From 0ee13418dc5c8867673fecab6e61c40fc6b78243 Mon Sep 17 00:00:00 2001
From: sbird <sbird@no.tld>
Date: Wed, 22 Sep 2021 13:15:43 +0200
Subject: [PATCH] [ai] use expected value move dmg calculation

---
 include/battle_script_commands.h |  1 +
 src/battle_ai_util.c             | 16 +++++++++++++---
 src/battle_script_commands.c     |  9 +++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/battle_script_commands.h b/include/battle_script_commands.h
index 2e6a0aa4eb..dec1596f21 100644
--- a/include/battle_script_commands.h
+++ b/include/battle_script_commands.h
@@ -13,6 +13,7 @@ struct StatFractions
 };
 
 s32 CalcCritChanceStage(u8 battlerAtk, u8 battlerDef, u32 move, bool32 recordAbility);
+s8 GetInverseCritChance(u8 battlerAtk, u8 battlerDef, u32 move);
 u32 GetTotalAccuracy(u32 battlerAtk, u32 battlerDef, u32 move);
 u8 GetBattlerTurnOrderNum(u8 battlerId);
 bool32 NoAliveMonsForEitherParty(void);
diff --git a/src/battle_ai_util.c b/src/battle_ai_util.c
index 48d3817c8e..b68c68e1bf 100644
--- a/src/battle_ai_util.c
+++ b/src/battle_ai_util.c
@@ -711,7 +711,8 @@ static bool32 AI_GetIfCrit(u32 move, u8 battlerAtk, u8 battlerDef)
 
 s32 AI_CalcDamage(u16 move, u8 battlerAtk, u8 battlerDef)
 {
-    s32 dmg, moveType;
+    s32 dmg, moveType, critDmg, normalDmg;
+    s8 critChance;
 
     SaveBattlerData(battlerAtk);
     SaveBattlerData(battlerDef);
@@ -722,7 +723,15 @@ s32 AI_CalcDamage(u16 move, u8 battlerAtk, u8 battlerDef)
     gBattleStruct->dynamicMoveType = 0;
     SetTypeBeforeUsingMove(move, battlerAtk);
     GET_MOVE_TYPE(move, moveType);
-    dmg = CalculateMoveDamage(move, battlerAtk, battlerDef, moveType, 0, AI_GetIfCrit(move, battlerAtk, battlerDef), FALSE, FALSE);
+
+    critChance = GetInverseCritChance(battlerAtk, battlerDef, move);
+    normalDmg = CalculateMoveDamage(move, battlerAtk, battlerDef, moveType, 0, FALSE, FALSE, FALSE);
+    critDmg = CalculateMoveDamage(move, battlerAtk, battlerDef, moveType, 0, TRUE, FALSE, FALSE);
+
+    if(critChance == -1)
+        dmg = normalDmg;
+    else
+        dmg = (critDmg + normalDmg * (critChance - 1)) / critChance;
 
     // handle dynamic move damage
     switch (gBattleMoves[move].effect)
@@ -749,7 +758,8 @@ s32 AI_CalcDamage(u16 move, u8 battlerAtk, u8 battlerDef)
     //case EFFECT_METAL_BURST:
     //case EFFECT_COUNTER:
     default:
-        dmg *= (100 - (Random() % 10)) / 100;   // add random factor
+        //do not add the random factor, it's an average case analysis
+        //dmg *= (100 - (Random() % 10)) / 100;   // add random factor
         break;
     }
 
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index e1d51bd05e..a10635e1a8 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -1822,6 +1822,15 @@ s32 CalcCritChanceStage(u8 battlerAtk, u8 battlerDef, u32 move, bool32 recordAbi
     return critChance;
 }
 
+s8 GetInverseCritChance(u8 battlerAtk, u8 battlerDef, u32 move)
+{
+    s32 critChanceIndex = CalcCritChanceStage(battlerAtk, battlerDef, move, FALSE);
+    if(critChanceIndex < 0)
+        return -1;
+    else
+        return sCriticalHitChance[critChanceIndex];
+}
+
 static void Cmd_critcalc(void)
 {
     s32 critChance = CalcCritChanceStage(gBattlerAttacker, gBattlerTarget, gCurrentMove, TRUE);