Add piston events (#5798)

patches/minecraft/net/minecraft/block/PistonBlock.java.patch

@@ -1,6 +1,22 @@
 --- a/net/minecraft/block/PistonBlock.java
 +++ b/net/minecraft/block/PistonBlock.java
-@@ -197,7 +197,7 @@
+@@ -166,6 +166,7 @@
+       }
+ 
+       if (p_189539_4_ == 0) {
++         if(net.minecraftforge.event.ForgeEventFactory.onPistonMovePre(p_189539_2_, p_189539_3_, direction, true)) return false;
+          if (!this.func_176319_a(p_189539_2_, p_189539_3_, direction, true)) {
+             return false;
+          }
+@@ -173,6 +174,7 @@
+          p_189539_2_.func_180501_a(p_189539_3_, p_189539_1_.func_206870_a(field_176320_b, Boolean.valueOf(true)), 67);
+          p_189539_2_.func_184133_a((PlayerEntity)null, p_189539_3_, SoundEvents.field_187715_dR, SoundCategory.BLOCKS, 0.5F, p_189539_2_.field_73012_v.nextFloat() * 0.25F + 0.6F);
+       } else if (p_189539_4_ == 1 || p_189539_4_ == 2) {
++          if(net.minecraftforge.event.ForgeEventFactory.onPistonMovePre(p_189539_2_, p_189539_3_, direction, false)) return false;
+          TileEntity tileentity1 = p_189539_2_.func_175625_s(p_189539_3_.func_177972_a(direction));
+          if (tileentity1 instanceof PistonTileEntity) {
+             ((PistonTileEntity)tileentity1).func_145866_f();
+@@ -197,7 +199,7 @@
              }
  
              if (!flag1) {
@@ -9,7 +25,15 @@
                    p_189539_2_.func_217377_a(p_189539_3_.func_177972_a(direction), false);
                 } else {
                    this.func_176319_a(p_189539_2_, p_189539_3_, direction, false);
-@@ -238,7 +238,7 @@
+@@ -210,6 +212,7 @@
+          p_189539_2_.func_184133_a((PlayerEntity)null, p_189539_3_, SoundEvents.field_187712_dQ, SoundCategory.BLOCKS, 0.5F, p_189539_2_.field_73012_v.nextFloat() * 0.15F + 0.6F);
+       }
+ 
++      net.minecraftforge.event.ForgeEventFactory.onPistonMovePost(p_189539_2_, p_189539_3_, direction, (p_189539_4_ == 0));
+       return true;
+    }
+ 
+@@ -238,7 +241,7 @@
                 return false;
              }
  
@@ -18,7 +42,7 @@
           } else {
              return false;
           }
-@@ -274,7 +274,7 @@
+@@ -274,7 +277,7 @@
           for(int j = list2.size() - 1; j >= 0; --j) {
              BlockPos blockpos2 = list2.get(j);
              BlockState blockstate = p_176319_1_.func_180495_p(blockpos2);
@@ -27,7 +51,7 @@
              func_220059_a(blockstate, p_176319_1_, blockpos2, tileentity);
              p_176319_1_.func_180501_a(blockpos2, Blocks.field_150350_a.func_176223_P(), 18);
              --k;
-@@ -328,6 +328,10 @@
+@@ -328,6 +331,10 @@
        return p_185499_1_.func_206870_a(field_176387_N, p_185499_2_.func_185831_a(p_185499_1_.func_177229_b(field_176387_N)));
     }
  

src/main/java/net/minecraftforge/event/ForgeEventFactory.java

@@ -126,6 +126,7 @@ import net.minecraftforge.event.world.BlockEvent.NeighborNotifyEvent;
 import net.minecraftforge.event.world.ChunkWatchEvent;
 import net.minecraftforge.event.world.ExplosionEvent;
 import net.minecraftforge.event.world.GetCollisionBoxesEvent;
+import net.minecraftforge.event.world.PistonEvent;
 import net.minecraftforge.event.world.SaplingGrowTreeEvent;
 import net.minecraftforge.event.world.WorldEvent;
 import net.minecraftforge.eventbus.api.Event;
@@ -688,4 +689,14 @@ public class ForgeEventFactory
         else
             MinecraftForge.EVENT_BUS.post(new ChunkWatchEvent.UnWatch(entity, chunkpos, world));
     }
+
+    public static boolean onPistonMovePre(World world, BlockPos pos, Direction direction, boolean extending)
+    {
+        return MinecraftForge.EVENT_BUS.post(new PistonEvent.Pre(world, pos, direction, extending ? PistonEvent.PistonMoveType.EXTEND : PistonEvent.PistonMoveType.RETRACT));
+    }
+
+    public static boolean onPistonMovePost(World world, BlockPos pos, Direction direction, boolean extending)
+    {
+        return MinecraftForge.EVENT_BUS.post(new PistonEvent.Post(world, pos, direction, extending ? PistonEvent.PistonMoveType.EXTEND : PistonEvent.PistonMoveType.RETRACT));
+    }
 }

src/main/java/net/minecraftforge/event/world/PistonEvent.java

@@ -0,0 +1,128 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.event.world;
+
+import javax.annotation.Nullable;
+
+import net.minecraft.block.state.PistonBlockStructureHelper;
+import net.minecraft.util.Direction;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.World;
+import net.minecraftforge.eventbus.api.Cancelable;
+
+/**
+ * Base piston event, use {@link PistonEvent.Post} and {@link PistonEvent.Pre}
+ */
+public abstract class PistonEvent extends BlockEvent
+{
+
+    private final Direction direction;
+    private final PistonMoveType moveType;
+
+    /**
+     * @param world
+     * @param pos - The position of the piston
+     * @param direction - The direction of the piston
+     * @param direction - The move direction of the piston
+     */
+    public PistonEvent(World world, BlockPos pos, Direction direction, PistonMoveType moveType)
+    {
+        super(world, pos, world.getBlockState(pos));
+        this.direction = direction;
+        this.moveType = moveType;
+    }
+
+    /**
+     * @return The direction of the piston block
+     */
+    public Direction getDirection()
+    {
+        return this.direction;
+    }
+
+    /**
+     * Helper method that gets the piston position offset by its facing
+     */
+    public BlockPos getFaceOffsetPos()
+    {
+        return this.getPos().offset(direction);
+    }
+
+    /**
+     * @return The movement type of the piston (extension, retraction)
+     */
+    public PistonMoveType getPistonMoveType()
+    {
+        return moveType;
+    }
+
+    /**
+     * @return A piston structure helper for this movement. Returns null if the world stored is not a {@link World}
+     */
+    @Nullable
+    public PistonBlockStructureHelper getStructureHelper()
+    {
+        if(this.getWorld() instanceof World) {
+            return new PistonBlockStructureHelper((World) this.getWorld(), this.getPos(), this.getDirection(), this.getPistonMoveType().isExtend);
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Fires after the piston has moved and set surrounding states. This will not fire if {@link PistonEvent.Pre} is cancelled.
+     */
+    public static class Post extends PistonEvent
+    {
+
+        public Post(World world, BlockPos pos, Direction direction, PistonMoveType moveType)
+        {
+            super(world, pos, direction, moveType);
+        }
+
+    }
+
+    /**
+     * Fires before the piston has updated block states. Cancellation prevents movement.
+     */
+    @Cancelable
+    public static class Pre extends PistonEvent
+    {
+
+        public Pre(World world, BlockPos pos, Direction direction, PistonMoveType moveType)
+        {
+            super(world, pos, direction, moveType);
+        }
+
+    }
+
+    public static enum PistonMoveType
+    {
+        EXTEND(true), RETRACT(false);
+
+        public final boolean isExtend;
+
+        PistonMoveType(boolean isExtend)
+        {
+            this.isExtend = isExtend;
+        }
+    }
+
+}

src/test/java/net/minecraftforge/debug/block/PistonEventTest.java

@@ -0,0 +1,154 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.debug.block;
+
+import java.util.List;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
+import net.minecraft.block.PistonBlock;
+import net.minecraft.block.material.Material;
+import net.minecraft.block.state.PistonBlockStructureHelper;
+import net.minecraft.client.Minecraft;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.BlockItem;
+import net.minecraft.item.Item;
+import net.minecraft.item.ItemGroup;
+import net.minecraft.util.Direction;
+import net.minecraft.util.ResourceLocation;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.StringTextComponent;
+import net.minecraft.world.World;
+import net.minecraftforge.event.RegistryEvent;
+import net.minecraftforge.event.world.PistonEvent;
+import net.minecraftforge.event.world.PistonEvent.PistonMoveType;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.common.Mod;
+
+/**
+ * This test mod blocks pistons from moving cobblestone at all except indirectly
+ * This test mod adds a block that moves upwards when pushed by a piston
+ * This test mod informs the user what will happen the piston and affected blocks when changes are made
+ * This test mod makes black wool pushed by a piston drop after being pushed.
+ */
+@Mod.EventBusSubscriber(modid = PistonEventTest.MODID)
+@Mod(value = PistonEventTest.MODID)
+public class PistonEventTest
+{
+
+    public static final String MODID = "pistoneventtest";
+
+    private static Block shiftOnMove = new BlockShiftOnMove();
+
+    @SubscribeEvent
+    public static void regItem(RegistryEvent.Register<Item> event)
+    {
+        event.getRegistry().register(new BlockItem(shiftOnMove, new Item.Properties().group(ItemGroup.BUILDING_BLOCKS)).setRegistryName(shiftOnMove.getRegistryName()));
+    }
+
+    @SubscribeEvent
+    public static void regBlock(RegistryEvent.Register<Block> event)
+    {
+        event.getRegistry().register(shiftOnMove);
+    }
+
+    @SubscribeEvent
+    public static void pistonPre(PistonEvent.Pre event)
+    {
+        if (event.getPistonMoveType() == PistonMoveType.EXTEND)
+        {
+            World world = (World) event.getWorld();
+            PistonBlockStructureHelper pistonHelper = event.getStructureHelper();
+            if (world.isRemote)
+            {
+                PlayerEntity player = Minecraft.getInstance().player;
+                if (pistonHelper.canMove())
+                {
+                    player.sendMessage(new StringTextComponent(String.format("Piston will extend moving %d blocks and destroy %d blocks", pistonHelper.getBlocksToMove().size(), pistonHelper.getBlocksToDestroy().size())));
+                }
+                else
+                {
+                    player.sendMessage(new StringTextComponent("Piston won't extend"));
+                }
+            }
+
+            if (pistonHelper.canMove())
+            {
+                List<BlockPos> posList = pistonHelper.getBlocksToMove();
+                for (BlockPos newPos : posList)
+                {
+                    BlockState state = event.getWorld().getBlockState(newPos);
+                    if (state.getBlock() == Blocks.BLACK_WOOL)
+                    {
+                        Block.spawnDrops(state, world, newPos);
+                        world.setBlockState(newPos, Blocks.AIR.getDefaultState());
+                    }
+                }
+            }
+
+            // Make the block move up and out of the way so long as it won't replace the piston
+            BlockPos pushedBlockPos = event.getFaceOffsetPos();
+            if (world.getBlockState(pushedBlockPos).getBlock() == shiftOnMove && event.getDirection() != Direction.DOWN)
+            {
+                world.setBlockState(pushedBlockPos, Blocks.AIR.getDefaultState());
+                world.setBlockState(pushedBlockPos.up(), shiftOnMove.getDefaultState());
+            }
+
+            // Block pushing cobblestone (directly, indirectly works)
+            event.setCanceled(event.getWorld().getBlockState(event.getFaceOffsetPos()).getBlock() == Blocks.COBBLESTONE);
+        }
+        else
+        {
+            boolean isSticky = event.getWorld().getBlockState(event.getPos()).getBlock() == Blocks.STICKY_PISTON;
+            if (event.getWorld().isRemote())
+            {
+                PlayerEntity player = Minecraft.getInstance().player;
+                if (isSticky)
+                {
+                    BlockPos targetPos = event.getFaceOffsetPos().offset(event.getDirection());
+                    boolean canPush = PistonBlock.canPush(event.getWorld().getBlockState(targetPos), (World) event.getWorld(), event.getFaceOffsetPos(), event.getDirection().getOpposite(), false, event.getDirection());
+                    boolean isAir = event.getWorld().isAirBlock(targetPos);
+                    player.sendMessage(new StringTextComponent(String.format("Piston will retract moving %d blocks", !isAir && canPush ? 1 : 0)));
+                }
+                else
+                {
+                    player.sendMessage(new StringTextComponent("Piston will retract"));
+                }
+            }
+            // Offset twice to see if retraction will pull cobblestone
+            event.setCanceled(event.getWorld().getBlockState(event.getFaceOffsetPos().offset(event.getDirection())).getBlock() == Blocks.COBBLESTONE && isSticky);
+        }
+    }
+
+    public static class BlockShiftOnMove extends Block
+    {
+        public static String blockName = "shiftonmove";
+        public static ResourceLocation blockId = new ResourceLocation(MODID, blockName);
+
+        public BlockShiftOnMove()
+        {
+            super(Block.Properties.create(Material.ROCK));
+            this.setRegistryName(blockId);
+        }
+
+    }
+
+}