From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 9 Sep 2018 13:30:00 -0400
Subject: [PATCH] Mob Pathfinding API

Implements Pathfinding API for mobs

== AT ==
public net.minecraft.world.entity.ai.navigation.PathNavigation pathFinder
public net.minecraft.world.level.pathfinder.PathFinder nodeEvaluator
public net.minecraft.world.level.pathfinder.Path nodes

diff --git a/src/main/java/com/destroystokyo/paper/entity/PaperPathfinder.java b/src/main/java/com/destroystokyo/paper/entity/PaperPathfinder.java
new file mode 100644
index 0000000000000000000000000000000000000000..064712e7b27a200b29c72076a82f4f5611fa507f
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/entity/PaperPathfinder.java
@@ -0,0 +1,143 @@
+package com.destroystokyo.paper.entity;
+
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.entity.CraftLivingEntity;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.entity.Mob;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import net.minecraft.world.level.pathfinder.Node;
+import net.minecraft.world.level.pathfinder.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+public class PaperPathfinder implements com.destroystokyo.paper.entity.Pathfinder {
+
+    private net.minecraft.world.entity.Mob entity;
+
+    public PaperPathfinder(net.minecraft.world.entity.Mob entity) {
+        this.entity = entity;
+    }
+
+    @Override
+    public Mob getEntity() {
+        return entity.getBukkitMob();
+    }
+
+    public void setHandle(net.minecraft.world.entity.Mob entity) {
+        this.entity = entity;
+    }
+
+    @Override
+    public void stopPathfinding() {
+        entity.getNavigation().stop();
+    }
+
+    @Override
+    public boolean hasPath() {
+        return entity.getNavigation().getPath() != null && !entity.getNavigation().getPath().isDone();
+    }
+
+    @Nullable
+    @Override
+    public PathResult getCurrentPath() {
+        Path path = entity.getNavigation().getPath();
+        return path != null && !path.isDone() ? new PaperPathResult(path) : null;
+    }
+
+    @Nullable
+    @Override
+    public PathResult findPath(Location loc) {
+        Validate.notNull(loc, "Location can not be null");
+        Path path = entity.getNavigation().createPath(loc.getX(), loc.getY(), loc.getZ(), 0);
+        return path != null ? new PaperPathResult(path) : null;
+    }
+
+    @Nullable
+    @Override
+    public PathResult findPath(LivingEntity target) {
+        Validate.notNull(target, "Target can not be null");
+        Path path = entity.getNavigation().createPath(((CraftLivingEntity) target).getHandle(), 0);
+        return path != null ? new PaperPathResult(path) : null;
+    }
+
+    @Override
+    public boolean moveTo(@Nonnull PathResult path, double speed) {
+        Validate.notNull(path, "PathResult can not be null");
+        Path pathEntity = ((PaperPathResult) path).path;
+        return entity.getNavigation().moveTo(pathEntity, speed);
+    }
+
+    @Override
+    public boolean canOpenDoors() {
+        return entity.getNavigation().pathFinder.nodeEvaluator.canOpenDoors();
+    }
+
+    @Override
+    public void setCanOpenDoors(boolean canOpenDoors) {
+        entity.getNavigation().pathFinder.nodeEvaluator.setCanOpenDoors(canOpenDoors);
+    }
+
+    @Override
+    public boolean canPassDoors() {
+        return entity.getNavigation().pathFinder.nodeEvaluator.canPassDoors();
+    }
+
+    @Override
+    public void setCanPassDoors(boolean canPassDoors) {
+        entity.getNavigation().pathFinder.nodeEvaluator.setCanPassDoors(canPassDoors);
+    }
+
+    @Override
+    public boolean canFloat() {
+        return entity.getNavigation().pathFinder.nodeEvaluator.canFloat();
+    }
+
+    @Override
+    public void setCanFloat(boolean canFloat) {
+        entity.getNavigation().pathFinder.nodeEvaluator.setCanFloat(canFloat);
+    }
+
+    public class PaperPathResult implements com.destroystokyo.paper.entity.PaperPathfinder.PathResult {
+
+        private final Path path;
+        PaperPathResult(Path path) {
+            this.path = path;
+        }
+
+        @Nullable
+        @Override
+        public Location getFinalPoint() {
+            Node point = path.getEndNode();
+            return point != null ? toLoc(point) : null;
+        }
+
+        @Override
+        public List<Location> getPoints() {
+            List<Location> points = new ArrayList<>();
+            for (Node point : path.nodes) {
+                points.add(toLoc(point));
+            }
+            return points;
+        }
+
+        @Override
+        public int getNextPointIndex() {
+            return path.getNextNodeIndex();
+        }
+
+        @Nullable
+        @Override
+        public Location getNextPoint() {
+            if (!path.hasNext()) {
+                return null;
+            }
+            return toLoc(path.nodes.get(path.getNextNodeIndex()));
+        }
+    }
+
+    private Location toLoc(Node point) {
+        return new Location(entity.level().getWorld(), point.x, point.y, point.z);
+    }
+}
diff --git a/src/main/java/net/minecraft/world/level/pathfinder/Path.java b/src/main/java/net/minecraft/world/level/pathfinder/Path.java
index 539dc45c3c7ffc60cf3fb47ae4df65e604e8627b..eea4c932d909145e7af848cf76e3f49dbb2deff2 100644
--- a/src/main/java/net/minecraft/world/level/pathfinder/Path.java
+++ b/src/main/java/net/minecraft/world/level/pathfinder/Path.java
@@ -18,6 +18,7 @@ public class Path {
     private final BlockPos target;
     private final float distToTarget;
     private final boolean reached;
+    public boolean hasNext() { return getNextNodeIndex() < this.nodes.size(); } // Paper
 
     public Path(List<Node> nodes, BlockPos target, boolean reachesTarget) {
         this.nodes = nodes;
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
index 659ccb6532506b2a8c9feb55dc5aee962f6da795..f36713771598ac5afdae5d94db10a5790949611d 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
@@ -15,8 +15,11 @@ import org.bukkit.loot.LootTable;
 public abstract class CraftMob extends CraftLivingEntity implements Mob {
     public CraftMob(CraftServer server, net.minecraft.world.entity.Mob entity) {
         super(server, entity);
+         paperPathfinder = new com.destroystokyo.paper.entity.PaperPathfinder(entity); // Paper
     }
 
+    private final com.destroystokyo.paper.entity.PaperPathfinder paperPathfinder; // Paper
+    @Override public com.destroystokyo.paper.entity.Pathfinder getPathfinder() { return paperPathfinder; } // Paper
     @Override
     public void setTarget(LivingEntity target) {
         Preconditions.checkState(!this.getHandle().generation, "Cannot set target during world generation");
@@ -57,6 +60,14 @@ public abstract class CraftMob extends CraftLivingEntity implements Mob {
         return (net.minecraft.world.entity.Mob) entity;
     }
 
+    // Paper start
+    @Override
+    public void setHandle(net.minecraft.world.entity.Entity entity) {
+        super.setHandle(entity);
+        paperPathfinder.setHandle(getHandle());
+    }
+    // Paper end
+
     @Override
     public String toString() {
         return "CraftMob";