Fix illegal distributions

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

@@ -2149,7 +2149,7 @@ public class AiController {
     public int chooseNumber(SpellAbility sa, String title, List<Integer> options, Player relatedPlayer) {
         switch(sa.getApi())
         {
-            case SetLife:
+            case SetLife: // Reverse the Sands
                 if (relatedPlayer.equals(sa.getHostCard().getController())) {
                     return Collections.max(options);
                 } else if (relatedPlayer.isOpponentOf(sa.getHostCard().getController())) {

forge-game/src/main/java/forge/game/ability/effects/LifeSetEffect.java

@@ -3,9 +3,12 @@ package forge.game.ability.effects;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.google.common.collect.Lists;
+
 import forge.game.ability.AbilityUtils;
 import forge.game.ability.SpellAbilityEffect;
 import forge.game.player.Player;
+import forge.game.player.PlayerCollection;
 import forge.game.spellability.SpellAbility;
 import forge.game.spellability.TargetRestrictions;
 import forge.util.Localizer;
@@ -18,31 +21,75 @@ public class LifeSetEffect extends SpellAbilityEffect {
     @Override
     public void resolve(SpellAbility sa) {
         final boolean redistribute = sa.hasParam("Redistribute");
-        final int lifeAmount = redistribute ? 20 : AbilityUtils.calculateAmount(sa.getHostCard(), sa.getParam("LifeAmount"), sa);
+        final int lifeAmount = redistribute ? 0 : AbilityUtils.calculateAmount(sa.getHostCard(), sa.getParam("LifeAmount"), sa);
         final TargetRestrictions tgt = sa.getTargetRestrictions();
         final List<Integer> lifetotals = new ArrayList<>();
+        final PlayerCollection players = getTargetPlayers(sa);
 
         if (redistribute) {
-            for (final Player p : getTargetPlayers(sa)) {
+            for (final Player p : players) {
                 if (tgt == null || p.canBeTargetedBy(sa)) {
                     lifetotals.add(p.getLife());
                 }
             }
         }
 
-        for (final Player p : getTargetPlayers(sa)) {
+        for (final Player p : players.threadSafeIterable()) {
             if (tgt == null || p.canBeTargetedBy(sa)) {
                 if (!redistribute) {
                     p.setLife(lifeAmount, sa.getHostCard());
                 } else {
-                    int life = sa.getActivatingPlayer().getController().chooseNumber(sa, Localizer.getInstance().getMessage("lblLifeTotal") + ": " + p, lifetotals, p);
+                    List<Integer> validChoices = getDistribution(players, true, lifetotals);
+                    int life = sa.getActivatingPlayer().getController().chooseNumber(sa, Localizer.getInstance().getMessage("lblLifeTotal") + ": " + p, validChoices, p);
                     p.setLife(life, sa.getHostCard());
                     lifetotals.remove((Integer) life);
+                    players.remove(p);
                 }
             }
         }
     }
 
+    private static List<Integer> getDistribution(PlayerCollection players, boolean top, List<Integer> remainingChoices) {
+        // distribution was successful
+        if (players.isEmpty()) {
+            // carry signal back
+            remainingChoices.add(1);
+            return remainingChoices;
+        }
+        List<Integer> validChoices = Lists.newArrayList(remainingChoices);
+        for (Player p : players) {
+            for (Integer choice : remainingChoices) {
+                // 119.7/8 illegal choice
+                if ((p.getLife() < choice && !p.canGainLife()) || (p.getLife() > choice && !p.canLoseLife())) {
+                    if (top) {
+                        validChoices.remove(choice);
+                    }
+                    continue;
+                }
+
+                // combination is valid, check next
+                PlayerCollection nextPlayers = new PlayerCollection(players);
+                nextPlayers.remove(p);
+                List<Integer> nextChoices = new ArrayList<>(remainingChoices);
+                nextChoices.remove(choice);
+                nextChoices = getDistribution(nextPlayers, false, nextChoices);
+                if (nextChoices.isEmpty()) {
+                    if (top) {
+                        // top of recursion stack
+                        validChoices.remove(choice);
+                    }
+                } else if (!top) {
+                    return nextChoices;
+                }
+            }
+            if (top) {
+                // checking first player is enough
+                return validChoices;
+            }
+        }
+        return new ArrayList<Integer>();
+    }
+
     /* (non-Javadoc)
      * @see forge.card.abilityfactory.AbilityFactoryAlterLife.SpellEffect#getStackDescription(java.util.Map, forge.card.spellability.SpellAbility)
      */

forge-game/src/main/java/forge/game/player/Player.java

@@ -483,15 +483,15 @@ public class Player extends GameEntity implements Comparable<Player> {
         return gainLife(lifeGain, source, null);
     }
     public final boolean gainLife(int lifeGain, final Card source, final SpellAbility sa) {
+        if (!canGainLife()) {
+            return false;
+        }
+
         // Run any applicable replacement effects.
         final Map<AbilityKey, Object> repParams = AbilityKey.mapFromAffected(this);
         repParams.put(AbilityKey.LifeGained, lifeGain);
         repParams.put(AbilityKey.Source, source);
 
-        if (!canGainLife()) {
-            return false;
-        }
-
         switch (getGame().getReplacementHandler().run(ReplacementType.GainLife, repParams)) {
         case NotReplaced:
             break;