1 files changed, 174 insertions, 0 deletions
diff --git a/src/field/lottery_corner.c b/src/field/lottery_corner.c
new file mode 100644
index 000000000..c2c25b9ac
--- /dev/null
+++ b/src/field/lottery_corner.c
@@ -0,0 +1,174 @@
+#include "global.h"
+#include "lottery_corner.h"
+#include "event_data.h"
+#include "items.h"
+#include "rng.h"
+#include "species.h"
+#include "string_util.h"
+#include "text.h"
+
+extern u16 gScriptResult;
+extern u16 gSpecialVar_0x8004;
+extern struct PokemonStorage gPokemonStorage;
+extern u16 gSpecialVar_0x8005;
+extern u16 gSpecialVar_0x8006;
+static EWRAM_DATA u16 sWinNumberDigit = 0;
+static EWRAM_DATA u16 sOtIdDigit = 0;
+
+static const u16 sLotteryPrizes[] =
+{
+    ITEM_PP_UP,
+    ITEM_EXP_SHARE,
+    ITEM_MAX_REVIVE,
+    ITEM_MASTER_BALL,
+};
+
+static u8 GetMatchingDigits(u16, u16);
+
+void ResetLotteryCorner(void)
+{
+    u16 rand = Random();
+
+    SetLotteryNumber((Random() << 16) | rand);
+    VarSet(VAR_POKELOT_PRIZE, 0);
+}
+
+void SetRandomLotteryNumber(u16 i)
+{
+    u32 var = Random();
+
+    while (--i != 0xFFFF)
+        var = var * 1103515245 + 12345;
+
+    SetLotteryNumber(var);
+}
+
+void RetrieveLotteryNumber(void)
+{
+    u16 lottoNumber = GetLotteryNumber();
+    gScriptResult = lottoNumber;
+}
+
+void PickLotteryCornerTicket(void)
+{
+    u16 i;
+    u16 j;
+    u32 box;
+    u32 slot;
+
+    gSpecialVar_0x8004 = 0;
+    slot = 0;
+    box = 0;
+    for (i = 0; i < 6; i++)
+    {
+        struct Pokemon *pkmn = &gPlayerParty[i];
+
+        // UB: Too few arguments for function GetMonData
+        if (GetMonData(pkmn, MON_DATA_SPECIES) != SPECIES_NONE)
+        {
+            // do not calculate ticket values for eggs.
+            if (!GetMonData(pkmn, MON_DATA_IS_EGG))
+            {
+                u32 otId = GetMonData(pkmn, MON_DATA_OT_ID);
+                u8 numMatchingDigits = GetMatchingDigits(gScriptResult, otId);
+
+                if (numMatchingDigits > gSpecialVar_0x8004 && numMatchingDigits > 1)
+                {
+                    gSpecialVar_0x8004 = numMatchingDigits - 1;
+                    box = 14;
+                    slot = i;
+                }
+            }
+        }
+        else // pokemon are always arranged from populated spots first to unpopulated, so the moment a NONE species is found, that's the end of the list.
+            break;
+    }
+
+    // player has 14 boxes.
+    for (i = 0; i < 14; i++)
+    {
+        // player has 30 slots per box.
+        for (j = 0; j < 30; j++)
+        {
+            struct BoxPokemon *pkmn = &gPokemonStorage.boxes[i][j];
+
+            // UB: Too few arguments for function GetMonData
+            if (GetBoxMonData(pkmn, MON_DATA_SPECIES) != SPECIES_NONE &&
+            !GetBoxMonData(pkmn, MON_DATA_IS_EGG))
+            {
+                u32 otId = GetBoxMonData(pkmn, MON_DATA_OT_ID);
+                u8 numMatchingDigits = GetMatchingDigits(gScriptResult, otId);
+
+                if (numMatchingDigits > gSpecialVar_0x8004 && numMatchingDigits > 1)
+                {
+                    gSpecialVar_0x8004 = numMatchingDigits - 1;
+                    box = i;
+                    slot = j;
+                }
+            }
+        }
+    }
+
+    if (gSpecialVar_0x8004 != 0)
+    {
+        gSpecialVar_0x8005 = sLotteryPrizes[gSpecialVar_0x8004 - 1];
+
+        if (box == 14)
+        {
+            gSpecialVar_0x8006 = 0;
+            GetMonData(&gPlayerParty[slot], MON_DATA_NICKNAME, gStringVar1);
+        }
+        else
+        {
+            gSpecialVar_0x8006 = 1;
+            GetBoxMonData(&gPokemonStorage.boxes[box][slot], MON_DATA_NICKNAME, gStringVar1);
+        }
+        StringGetEnd10(gStringVar1);
+    }
+}
+
+static u8 GetMatchingDigits(u16 winNumber, u16 otId)
+{
+    u8 i;
+    u8 matchingDigits = 0;
+
+    for (i = 0; i < 5; i++)
+    {
+        sWinNumberDigit = winNumber % 10;
+        sOtIdDigit = otId % 10;
+
+        if (sWinNumberDigit == sOtIdDigit)
+        {
+            winNumber = winNumber / 10;
+            otId = otId / 10;
+            matchingDigits++;
+        }
+        else
+            break;
+    }
+    return matchingDigits;
+}
+
+// lottery numbers go from 0 to 99999, not 65535 (0xFFFF). interestingly enough, the function that calls GetLotteryNumber shifts to u16, so it cant be anything above 65535 anyway.
+void SetLotteryNumber(u32 lotteryNum)
+{
+    u16 lowNum = lotteryNum >> 16;
+    u16 highNum = lotteryNum;
+
+    VarSet(VAR_POKELOT_RND1, highNum);
+    VarSet(VAR_POKELOT_RND2, lowNum);
+}
+
+u32 GetLotteryNumber(void)
+{
+    u16 highNum = VarGet(VAR_POKELOT_RND1);
+    u16 lowNum = VarGet(VAR_POKELOT_RND2);
+
+    return (lowNum << 16) | highNum;
+}
+
+// interestingly, this may have been the original lottery number set function, but GF tried to change it to 32-bit later but didnt finish changing all calls as one GetLotteryNumber still shifts to u16.
+void SetLotteryNumber16_Unused(u16 lotteryNum)
+{
+    SetLotteryNumber(lotteryNum);
+}