From 3fa57381cd9d3cfb74992fd644120b3355f60654 Mon Sep 17 00:00:00 2001
From: Pawkkie <61265402+Pawkkie@users.noreply.github.com>
Date: Mon, 17 Mar 2025 16:01:03 -0400
Subject: [PATCH] Fix Focus Sash being considered in switch AI's hits to KO
 calcs (#6436)

---
 src/battle_ai_switch_items.c |  5 +++--
 test/battle/ai/ai.c          | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/battle_ai_switch_items.c b/src/battle_ai_switch_items.c
index ef8f45fb17..f4b72c65b5 100644
--- a/src/battle_ai_switch_items.c
+++ b/src/battle_ai_switch_items.c
@@ -255,7 +255,8 @@ static bool32 ShouldSwitchIfHasBadOdds(u32 battler)
     }
 
     // Check if mon gets one shot
-    if(maxDamageTaken > gBattleMons[battler].hp)
+    if(maxDamageTaken > gBattleMons[battler].hp
+        && !(gItemsInfo[gBattleMons[battler].item].holdEffect == HOLD_EFFECT_FOCUS_SASH || (!IsMoldBreakerTypeAbility(opposingBattler, gBattleMons[opposingBattler].ability) && B_STURDY >= GEN_5 && aiAbility == ABILITY_STURDY)))
     {
         getsOneShot = TRUE;
     }
@@ -1687,7 +1688,7 @@ static u32 GetSwitchinHitsToKO(s32 damageTaken, u32 battler)
         currentHP = currentHP - damageTaken;
 
         // One shot prevention effects
-        if (damageTaken >= maxHP && currentHP == maxHP && (heldItemEffect == HOLD_EFFECT_FOCUS_SASH || (!opponentCanBreakMold && B_STURDY >= GEN_5 && ability == ABILITY_STURDY)))
+        if (damageTaken >= maxHP && startingHP == maxHP && (heldItemEffect == HOLD_EFFECT_FOCUS_SASH || (!opponentCanBreakMold && B_STURDY >= GEN_5 && ability == ABILITY_STURDY)) && hitsToKO < 1)
             currentHP = 1;
 
         // If mon is still alive, apply weather impact first, as it might KO the mon before it can heal with its item (order is weather -> item -> status)
diff --git a/test/battle/ai/ai.c b/test/battle/ai/ai.c
index da77f828e4..1c57c88732 100644
--- a/test/battle/ai/ai.c
+++ b/test/battle/ai/ai.c
@@ -845,3 +845,18 @@ AI_SINGLE_BATTLE_TEST("AI won't use Sucker Punch if it expects a move of the sam
         TURN { MOVE(player, MOVE_QUICK_ATTACK); EXPECT_MOVE(opponent, MOVE_TACKLE); }
     }
 }
+
+AI_SINGLE_BATTLE_TEST("AI_FLAG_SMART_SWITCHING: AI considers Focus Sash when determining if it should switch out")
+{
+    GIVEN {
+        ASSUME(gItemsInfo[ITEM_FOCUS_SASH].holdEffect == HOLD_EFFECT_FOCUS_SASH);
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_TRY_TO_FAINT | AI_FLAG_SMART_MON_CHOICES | AI_FLAG_SMART_SWITCHING | AI_FLAG_OMNISCIENT);
+        PLAYER(SPECIES_BEAUTIFLY) { Speed(10); Moves(MOVE_AIR_SLASH); }
+        OPPONENT(SPECIES_CACNEA) { Speed(1); Moves(MOVE_TACKLE); }
+        OPPONENT(SPECIES_COMBUSKEN) { Speed(1); Moves(MOVE_FLAMETHROWER); Item(ITEM_FOCUS_SASH); }
+        OPPONENT(SPECIES_CROBAT) { Speed(11); Moves(MOVE_SLUDGE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_AIR_SLASH); EXPECT_MOVE(opponent, MOVE_TACKLE); EXPECT_SEND_OUT(opponent, 1); }
+        TURN { MOVE(player, MOVE_AIR_SLASH); EXPECT_MOVE(opponent, MOVE_FLAMETHROWER); }
+    }
+}