From f278abc76a779ff88ce52ea90d77d74e2edde3d4 Mon Sep 17 00:00:00 2001
From: David Kirchner <dpk@dpk.net>
Date: Thu, 5 Oct 2017 19:41:43 -0700
Subject: [PATCH] Only create a hopper "target" as long as the block is
 actually a hopper.

This fixes a bug that led to abandoned ArmorStands (what I was referring
to when I said "target") that lingered after the hopper was destroyed.
The issue was that tick (called asynchronously) was creating a new
ArmorStand (via InfusedHopper.getArmorStand()) after the block handler's
onBreak call removed the one that was created in onPlace.

The code that recreates the ArmorStand remains in tick() just in case,
somehow, it ends up getting removed by some other force. However, this
code should never be reached if the hopper itself is removed.

This fixes TheBusyBiscuit/Slimefun4#189,
fixes TheBusyBiscuit/Slimefun4#190, and
fixes TheBusyBiscuit/Slimefun4#428.
---
 .../mrCookieSlime/Slimefun/Setup/SlimefunSetup.java | 13 ++++++++++---
 .../Slimefun/holograms/InfusedHopper.java           |  6 +++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/me/mrCookieSlime/Slimefun/Setup/SlimefunSetup.java b/src/me/mrCookieSlime/Slimefun/Setup/SlimefunSetup.java
index 172349ebc..6cbb01772 100644
--- a/src/me/mrCookieSlime/Slimefun/Setup/SlimefunSetup.java
+++ b/src/me/mrCookieSlime/Slimefun/Setup/SlimefunSetup.java
@@ -4644,7 +4644,11 @@ public class SlimefunSetup {
 
 			@Override
 			public void tick(Block b, SlimefunItem item, Config data) {
-				ArmorStand hologram = InfusedHopper.getArmorStand(b);
+				if (b.getType() != Material.HOPPER) {
+					// we're no longer a hopper, we were probably destroyed. skipping this tick.
+					return;
+				}
+				ArmorStand hologram = InfusedHopper.getArmorStand(b, true);
 				boolean sound = false;
 				for (Entity n: hologram.getNearbyEntities(3.5D, 3.5D, 3.5D)) {
 					if (n instanceof Item && !n.hasMetadata("no_pickup") && n.getLocation().distance(hologram.getLocation()) > 0.4D) {
@@ -4666,12 +4670,15 @@ public class SlimefunSetup {
 
 			@Override
 			public void onPlace(Player p, Block b, SlimefunItem item) {
-				InfusedHopper.getArmorStand(b);
+				InfusedHopper.getArmorStand(b, true);
 			}
 
 			@Override
 			public boolean onBreak(Player p, Block b, SlimefunItem item, UnregisterReason reason) {
-				InfusedHopper.getArmorStand(b).remove();
+				final ArmorStand hologram = InfusedHopper.getArmorStand(b, false);
+				if (hologram != null) {
+					hologram.remove();
+				}
 				return true;
 			}
 		});
diff --git a/src/me/mrCookieSlime/Slimefun/holograms/InfusedHopper.java b/src/me/mrCookieSlime/Slimefun/holograms/InfusedHopper.java
index d6d860a4b..da1a5767e 100644
--- a/src/me/mrCookieSlime/Slimefun/holograms/InfusedHopper.java
+++ b/src/me/mrCookieSlime/Slimefun/holograms/InfusedHopper.java
@@ -11,7 +11,7 @@ public class InfusedHopper {
 	
 	private static final double offset = 1.2;
 	
-	public static ArmorStand getArmorStand(Block hopper) {
+	public static ArmorStand getArmorStand(Block hopper, boolean createIfNoneFound) {
 		Location l = new Location(hopper.getWorld(), hopper.getX() + 0.5, hopper.getY() + offset, hopper.getZ() + 0.5);
 		
 		for (Entity n: l.getChunk().getEntities()) {
@@ -19,6 +19,10 @@ public class InfusedHopper {
 				if (n.getCustomName() == null && l.distanceSquared(n.getLocation()) < 0.4D) return (ArmorStand) n;
 			}
 		}
+
+		if (!createIfNoneFound) {
+			return null;
+		}
 		
 		ArmorStand hologram = ArmorStandFactory.createHidden(l);
 		hologram.setCustomNameVisible(false);