From 42343eac0abc983d8a61e91b5809fc7bde47e73f 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/server/Navigation.java b/src/main/java/net/minecraft/server/Navigation.java
index 3fdeda0cea..abf450917e 100644
--- a/src/main/java/net/minecraft/server/Navigation.java
+++ b/src/main/java/net/minecraft/server/Navigation.java
@@ -60,7 +60,7 @@ public class Navigation extends NavigationAbstract {
 
     @Override
     public PathEntity a(Entity entity, int i) {
-        return this.a(new BlockPosition(entity), i);
+        return this.a(new BlockPosition(entity), entity, i); // Paper - Forward target entity
     }
 
     private int t() {
diff --git a/src/main/java/net/minecraft/server/NavigationAbstract.java b/src/main/java/net/minecraft/server/NavigationAbstract.java
index a600ee7654..5e7158ba10 100644
--- a/src/main/java/net/minecraft/server/NavigationAbstract.java
+++ b/src/main/java/net/minecraft/server/NavigationAbstract.java
@@ -8,7 +8,7 @@ import javax.annotation.Nullable;
 
 public abstract class NavigationAbstract {
 
-    protected final EntityInsentient a;
+    protected final EntityInsentient a; public Entity getEntity() { return a; } // Paper - OBFHELPER
     protected final World b;
     @Nullable
     protected PathEntity c;
@@ -91,16 +91,26 @@ public abstract class NavigationAbstract {
 
     @Nullable
     public PathEntity a(BlockPosition blockposition, int i) {
-        return this.a(ImmutableSet.of(blockposition), 8, false, i);
+        // Paper start - add target parameter
+        return this.a(blockposition, null, i);
+    }
+    @Nullable public PathEntity a(BlockPosition blockposition, Entity target, int i) {
+        return this.a(ImmutableSet.of(blockposition), target, 8, false, i);
+        // Paper end
     }
 
     @Nullable
     public PathEntity a(Entity entity, int i) {
-        return this.a(ImmutableSet.of(new BlockPosition(entity)), 16, true, i);
+        return this.a(ImmutableSet.of(new BlockPosition(entity)), entity, 16, true, i); // Paper
     }
 
     @Nullable
+    // Paper start - Add target
     protected PathEntity a(Set<BlockPosition> set, int i, boolean flag, int j) {
+        return this.a(set, null, i, flag, j);
+    }
+    @Nullable protected PathEntity a(Set<BlockPosition> set, Entity target, int i, boolean flag, int j) {
+        // Paper end
         if (set.isEmpty()) {
             return null;
         } else if (this.a.locY() < 0.0D) {
@@ -110,6 +120,23 @@ public abstract class NavigationAbstract {
         } else if (this.c != null && !this.c.b() && set.contains(this.q)) {
             return this.c;
         } else {
+            // Paper start - Pathfind event
+            boolean copiedSet = false;
+            for (BlockPosition possibleTarget : set) {
+                if (!new com.destroystokyo.paper.event.entity.EntityPathfindEvent(getEntity().getBukkitEntity(),
+                    MCUtil.toLocation(getEntity().world, possibleTarget), target == null ? null : target.getBukkitEntity()).callEvent()) {
+                    if (!copiedSet) {
+                        copiedSet = true;
+                        set = new java.util.HashSet<>(set);
+                    }
+                    // note: since we copy the set this remove call is safe, since we're iterating over the old copy
+                    set.remove(possibleTarget);
+                    if (set.isEmpty()) {
+                        return null;
+                    }
+                }
+            }
+            // Paper end
             this.b.getMethodProfiler().enter("pathfind");
             float f = (float) this.p.getValue();
             BlockPosition blockposition = flag ? (new BlockPosition(this.a)).up() : new BlockPosition(this.a);
diff --git a/src/main/java/net/minecraft/server/NavigationFlying.java b/src/main/java/net/minecraft/server/NavigationFlying.java
index 5b057e96db..f16c6d1faa 100644
--- a/src/main/java/net/minecraft/server/NavigationFlying.java
+++ b/src/main/java/net/minecraft/server/NavigationFlying.java
@@ -25,7 +25,7 @@ public class NavigationFlying extends NavigationAbstract {
 
     @Override
     public PathEntity a(Entity entity, int i) {
-        return this.a(new BlockPosition(entity), i);
+        return this.a(new BlockPosition(entity), entity, i); // Paper - Forward target entity
     }
 
     @Override
-- 
2.26.2