From 4d5a745e31759c15b6dbb013761a4de73b95cb6e Mon Sep 17 00:00:00 2001
From: Alex <93446519+AlexOn1ine@users.noreply.github.com>
Date: Thu, 18 Apr 2024 10:34:33 +0200
Subject: [PATCH] Fix bug involved infinite loop when player mon has only
 status moves (#4403)

---
 src/battle_ai_switch_items.c |  2 +-
 test/battle/ai.c             | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/battle_ai_switch_items.c b/src/battle_ai_switch_items.c
index 66bea62206..6feff721c4 100644
--- a/src/battle_ai_switch_items.c
+++ b/src/battle_ai_switch_items.c
@@ -1535,7 +1535,7 @@ static u32 GetSwitchinHitsToKO(s32 damageTaken, u32 battler)
     s32 currentHP = startingHP;
 
     // No damage being dealt
-    if (damageTaken + statusDamage + recurringDamage < recurringHealing)
+    if ((damageTaken + statusDamage + recurringDamage < recurringHealing) || damageTaken + statusDamage + recurringDamage == 0)
         return startingHP;
 
     // Mon fainted to hazards
diff --git a/test/battle/ai.c b/test/battle/ai.c
index c8a64faceb..0597925356 100644
--- a/test/battle/ai.c
+++ b/test/battle/ai.c
@@ -545,6 +545,22 @@ AI_SINGLE_BATTLE_TEST("AI_FLAG_SMART_MON_CHOICES: Number of hits to KO calculati
     }
 }
 
+AI_SINGLE_BATTLE_TEST("AI_FLAG_SMART_MON_CHOICES: Number of hits to KO calculation checks whether incoming damage is zero to avoid an infinite loop")
+{
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_TRY_TO_FAINT | AI_FLAG_CHECK_VIABILITY | AI_FLAG_SMART_SWITCHING | AI_FLAG_SMART_MON_CHOICES);
+        PLAYER(SPECIES_BULBASAUR) { Level(5); Moves(MOVE_SWORDS_DANCE, MOVE_WHIRLWIND, MOVE_SAND_ATTACK, MOVE_TAIL_WHIP); }
+        // Scenario courtesy of Duke, who triggered the bug in the first place
+        OPPONENT(SPECIES_GEODUDE) { Level(100); Moves(MOVE_TACKLE); }
+        OPPONENT(SPECIES_GEODUDE) { Level(100); Moves(MOVE_TACKLE); }
+        OPPONENT(SPECIES_NOSEPASS) { Level(100); Moves(MOVE_TACKLE); }
+    } WHEN {
+            TURN { MOVE(player, MOVE_SWORDS_DANCE); EXPECT_MOVES(opponent, MOVE_TACKLE); }
+    } SCENE {
+        MESSAGE("Bulbasaur fainted!");
+    }
+}
+
 AI_SINGLE_BATTLE_TEST("AI_FLAG_SMART_MON_CHOICES: AI will not switch in a Pokemon which is slower and gets 1HKOed after fainting")
 {
     bool32 alakazamFirst;