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 b81a5149720daf23d3d33f0aaae51216121ea2e2..2bd66da93227d4e4fc2ec4df47ae94b17f4d39d3 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
@@ -39,7 +39,7 @@ 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 - EntityPathfindEvent
     }
 
     @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 90a7940bf8b32cb245e9253d957cb437fa600857..2796df7af365c452b28373adfd7daf1d6730bac5 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
@@ -41,7 +41,7 @@ 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 - EntityPathfindEvent
         LevelChunk levelChunk = this.level
             .getChunkSource()
             .getChunkNow(SectionPos.blockToSectionCoord(target.getX()), SectionPos.blockToSectionCoord(target.getZ()));
@@ -56,7 +56,7 @@ public class GroundPathNavigation extends PathNavigation {
                 }
 
                 if (mutableBlockPos.getY() > this.level.getMinY()) {
-                    return super.createPath(mutableBlockPos.above(), distance);
+                    return super.createPath(mutableBlockPos.above(), entity, distance); // Paper - EntityPathfindEvent
                 }
 
                 mutableBlockPos.setY(target.getY() + 1);
@@ -69,7 +69,7 @@ public class GroundPathNavigation extends PathNavigation {
             }
 
             if (!levelChunk.getBlockState(target).isSolid()) {
-                return super.createPath(target, distance);
+                return super.createPath(target, entity, distance); // Paper - EntityPathfindEvent
             } else {
                 BlockPos.MutableBlockPos mutableBlockPos2 = target.mutable().move(Direction.UP);
 
@@ -77,14 +77,14 @@ public class GroundPathNavigation extends PathNavigation {
                     mutableBlockPos2.move(Direction.UP);
                 }
 
-                return super.createPath(mutableBlockPos2.immutable(), distance);
+                return super.createPath(mutableBlockPos2.immutable(), entity, distance);  // Paper - EntityPathfindEvent
             }
         }
     }
 
     @Override
     public Path createPath(Entity entity, int distance) {
-        return this.createPath(entity.blockPosition(), distance);
+        return this.createPath(entity.blockPosition(), entity, distance); // Paper - EntityPathfindEvent
     }
 
     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 7d3cb358fe543253e988531df3434ae1274814d3..1d5ce4caf99a3fb376b350968a6bd1ac8471ffec 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
@@ -125,7 +125,13 @@ public abstract class PathNavigation {
 
     @Nullable
     public Path createPath(BlockPos target, int distance) {
-        return this.createPath(ImmutableSet.of(target), 8, false, distance);
+        // Paper start - EntityPathfindEvent
+        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 - EntityPathfindEvent
     }
 
     @Nullable
@@ -135,7 +141,7 @@ 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 - EntityPathfindEvent
     }
 
     @Nullable
@@ -145,6 +151,17 @@ public abstract class PathNavigation {
 
     @Nullable
     protected Path createPath(Set<BlockPos> positions, int range, boolean useHeadPos, int distance, float followRange) {
+        // Paper start - EntityPathfindEvent
+        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 - EntityPathfindEvent
         if (positions.isEmpty()) {
             return null;
         } else if (this.mob.getY() < (double)this.level.getMinY()) {
@@ -154,6 +171,23 @@ public abstract class PathNavigation {
         } else if (this.path != null && !this.path.isDone() && positions.contains(this.targetPos)) {
             return this.path;
         } else {
+            // Paper start - EntityPathfindEvent
+            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 - EntityPathfindEvent
             ProfilerFiller profilerFiller = Profiler.get();
             profilerFiller.push("pathfind");
             BlockPos blockPos = useHeadPos ? this.mob.blockPosition().above() : this.mob.blockPosition();
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 1a1bc30b425858d82dbfb84b4a94d7793cab7125..5bbfa43d1e97970f035fcb101c3252c01ffead0d 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 - EntityPathfindEvent
         this.pathToPosition = target;
-        return super.createPath(target, distance);
+        return super.createPath(target, entity, distance); // Paper - EntityPathfindEvent
     }
 
     @Override