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 57a17458dbe1629ebbf58fea9f43f09511b91fb0..dda38820f763f93513b5d83a4239197b48a45238 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
@@ -35,7 +35,7 @@ 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 a9fd90d5282bd013e031b9d7481e3f777d6892c6..a6f8ca71ba5d107cfbd24b8e8a225195dc233637 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
@@ -69,7 +69,7 @@ public class GroundPathNavigation 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
     }
 
     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 6b47e7abe63c196ab17c5816fdb4f79a89225178..4335bd9d6413d56326be573f7c07c8cd0503d352 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
@@ -10,6 +10,7 @@ import net.minecraft.core.BlockPos;
 import net.minecraft.core.Vec3i;
 import net.minecraft.network.protocol.game.DebugPackets;
 import net.minecraft.tags.BlockTags;
+import net.minecraft.server.MCUtil;
 import net.minecraft.util.Mth;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.Mob;
@@ -106,7 +107,13 @@ 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, Entity entity, int distance) {
+        return this.createPath(ImmutableSet.of(target), entity, 8, false, distance);
+        // Paper end
     }
 
     @Nullable
@@ -116,7 +123,7 @@ 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
@@ -126,6 +133,16 @@ 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, (float) this.mob.getAttributeValue(Attributes.FOLLOW_RANGE));
+    }
+
+    @Nullable
+    protected Path createPath(Set<BlockPos> positions, 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, 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()) {
@@ -135,6 +152,23 @@ 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(),
+                    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);