fix: enchantment table + frost walker (kinda)

fixes:
- treasure enchants being selectable within the enchantment table menu
- frost walker resemblance to decompiled legacy console edition
- enchantment table featuring hot-swappable abilities where the player could replace one tool with another whilst keeping the exact same potential enchantments in the enchant menu

Minecraft.World/Enchantment.cpp

@@ -94,7 +94,7 @@ void Enchantment::staticCtor()
 	for(unsigned int i = 0; i < 256; ++i)
 	{
 		Enchantment *enchantment = enchantments[i];
-		if (enchantment != nullptr && !enchantment->isTreasureEnchantment())
+		if (enchantment != nullptr && !enchantment->isTreasureOnly())
 		{
 			validEnchantments.push_back(enchantment);
 		}

Minecraft.World/Enchantment.h

@@ -85,9 +85,9 @@ public:
 	virtual int getDamageProtection(int level, DamageSource *source);
 	virtual float getDamageBonus(int level, shared_ptr<LivingEntity> target);
 	virtual bool isCompatibleWith(Enchantment *other) const;
-	virtual bool isTreasureEnchantment() const { return false; }
 	virtual Enchantment *setDescriptionId(int id);
 	virtual int getDescriptionId();
+	virtual bool isTreasureOnly() { return false; }
 	virtual HtmlString getFullname(int level);
 	virtual bool canEnchant(shared_ptr<ItemInstance> item);
 	// 4J Added

Minecraft.World/EnchantmentHelper.cpp

@@ -481,6 +481,11 @@ unordered_map<int, EnchantmentInstance *> *EnchantmentHelper::getAvailableEnchan
 			continue;
 		}
 
+		if (e->isTreasureOnly())
+		{
+			continue;
+		}
+
 		// Only picks "normal" enchantments, no specialcases
 		if (!e->category->canEnchant(item) && !isBook)
 		{

Minecraft.World/EnchantmentHelper.h

@@ -5,6 +5,7 @@ class Inventory;
 class DamageSource;
 class Enchantment;
 class EnchantmentInstance;
+class LivingEntity;
 
 class EnchantmentHelper
 {
@@ -50,6 +51,7 @@ private:
 	*/
 public:
 	static int getDamageProtection(ItemInstanceArray armor, DamageSource *source);
+	static bool hasFrostWalker(shared_ptr<LivingEntity> living);
 
 private:
 	class GetDamageBonusIteration : public EnchantmentIterationMethod

Minecraft.World/EnchantmentMenu.cpp

@@ -98,9 +98,36 @@ vector<EnchantmentInstance*> EnchantmentMenu::getEnchantment() {
 void EnchantmentMenu::slotsChanged(int a) // 4J used to take a shared_ptr<Container> container but wasn't using it, so removed to simplify things
 {
 	shared_ptr<ItemInstance> item = enchantSlots->getItem(0);
-
 	shared_ptr<ItemInstance> lapis = lapisSlot->getItem(1);
 
+	bool itemChanged = false;
+	if (item == nullptr || lastEnchantmentItem == nullptr)
+	{
+		itemChanged = (item == nullptr) != (lastEnchantmentItem == nullptr);
+	}
+	else if (item->id != lastEnchantmentItem->id || item->getDamageValue() != lastEnchantmentItem->getDamageValue())
+	{
+		itemChanged = true;
+	}
+
+	if (itemChanged)
+	{
+		alreadyRan = false;
+		for (int i = 0; i < 3; ++i)
+		{
+			if (cachedEnchantments[i] != nullptr)
+			{
+				for (EnchantmentInstance *cached : *cachedEnchantments[i])
+				{
+					delete cached;
+				}
+				cachedEnchantments[i]->clear();
+				delete cachedEnchantments[i];
+				cachedEnchantments[i] = nullptr;
+			}
+		}
+	}
+
 	if (item == nullptr || !item->isEnchantable())
 	{
 		if (!level->isClientSide)
@@ -220,6 +247,7 @@ void EnchantmentMenu::slotsChanged(int a) // 4J used to take a shared_ptr<Contai
 	}
 
 	wasLapis = lapis != nullptr;
+	lastEnchantmentItem = item;
 }
 
 bool EnchantmentMenu::clickMenuButton(shared_ptr<Player> player, int i)
@@ -257,6 +285,7 @@ bool EnchantmentMenu::clickMenuButton(shared_ptr<Player> player, int i)
 					delete e;
 				}
 				delete newEnchantment;
+				cachedEnchantments[i] = nullptr;
 				slotsChanged(1);// Removed enchantSlots parameter as the function can reference it directly
 			}
 		}

Minecraft.World/EnchantmentMenu.h

@@ -17,6 +17,7 @@ public:
 public:
 	shared_ptr<Container> enchantSlots;
 	shared_ptr<Container> lapisSlot;
+	shared_ptr<ItemInstance> lastEnchantmentItem;
 	bool alreadyRan = false;
 	bool en = false;
 	// Header

Minecraft.World/FrostWalkerEnchantment.cpp

@@ -2,9 +2,12 @@
 #include "net.minecraft.world.level.h"
 #include "net.minecraft.world.level.tile.h"
 #include "net.minecraft.world.entity.h"
+#include "net.minecraft.world.entity.player.h"
 #include "Material.h"
 #include "Mth.h"
+#include "BlockPos.h"
 #include "FrostWalkerEnchantment.h"
+#include "EnchantmentHelper.h"
 
 FrostWalkerEnchantment::FrostWalkerEnchantment(int id, int frequency) : Enchantment(id, frequency, EnchantmentCategory::armor_feet)
 {
@@ -26,38 +29,56 @@ int FrostWalkerEnchantment::getMaxLevel()
 	return 2;
 }
 
-void FrostWalkerEnchantment::freezeNearby(shared_ptr<LivingEntity> living, Level *level, int px, int py, int pz, int enchLevel)
+bool FrostWalkerEnchantment::isCompatibleWith(Enchantment *other) const
+{
+	if (!Enchantment::isCompatibleWith(other)) return false;
+	return other != Enchantment::waterWalker;
+}
+
+bool EnchantmentHelper::hasFrostWalker(shared_ptr<LivingEntity> living)
+{
+	return getFrostWalker(living) != 0;
+}
+
+void FrostWalkerEnchantment::onEntityMoved(shared_ptr<LivingEntity> living, Level *level, BlockPos pos, int enchLevel)
 {
 	if (!living->onGround) return;
 
-	int radius = 2 + enchLevel;
+	Player *player = dynamic_cast<Player *>(living.get());
+	if (player != nullptr && player->abilities.flying) return;
+
+	int radius = enchLevel + 2;
 	if (radius > 16) radius = 16;
-	float f = (float)radius;
-	int r = radius;
+	float f = static_cast<float>(radius);
 
-	for (int dx = -r; dx <= r; dx++)
+	BlockPos minPos = pos.offset(-radius, -1, -radius);
+	BlockPos maxPos = pos.offset(radius, -1, radius);
+
+	for (int x = minPos.getX(); x <= maxPos.getX(); ++x)
 	{
-		for (int dz = -r; dz <= r; dz++)
+		for (int y = minPos.getY(); y <= maxPos.getY(); ++y)
 		{
-			int bx = px + dx;
-			int by = py - 1;
-			int bz = pz + dz;
-
-			double ddx = (bx + 0.5) - living->x;
-			double ddy = (by + 0.5) - living->y;
-			double ddz = (bz + 0.5) - living->z;
-			if (ddx * ddx + ddy * ddy + ddz * ddz > (double)(f * f)) continue;
-
-			if (level->getTile(bx, by + 1, bz) != 0) continue;
-
-			Material *ground = level->getMaterial(bx, by, bz);
-			if (ground != Material::water) continue;
-			if (level->getData(bx, by, bz) != 0) continue;
-
-			if (Tile::frosted_ice->mayPlace(level, bx, by, bz))
+			for (int z = minPos.getZ(); z <= maxPos.getZ(); ++z)
 			{
-				level->setTileAndData(bx, by, bz, Tile::frosted_ice_Id, 0, Tile::UPDATE_ALL);
+				double dx = (x + 0.5) - living->x;
+				double dy = (y + 0.5) - living->y;
+				double dz = (z + 0.5) - living->z;
+				if (dx * dx + dy * dy + dz * dz > static_cast<double>(f * f)) continue;
+
+				if (level->getTile(x, y + 1, z) != 0) continue;
+
+				Material *ground = level->getMaterial(x, y, z);
+				if (ground != Material::water) continue;
+				if (level->getData(x, y, z) != 0) continue;
+
+				bool canPlace = level->mayPlace(Tile::frosted_ice_Id, x, y, z, false, 0, nullptr, nullptr);
+				if (!canPlace) continue;
+
+				level->setTileAndData(x, y, z, Tile::frosted_ice_Id, 0, Tile::UPDATE_ALL);
+
+				int ticks = Mth::nextInt(living->getRandom(), 60, 120);
+				level->addToTickNextTick(x, y, z, Tile::frosted_ice_Id, ticks);
 			}
 		}
 	}
-}
+}

Minecraft.World/FrostWalkerEnchantment.h

@@ -4,6 +4,7 @@
 
 class Level;
 class LivingEntity;
+class BlockPos;
 
 class FrostWalkerEnchantment : public Enchantment
 {
@@ -13,7 +14,9 @@ public:
 	virtual int getMinCost(int level) override;
 	virtual int getMaxCost(int level) override;
 	virtual int getMaxLevel() override;
-	virtual bool isTreasureEnchantment() const override { return true; }
+	virtual bool isCompatibleWith(Enchantment *other) const override;
+	virtual bool isTreasureOnly() override { return true; }
 
-	static void freezeNearby(shared_ptr<LivingEntity> living, Level *level, int px, int py, int pz, int enchLevel);
+	static void freezeNearby(shared_ptr<LivingEntity> living, Level *level, int x, int y, int z, int enchLevel);
+	static void onEntityMoved(shared_ptr<LivingEntity> living, Level *level, BlockPos pos, int enchLevel);
 };

Minecraft.World/LivingEntity.cpp

@@ -33,6 +33,8 @@
 #include "Dimension.h"
 #include "GenericStats.h"
 #include "ItemEntity.h"
+#include "TilePos.h"
+
 #if defined(_WINDOWS64) && defined(MINECRAFT_SERVER_BUILD)
 #include "../Minecraft.Server/FourKitBridge.h"
 #endif
@@ -296,17 +298,7 @@ void LivingEntity::baseTick()
 	tickEffects();
 
 	animStepO = animStep;
-
-	if (!level->isClientSide && isAlive())
-	{
-		int frostWalkerLevel = EnchantmentHelper::getFrostWalker(dynamic_pointer_cast<LivingEntity>(shared_from_this()));
-		if (frostWalkerLevel > 0)
-		{
-			FrostWalkerEnchantment::freezeNearby(dynamic_pointer_cast<LivingEntity>(shared_from_this()), level,
-				Mth::floor(x), Mth::floor(y), Mth::floor(z), frostWalkerLevel);
-		}
-	}
-
+	
 	yBodyRotO = yBodyRot;
 	yHeadRotO = yHeadRot;
 	yRotO = yRot;
@@ -1075,6 +1067,21 @@ int LivingEntity::getDeathSound()
 	return eSoundType_DAMAGE_HURT;
 }
 
+// frost walker-specific
+
+void LivingEntity::onChangedBlock(BlockPos pos)
+{
+	shared_ptr<LivingEntity> self = dynamic_pointer_cast<LivingEntity>(shared_from_this());
+
+	int frostWalkerLevel = EnchantmentHelper::getEnchantmentLevel(Enchantment::frostWalker->id, getEquipmentSlots());
+	if (frostWalkerLevel < 1)
+	{
+		return;
+	}
+
+	FrostWalkerEnchantment::onEntityMoved(self, level, pos, frostWalkerLevel);
+}
+
 /**
 * Drop extra rare loot. Only occurs roughly 5% of the time, rareRootLevel
 * is set to 1 (otherwise 0) 1% of the time.

Minecraft.World/LivingEntity.h

@@ -203,6 +203,7 @@ public:
 	virtual bool onLadder();
 	virtual bool isShootable();
 	virtual bool isAlive();
+	virtual void onChangedBlock(BlockPos pos);
 	virtual void causeFallDamage(float distance);
 	virtual void animateHurt();
 	virtual int getArmorValue();

Minecraft.World/MendingEnchantment.cpp

@@ -26,4 +26,4 @@ int MendingEnchantment::getMaxLevel()
 bool MendingEnchantment::canEnchant(shared_ptr<ItemInstance> item)
 {
 	return item->isDamageableItem();
-}
+}

Minecraft.World/MendingEnchantment.h

@@ -10,6 +10,6 @@ public:
 	virtual int getMinCost(int level) override;
 	virtual int getMaxCost(int level) override;
 	virtual int getMaxLevel() override;
-	virtual bool isTreasureEnchantment() const override { return true; }
+	virtual bool isTreasureOnly() override { return true; };
 	virtual bool canEnchant(shared_ptr<ItemInstance> item) override;
 };

Minecraft.World/Player.cpp

@@ -145,6 +145,7 @@ Player::Player(Level *level, const wstring &name) : LivingEntity( level )
 	Pos *spawnPos = level->getSharedSpawnPos();
 	moveTo(spawnPos->x + 0.5, spawnPos->y + 1, spawnPos->z + 0.5, 0, 0);
 	delete spawnPos;
+	lastChangedBlockPos = BlockPos(x, y, z);
 
 	rotOffs = 180;
 	flameTime = 20;
@@ -330,6 +331,13 @@ void Player::tick()
 
 	LivingEntity::tick();
 
+	BlockPos currentBlockPos(Mth::floor(x), Mth::floor(y), Mth::floor(z));
+	if (currentBlockPos != lastChangedBlockPos)
+	{
+		lastChangedBlockPos = currentBlockPos;
+		onChangedBlock(currentBlockPos);
+	}
+
 	if (!level->isClientSide)
 	{
 		if (containerMenu != nullptr && !containerMenu->stillValid( dynamic_pointer_cast<Player>( shared_from_this() ) ))
@@ -624,6 +632,14 @@ bool Player::isImmobile()
 	return getHealth() <= 0 || isSleeping();
 }
 
+void Player::onChangedBlock(BlockPos pos)
+{
+	if (true /*!isSpectator()*/) // spectator is not a thing yet
+	{
+		LivingEntity::onChangedBlock(pos);
+	}
+}
+
 void Player::closeContainer()
 {
 	containerMenu = inventoryMenu;

Minecraft.World/Player.h

@@ -8,6 +8,7 @@ using namespace std;
 #include "PlayerEnderChestContainer.h"
 #include "CommandSender.h"
 #include "ScoreHolder.h"
+#include "BlockPos.h"
 
 class AbstractContainerMenu;
 class Stats;
@@ -133,6 +134,7 @@ public:
 private:
 	int sleepCounter; // animation timer
 	int deathFadeCounter; // animation timer
+	BlockPos lastChangedBlockPos;
 
 public:
 	float bedOffsetX, bedOffsetY, bedOffsetZ;
@@ -207,6 +209,7 @@ protected:
 
 public:
 	virtual void handleEntityEvent(byte id);
+	void onChangedBlock(BlockPos pos);
 
 protected:
 	bool isImmobile();