Add a function to unlock the Egg Ticket for Japanese Pokémon Crystal

include/gen2/Gen2Common.h

@@ -12,6 +12,7 @@ typedef struct Gen2DistributionPokemon Gen2DistributionPokemon;
 
 // source: https://bulbapedia.bulbagarden.net/wiki/List_of_items_by_index_number_(Generation_II)
 #define CRYSTAL_ITEM_ID_GS_BALL 0x73
+#define CRYSTAL_ITEM_ID_EGG_TICKET 0x81
 
 // Based on https://github.com/kwsch/PKHeX/blob/master/PKHeX.Core/Resources/text/script/gen2/flags_c_en.txt
 // Look at this file to see more events
@@ -19,6 +20,7 @@ typedef struct Gen2DistributionPokemon Gen2DistributionPokemon;
 #define CRYSTAL_EVENTFLAG_KURT_READY_TO_RETURN_GSBALL 191
 #define CRYSTAL_EVENTFLAG_GSBALL_USABLE_IN_ILEX_FOREST_SHRINE 192
 #define CRYSTAL_EVENTFLAG_RECEIVED_GSBALL 832
+#define CRYSTAL_EVENTFLAG_EGG_TICKET 830
 #define CRYSTAL_GS_BALL_ENABLE_VALUE 0xB
 
 enum class Gen2GameType

include/gen2/Gen2GameReader.h

@@ -215,6 +215,11 @@ public:
      */
     void unlockGsBallEvent();
 
+    /**
+     * @brief This function unlocks the Egg Ticket in Japanese Pokémon Crystal saves.
+     */
+    void unlockEggTicketEvent();
+
     /**
      * @brief Retrieves the value of the given event flag
      * Hint: You can find the number and meaning of various event flags here:

src/gen2/Gen2GameReader.cpp

@@ -876,6 +876,20 @@ void Gen2GameReader::unlockGsBallEvent()
     saveManager_.writeByte(CRYSTAL_GS_BALL_ENABLE_VALUE);
 }
 
+void Gen2GameReader::unlockEggTicketEvent()
+{
+    if(!isGameCrystal() || getGameLanguage() != Gen2LocalizationLanguage::JAPANESE)
+    {
+        return;
+    }
+
+    // let's remove the Egg Ticket from the players' inventory first (if it exists)
+    Gen2ItemList itemList = getItemList(Gen2ItemListType::GEN2_ITEMLISTTYPE_KEYITEMPOCKET);
+    itemList.remove(CRYSTAL_ITEM_ID_EGG_TICKET);
+
+    setEventFlag(CRYSTAL_EVENTFLAG_EGG_TICKET, true);
+}
+
 bool Gen2GameReader::getEventFlag(uint16_t flagNumber)
 {
     const uint32_t saveOffset = gen2_getSRAMOffsets(gameType_, localization_).eventFlags;