AI knows how to handle Illusion (#2726)

* AI knows how to handle Illusion

include/battle.h

@@ -252,6 +252,7 @@ struct AI_SavedBattleMon
     u16 moves[MAX_MON_MOVES];
     u16 heldItem;
     u16 species;
+    u8 types[3];
 };
 
 struct AiPartyMon

src/battle_ai_util.c

@@ -538,23 +538,73 @@ void SaveBattlerData(u8 battlerId)
         AI_THINKING_STRUCT->saved[battlerId].species = gBattleMons[battlerId].species;
         for (i = 0; i < 4; i++)
             AI_THINKING_STRUCT->saved[battlerId].moves[i] = gBattleMons[battlerId].moves[i];
+        AI_THINKING_STRUCT->saved[battlerId].types[0] = gBattleMons[battlerId].type1;
+        AI_THINKING_STRUCT->saved[battlerId].types[1] = gBattleMons[battlerId].type2;
     }
 }
 
+static bool32 ShouldFailForIllusion(u16 illusionSpecies, u32 battlerId)
+{
+    u32 i, j;
+
+    if (BATTLE_HISTORY->abilities[battlerId] == ABILITY_ILLUSION)
+        return FALSE;
+
+    // Don't fall for Illusion if the mon used a move it cannot know.
+    for (i = 0; i < MAX_MON_MOVES; i++)
+    {
+        u16 move = BATTLE_HISTORY->usedMoves[battlerId][i];
+        if (move == MOVE_NONE)
+            continue;
+
+        for (j = 0; gLevelUpLearnsets[illusionSpecies][j].move != MOVE_UNAVAILABLE; j++)
+        {
+            if (gLevelUpLearnsets[illusionSpecies][j].move == move)
+                break;
+        }
+        // The used move is in the learnsets of the fake species.
+        if (gLevelUpLearnsets[illusionSpecies][j].move != MOVE_UNAVAILABLE)
+            continue;
+
+        // The used move can be learned from Tm/Hm or Move Tutors.
+        if (CanLearnTeachableMove(illusionSpecies, move))
+            continue;
+
+        // 'Illegal move', AI won't fail for the illusion.
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
 void SetBattlerData(u8 battlerId)
 {
     if (!IsBattlerAIControlled(battlerId))
     {
-        struct Pokemon *illusionMon;
+        u32 i, species, illusionSpecies;
-        u32 i;
+
+        // Simulate Illusion
+        species = gBattleMons[battlerId].species;
+        illusionSpecies = GetIllusionMonSpecies(battlerId);
+        if (illusionSpecies != SPECIES_NONE && ShouldFailForIllusion(illusionSpecies, battlerId))
+        {
+            // If the battler's type has not been changed, AI assumes the types of the illusion mon.
+            if (gBattleMons[battlerId].type1 == gSpeciesInfo[species].types[0]
+                && gBattleMons[battlerId].type2 == gSpeciesInfo[species].types[1])
+            {
+                gBattleMons[battlerId].type1 = gSpeciesInfo[illusionSpecies].types[0];
+                gBattleMons[battlerId].type2 = gSpeciesInfo[illusionSpecies].types[1];
+            }
+            species = illusionSpecies;
+        }
 
         // Use the known battler's ability.
         if (BATTLE_HISTORY->abilities[battlerId] != ABILITY_NONE)
             gBattleMons[battlerId].ability = BATTLE_HISTORY->abilities[battlerId];
         // Check if mon can only have one ability.
-        else if (gSpeciesInfo[gBattleMons[battlerId].species].abilities[1] == ABILITY_NONE
+        else if (gSpeciesInfo[species].abilities[1] == ABILITY_NONE
-                 || gSpeciesInfo[gBattleMons[battlerId].species].abilities[1] == gSpeciesInfo[gBattleMons[battlerId].species].abilities[0])
+                 || gSpeciesInfo[species].abilities[1] == gSpeciesInfo[species].abilities[0])
-            gBattleMons[battlerId].ability = gSpeciesInfo[gBattleMons[battlerId].species].abilities[0];
+            gBattleMons[battlerId].ability = gSpeciesInfo[species].abilities[0];
         // The ability is unknown.
         else
             gBattleMons[battlerId].ability = ABILITY_NONE;
@@ -567,10 +617,6 @@ void SetBattlerData(u8 battlerId)
             if (BATTLE_HISTORY->usedMoves[battlerId][i] == 0)
                 gBattleMons[battlerId].moves[i] = 0;
         }
-
-        // Simulate Illusion
-        if ((illusionMon = GetIllusionMonPtr(battlerId)) != NULL)
-            gBattleMons[battlerId].species = GetMonData(illusionMon, MON_DATA_SPECIES2);
     }
 }
 
@@ -585,6 +631,8 @@ void RestoreBattlerData(u8 battlerId)
         gBattleMons[battlerId].species = AI_THINKING_STRUCT->saved[battlerId].species;
         for (i = 0; i < 4; i++)
             gBattleMons[battlerId].moves[i] = AI_THINKING_STRUCT->saved[battlerId].moves[i];
+        gBattleMons[battlerId].type1 = AI_THINKING_STRUCT->saved[battlerId].types[0];
+        gBattleMons[battlerId].type2 = AI_THINKING_STRUCT->saved[battlerId].types[1];
     }
 }
 

src/battle_util.c

@@ -9817,6 +9817,18 @@ static void MulByTypeEffectiveness(u16 *modifier, u16 move, u8 moveType, u8 batt
     MulModifier(modifier, mod);
 }
 
+static void TryNoticeIllusionInTypeEffectiveness(u32 move, u32 moveType, u32 battlerAtk, u32 battlerDef, u16 resultingModifier, u32 illusionSpecies)
+{
+    // Check if the type effectiveness would've been different if the pokemon really had the types as the disguise.
+    u16 presumedModifier = UQ_4_12(1.0);
+    MulByTypeEffectiveness(&presumedModifier, move, moveType, battlerDef, gSpeciesInfo[illusionSpecies].types[0], battlerAtk, FALSE);
+    if (gSpeciesInfo[illusionSpecies].types[1] != gSpeciesInfo[illusionSpecies].types[0])
+        MulByTypeEffectiveness(&presumedModifier, move, moveType, battlerDef, gSpeciesInfo[illusionSpecies].types[1], battlerAtk, FALSE);
+
+    if (presumedModifier != resultingModifier)
+        RecordAbilityBattle(battlerDef, ABILITY_ILLUSION);
+}
+
 static void UpdateMoveResultFlags(u16 modifier)
 {
     if (modifier == UQ_4_12(0.0))
@@ -9842,6 +9854,7 @@ static void UpdateMoveResultFlags(u16 modifier)
 
 static u16 CalcTypeEffectivenessMultiplierInternal(u16 move, u8 moveType, u8 battlerAtk, u8 battlerDef, bool32 recordAbilities, u16 modifier)
 {
+    u32 illusionSpecies;
     u16 defAbility = GetBattlerAbility(battlerDef);
 
     MulByTypeEffectiveness(&modifier, move, moveType, battlerDef, gBattleMons[battlerDef].type1, battlerAtk, recordAbilities);
@@ -9851,15 +9864,18 @@ static u16 CalcTypeEffectivenessMultiplierInternal(u16 move, u8 moveType, u8 bat
         && gBattleMons[battlerDef].type3 != gBattleMons[battlerDef].type1)
         MulByTypeEffectiveness(&modifier, move, moveType, battlerDef, gBattleMons[battlerDef].type3, battlerAtk, recordAbilities);
 
+    if (recordAbilities && (illusionSpecies = GetIllusionMonSpecies(battlerDef)))
+        TryNoticeIllusionInTypeEffectiveness(move, moveType, battlerAtk, battlerDef, modifier, illusionSpecies);
+
     if (gBattleMoves[move].split == SPLIT_STATUS && move != MOVE_THUNDER_WAVE)
     {
         modifier = UQ_4_12(1.0);
-        #if B_GLARE_GHOST <= GEN_3
+    #if B_GLARE_GHOST <= GEN_3
-            if (move == MOVE_GLARE && IS_BATTLER_OF_TYPE(battlerDef, TYPE_GHOST))
+        if (move == MOVE_GLARE && IS_BATTLER_OF_TYPE(battlerDef, TYPE_GHOST))
-            {
+        {
-                modifier = UQ_4_12(0.0);
+            modifier = UQ_4_12(0.0);
-            }
+        }
-        #endif
+    #endif
     }
     else if (moveType == TYPE_GROUND && !IsBattlerGrounded2(battlerDef, TRUE) && !(gBattleMoves[move].flags & FLAG_DMG_UNGROUNDED_IGNORE_TYPE_IF_FLYING))
     {