Bunch of fixes (#2706)

* Fix Tawnos's Coffin not using ETB counters

* Cost fix

* Saga tweaks

---------

Co-authored-by: tool4EvEr <tool4EvEr@192.168.0.59>

forge-ai/src/main/java/forge/ai/AiController.java

@@ -355,6 +355,31 @@ public class AiController {
                 return false;
             }
         }
+
+        for (final Trigger tr : card.getTriggers()) {
+            if (!card.hasStartOfKeyword("Saga") && !card.hasStartOfKeyword("Read ahead")) {
+                break;
+            }
+
+            if (tr.getMode() != TriggerType.CounterAdded) {
+                continue;
+            }
+
+            SpellAbility exSA = tr.ensureAbility().copy(activator);
+
+            if (api != null && exSA.getApi() == api) {
+                rightapi = true;
+            }
+
+            if (exSA instanceof AbilitySub && !doTrigger(exSA, false)) {
+                // AI would not run this chapter if given the chance
+                // TODO eventually we'll want to consider playing it anyway, especially if Read ahead would still allow an immediate benefit
+                return false;
+            }
+
+            break;
+        }
+
         if (api != null && !rightapi) {
             return false;
         }

forge-ai/src/main/java/forge/ai/AiCostDecision.java

@@ -177,7 +177,7 @@ public class AiCostDecision extends CostDecisionMakerBase {
             // TODO Determine exile from same zone for AI
             return null;
         } else {
-            CardCollectionView chosen = ComputerUtil.chooseExileFrom(player, cost.getFrom(), cost.getType(), source, ability.getTargetCard(), c, ability);
+            CardCollectionView chosen = ComputerUtil.chooseExileFrom(player, cost, source, c, ability);
             return null == chosen ? null : PaymentDecision.card(chosen);
         }
     }

forge-ai/src/main/java/forge/ai/ComputerUtil.java

@@ -66,6 +66,7 @@ import forge.game.combat.Combat;
 import forge.game.combat.CombatUtil;
 import forge.game.cost.Cost;
 import forge.game.cost.CostDiscard;
+import forge.game.cost.CostExile;
 import forge.game.cost.CostPart;
 import forge.game.cost.CostPayment;
 import forge.game.cost.CostPutCounter;
@@ -641,9 +642,14 @@ public class ComputerUtil {
         return sacList;
     }
 
-    public static CardCollection chooseExileFrom(final Player ai, final ZoneType zone, final String type, final Card activate,
-            final Card target, final int amount, SpellAbility sa) {
-        CardCollection typeList = CardLists.getValidCards(ai.getCardsIn(zone), type.split(";"), activate.getController(), activate, sa);
+    public static CardCollection chooseExileFrom(final Player ai, CostExile cost, final Card activate, final int amount, SpellAbility sa) {
+        CardCollection typeList;
+        if (cost.zoneRestriction != 1) {
+            typeList = new CardCollection(ai.getGame().getCardsIn(cost.from));
+        } else {
+            typeList = new CardCollection(ai.getCardsIn(cost.from));
+        }
+        typeList = CardLists.getValidCards(typeList, cost.getType().split(";"), activate.getController(), activate, sa);
 
         // don't exile the card we're pumping
         typeList = ComputerUtilCost.paymentChoicesWithoutTargets(typeList, sa, ai);

forge-ai/src/main/java/forge/ai/ComputerUtilCombat.java

@@ -2410,7 +2410,6 @@ public class ComputerUtilCombat {
         // (currently looks for the creature with maximum raw power since that's what the AI usually judges by when
         // deciding whether the creature is worth blocking).
         // If the creature doesn't change into anything, returns the original creature.
-        if (attacker == null) { return null; }
         Card attackerAfterTrigs = attacker;
 
         // Test for some special triggers that can change the creature in combat

forge-ai/src/main/java/forge/ai/ability/AttachAi.java

@@ -1412,7 +1412,7 @@ public class AttachAi extends SpellAbilityAi {
             }
 
             // avoid randomly moving the equipment back and forth between several creatures in one turn
-            if (AiCardMemory.isRememberedCard(aiPlayer, sa.getHostCard(), AiCardMemory.MemorySet.ATTACHED_THIS_TURN) && !mandatory) {
+            if (AiCardMemory.isRememberedCard(aiPlayer, attachSource, AiCardMemory.MemorySet.ATTACHED_THIS_TURN) && !mandatory) {
                 return null;
             }
 
@@ -1423,7 +1423,7 @@ public class AttachAi extends SpellAbilityAi {
             }
         }
 
-        AiCardMemory.rememberCard(aiPlayer, sa.getHostCard(), AiCardMemory.MemorySet.ATTACHED_THIS_TURN);
+        AiCardMemory.rememberCard(aiPlayer, attachSource, AiCardMemory.MemorySet.ATTACHED_THIS_TURN);
 
         if (c == null && mandatory) {
             CardLists.shuffle(list);
@@ -1674,12 +1674,6 @@ public class AttachAi extends SpellAbilityAi {
         if (c == null) {
             return false;
         }
-        if (sa.getHostCard() == null) {
-            // FIXME: Not sure what should the resolution be if a SpellAbility has no host card. This should
-            // not happen normally. Possibly remove this block altogether? (if it's an impossible condition).
-            System.out.println("AttachAi: isUsefulAttachAction unexpectedly called with SpellAbility with no host card. Assuming it's a determined useful action.");
-            return true;
-        }
 
         // useless to equip a creature that can't attack or block.
         return !sa.getHostCard().isEquipment() || !ComputerUtilCard.isUselessCreature(ai, c);

forge-ai/src/main/java/forge/ai/ability/CloneAi.java

@@ -69,7 +69,6 @@ public class CloneAi extends SpellAbilityAi {
                         bFlag = true;
                     }
                 }
-
             }
 
             if (!bFlag) { // All of the defined stuff is cloned, not very useful

forge-ai/src/main/java/forge/ai/ability/CountersPutAi.java

@@ -1221,4 +1221,12 @@ public class CountersPutAi extends CountersAi {
         return false;
     }
 
+    @Override
+    public int chooseNumber(Player player, SpellAbility sa, int min, int max, Map<String, Object> params) {
+        if (sa.hasParam("ReadAhead")) {
+            return 1;
+        }
+        return max;
+    }
+
 }