implement and test ExpendTriggeredAbility

Mage/src/main/java/mage/abilities/common/ExpendTriggeredAbility.java

@@ -1,31 +1,65 @@
 package mage.abilities.common;
 
+import mage.MageObject;
+import mage.abilities.Ability;
 import mage.abilities.TriggeredAbilityImpl;
+import mage.abilities.dynamicvalue.DynamicValue;
 import mage.abilities.effects.Effect;
+import mage.abilities.hint.Hint;
+import mage.abilities.hint.ValueHint;
+import mage.constants.WatcherScope;
 import mage.constants.Zone;
 import mage.game.Game;
 import mage.game.events.GameEvent;
+import mage.game.stack.Spell;
+import mage.util.CardUtil;
+import mage.watchers.Watcher;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
 
 /**
- * @author TheElk801
- * TODO: Implement this
+ * @author Susucr
  */
 public class ExpendTriggeredAbility extends TriggeredAbilityImpl {
 
-    private final int amount;
+    private static final Hint hint = new ValueHint("Mana you expended this turn", ExpendValue.instance);
 
-    public ExpendTriggeredAbility(Effect effect, int amount) {
+    /**
+     * For memory-usage purpose, we only support expend 4 and expend 8 so far.
+     */
+    public enum Expend {
+        FOUR(4),
+        EIGHT(8);
+
+        private final int amount;
+
+        public int getAmount() {
+            return amount;
+        }
+
+        Expend(int amount) {
+            this.amount = amount;
+        }
+    }
+
+    private final Expend amount;
+
+    public ExpendTriggeredAbility(Effect effect, Expend amount) {
         this(effect, amount, false);
     }
 
-    public ExpendTriggeredAbility(Effect effect, int amount, boolean optional) {
+    public ExpendTriggeredAbility(Effect effect, Expend amount, boolean optional) {
         this(Zone.BATTLEFIELD, effect, amount, optional);
     }
 
-    public ExpendTriggeredAbility(Zone zone, Effect effect, int amount, boolean optional) {
+    public ExpendTriggeredAbility(Zone zone, Effect effect, Expend amount, boolean optional) {
         super(zone, effect, optional);
         this.amount = amount;
-        setTriggerPhrase("Whenever you expend " + amount + ", ");
+        setTriggerPhrase("Whenever you expend " + amount.getAmount() + ", ");
+        this.addWatcher(new ExpendWatcher());
+        this.addHint(hint);
     }
 
     private ExpendTriggeredAbility(final ExpendTriggeredAbility ability) {
@@ -40,11 +74,109 @@ public class ExpendTriggeredAbility extends TriggeredAbilityImpl {
 
     @Override
     public boolean checkEventType(GameEvent event, Game game) {
-        return false;
+        return event.getType() == GameEvent.EventType.MANA_PAID;
     }
 
     @Override
     public boolean checkTrigger(GameEvent event, Game game) {
-        return false;
+        return ExpendWatcher.checkExpend(getControllerId(), event, amount, game);
+    }
+}
+
+enum ExpendValue implements DynamicValue {
+    instance;
+
+    @Override
+    public int calculate(Game game, Ability sourceAbility, Effect effect) {
+        return ExpendWatcher.getManaExpended(sourceAbility.getControllerId(), game);
+    }
+
+    @Override
+    public ExpendValue copy() {
+        return instance;
+    }
+
+    @Override
+    public String getMessage() {
+        return "mana you expended this turn";
+    }
+}
+
+
+/**
+ * Watcher for mana expended this turn.
+ * <p>
+ * Of note, to reduce memory usage, only tracks the events that did expend 4 and expend 8.
+ * If expend N extends to more than a couple values, storing the full list (in order) of event id is advised.
+ */
+class ExpendWatcher extends Watcher {
+
+    // Player id -> number of mana expended this turn
+    private final Map<UUID, Integer> manaExpended = new HashMap<>();
+
+    // Player id -> event id for the 4th mana expended this turn
+    private final Map<UUID, UUID> eventFor4thExpend = new HashMap<>();
+    // Player id -> event id for the 8th mana expended this turn
+    private final Map<UUID, UUID> eventFor8thExpend = new HashMap<>();
+
+    public ExpendWatcher() {
+        super(WatcherScope.GAME);
+    }
+
+    @Override
+    public void watch(GameEvent event, Game game) {
+        if (!GameEvent.EventType.MANA_PAID.equals(event.getType())) {
+            return;
+        }
+        MageObject ability = game.getObject(event.getTargetId());
+        if (!(ability instanceof Spell)) {
+            // Only cares about mana paid for casting Spells
+            return;
+        }
+        UUID playerId = event.getPlayerId();
+        UUID eventId = event.getId();
+        manaExpended.compute(playerId, CardUtil::setOrIncrementValue);
+        int currentValue = manaExpended.get(playerId);
+        switch (currentValue) {
+            case 4:
+                eventFor4thExpend.put(playerId, eventId);
+                break;
+            case 8:
+                eventFor8thExpend.put(playerId, eventId);
+                break;
+        }
+    }
+
+    @Override
+    public void reset() {
+        super.reset();
+        manaExpended.clear();
+        eventFor4thExpend.clear();
+        eventFor8thExpend.clear();
+    }
+
+    public static boolean checkExpend(UUID playerId, GameEvent event, ExpendTriggeredAbility.Expend expendToCheck, Game game) {
+        ExpendWatcher watcher = game.getState().getWatcher(ExpendWatcher.class);
+        if (watcher == null) {
+            return false;
+        }
+        switch (expendToCheck) {
+            case FOUR:
+                return watcher.eventFor4thExpend.containsKey(playerId)
+                        && watcher.eventFor4thExpend.get(playerId).equals(event.getId());
+            case EIGHT:
+                return watcher.eventFor8thExpend.containsKey(playerId)
+                        && watcher.eventFor8thExpend.get(playerId).equals(event.getId());
+            default:
+                throw new IllegalArgumentException("Unsupported expend value: " + expendToCheck.getAmount());
+        }
+    }
+
+    public static int getManaExpended(UUID playerId, Game game) {
+        ExpendWatcher watcher = game.getState().getWatcher(ExpendWatcher.class);
+        if (watcher == null) {
+            return 0;
+        }
+        return watcher.manaExpended.getOrDefault(playerId, 0);
     }
 }