From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 28 Mar 2016 21:22:26 -0400
Subject: [PATCH] EntityPathfindEvent

Fires when an Entity decides to start moving to a location.

diff --git a/src/main/java/net/minecraft/world/entity/ai/navigation/FlyingPathNavigation.java b/src/main/java/net/minecraft/world/entity/ai/navigation/FlyingPathNavigation.java
index a8f69e48937b3ebd2f57a4da747e6762c4a77934..acd0b946cab86eb173e713535194d3a9347c7d48 100644
--- a/src/main/java/net/minecraft/world/entity/ai/navigation/FlyingPathNavigation.java
+++ b/src/main/java/net/minecraft/world/entity/ai/navigation/FlyingPathNavigation.java
@@ -40,7 +40,7 @@ public class FlyingPathNavigation extends PathNavigation {
 
     @Override
     public Path createPath(Entity entity, int distance) {
-        return this.createPath(entity.blockPosition(), distance);
+        return this.createPath(entity.blockPosition(), entity, distance); // Paper - Forward target entity
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/entity/ai/navigation/GroundPathNavigation.java b/src/main/java/net/minecraft/world/entity/ai/navigation/GroundPathNavigation.java
index 518f47f52105e299e037fe2e7d5870d7555be4bc..71934af2dc4d209a9fbccfd36b5f2815ec196892 100644
--- a/src/main/java/net/minecraft/world/entity/ai/navigation/GroundPathNavigation.java
+++ b/src/main/java/net/minecraft/world/entity/ai/navigation/GroundPathNavigation.java
@@ -39,14 +39,14 @@ public class GroundPathNavigation extends PathNavigation {
     }
 
     @Override
-    public Path createPath(BlockPos target, int distance) {
+    public Path createPath(BlockPos target, @javax.annotation.Nullable Entity entity, int distance) { // Paper
         if (this.level.getBlockState(target).isAir()) {
             BlockPos blockPos;
             for(blockPos = target.below(); blockPos.getY() > this.level.getMinBuildHeight() && this.level.getBlockState(blockPos).isAir(); blockPos = blockPos.below()) {
             }
 
             if (blockPos.getY() > this.level.getMinBuildHeight()) {
-                return super.createPath(blockPos.above(), distance);
+                return super.createPath(blockPos.above(), entity, distance); // Paper
             }
 
             while(blockPos.getY() < this.level.getMaxBuildHeight() && this.level.getBlockState(blockPos).isAir()) {
@@ -57,19 +57,19 @@ public class GroundPathNavigation extends PathNavigation {
         }
 
         if (!this.level.getBlockState(target).isSolid()) {
-            return super.createPath(target, distance);
+            return super.createPath(target, entity, distance); // Paper
         } else {
             BlockPos blockPos2;
             for(blockPos2 = target.above(); blockPos2.getY() < this.level.getMaxBuildHeight() && this.level.getBlockState(blockPos2).isSolid(); blockPos2 = blockPos2.above()) {
             }
 
-            return super.createPath(blockPos2, distance);
+            return super.createPath(blockPos2, entity, distance); // Paper
         }
     }
 
     @Override
     public Path createPath(Entity entity, int distance) {
-        return this.createPath(entity.blockPosition(), distance);
+        return this.createPath(entity.blockPosition(), entity, distance); // Paper - Forward target entity
     }
 
     private int getSurfaceY() {
diff --git a/src/main/java/net/minecraft/world/entity/ai/navigation/PathNavigation.java b/src/main/java/net/minecraft/world/entity/ai/navigation/PathNavigation.java
index f16e9bcefedb582a4bfe7a0b7ec8a97799f5e5ad..1a69a46340eee4f0273c373cc1a40b4d069a89d4 100644
--- a/src/main/java/net/minecraft/world/entity/ai/navigation/PathNavigation.java
+++ b/src/main/java/net/minecraft/world/entity/ai/navigation/PathNavigation.java
@@ -110,7 +110,13 @@ public abstract class PathNavigation {
 
     @Nullable
     public Path createPath(BlockPos target, int distance) {
-        return this.createPath(ImmutableSet.of(target), 8, false, distance);
+        // Paper start - add target entity parameter
+        return this.createPath(target, null, distance);
+    }
+    @Nullable
+    public Path createPath(BlockPos target, @Nullable Entity entity, int distance) {
+        return this.createPath(ImmutableSet.of(target), entity, 8, false, distance);
+        // Paper end
     }
 
     @Nullable
@@ -120,7 +126,7 @@ public abstract class PathNavigation {
 
     @Nullable
     public Path createPath(Entity entity, int distance) {
-        return this.createPath(ImmutableSet.of(entity.blockPosition()), 16, true, distance);
+        return this.createPath(ImmutableSet.of(entity.blockPosition()), entity, 16, true, distance); // Paper
     }
 
     @Nullable
@@ -130,6 +136,16 @@ public abstract class PathNavigation {
 
     @Nullable
     protected Path createPath(Set<BlockPos> positions, int range, boolean useHeadPos, int distance, float followRange) {
+        return this.createPath(positions, null, range, useHeadPos, distance, followRange);
+    }
+
+    @Nullable
+    protected Path createPath(Set<BlockPos> positions, @Nullable Entity target, int range, boolean useHeadPos, int distance) {
+        return this.createPath(positions, target, range, useHeadPos, distance, (float) this.mob.getAttributeValue(Attributes.FOLLOW_RANGE));
+    }
+
+    @Nullable protected Path createPath(Set<BlockPos> positions, @Nullable Entity target, int range, boolean useHeadPos, int distance, float followRange) {
+        // Paper end
         if (positions.isEmpty()) {
             return null;
         } else if (this.mob.getY() < (double)this.level.getMinBuildHeight()) {
@@ -139,6 +155,23 @@ public abstract class PathNavigation {
         } else if (this.path != null && !this.path.isDone() && positions.contains(this.targetPos)) {
             return this.path;
         } else {
+            // Paper start - Pathfind event
+            boolean copiedSet = false;
+            for (BlockPos possibleTarget : positions) {
+                if (!new com.destroystokyo.paper.event.entity.EntityPathfindEvent(this.mob.getBukkitEntity(),
+                    io.papermc.paper.util.MCUtil.toLocation(this.mob.level(), possibleTarget), target == null ? null : target.getBukkitEntity()).callEvent()) {
+                    if (!copiedSet) {
+                        copiedSet = true;
+                        positions = new java.util.HashSet<>(positions);
+                    }
+                    // note: since we copy the set this remove call is safe, since we're iterating over the old copy
+                    positions.remove(possibleTarget);
+                    if (positions.isEmpty()) {
+                        return null;
+                    }
+                }
+            }
+            // Paper end
             this.level.getProfiler().push("pathfind");
             BlockPos blockPos = useHeadPos ? this.mob.blockPosition().above() : this.mob.blockPosition();
             int i = (int)(followRange + (float)range);
diff --git a/src/main/java/net/minecraft/world/entity/ai/navigation/WallClimberNavigation.java b/src/main/java/net/minecraft/world/entity/ai/navigation/WallClimberNavigation.java
index e9b49c72aa73dfcef6c136d9ed7bb5044fe8405d..2d1b2b84d7cf5bafe2cccfa0dec2bae805dbe7cf 100644
--- a/src/main/java/net/minecraft/world/entity/ai/navigation/WallClimberNavigation.java
+++ b/src/main/java/net/minecraft/world/entity/ai/navigation/WallClimberNavigation.java
@@ -16,9 +16,9 @@ public class WallClimberNavigation extends GroundPathNavigation {
     }
 
     @Override
-    public Path createPath(BlockPos target, int distance) {
+    public Path createPath(BlockPos target, @Nullable Entity entity, int distance) { // Paper
         this.pathToPosition = target;
-        return super.createPath(target, distance);
+        return super.createPath(target, entity, distance); // Paper
     }
 
     @Override