Add BlockBreakBlockEvent (#4989)

patches/api/Add-BlockBreakBlockEvent.patch

@@ -0,0 +1,71 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Sun, 3 Jan 2021 17:58:25 -0800
+Subject: [PATCH] Add BlockBreakBlockEvent
+
+
+diff --git a/src/main/java/io/papermc/paper/event/block/BlockBreakBlockEvent.java b/src/main/java/io/papermc/paper/event/block/BlockBreakBlockEvent.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
+--- /dev/null
++++ b/src/main/java/io/papermc/paper/event/block/BlockBreakBlockEvent.java
+@@ -0,0 +0,0 @@
++package io.papermc.paper.event.block;
++
++import org.bukkit.block.Block;
++import org.bukkit.event.HandlerList;
++import org.bukkit.event.block.BlockEvent;
++import org.bukkit.inventory.ItemStack;
++import org.jetbrains.annotations.NotNull;
++
++import java.util.List;
++
++/**
++ * Called when a block forces another block to break and drop items.
++ * <p>
++ * Currently called for piston's and liquid flows.
++ */
++public class BlockBreakBlockEvent extends BlockEvent {
++
++    private static final HandlerList HANDLER_LIST = new HandlerList();
++
++    private final List<ItemStack> drops;
++    private final Block source;
++
++    public BlockBreakBlockEvent(@NotNull Block block, @NotNull Block source, @NotNull List<ItemStack> drops) {
++        super(block);
++        this.source = source;
++        this.drops = drops;
++    }
++
++    /**
++     * Get the drops of this event
++     *
++     * @return the drops
++     */
++    @NotNull
++    public List<ItemStack> getDrops() {
++        return drops;
++    }
++
++    /**
++     * Gets the block that cause this (e.g. a piston, or adjacent liquid)
++     *
++     * @return the source
++     */
++    @NotNull
++    public Block getSource() {
++        return source;
++    }
++
++    @NotNull
++    @Override
++    public HandlerList getHandlers() {
++        return HANDLER_LIST;
++    }
++
++    @NotNull
++    public static HandlerList getHandlerList() {
++        return HANDLER_LIST;
++    }
++}

patches/server/Add-BlockBreakBlockEvent.patch

@@ -0,0 +1,86 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Sun, 3 Jan 2021 17:58:11 -0800
+Subject: [PATCH] Add BlockBreakBlockEvent
+
+
+diff --git a/src/main/java/net/minecraft/world/level/block/Block.java b/src/main/java/net/minecraft/world/level/block/Block.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/level/block/Block.java
++++ b/src/main/java/net/minecraft/world/level/block/Block.java
+@@ -0,0 +0,0 @@ public class Block extends BlockBehaviour implements ItemLike {
+         }
+ 
+     }
++    // Paper start
++    public static boolean dropResources(BlockState state, LevelAccessor world, BlockPos pos, @Nullable BlockEntity blockEntity, BlockPos source) {
++        if (world instanceof ServerLevel) {
++            List<org.bukkit.inventory.ItemStack> items = com.google.common.collect.Lists.newArrayList();
++            for (net.minecraft.world.item.ItemStack drop : net.minecraft.world.level.block.Block.getDrops(state, world.getMinecraftWorld(), pos, blockEntity)) {
++                items.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asBukkitCopy(drop));
++            }
++            io.papermc.paper.event.block.BlockBreakBlockEvent event = new io.papermc.paper.event.block.BlockBreakBlockEvent(org.bukkit.craftbukkit.block.CraftBlock.at(world, pos), org.bukkit.craftbukkit.block.CraftBlock.at(world, source), items);
++            event.callEvent();
++            for (var drop : event.getDrops()) {
++                popResource(world.getMinecraftWorld(), pos, org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(drop));
++            }
++            state.spawnAfterBreak(world.getMinecraftWorld(), pos, ItemStack.EMPTY);
++        }
++        return true;
++    }
++    // Paper end
+ 
+     public static void dropResources(BlockState state, Level world, BlockPos pos, @Nullable BlockEntity blockEntity, Entity entity, ItemStack stack) {
+         if (world instanceof ServerLevel) {
+diff --git a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
++++ b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
+@@ -0,0 +0,0 @@ public class PistonBaseBlock extends DirectionalBlock {
+                 iblockdata1 = world.getBlockState(blockposition3);
+                 BlockEntity tileentity = iblockdata1.hasBlockEntity() ? world.getBlockEntity(blockposition3) : null;
+ 
+-                dropResources(iblockdata1, (LevelAccessor) world, blockposition3, tileentity);
++                dropResources(iblockdata1, (LevelAccessor) world, blockposition3, tileentity, pos); // Paper
+                 world.setBlock(blockposition3, Blocks.AIR.defaultBlockState(), 18);
+                 if (!iblockdata1.is((Tag) BlockTags.FIRE)) {
+                     world.addDestroyBlockEffect(blockposition3, iblockdata1);
+diff --git a/src/main/java/net/minecraft/world/level/material/FlowingFluid.java b/src/main/java/net/minecraft/world/level/material/FlowingFluid.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/level/material/FlowingFluid.java
++++ b/src/main/java/net/minecraft/world/level/material/FlowingFluid.java
+@@ -0,0 +0,0 @@ public abstract class FlowingFluid extends Fluid {
+             ((LiquidBlockContainer) state.getBlock()).placeLiquid(world, pos, state, fluidState);
+         } else {
+             if (!state.isAir()) {
+-                this.beforeDestroyingBlock(world, pos, state);
++                this.beforeDestroyingBlock(world, pos, state, pos.relative(direction.getOpposite())); // Paper
+             }
+ 
+             world.setBlock(pos, fluidState.createLegacyBlock(), 3);
+@@ -0,0 +0,0 @@ public abstract class FlowingFluid extends Fluid {
+ 
+     }
+ 
++    protected void beforeDestroyingBlock(LevelAccessor world, BlockPos pos, BlockState state, BlockPos source) { beforeDestroyingBlock(world, pos, state); } // Paper - add source parameter
+     protected abstract void beforeDestroyingBlock(LevelAccessor world, BlockPos pos, BlockState state);
+ 
+     private static short getCacheKey(BlockPos blockposition, BlockPos blockposition1) {
+diff --git a/src/main/java/net/minecraft/world/level/material/WaterFluid.java b/src/main/java/net/minecraft/world/level/material/WaterFluid.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/level/material/WaterFluid.java
++++ b/src/main/java/net/minecraft/world/level/material/WaterFluid.java
+@@ -0,0 +0,0 @@ public abstract class WaterFluid extends FlowingFluid {
+         return true;
+     }
+ 
++    // Paper start
++    @Override
++    protected void beforeDestroyingBlock(LevelAccessor world, BlockPos pos, BlockState state,  BlockPos source) {
++        BlockEntity tileentity = state.hasBlockEntity() ? world.getBlockEntity(pos) : null;
++        Block.dropResources(state, world, pos, tileentity, source);
++    }
++    // Paper end
+     @Override
+     protected void beforeDestroyingBlock(LevelAccessor world, BlockPos pos, BlockState state) {
+         BlockEntity blockEntity = state.hasBlockEntity() ? world.getBlockEntity(pos) : null;