PaperMC/nms-patches/ItemBlock.patch

--- a/net/minecraft/server/ItemBlock.java
+++ b/net/minecraft/server/ItemBlock.java
@@ -3,6 +3,11 @@
 import java.util.Iterator;
 import java.util.Map;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import org.bukkit.craftbukkit.block.CraftBlock;
+import org.bukkit.craftbukkit.block.data.CraftBlockData;
+import org.bukkit.event.block.BlockCanBuildEvent;
+// CraftBukkit end
 
 public class ItemBlock extends Item {
 
@@ -31,6 +36,12 @@
                 return EnumInteractionResult.FAIL;
             } else {
                 IBlockData iblockdata = this.c(blockactioncontext1);
+                // CraftBukkit start - special case for handling block placement with water lilies
+                org.bukkit.block.BlockState blockstate = null;
+                if (this instanceof ItemWaterLily) {
+                    blockstate = org.bukkit.craftbukkit.block.CraftBlockState.getBlockState(blockactioncontext1.getWorld(), blockactioncontext1.getClickPosition());
+                }
+                // CraftBukkit end
 
                 if (iblockdata == null) {
                     return EnumInteractionResult.FAIL;
@@ -48,6 +59,15 @@
                         iblockdata1 = this.a(blockposition, world, itemstack, iblockdata1);
                         this.a(blockposition, world, entityhuman, itemstack, iblockdata1);
                         block.postPlace(world, blockposition, iblockdata1, entityhuman, itemstack);
+                        // CraftBukkit start
+                        if (blockstate != null) {
+                            org.bukkit.event.block.BlockPlaceEvent placeEvent = org.bukkit.craftbukkit.event.CraftEventFactory.callBlockPlaceEvent((WorldServer) world, entityhuman, blockactioncontext1.getHand(), blockstate, blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                            if (placeEvent != null && (placeEvent.isCancelled() || !placeEvent.canBuild())) {
+                                blockstate.update(true, false);
+                                return EnumInteractionResult.FAIL;
+                            }
+                        }
+                        // CraftBukkit end
                         if (entityhuman instanceof EntityPlayer) {
                             CriterionTriggers.y.a((EntityPlayer) entityhuman, blockposition, itemstack);
                         }
@@ -55,8 +75,8 @@
 
                     SoundEffectType soundeffecttype = iblockdata1.getStepSound();
 
-                    world.playSound(entityhuman, blockposition, this.a(iblockdata1), SoundCategory.BLOCKS, (soundeffecttype.a() + 1.0F) / 2.0F, soundeffecttype.b() * 0.8F);
-                    if (entityhuman == null || !entityhuman.abilities.canInstantlyBuild) {
+                    // world.playSound(entityhuman, blockposition, this.a(iblockdata1), SoundCategory.BLOCKS, (soundeffecttype.a() + 1.0F) / 2.0F, soundeffecttype.b() * 0.8F);
+                    if ((entityhuman == null || !entityhuman.abilities.canInstantlyBuild) && itemstack != ItemStack.b) { // CraftBukkit
                         itemstack.subtract(1);
                     }
 
@@ -92,6 +112,21 @@
 
         if (nbttagcompound != null) {
             NBTTagCompound nbttagcompound1 = nbttagcompound.getCompound("BlockStateTag");
+            // CraftBukkit start
+            iblockdata1 = getBlockState(iblockdata1, nbttagcompound1);
+        }
+
+        if (iblockdata1 != iblockdata) {
+            world.setTypeAndData(blockposition, iblockdata1, 2);
+        }
+
+        return iblockdata1;
+    }
+
+    public static IBlockData getBlockState(IBlockData iblockdata, NBTTagCompound nbttagcompound1) {
+        IBlockData iblockdata1 = iblockdata;
+        {
+            // CraftBukkit end
             BlockStateList<Block, IBlockData> blockstatelist = iblockdata.getBlock().getStates();
             Iterator iterator = nbttagcompound1.getKeys().iterator();
 
@@ -106,11 +141,6 @@
                 }
             }
         }
-
-        if (iblockdata1 != iblockdata) {
-            world.setTypeAndData(blockposition, iblockdata1, 2);
-        }
-
         return iblockdata1;
     }
 
@@ -123,8 +153,15 @@
     protected boolean b(BlockActionContext blockactioncontext, IBlockData iblockdata) {
         EntityHuman entityhuman = blockactioncontext.getEntity();
         VoxelShapeCollision voxelshapecollision = entityhuman == null ? VoxelShapeCollision.a() : VoxelShapeCollision.a((Entity) entityhuman);
+        // CraftBukkit start - store default return
+        boolean defaultReturn = (!this.isCheckCollisions() || iblockdata.canPlace(blockactioncontext.getWorld(), blockactioncontext.getClickPosition())) && blockactioncontext.getWorld().a(iblockdata, blockactioncontext.getClickPosition(), voxelshapecollision);
+        org.bukkit.entity.Player player = (blockactioncontext.getEntity() instanceof EntityPlayer) ? (org.bukkit.entity.Player) blockactioncontext.getEntity().getBukkitEntity() : null;
+
+        BlockCanBuildEvent event = new BlockCanBuildEvent(CraftBlock.at(blockactioncontext.getWorld(), blockactioncontext.getClickPosition()), player, CraftBlockData.fromData(iblockdata), defaultReturn);
+        blockactioncontext.getWorld().getServer().getPluginManager().callEvent(event);
 
-        return (!this.isCheckCollisions() || iblockdata.canPlace(blockactioncontext.getWorld(), blockactioncontext.getClickPosition())) && blockactioncontext.getWorld().a(iblockdata, blockactioncontext.getClickPosition(), voxelshapecollision);
+        return event.isBuildable();
+        // CraftBukkit end
     }
 
     protected boolean isCheckCollisions() {