Improve FollowEntityAI to recompute path only on demand

api/src/main/java/com/bartlomiejpluta/base/lib/ai/FollowEntityAI.java

@@ -4,47 +4,79 @@ import com.bartlomiejpluta.base.api.ai.AI;
 import com.bartlomiejpluta.base.api.ai.NPC;
 import com.bartlomiejpluta.base.api.entity.Entity;
 import com.bartlomiejpluta.base.api.map.layer.object.ObjectLayer;
-import com.bartlomiejpluta.base.api.move.Direction;
+import com.bartlomiejpluta.base.api.move.MoveEvent;
+import com.bartlomiejpluta.base.util.path.MovementPath;
+import com.bartlomiejpluta.base.util.path.PathExecutor;
 import com.bartlomiejpluta.base.util.pathfinder.PathFinder;
-import org.joml.Vector2i;
+import lombok.NonNull;
+import lombok.Setter;
 
-public class FollowEntityAI implements AI {
-   private final NPC npc;
-   private final Entity target;
-   private final PathFinder pathFinder;
-   private final int range;
+public abstract class FollowEntityAI<N extends NPC, T extends Entity> implements AI {
 
-   private final float recalculateInterval;
-   private float accumulator = 0.0f;
+   private final PathFinder finder;
+   private final PathExecutor<N> executor;
+   private final N npc;
+   private final T target;
 
-   public FollowEntityAI(PathFinder pathFinder, float recalculateInterval, NPC npc, Entity target, int range) {
-      this.pathFinder = pathFinder;
-      this.recalculateInterval = recalculateInterval;
+   @Setter
+   private AI idleAI;
+
+   @Setter
+   private int range = 20;
+
+   private MovementPath<N> path = null;
+
+   protected FollowEntityAI(@NonNull PathFinder finder, @NonNull N npc, @NonNull T target) {
+      this.finder = finder;
       this.npc = npc;
-      this.range = range;
       this.target = target;
+      this.executor = new PathExecutor<>(npc);
+   }
+
+   public void recomputePath() {
+      path = null;
+   }
+
+   public void recomputePath(@NonNull MoveEvent event) {
+      var movable = event.getMovable();
+
+      // Refresh only when target has been displaced
+      // or another entity is blocking current path
+      if (movable == target || (path != null && path.contains(movable))) {
+         path = null;
+      }
    }
 
    @Override
    public void nextActivity(ObjectLayer layer, float dt) {
-      var distance = npc.manhattanDistance(target);
+      if (!npc.isMoving()) {
+         var distance = npc.manhattanDistance(target);
 
-      if (!npc.isMoving() && 1 < distance && distance < range && accumulator >= recalculateInterval) {
-         var path = pathFinder.findSequence(layer, npc.getCoordinates(), target.getCoordinates());
+         if (distance == 1) {
+            npc.setFaceDirection(npc.getDirectionTowards(target));
+            interact(npc, target);
+         } else if (distance < range) {
+            follow(npc, target);
 
-         if (!path.isEmpty()) {
-            accumulator = recalculateInterval;
+            if (path == null) {
+               path = finder.findPath(layer, npc, target.getCoordinates());
+               executor.setPath(path);
+            }
 
-            var node = path.getFirst().sub(npc.getCoordinates(), new Vector2i());
-            var direction = Direction.ofVector(node);
-            var movement = npc.prepareMovement(direction);
-            layer.pushMovement(movement);
+            executor.execute(layer, dt);
          } else {
-            accumulator = 0.0f;
+            idle(npc, target);
+
+            if (idleAI != null) {
+               idleAI.nextActivity(layer, dt);
+            }
          }
-
       }
-
-      accumulator += dt;
    }
+
+   protected abstract void interact(N npc, T target);
+
+   protected abstract void follow(N npc, T target);
+
+   protected abstract void idle(N npc, T target);
 }

api/src/main/java/com/bartlomiejpluta/base/util/path/EntityPath.java

@@ -1,48 +1,48 @@
 package com.bartlomiejpluta.base.util.path;
 
-import com.bartlomiejpluta.base.api.ai.NPC;
+import com.bartlomiejpluta.base.api.entity.Entity;
 import com.bartlomiejpluta.base.api.move.Direction;
 import lombok.Getter;
 
 import java.util.ArrayList;
 import java.util.List;
 
-public class NPCPath<T extends NPC> implements Path<T> {
+public class EntityPath<T extends Entity> implements Path<T> {
 
    @Getter
    private final List<PathSegment<T>> path = new ArrayList<>();
 
-   public NPCPath<T> add(PathSegment<T> segment) {
+   public EntityPath<T> add(PathSegment<T> segment) {
       path.add(segment);
       return this;
    }
 
-   public NPCPath<T> addFirst(PathSegment<T> segment) {
+   public EntityPath<T> addFirst(PathSegment<T> segment) {
       path.add(0, segment);
       return this;
    }
 
-   public NPCPath<T> move(Direction direction) {
+   public EntityPath<T> move(Direction direction) {
       path.add(new MoveSegment<>(direction));
       return this;
    }
 
-   public NPCPath<T> move(Direction direction, boolean ignore) {
+   public EntityPath<T> move(Direction direction, boolean ignore) {
       path.add(new MoveSegment<>(direction, ignore));
       return this;
    }
 
-   public NPCPath<T> turn(Direction direction) {
+   public EntityPath<T> turn(Direction direction) {
       path.add(new TurnSegment<>(direction));
       return this;
    }
 
-   public NPCPath<T> wait(float seconds) {
+   public EntityPath<T> wait(float seconds) {
       path.add(new WaitSegment<>(seconds));
       return this;
    }
 
-   public NPCPath<T> run(Runnable runnable) {
+   public EntityPath<T> run(Runnable runnable) {
       path.add(new RunSegment<>(runnable));
       return this;
    }

api/src/main/java/com/bartlomiejpluta/base/util/path/MovementPath.java

@@ -2,6 +2,7 @@ package com.bartlomiejpluta.base.util.path;
 
 import com.bartlomiejpluta.base.api.move.Direction;
 import com.bartlomiejpluta.base.api.move.Movable;
+import org.joml.Vector2ic;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -24,6 +25,28 @@ public class MovementPath<T extends Movable> implements Path<T> {
       return this;
    }
 
+   public boolean contains(Movable movable) {
+      var coordinates = movable.getCoordinates();
+
+      for (var segment : path) {
+         if (segment.x == coordinates.x() && segment.y == coordinates.y()) {
+            return true;
+         }
+      }
+
+      return false;
+   }
+
+   public boolean contains(Vector2ic vector) {
+      for (var segment : path) {
+         if (segment.x == vector.x() && segment.y == vector.y()) {
+            return true;
+         }
+      }
+
+      return false;
+   }
+
    public boolean contains(int x, int y) {
       for (var segment : path) {
          if (segment.x == x && segment.y == y) {

api/src/main/java/com/bartlomiejpluta/base/util/path/TurnSegment.java

@@ -1,12 +1,12 @@
 package com.bartlomiejpluta.base.util.path;
 
-import com.bartlomiejpluta.base.api.ai.NPC;
+import com.bartlomiejpluta.base.api.entity.Entity;
 import com.bartlomiejpluta.base.api.map.layer.object.ObjectLayer;
 import com.bartlomiejpluta.base.api.move.Direction;
 
 import static java.util.Objects.requireNonNull;
 
-public class TurnSegment<T extends NPC> implements PathSegment<T> {
+public class TurnSegment<T extends Entity> implements PathSegment<T> {
    private final Direction direction;
 
    public TurnSegment(Direction direction) {
@@ -14,8 +14,8 @@ public class TurnSegment<T extends NPC> implements PathSegment<T> {
    }
 
    @Override
-   public PathProgress perform(T npc, ObjectLayer layer, float dt) {
-      npc.setFaceDirection(direction);
+   public PathProgress perform(T entity, ObjectLayer layer, float dt) {
+      entity.setFaceDirection(direction);
       return PathProgress.SEGMENT_DONE;
    }
 }