From b93976c980bcf833b26fb953f3611ce2465a9aec Mon Sep 17 00:00:00 2001
From: Alex <93446519+AlexOn1ine@users.noreply.github.com>
Date: Sun, 23 Mar 2025 23:34:24 +0100
Subject: [PATCH] Fixes Cheek Pouch mutating damage (#6466)

---
 include/battle.h                   |  3 ++-
 src/battle_script_commands.c       | 14 ++++++++++++++
 test/battle/ability/cheeck_pouch.c | 21 +++++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 test/battle/ability/cheeck_pouch.c

diff --git a/include/battle.h b/include/battle.h
index a6ba6d92e5..267abdc7f2 100644
--- a/include/battle.h
+++ b/include/battle.h
@@ -815,7 +815,8 @@ struct BattleStruct
     u8 monCausingSleepClause[NUM_BATTLE_SIDES]; // Stores which pokemon on a given side is causing Sleep Clause to be active as the mon's index in the party
     u8 additionalEffectsCounter:4; // A counter for the additionalEffects applied by the current move in Cmd_setadditionaleffects
     u8 redCardActivates:1;
-    u8 padding2:2; // padding in the middle so pursuit fields are together
+    u8 cheekPouchActivated:1;
+    u8 padding2:1; // padding in the middle so pursuit fields are together
     u8 pursuitStoredSwitch; // Stored id for the Pursuit target's switch
     s32 battlerExpReward;
     u16 prevTurnSpecies[MAX_BATTLERS_COUNT]; // Stores species the AI has in play at start of turn
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index 7c6b95352d..62ae2184ee 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -345,6 +345,7 @@ static u32 GetNextTarget(u32 moveTarget, bool32 excludeCurrent);
 static void TryUpdateEvolutionTracker(u32 evolutionMethod, u32 upAmount, u16 usedMove);
 static void AccuracyCheck(bool32 recalcDragonDarts, const u8 *nextInstr, const u8 *failInstr, u16 move);
 static void ResetValuesForCalledMove(void);
+static void TryRestoreDamageAfterCheeckPouch(u32 battler);
 
 static void Cmd_attackcanceler(void);
 static void Cmd_accuracycheck(void);
@@ -2669,6 +2670,7 @@ static void Cmd_datahpupdate(void)
         }
     }
 
+    TryRestoreDamageAfterCheeckPouch(battler);
     gBattlescriptCurrInstr = cmd->nextInstr;
 }
 
@@ -8929,6 +8931,8 @@ static bool32 TryCheekPouch(u32 battler, u32 itemId)
         && gBattleStruct->ateBerry[GetBattlerSide(battler)] & (1u << gBattlerPartyIndexes[battler])
         && !IsBattlerAtMaxHp(battler))
     {
+        gBattleStruct->cheekPouchActivated = TRUE;
+        gBattleScripting.savedDmg = gBattleStruct->moveDamage[battler];
         gBattleStruct->moveDamage[battler] = GetNonDynamaxMaxHP(battler) / 3;
         if (gBattleStruct->moveDamage[battler] == 0)
             gBattleStruct->moveDamage[battler] = 1;
@@ -8941,6 +8945,16 @@ static bool32 TryCheekPouch(u32 battler, u32 itemId)
     return FALSE;
 }
 
+// When Cheek Pouch activates mid-battle it overwrites the current damage, so restore it
+static void TryRestoreDamageAfterCheeckPouch(u32 battler)
+{
+    if (gBattleStruct->cheekPouchActivated)
+    {
+        gBattleStruct->moveDamage[battler] = gBattleScripting.savedDmg;
+        gBattleStruct->cheekPouchActivated = FALSE;
+    }
+}
+
 // Used by Bestow and Symbiosis to take an item from one battler and give to another.
 static void BestowItem(u32 battlerAtk, u32 battlerDef)
 {
diff --git a/test/battle/ability/cheeck_pouch.c b/test/battle/ability/cheeck_pouch.c
new file mode 100644
index 0000000000..3c932c4aa1
--- /dev/null
+++ b/test/battle/ability/cheeck_pouch.c
@@ -0,0 +1,21 @@
+#include "global.h"
+#include "test/battle.h"
+
+SINGLE_BATTLE_TEST("Cheek Pouch activation doesn't mutate damage when restoring HP mid battle")
+{
+    s16 damage;
+    s16 healing;
+
+    GIVEN {
+        PLAYER(SPECIES_GREEDENT) { Ability(ABILITY_CHEEK_POUCH); Item(ITEM_CHOPLE_BERRY); HP(100); }
+        OPPONENT(SPECIES_WOBBUFFET);
+    } WHEN {
+        TURN { MOVE(opponent, MOVE_KARATE_CHOP); }
+        ABILITY_POPUP(player, ABILITY_CHEEK_POUCH);
+        HP_BAR(player, captureDamage: &healing);
+        HP_BAR(player, captureDamage: &damage);
+    } THEN {
+        EXPECT_LT(healing, 0);
+        EXPECT_GT(damage, 0);
+    }
+}