From f38d3718c36838a187b39e5a4f785849b846c28d Mon Sep 17 00:00:00 2001
From: jglrxavpok <jglrxavpok@gmail.com>
Date: Fri, 1 May 2020 22:08:31 +0200
Subject: [PATCH] Neighbor updates

---
 .../java/fr/themode/demo/blocks/StoneBlock.java     |  9 ++++++++-
 .../minestom/server/instance/InstanceContainer.java | 12 ++++++++++++
 .../minestom/server/instance/block/CustomBlock.java | 13 +++++++++++++
 .../net/minestom/server/utils/BlockPosition.java    |  1 +
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/src/main/java/fr/themode/demo/blocks/StoneBlock.java b/src/main/java/fr/themode/demo/blocks/StoneBlock.java
index 798ea419d..ff4dcb859 100644
--- a/src/main/java/fr/themode/demo/blocks/StoneBlock.java
+++ b/src/main/java/fr/themode/demo/blocks/StoneBlock.java
@@ -15,7 +15,7 @@ public class StoneBlock extends CustomBlock {
 
     @Override
     public void onPlace(Instance instance, BlockPosition blockPosition, Data data) {
-        System.out.println("PLACED");
+        System.out.println("PLACED at "+blockPosition);
     }
 
     @Override
@@ -23,6 +23,13 @@ public class StoneBlock extends CustomBlock {
 
     }
 
+    @Override
+    public void updateFromNeighbor(Instance instance, BlockPosition thisPosition, BlockPosition neighborPosition, boolean directNeighbor) {
+        if(directNeighbor) {
+            System.out.println("Block at "+thisPosition+" has been updated by neighbor at "+neighborPosition);
+        }
+    }
+
     @Override
     public boolean onInteract(Player player, Player.Hand hand, BlockPosition blockPosition, Data data) {
         return false;
diff --git a/src/main/java/net/minestom/server/instance/InstanceContainer.java b/src/main/java/net/minestom/server/instance/InstanceContainer.java
index 5a0d446a8..b4768dab8 100644
--- a/src/main/java/net/minestom/server/instance/InstanceContainer.java
+++ b/src/main/java/net/minestom/server/instance/InstanceContainer.java
@@ -154,6 +154,18 @@ public class InstanceContainer extends Instance {
                             refreshBlockId(neighborX, neighborY, neighborZ, newNeighborId);
                         }
                     }
+
+                    // Update neighbors
+                    CustomBlock customBlock = getCustomBlock(neighborX, neighborY, neighborZ);
+                    if(customBlock != null) {
+                        boolean directNeighbor = false; // only if directly connected to neighbor (no diagonals)
+                        if(offsetX != 0 ^ offsetZ != 0) {
+                            directNeighbor = offsetY == 0;
+                        } else if(offsetX == 0 && offsetZ == 0) {
+                            directNeighbor = true;
+                        }
+                        customBlock.updateFromNeighbor(this, new BlockPosition(neighborX, neighborY, neighborZ), blockPosition, directNeighbor);
+                    }
                 }
             }
         }
diff --git a/src/main/java/net/minestom/server/instance/block/CustomBlock.java b/src/main/java/net/minestom/server/instance/block/CustomBlock.java
index d10d65fbe..106c60b86 100644
--- a/src/main/java/net/minestom/server/instance/block/CustomBlock.java
+++ b/src/main/java/net/minestom/server/instance/block/CustomBlock.java
@@ -91,4 +91,17 @@ public abstract class CustomBlock {
     public Data createData(Instance instance, BlockPosition blockPosition, Data data) {
         return data;
     }
+
+    /**
+     * Update this block from a neighbor. By default calls 'update' if directNeighbor is true
+     * @param instance current instance
+     * @param thisPosition this block's position
+     * @param neighborPosition the neighboring block which triggered the update
+     * @param directNeighbor is the neighbor directly connected to this block? (No diagonals)
+     */
+    public void updateFromNeighbor(Instance instance, BlockPosition thisPosition, BlockPosition neighborPosition, boolean directNeighbor) {
+        if(directNeighbor) {
+            update(instance, thisPosition, instance.getBlockData(thisPosition));
+        }
+    }
 }
diff --git a/src/main/java/net/minestom/server/utils/BlockPosition.java b/src/main/java/net/minestom/server/utils/BlockPosition.java
index b644d9af8..316f6902c 100644
--- a/src/main/java/net/minestom/server/utils/BlockPosition.java
+++ b/src/main/java/net/minestom/server/utils/BlockPosition.java
@@ -1,5 +1,6 @@
 package net.minestom.server.utils;
 
+// TODO: pool block positions?
 public class BlockPosition {
 
     private int x, y, z;