From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Noah van der Aa <ndvdaa@gmail.com>
Date: Sun, 8 Aug 2021 19:56:02 +0200
Subject: [PATCH] Add CompostItemEvent and EntityCompostItemEvent


diff --git a/src/main/java/net/minecraft/world/level/block/ComposterBlock.java b/src/main/java/net/minecraft/world/level/block/ComposterBlock.java
index e81bda56c58df6c3109382c17e86f4cc0f16cf81..ae90e86327957bb784e2d81694ee7eea288bb455 100644
--- a/src/main/java/net/minecraft/world/level/block/ComposterBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/ComposterBlock.java
@@ -236,6 +236,9 @@ public class ComposterBlock extends Block implements WorldlyContainerHolder {
                     return InteractionResult.sidedSuccess(world.isClientSide);
                 }
                 BlockState iblockdata1 = ComposterBlock.addItem(player, state, world, pos, itemstack, rand);
+                if (iblockdata1 == null) {
+                    return InteractionResult.PASS;
+                }
                 // Paper end
 
                 world.levelEvent(1500, pos, state != iblockdata1 ? 1 : 0);
@@ -265,6 +268,11 @@ public class ComposterBlock extends Block implements WorldlyContainerHolder {
                 return state;
             }
             iblockdata1 = ComposterBlock.addItem(user, state, world, pos, stack, rand);
+            // Paper start
+            if (iblockdata1 == null) {
+                return state;
+            }
+            // Paper end
             // CraftBukkit end
 
             stack.shrink(1);
@@ -315,7 +323,22 @@ public class ComposterBlock extends Block implements WorldlyContainerHolder {
         int i = (Integer) iblockdata.getValue(ComposterBlock.LEVEL);
         float f = ComposterBlock.COMPOSTABLES.getFloat(itemstack.getItem());
 
-        if ((i != 0 || f <= 0.0F) && rand >= (double) f) {
+        // Paper start
+        boolean willRaiseLevel = !((i != 0 || f <= 0.0F) && rand >= (double) f);
+        if (generatoraccess == DummyGeneratorAccess.INSTANCE || entity == null) { // call event on test run or when entity is null (via hopper)
+            final io.papermc.paper.event.block.CompostItemEvent event;
+            if (entity == null) {
+                event = new io.papermc.paper.event.block.CompostItemEvent(org.bukkit.craftbukkit.block.CraftBlock.at(generatoraccess, blockposition), itemstack.getBukkitStack(), willRaiseLevel);
+            } else {
+                event = new io.papermc.paper.event.entity.EntityCompostItemEvent(entity.getBukkitEntity(), org.bukkit.craftbukkit.block.CraftBlock.at(generatoraccess, blockposition), itemstack.getBukkitStack(), willRaiseLevel);
+            }
+            if (!event.callEvent()) {
+                return null;
+            }
+            willRaiseLevel = event.willRaiseLevel();
+        }
+        if (!willRaiseLevel) {
+            // Paper end
             return iblockdata;
         } else {
             int j = i + 1;
@@ -460,6 +483,11 @@ public class ComposterBlock extends Block implements WorldlyContainerHolder {
                 this.changed = true;
                 BlockState iblockdata = ComposterBlock.addItem((Entity) null, this.state, this.level, this.pos, itemstack);
 
+                // Paper start
+                if (iblockdata == null) {
+                    return;
+                }
+                // Paper end
                 this.level.levelEvent(1500, this.pos, iblockdata != this.state ? 1 : 0);
                 this.removeItemNoUpdate(0);
             }