--- a/net/minecraft/server/ItemStack.java
+++ b/net/minecraft/server/ItemStack.java
@@ -16,6 +16,24 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+// CraftBukkit start
+import com.mojang.datafixers.Dynamic;
+import java.util.List;
+import java.util.Map;
+
+import org.bukkit.Location;
+import org.bukkit.TreeType;
+import org.bukkit.block.BlockState;
+import org.bukkit.craftbukkit.block.CraftBlock;
+import org.bukkit.craftbukkit.block.CraftBlockState;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.util.CraftMagicNumbers;
+import org.bukkit.entity.Player;
+import org.bukkit.event.block.BlockFertilizeEvent;
+import org.bukkit.event.player.PlayerItemDamageEvent;
+import org.bukkit.event.world.StructureGrowEvent;
+// CraftBukkit end
+
 public final class ItemStack {
 
     private static final Logger LOGGER = LogManager.getLogger();
@@ -54,23 +72,42 @@
         this.checkEmpty();
     }
 
+    // Called to run this stack through the data converter to handle older storage methods and serialized items
+    public void convertStack(int version) {
+        if (0 < version && version < CraftMagicNumbers.INSTANCE.getDataVersion()) {
+            NBTTagCompound savedStack = new NBTTagCompound();
+            this.save(savedStack);
+            savedStack = (NBTTagCompound) MinecraftServer.getServer().dataConverterManager.update(DataConverterTypes.ITEM_STACK, new Dynamic(DynamicOpsNBT.a, savedStack), version, CraftMagicNumbers.INSTANCE.getDataVersion()).getValue();
+            this.load(savedStack);
+        }
+    }
+
     private void checkEmpty() {
+        if (this.h && this == ItemStack.a) throw new AssertionError("TRAP"); // CraftBukkit
         this.h = false;
         this.h = this.isEmpty();
     }
 
-    private ItemStack(NBTTagCompound nbttagcompound) {
+    // CraftBukkit - break into own method
+    private void load(NBTTagCompound nbttagcompound) {
         this.item = (Item) IRegistry.ITEM.get(new MinecraftKey(nbttagcompound.getString("id")));
         this.count = nbttagcompound.getByte("Count");
         if (nbttagcompound.hasKeyOfType("tag", 10)) {
-            this.tag = nbttagcompound.getCompound("tag");
-            this.getItem().a(nbttagcompound);
+            // CraftBukkit start - make defensive copy as this data may be coming from the save thread
+            this.tag = (NBTTagCompound) nbttagcompound.getCompound("tag").clone();
+            this.getItem().a(this.tag);
+            // CraftBukkit end
         }
 
         if (this.getItem().usesDurability()) {
             this.setDamage(this.getDamage());
         }
 
+    }
+
+    private ItemStack(NBTTagCompound nbttagcompound) {
+        this.load(nbttagcompound);
+        // CraftBukkit end
         this.checkEmpty();
     }
 
@@ -100,7 +137,7 @@
         return this.h ? Items.AIR : this.item;
     }
 
-    public EnumInteractionResult placeItem(ItemActionContext itemactioncontext) {
+    public EnumInteractionResult placeItem(ItemActionContext itemactioncontext, EnumHand enumhand) { // CraftBukkit - add hand
         EntityHuman entityhuman = itemactioncontext.getEntity();
         BlockPosition blockposition = itemactioncontext.getClickPosition();
         ShapeDetectorBlock shapedetectorblock = new ShapeDetectorBlock(itemactioncontext.getWorld(), blockposition, false);
@@ -108,12 +145,153 @@
         if (entityhuman != null && !entityhuman.abilities.mayBuild && !this.b(itemactioncontext.getWorld().t(), shapedetectorblock)) {
             return EnumInteractionResult.PASS;
         } else {
+            // CraftBukkit start - handle all block place event logic here
+            NBTTagCompound oldData = this.getTagClone();
+            int oldCount = this.getCount();
+            World world = itemactioncontext.getWorld();
+
+            if (!(this.getItem() instanceof ItemBucket)) { // if not bucket
+                world.captureBlockStates = true;
+                // special case bonemeal
+                if (this.getItem() == Items.BONE_MEAL) {
+                    world.captureTreeGeneration = true;
+                }
+            }
             Item item = this.getItem();
             EnumInteractionResult enuminteractionresult = item.a(itemactioncontext);
+            NBTTagCompound newData = this.getTagClone();
+            int newCount = this.getCount();
+            this.setCount(oldCount);
+            this.setTagClone(oldData);
+            world.captureBlockStates = false;
+            if (enuminteractionresult == EnumInteractionResult.SUCCESS && world.captureTreeGeneration && world.capturedBlockStates.size() > 0) {
+                world.captureTreeGeneration = false;
+                Location location = new Location(world.getWorld(), blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                TreeType treeType = BlockSapling.treeType;
+                BlockSapling.treeType = null;
+                List<BlockState> blocks = new java.util.ArrayList<>(world.capturedBlockStates.values());
+                world.capturedBlockStates.clear();
+                StructureGrowEvent structureEvent = null;
+                if (treeType != null) {
+                    boolean isBonemeal = getItem() == Items.BONE_MEAL;
+                    structureEvent = new StructureGrowEvent(location, treeType, isBonemeal, (Player) entityhuman.getBukkitEntity(), blocks);
+                    org.bukkit.Bukkit.getPluginManager().callEvent(structureEvent);
+                }
+
+                BlockFertilizeEvent fertilizeEvent = new BlockFertilizeEvent(CraftBlock.at(world, blockposition), (Player) entityhuman.getBukkitEntity(), blocks);
+                fertilizeEvent.setCancelled(structureEvent != null && structureEvent.isCancelled());
+                org.bukkit.Bukkit.getPluginManager().callEvent(fertilizeEvent);
+
+                if (!fertilizeEvent.isCancelled()) {
+                    // Change the stack to its new contents if it hasn't been tampered with.
+                    if (this.getCount() == oldCount && Objects.equals(this.tag, oldData)) {
+                        this.setTag(newData);
+                        this.setCount(newCount);
+                    }
+                    for (BlockState blockstate : blocks) {
+                        blockstate.update(true);
+                    }
+                }
+
+                return enuminteractionresult;
+            }
+            world.captureTreeGeneration = false;
 
             if (entityhuman != null && enuminteractionresult == EnumInteractionResult.SUCCESS) {
-                entityhuman.b(StatisticList.ITEM_USED.b(item));
+                org.bukkit.event.block.BlockPlaceEvent placeEvent = null;
+                List<BlockState> blocks = new java.util.ArrayList<>(world.capturedBlockStates.values());
+                world.capturedBlockStates.clear();
+                if (blocks.size() > 1) {
+                    placeEvent = org.bukkit.craftbukkit.event.CraftEventFactory.callBlockMultiPlaceEvent(world, entityhuman, enumhand, blocks, blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                } else if (blocks.size() == 1) {
+                    placeEvent = org.bukkit.craftbukkit.event.CraftEventFactory.callBlockPlaceEvent(world, entityhuman, enumhand, blocks.get(0), blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                }
+
+                if (placeEvent != null && (placeEvent.isCancelled() || !placeEvent.canBuild())) {
+                    enuminteractionresult = EnumInteractionResult.FAIL; // cancel placement
+                    // PAIL: Remove this when MC-99075 fixed
+                    placeEvent.getPlayer().updateInventory();
+                    // revert back all captured blocks
+                    for (BlockState blockstate : blocks) {
+                        blockstate.update(true, false);
+                    }
+
+                    // Brute force all possible updates
+                    BlockPosition placedPos = ((CraftBlock) placeEvent.getBlock()).getPosition();
+                    for (EnumDirection dir : EnumDirection.values()) {
+                        ((EntityPlayer) entityhuman).playerConnection.sendPacket(new PacketPlayOutBlockChange(world, placedPos.shift(dir)));
+                    }
+                } else {
+                    // Change the stack to its new contents if it hasn't been tampered with.
+                    if (this.getCount() == oldCount && Objects.equals(this.tag, oldData)) {
+                        this.setTag(newData);
+                        this.setCount(newCount);
+                    }
+
+                    for (Map.Entry<BlockPosition, TileEntity> e : world.capturedTileEntities.entrySet()) {
+                        world.setTileEntity(e.getKey(), e.getValue());
+                    }
+
+                    for (BlockState blockstate : blocks) {
+                        int updateFlag = ((CraftBlockState) blockstate).getFlag();
+                        IBlockData oldBlock = ((CraftBlockState) blockstate).getHandle();
+                        BlockPosition newblockposition = ((CraftBlockState) blockstate).getPosition();
+                        IBlockData block = world.getType(newblockposition);
+
+                        if (!(block.getBlock() instanceof BlockTileEntity)) { // Containers get placed automatically
+                            block.getBlock().onPlace(block, world, newblockposition, oldBlock, true);
+                        }
+
+                        world.notifyAndUpdatePhysics(newblockposition, null, oldBlock, block, world.getType(newblockposition), updateFlag); // send null chunk as chunk.k() returns false by this point
+                    }
+
+                    // Special case juke boxes as they update their tile entity. Copied from ItemRecord.
+                    // PAIL: checkme on updates.
+                    if (this.item instanceof ItemRecord) {
+                        ((BlockJukeBox) Blocks.JUKEBOX).a(world, blockposition, world.getType(blockposition), this);
+                        world.a((EntityHuman) null, 1010, blockposition, Item.getId(this.item));
+                        this.subtract(1);
+                        entityhuman.a(StatisticList.PLAY_RECORD);
+                    }
+
+                    if (this.item == Items.WITHER_SKELETON_SKULL) { // Special case skulls to allow wither spawns to be cancelled
+                        BlockPosition bp = blockposition;
+                        if (!world.getType(blockposition).getMaterial().isReplaceable()) {
+                            if (!world.getType(blockposition).getMaterial().isBuildable()) {
+                                bp = null;
+                            } else {
+                                bp = bp.shift(itemactioncontext.getClickedFace());
+                            }
+                        }
+                        if (bp != null) {
+                            TileEntity te = world.getTileEntity(bp);
+                            if (te instanceof TileEntitySkull) {
+                                BlockWitherSkull.a(world, bp, (TileEntitySkull) te);
+                            }
+                        }
+                    }
+
+                    // SPIGOT-4678
+                    if (this.item instanceof ItemSign && ItemSign.openSign != null) {
+                        try {
+                            entityhuman.openSign((TileEntitySign) world.getTileEntity(ItemSign.openSign));
+                        } finally {
+                            ItemSign.openSign = null;
+                        }
+                    }
+
+                    // SPIGOT-1288 - play sound stripped from ItemBlock
+                    if (this.item instanceof ItemBlock) {
+                        SoundEffectType soundeffecttype = ((ItemBlock) this.item).getBlock().stepSound;
+                        world.playSound(entityhuman, blockposition, soundeffecttype.e(), SoundCategory.BLOCKS, (soundeffecttype.a() + 1.0F) / 2.0F, soundeffecttype.b() * 0.8F);
+                    }
+
+                    entityhuman.b(StatisticList.ITEM_USED.b(item));
+                }
             }
+            world.capturedTileEntities.clear();
+            world.capturedBlockStates.clear();
+            // CraftBukkit end
 
             return enuminteractionresult;
         }
@@ -194,6 +372,21 @@
                 }
 
                 i -= k;
+                // CraftBukkit start
+                if (entityplayer != null) {
+                    PlayerItemDamageEvent event = new PlayerItemDamageEvent(entityplayer.getBukkitEntity(), CraftItemStack.asCraftMirror(this), i);
+                    event.getPlayer().getServer().getPluginManager().callEvent(event);
+
+                    if (i != event.getDamage() || event.isCancelled()) {
+                        event.getPlayer().updateInventory();
+                    }
+                    if (event.isCancelled()) {
+                        return false;
+                    }
+
+                    i = event.getDamage();
+                }
+                // CraftBukkit end
                 if (i <= 0) {
                     return false;
                 }
@@ -215,6 +408,11 @@
                 if (this.isDamaged(i, t0.getRandom(), t0 instanceof EntityPlayer ? (EntityPlayer) t0 : null)) {
                     consumer.accept(t0);
                     Item item = this.getItem();
+                    // CraftBukkit start - Check for item breaking
+                    if (this.count == 1 && t0 instanceof EntityHuman) {
+                        org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerItemBreakEvent((EntityHuman) t0, this);
+                    }
+                    // CraftBukkit end
 
                     this.subtract(1);
                     if (t0 instanceof EntityHuman) {
@@ -346,6 +544,17 @@
         return this.tag;
     }
 
+    // CraftBukkit start
+    @Nullable
+    private NBTTagCompound getTagClone() {
+        return this.tag == null ? null : this.tag.clone();
+    }
+
+    private void setTagClone(@Nullable NBTTagCompound nbtttagcompound) {
+        this.setTag(nbtttagcompound == null ? null : nbtttagcompound.clone());
+    }
+    // CraftBukkit end
+
     public NBTTagCompound getOrCreateTag() {
         if (this.tag == null) {
             this.setTag(new NBTTagCompound());
@@ -498,6 +707,12 @@
     }
 
     public void setRepairCost(int i) {
+        // CraftBukkit start - remove RepairCost tag when 0 (SPIGOT-3945)
+        if (i == 0) {
+            this.removeTag("RepairCost");
+            return;
+        }
+        // CraftBukkit end
         this.getOrCreateTag().setInt("RepairCost", i);
     }
 
@@ -520,7 +735,7 @@
             object = this.getItem().a(enumitemslot);
         }
 
-        ((Multimap) object).values().forEach((attributemodifier1) -> {
+        ((Multimap<String, AttributeModifier>) object).values().forEach((attributemodifier1) -> { // CraftBukkit - decompile error
             attributemodifier1.a(false);
         });
         return (Multimap) object;
@@ -543,6 +758,13 @@
         nbttaglist.add(nbttagcompound);
     }
 
+    // CraftBukkit start
+    @Deprecated
+    public void setItem(Item item) {
+        this.item = item;
+    }
+    // CraftBukkit end
+
     public IChatBaseComponent B() {
         IChatBaseComponent ichatbasecomponent = (new ChatComponentText("")).addSibling(this.getName());
 
