Make arcane lock work on both halves of a double chest at once

src/main/java/electroblob/wizardry/spell/ArcaneLock.java

@@ -47,28 +47,39 @@ public class ArcaneLock extends SpellRay {
 	protected boolean onBlockHit(World world, BlockPos pos, EnumFacing side, Vec3d hit, EntityLivingBase caster, Vec3d origin, int ticksInUse, SpellModifiers modifiers){
 		
 		if(caster instanceof EntityPlayer){
-			
-			TileEntity tileentity = world.getTileEntity(pos);
 
-			if(tileentity != null){
-
-				if(tileentity.getTileData().hasUniqueId(NBT_KEY)){
-					// Unlocking
-					if(world.getPlayerEntityByUUID(tileentity.getTileData().getUniqueId(NBT_KEY)) == caster){
-						NBTExtras.removeUniqueId(tileentity.getTileData(), NBT_KEY);
-						return true;
-					}
-				}else{
-					// Locking
-					tileentity.getTileData().setUniqueId(NBT_KEY, caster.getUniqueID());
-					return true;
-				}
+			if(toggleLock(world, pos, (EntityPlayer)caster)){
+				BlockPos otherHalf = WizardryUtilities.getConnectedChest(world, pos);
+				if(otherHalf != null) toggleLock(world, otherHalf, (EntityPlayer)caster);
+				return true;
 			}
 		}
 		
 		return false;
 	}
 
+	private boolean toggleLock(World world, BlockPos pos, EntityPlayer player){
+
+		TileEntity tileentity = world.getTileEntity(pos);
+
+		if(tileentity != null){
+
+			if(tileentity.getTileData().hasUniqueId(NBT_KEY)){
+				// Unlocking
+				if(world.getPlayerEntityByUUID(tileentity.getTileData().getUniqueId(NBT_KEY)) == player){
+					NBTExtras.removeUniqueId(tileentity.getTileData(), NBT_KEY);
+					return true;
+				}
+			}else{
+				// Locking
+				tileentity.getTileData().setUniqueId(NBT_KEY, player.getUniqueID());
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	@Override
 	protected boolean onMiss(World world, EntityLivingBase caster, Vec3d origin, Vec3d direction, int ticksInUse, SpellModifiers modifiers){
 		return false;

src/main/java/electroblob/wizardry/util/WizardryUtilities.java

@@ -9,6 +9,7 @@ import electroblob.wizardry.item.ISpellCastingItem;
 import electroblob.wizardry.spell.Spell;
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockCactus;
+import net.minecraft.block.BlockChest;
 import net.minecraft.block.BlockLog;
 import net.minecraft.block.properties.IProperty;
 import net.minecraft.block.state.IBlockState;
@@ -39,7 +40,6 @@ import javax.annotation.Nullable;
 import java.util.*;
 import java.util.function.BiPredicate;
 import java.util.function.Predicate;
-import java.util.stream.Collectors;
 
 /**
  * <i>"Where do you put random but useful bits and pieces? {@code WizardryUtilities} of course - the 'stuff that doesn't
@@ -307,6 +307,29 @@ public final class WizardryUtilities {
 				|| Settings.containsMetaBlock(Wizardry.settings.treeBlocks, world.getBlockState(pos));
 	}
 
+	/**
+	 * Given the position of one half of a double chest, returns the position of the other half of that double chest.
+	 * @param world The world in which the chest is located
+	 * @param pos The position of one half of the double chest
+	 * @return The position of the other half of the double chest, or null if the given position is not part of a
+	 * double chest.
+	 */
+	public static BlockPos getConnectedChest(World world, BlockPos pos){
+
+		Block block = world.getBlockState(pos).getBlock();
+
+		if(block instanceof BlockChest){
+			for(EnumFacing enumfacing : EnumFacing.Plane.HORIZONTAL){
+				BlockPos pos1 = pos.offset(enumfacing);
+				if(world.getBlockState(pos1).getBlock() == block){
+					return pos1;
+				}
+			}
+		}
+
+		return null;
+	}
+
 	/**
 	 * Finds the nearest floor level in the given direction from the given position,
 	 * within the range specified. This is a shorthand for