From 36e77d2a5e32e3b1f86c31cf97c949bf2437671d Mon Sep 17 00:00:00 2001
From: tom-overton <tom.overton@outlook.com>
Date: Fri, 21 Oct 2022 04:39:33 -0700
Subject: Gen 2: Add support for Guaranteed Pokemon Catching

---
 src/com/sneed/pkrandom/config/gen2_offsets.ini     |  4 +++
 .../sneed/pkrandom/romhandlers/Gen2RomHandler.java | 35 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/com/sneed/pkrandom/config/gen2_offsets.ini b/src/com/sneed/pkrandom/config/gen2_offsets.ini
index daa3373..7033fe5 100755
--- a/src/com/sneed/pkrandom/config/gen2_offsets.ini
+++ b/src/com/sneed/pkrandom/config/gen2_offsets.ini
@@ -49,6 +49,7 @@ CatchingTutorialOffsets=[0x128DBB, 0x128DF1, 0x128E39]
 PicPointers=0x48000
 PokemonPalettes=0xAD3D
 TypeEffectivenessOffset=0x34D01
+GuaranteedCatchPrefix=D147FA19D1FE03
 StaticPokemonSupport=1
 GameCornerPokemonNameLength=11
 StaticPokemon{}={Species=[0x111772, 0x111775], Level=[0x111776]} // Lapras
@@ -195,6 +196,7 @@ MoveTutorMoves=[0x492B4, 0x492B7, 0x492B1]
 MoveTutorMenuOffset=0x19896C
 MoveTutorMenuNewSpace=0x19BB00
 TypeEffectivenessOffset=0x34BB1
+GuaranteedCatchPrefix=47FA30D2FE03
 StaticPokemonSupport=1
 GameCornerPokemonNameLength=11
 StaticPokemon{}={Species=[0x5A321, 0x5A324], Level=[0x5A325]} // Lapras
@@ -387,6 +389,7 @@ CatchingTutorialOffsets=[0xD1295, 0xD12CB, 0xD1313]
 PicPointers=0x48000
 PokemonPalettes=0xACC3
 TypeEffectivenessOffset=0x34CFD
+GuaranteedCatchPrefix=47FA0BD1FE03
 StaticPokemonSupport=0
 CRC32=524478D4
 
@@ -458,6 +461,7 @@ TextDelayFunctionOffset=0x3109
 PicPointers=0x120000
 PokemonPalettes=0xA88B
 TypeEffectivenessOffset=0x34BB1
+GuaranteedCatchPrefix=47FA61D2FE03
 StaticPokemonSupport=0
 IntroSpriteOffset=0x5FC2
 IntroCryOffset=0x60BE
diff --git a/src/com/sneed/pkrandom/romhandlers/Gen2RomHandler.java b/src/com/sneed/pkrandom/romhandlers/Gen2RomHandler.java
index ef2c6ac..ba34e74 100755
--- a/src/com/sneed/pkrandom/romhandlers/Gen2RomHandler.java
+++ b/src/com/sneed/pkrandom/romhandlers/Gen2RomHandler.java
@@ -80,6 +80,7 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
         private List<TMTextEntry> tmTexts = new ArrayList<>();
         private Map<String, Integer> entries = new HashMap<>();
         private Map<String, int[]> arrayEntries = new HashMap<>();
+        private Map<String, String> strings = new HashMap<>();
         private List<StaticPokemon> staticPokemon = new ArrayList<>();
 
         private int getValue(String key) {
@@ -88,6 +89,13 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
             }
             return entries.get(key);
         }
+
+        private String getString(String key) {
+            if (!strings.containsKey(key)) {
+                strings.put(key, "");
+            }
+            return strings.get(key);
+        }
     }
 
     private static class TMTextEntry {
@@ -166,6 +174,7 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
                                     boolean cTT = (current.getValue("CopyTMText") == 1);
                                     current.arrayEntries.putAll(otherEntry.arrayEntries);
                                     current.entries.putAll(otherEntry.entries);
+                                    current.strings.putAll(otherEntry.strings);
                                     if (cSP) {
                                         current.staticPokemon.addAll(otherEntry.staticPokemon);
                                         current.entries.put("StaticPokemonSupport", 1);
@@ -180,6 +189,8 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
                                     current.extraTableFile = otherEntry.extraTableFile;
                                 }
                             }
+                        } else if (r[0].endsWith("Locator") || r[0].endsWith("Prefix")) {
+                            current.strings.put(r[0], r[1]);
                         } else {
                             if (r[1].startsWith("[") && r[1].endsWith("]")) {
                                 String[] offsets = r[1].substring(1, r[1].length() - 1).split(",");
@@ -2215,6 +2226,9 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
             available |= MiscTweak.RANDOMIZE_CATCHING_TUTORIAL.getValue();
         }
         available |= MiscTweak.BAN_LUCKY_EGG.getValue();
+        if (romEntry.strings.containsKey("GuaranteedCatchPrefix")) {
+            available |= MiscTweak.GUARANTEED_POKEMON_CATCHING.getValue();
+        }
         return available;
     }
 
@@ -2233,6 +2247,8 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
             nonBadItems.banSingles(Gen2Items.luckyEgg);
         } else if (tweak == MiscTweak.UPDATE_TYPE_EFFECTIVENESS) {
             updateTypeEffectiveness();
+        } else if (tweak == MiscTweak.GUARANTEED_POKEMON_CATCHING) {
+            enableGuaranteedPokemonCatching();
         }
     }
 
@@ -2360,6 +2376,25 @@ public class Gen2RomHandler extends AbstractGBCRomHandler {
         }
     }
 
+    private void enableGuaranteedPokemonCatching() {
+        String prefix = romEntry.getString("GuaranteedCatchPrefix");
+        int offset = find(rom, prefix);
+        if (offset > 0) {
+            offset += prefix.length() / 2; // because it was a prefix
+
+            // The game guarantees that the catching tutorial always succeeds in catching by running
+            // the following code:
+            // ld a, [wBattleType]
+            // cp BATTLETYPE_TUTORIAL
+            // jp z, .catch_without_fail
+            // By making the jump here unconditional, we can ensure that catching always succeeds no
+            // matter the battle type. We check that the original condition is present just for safety.
+            if (rom[offset] == (byte)0xCA) {
+                rom[offset] = (byte)0xC3;
+            }
+        }
+    }
+
     @Override
     public void randomizeIntroPokemon() {
         // Intro sprite
-- 
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