 @@ public abstract class PlayerImpl implements Player, Serializable {
                 }
                 // Update the zcc to the stack
                 ability.setSourceObjectZoneChangeCounter(game.getState().getZoneChangeCounter(ability.getSourceId()));
+
+                // ALTERNATIVE COST from dynamic effects
                 // some effects set sourceId to cast without paying mana costs or other costs
-                if (ability.getSourceId().equals(getCastSourceIdWithAlternateMana())) {
+                if (getCastSourceIdWithAlternateMana().contains(ability.getSourceId())) {
                     Ability spellAbility = spell.getSpellAbility();
-                    ManaCosts alternateCosts = getCastSourceIdManaCosts();
-                    Costs<Cost> costs = getCastSourceIdCosts();
+                    ManaCosts alternateCosts = getCastSourceIdManaCosts().get(ability.getSourceId());
+                    Costs<Cost> costs = getCastSourceIdCosts().get(ability.getSourceId());
                     if (alternateCosts == null) {
                         noMana = true;
                     } else {
@@ -1162,7 +1173,8 @@ public abstract class PlayerImpl implements Player, Serializable {
                         spellAbility.getCosts().addAll(costs);
                     }
                 }
-                setCastSourceIdWithAlternateMana(null, null, null);
+                clearCastSourceIdManaCosts(); // TODO: test multiple alternative cost for different cards as same time
+
                 GameEvent event = GameEvent.getEvent(GameEvent.EventType.CAST_SPELL,
                         spell.getSpellAbility().getId(), spell.getSpellAbility().getSourceId(), playerId, permittingObject);
                 game.fireEvent(event);
@@ -3093,6 +3105,7 @@ public abstract class PlayerImpl implements Player, Serializable {
                 }
             }
 
+            // ALTERNATIVE COST from source card (AlternativeCostSourceAbility)
             for (Ability objectAbility : sourceObject.getAbilities()) {
                 if (objectAbility instanceof AlternativeCostSourceAbility) {
                     if (objectAbility.getCosts().canPay(copy, copy.getSourceId(), playerId, game)) {
@@ -3100,7 +3113,27 @@ public abstract class PlayerImpl implements Player, Serializable {
                     }
                 }
             }
-            return canPlayCardByAlternateCost(card, available, ability, game);
+
+            // ALTERNATIVE COST FROM dynamic effects
+            if (getCastSourceIdWithAlternateMana().contains(copy.getSourceId())) {
+                ManaCosts alternateCosts = getCastSourceIdManaCosts().get(copy.getSourceId());
+                Costs<Cost> costs = getCastSourceIdCosts().get(copy.getSourceId());
+
+                boolean canPutToPlay = true;
+                if (alternateCosts != null && !alternateCosts.canPay(copy, copy.getSourceId(), playerId, game)) {
+                    canPutToPlay = false;
+                }
+                if (costs != null && !costs.canPay(copy, copy.getSourceId(), playerId, game)) {
+                    canPutToPlay = false;
+                }
+
+                if (canPutToPlay) {
+                    return true;
+                }
+            }
+
+            // ALTERNATIVE COST from source card (any AlternativeSourceCosts)
+            return canPlayCardByAlternateCost(card, available, copy, game);
         }
         return false;
     }
@@ -3991,7 +4024,7 @@ public abstract class PlayerImpl implements Player, Serializable {
             // identify cards from one owner
             Cards cards = new CardsImpl();
             UUID ownerId = null;
-            for (Iterator<Card> it = allCards.iterator(); it.hasNext();) {
+            for (Iterator<Card> it = allCards.iterator(); it.hasNext(); ) {
                 Card card = it.next();
                 if (cards.isEmpty()) {
                     ownerId = card.getOwnerId();