From 3e91a56ced44d6d4617df5ed42fb5e787e8676dd Mon Sep 17 00:00:00 2001
From: Myrd <myrd@cardforge.org>
Date: Thu, 22 Dec 2016 20:31:41 +0000
Subject: [PATCH] Fix NPE in CardUtil.getLKICopy() that would happen when
 Thespian's Stage would copy itself.

The problem would happen when executing:
        newCopy.getCurrentState().copyFrom(in, in.getState(in.getCurrentStateName()));

Because the clone code was clearing the cloned state without updating currentStateName.

Also added a test for this in the context of simulated AI, although the actual bug was not in simulation code - it's just simulation code would run into it since it tries all possible targets to copy (while humans would likely not try it).
---
 .../src/main/java/forge/game/card/Card.java   |  9 +++++++--
 .../ai/simulation/GameSimulatorTest.java      | 19 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/forge-game/src/main/java/forge/game/card/Card.java b/forge-game/src/main/java/forge/game/card/Card.java
index 1a1c39854ba..74207c3f38a 100644
--- a/forge-game/src/main/java/forge/game/card/Card.java
+++ b/forge-game/src/main/java/forge/game/card/Card.java
@@ -356,7 +356,6 @@ public class Card extends GameEntity implements Comparable<Card> {
         return states.get(state);
     }
     public boolean setState(final CardStateName state, boolean updateView) {
-
         if (!states.containsKey(state)) {
             System.out.println(getName() + " tried to switch to non-existant state \"" + state + "\"!");
             return false; // Nonexistant state.
@@ -427,7 +426,13 @@ public class Card extends GameEntity implements Comparable<Card> {
     }
 
     public void clearStates(final CardStateName state, boolean updateView) {
-        if (states.remove(state) != null && updateView) {
+        if (states.remove(state) == null) {
+            return;
+        }
+        if (state == currentStateName) {
+            currentStateName = CardStateName.Original;
+        }
+        if (updateView) {
             view.updateState(this);
         }
     }
diff --git a/forge-gui-desktop/src/test/java/forge/ai/simulation/GameSimulatorTest.java b/forge-gui-desktop/src/test/java/forge/ai/simulation/GameSimulatorTest.java
index 46c76bc793a..79a76d029db 100644
--- a/forge-gui-desktop/src/test/java/forge/ai/simulation/GameSimulatorTest.java
+++ b/forge-gui-desktop/src/test/java/forge/ai/simulation/GameSimulatorTest.java
@@ -561,4 +561,23 @@ public class GameSimulatorTest extends TestCase {
         assertNull(strSimGame, findCardWithName(simGame, "Thespian's Stage"));
         assertNotNull(strSimGame, findCardWithName(simGame, "Marit Lage"));
     }
+    
+    public void testThespianStageSelfCopy() {
+        Game game = initAndCreateGame();
+        Player p = game.getPlayers().get(1);
+        addCard("Swamp", p);
+        addCard("Swamp", p);
+        Card thespian = addCard("Thespian's Stage", p);
+        game.getPhaseHandler().devModeSet(PhaseType.MAIN2, p);
+        game.getAction().checkStateEffects(true);
+        
+        SpellAbility sa = findSAWithPrefix(thespian, "{2}, {T}: CARDNAME becomes a copy of target land and gains this ability.");
+        assertNotNull(sa);
+        sa.getTargets().add(thespian);
+
+        GameSimulator sim = createSimulator(game, p);
+        sim.simulateSpellAbility(sa);
+        Game simGame = sim.getSimulatedGameState();
+        assertNotNull(gameStateToString(simGame), findCardWithName(simGame, "Thespian's Stage"));
+    }
 }