From 7cd614a0cd2019d913f78bd83467ce8bd7d0d268 Mon Sep 17 00:00:00 2001
From: moostoet <70690976+moostoet@users.noreply.github.com>
Date: Sat, 15 Feb 2025 22:48:26 +0100
Subject: [PATCH] Fix AI wrongly thinking it strikes first with priority even
 if player is using priority themselves (#6274)

---
 src/battle_ai_util.c |  9 ++++++++-
 test/battle/ai/ai.c  | 14 ++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/battle_ai_util.c b/src/battle_ai_util.c
index e440091183..b765616802 100644
--- a/src/battle_ai_util.c
+++ b/src/battle_ai_util.c
@@ -1094,8 +1094,15 @@ s32 AI_WhoStrikesFirst(u32 battlerAI, u32 battler, u32 moveConsidered)
     u32 abilityAI = AI_DATA->abilities[battlerAI];
     u32 abilityPlayer = AI_DATA->abilities[battler];
 
-    if (GetMovePriority(battlerAI, moveConsidered) > 0)
+    u32 predictedMove = AI_DATA->lastUsedMove[battler]; // TODO update for move prediction
+
+    s8 aiPriority = GetMovePriority(battlerAI, moveConsidered);
+    s8 playerPriority = GetMovePriority(battler, predictedMove);
+
+    if (aiPriority > playerPriority)
         return AI_IS_FASTER;
+    else if (aiPriority < playerPriority)
+        return AI_IS_SLOWER;
 
     speedBattlerAI = GetBattlerTotalSpeedStatArgs(battlerAI, abilityAI, holdEffectAI);
     speedBattler   = GetBattlerTotalSpeedStatArgs(battler, abilityPlayer, holdEffectPlayer);
diff --git a/test/battle/ai/ai.c b/test/battle/ai/ai.c
index 0883e3cc59..5f01c761a6 100644
--- a/test/battle/ai/ai.c
+++ b/test/battle/ai/ai.c
@@ -831,3 +831,17 @@ AI_SINGLE_BATTLE_TEST("AI stays choice locked into moves in spite of the player'
         TURN { EXPECT_MOVE(opponent, aiMove); }
     }
 }
+
+AI_SINGLE_BATTLE_TEST("AI won't use Sucker Punch if it expects a move of the same priority bracket and the opponent is faster")
+{
+    GIVEN {
+        ASSUME(gMovesInfo[MOVE_QUICK_ATTACK].priority == 1);
+        ASSUME(gMovesInfo[MOVE_SUCKER_PUNCH].priority == 1);
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_VIABILITY | AI_FLAG_TRY_TO_FAINT);
+        PLAYER(SPECIES_WOBBUFFET) { Speed(300); Moves(MOVE_QUICK_ATTACK); }
+        OPPONENT(SPECIES_WOBBUFFET) { Speed(100); Moves(MOVE_SUCKER_PUNCH, MOVE_TACKLE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_QUICK_ATTACK); EXPECT_MOVE(opponent, MOVE_SUCKER_PUNCH); }
+        TURN { MOVE(player, MOVE_QUICK_ATTACK); EXPECT_MOVE(opponent, MOVE_TACKLE); }
+    }
+}