PaperMC/paper-server/nms-patches/net/minecraft/world/entity/item/EntityItem.patch

--- a/net/minecraft/world/entity/item/EntityItem.java
+++ b/net/minecraft/world/entity/item/EntityItem.java
@@ -34,6 +34,15 @@
 import net.minecraft.world.level.portal.DimensionTransition;
 import net.minecraft.world.phys.Vec3D;
 
+// CraftBukkit start
+import net.minecraft.server.MinecraftServer;
+import org.bukkit.craftbukkit.event.CraftEventFactory;
+import org.bukkit.entity.Player;
+import org.bukkit.event.entity.EntityPickupItemEvent;
+import org.bukkit.event.entity.EntityRemoveEvent;
+import org.bukkit.event.player.PlayerPickupItemEvent;
+// CraftBukkit end
+
 public class EntityItem extends Entity implements TraceableEntity {
 
     private static final DataWatcherObject<ItemStack> DATA_ITEM = DataWatcher.defineId(EntityItem.class, DataWatcherRegistry.ITEM_STACK);
@@ -52,6 +61,7 @@
     @Nullable
     public UUID target;
     public final float bobOffs;
+    private int lastTick = MinecraftServer.currentTick - 1; // CraftBukkit
 
     public EntityItem(EntityTypes<? extends EntityItem> entitytypes, World world) {
         super(entitytypes, world);
@@ -133,12 +143,15 @@
     @Override
     public void tick() {
         if (this.getItem().isEmpty()) {
-            this.discard();
+            this.discard(EntityRemoveEvent.Cause.DESPAWN); // CraftBukkit - add Bukkit remove cause
         } else {
             super.tick();
-            if (this.pickupDelay > 0 && this.pickupDelay != 32767) {
-                --this.pickupDelay;
-            }
+            // CraftBukkit start - Use wall time for pickup and despawn timers
+            int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
+            if (this.pickupDelay != 32767) this.pickupDelay -= elapsedTicks;
+            if (this.age != -32768) this.age += elapsedTicks;
+            this.lastTick = MinecraftServer.currentTick;
+            // CraftBukkit end
 
             this.xo = this.getX();
             this.yo = this.getY();
@@ -187,9 +200,11 @@
                 this.mergeWithNeighbours();
             }
 
+            /* CraftBukkit start - moved up
             if (this.age != -32768) {
                 ++this.age;
             }
+            // CraftBukkit end */
 
             this.hasImpulse |= this.updateInWaterStateAndDoFluidPushing();
             if (!this.level().isClientSide) {
@@ -201,7 +216,13 @@
             }
 
             if (!this.level().isClientSide && this.age >= 6000) {
-                this.discard();
+                // CraftBukkit start - fire ItemDespawnEvent
+                if (CraftEventFactory.callItemDespawnEvent(this).isCancelled()) {
+                    this.age = 0;
+                    return;
+                }
+                // CraftBukkit end
+                this.discard(EntityRemoveEvent.Cause.DESPAWN); // CraftBukkit - add Bukkit remove cause
             }
 
         }
@@ -284,11 +305,16 @@
     }
 
     private static void merge(EntityItem entityitem, ItemStack itemstack, EntityItem entityitem1, ItemStack itemstack1) {
+        // CraftBukkit start
+        if (!CraftEventFactory.callItemMergeEvent(entityitem1, entityitem)) {
+            return;
+        }
+        // CraftBukkit end
         merge(entityitem, itemstack, itemstack1);
         entityitem.pickupDelay = Math.max(entityitem.pickupDelay, entityitem1.pickupDelay);
         entityitem.age = Math.min(entityitem.age, entityitem1.age);
         if (itemstack1.isEmpty()) {
-            entityitem1.discard();
+            entityitem1.discard(EntityRemoveEvent.Cause.MERGE); // CraftBukkit - add Bukkit remove cause);
         }
 
     }
@@ -309,12 +335,17 @@
         } else if (this.level().isClientSide) {
             return true;
         } else {
+            // CraftBukkit start
+            if (CraftEventFactory.handleNonLivingEntityDamageEvent(this, damagesource, f)) {
+                return false;
+            }
+            // CraftBukkit end
             this.markHurt();
             this.health = (int) ((float) this.health - f);
             this.gameEvent(GameEvent.ENTITY_DAMAGE, damagesource.getEntity());
             if (this.health <= 0) {
                 this.getItem().onDestroyed(this);
-                this.discard();
+                this.discard(EntityRemoveEvent.Cause.DEATH); // CraftBukkit - add Bukkit remove cause
             }
 
             return true;
@@ -366,7 +397,7 @@
         }
 
         if (this.getItem().isEmpty()) {
-            this.discard();
+            this.discard(null); // CraftBukkit - add Bukkit remove cause
         }
 
     }
@@ -378,10 +409,50 @@
             Item item = itemstack.getItem();
             int i = itemstack.getCount();
 
+            // CraftBukkit start - fire PlayerPickupItemEvent
+            int canHold = entityhuman.getInventory().canHold(itemstack);
+            int remaining = i - canHold;
+
+            if (this.pickupDelay <= 0 && canHold > 0) {
+                itemstack.setCount(canHold);
+                // Call legacy event
+                PlayerPickupItemEvent playerEvent = new PlayerPickupItemEvent((Player) entityhuman.getBukkitEntity(), (org.bukkit.entity.Item) this.getBukkitEntity(), remaining);
+                playerEvent.setCancelled(!playerEvent.getPlayer().getCanPickupItems());
+                this.level().getCraftServer().getPluginManager().callEvent(playerEvent);
+                if (playerEvent.isCancelled()) {
+                    itemstack.setCount(i); // SPIGOT-5294 - restore count
+                    return;
+                }
+
+                // Call newer event afterwards
+                EntityPickupItemEvent entityEvent = new EntityPickupItemEvent((Player) entityhuman.getBukkitEntity(), (org.bukkit.entity.Item) this.getBukkitEntity(), remaining);
+                entityEvent.setCancelled(!entityEvent.getEntity().getCanPickupItems());
+                this.level().getCraftServer().getPluginManager().callEvent(entityEvent);
+                if (entityEvent.isCancelled()) {
+                    itemstack.setCount(i); // SPIGOT-5294 - restore count
+                    return;
+                }
+
+                // Update the ItemStack if it was changed in the event
+                ItemStack current = this.getItem();
+                if (!itemstack.equals(current)) {
+                    itemstack = current;
+                } else {
+                    itemstack.setCount(canHold + remaining); // = i
+                }
+
+                // Possibly < 0; fix here so we do not have to modify code below
+                this.pickupDelay = 0;
+            } else if (this.pickupDelay == 0) {
+                // ensure that the code below isn't triggered if canHold says we can't pick the items up
+                this.pickupDelay = -1;
+            }
+            // CraftBukkit end
+
             if (this.pickupDelay == 0 && (this.target == null || this.target.equals(entityhuman.getUUID())) && entityhuman.getInventory().add(itemstack)) {
                 entityhuman.take(this, i);
                 if (itemstack.isEmpty()) {
-                    this.discard();
+                    this.discard(EntityRemoveEvent.Cause.PICKUP); // CraftBukkit - add Bukkit remove cause
                     itemstack.setCount(i);
                 }