Implement offspring mechanic (#12572)

* implement offspring mechanic

* create offspring test

Mage/src/main/java/mage/abilities/keyword/OffspringAbility.java

@@ -1,26 +1,58 @@
 package mage.abilities.keyword;
 
+import mage.abilities.Ability;
+import mage.abilities.SpellAbility;
 import mage.abilities.StaticAbility;
-import mage.abilities.costs.Cost;
+import mage.abilities.common.EntersBattlefieldTriggeredAbility;
+import mage.abilities.condition.Condition;
+import mage.abilities.costs.*;
 import mage.abilities.costs.mana.ManaCostsImpl;
+import mage.abilities.decorator.ConditionalInterveningIfTriggeredAbility;
+import mage.abilities.effects.OneShotEffect;
+import mage.abilities.effects.common.CreateTokenCopyTargetEffect;
+import mage.constants.Outcome;
 import mage.constants.Zone;
+import mage.game.Game;
+import mage.game.permanent.Permanent;
+import mage.players.Player;
+import mage.util.CardUtil;
 
 /**
  * @author TheElk801
- * TODO: Implement this
  */
-public class OffspringAbility extends StaticAbility {
+public class OffspringAbility extends StaticAbility implements OptionalAdditionalSourceCosts {
+
+    private static final String keywordText = "Offspring";
+    private static final String reminderText = "You may pay an additional %s as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.";
+    private final String rule;
+
+    public static final String OFFSPRING_ACTIVATION_VALUE_KEY = "offspringActivation";
+
+    protected OptionalAdditionalCost additionalCost;
 
     public OffspringAbility(String manaString) {
         this(new ManaCostsImpl<>(manaString));
     }
 
     public OffspringAbility(Cost cost) {
-        super(Zone.ALL, null);
+        super(Zone.STACK, null);
+        this.additionalCost = new OptionalAdditionalCostImpl(
+                keywordText + ' ' + cost.getText(),
+                String.format(reminderText, cost.getText()), cost
+        );
+        this.additionalCost.setRepeatable(false);
+        this.rule = additionalCost.getName() + ' ' + additionalCost.getReminderText();
+        this.setRuleAtTheTop(true);
+        this.addSubAbility(new ConditionalInterveningIfTriggeredAbility(
+                new EntersBattlefieldTriggeredAbility(new OffspringEffect()), OffspringCondition.instance,
+                "When this creature enters, if its offspring cost was paid, create a 1/1 token copy of it."
+        ).setRuleVisible(false));
     }
 
     private OffspringAbility(final OffspringAbility ability) {
         super(ability);
+        this.rule = ability.rule;
+        this.additionalCost = ability.additionalCost.copy();
     }
 
     @Override
@@ -28,8 +60,73 @@ public class OffspringAbility extends StaticAbility {
         return new OffspringAbility(this);
     }
 
+    @Override
+    public void addOptionalAdditionalCosts(Ability ability, Game game) {
+        if (!(ability instanceof SpellAbility)) {
+            return;
+        }
+        Player player = game.getPlayer(ability.getControllerId());
+        if (player == null) {
+            return;
+        }
+        additionalCost.reset();
+        if (!additionalCost.canPay(ability, this, ability.getControllerId(), game)
+                || !player.chooseUse(Outcome.PutCreatureInPlay, "Pay " + additionalCost.getText(true) + " for offspring?", ability, game)) {
+            return;
+        }
+        additionalCost.activate();
+        for (Cost cost : ((Costs<Cost>) additionalCost)) {
+            ability.getCosts().add(cost.copy());
+        }
+        ability.setCostsTag(OFFSPRING_ACTIVATION_VALUE_KEY, null);
+    }
+
+    @Override
+    public String getCastMessageSuffix() {
+        return additionalCost.getCastSuffixMessage(0);
+    }
+
     @Override
     public String getRule() {
-        return "Offspring";
+        return rule;
+    }
+}
+
+class OffspringEffect extends OneShotEffect {
+
+    OffspringEffect() {
+        super(Outcome.Benefit);
+    }
+
+    private OffspringEffect(final OffspringEffect effect) {
+        super(effect);
+    }
+
+    @Override
+    public OffspringEffect copy() {
+        return new OffspringEffect(this);
+    }
+
+    @Override
+    public boolean apply(Game game, Ability source) {
+        Permanent permanent = source.getSourcePermanentOrLKI(game);
+        return permanent != null && new CreateTokenCopyTargetEffect(
+                null, null, false, 1, false,
+                false, null, 1, 1, false
+        ).setSavedPermanent(permanent).apply(game, source);
+    }
+}
+
+enum OffspringCondition implements Condition {
+    instance;
+
+    @Override
+    public boolean apply(Game game, Ability source) {
+        return CardUtil.checkSourceCostsTagExists(game, source, OffspringAbility.OFFSPRING_ACTIVATION_VALUE_KEY);
+    }
+
+    @Override
+    public String toString() {
+        return "Offspring cost was paid";
     }
 }