Improve Paths and fix some path issues

- implement insertPath() method which should be especially useful to insert some automatically generated path with pathfinder algorithms
- fix CompletableFutureSegment - the supplier should be invoked only once and then it should be cached instead of triggering it over and over again
- make FollowPathAI aware of the path progress - also expose it with getter

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

@@ -5,10 +5,15 @@ import com.bartlomiejpluta.base.api.ai.NPC;
 import com.bartlomiejpluta.base.api.map.layer.object.ObjectLayer;
 import com.bartlomiejpluta.base.util.path.Path;
 import com.bartlomiejpluta.base.util.path.PathExecutor;
+import com.bartlomiejpluta.base.util.path.PathProgress;
+import lombok.Getter;
 
 public class FollowPathAI<T extends NPC> implements AI {
    private final PathExecutor<T> executor;
 
+   @Getter
+   private PathProgress progress = PathProgress.NOT_STARTED;
+
    public FollowPathAI(T npc) {
       this.executor = new PathExecutor<>(npc);
    }
@@ -23,8 +28,13 @@ public class FollowPathAI<T extends NPC> implements AI {
       return this;
    }
 
+   public FollowPathAI<T> reset() {
+      executor.reset();
+      return this;
+   }
+
    @Override
    public void nextActivity(ObjectLayer layer, float dt) {
-      executor.execute(layer, dt);
+      progress = executor.execute(layer, dt);
    }
 }

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

@@ -35,6 +35,11 @@ public class BasePath<T extends Movable> implements Path<T> {
       return this;
    }
 
+   public Path<T> insertPath(Path<T> path) {
+      this.path.addAll(path.getPath());
+      return this;
+   }
+
    public Path<T> move(Direction direction) {
       path.add(new MoveSegment<>(direction));
       return this;

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

@@ -35,6 +35,11 @@ public class CharacterPath<T extends Character> implements Path<T> {
       return this;
    }
 
+   public CharacterPath<T> insertPath(Path<T> path) {
+      this.path.addAll(path.getPath());
+      return this;
+   }
+
    public CharacterPath<T> move(Direction direction) {
       path.add(new MoveSegment<>(direction));
       return this;

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

@@ -10,10 +10,13 @@ import java.util.function.Supplier;
 @RequiredArgsConstructor
 public class CompletableFutureSegment<T extends Movable> implements PathSegment<T> {
    private final Supplier<CompletableFuture<?>> futureSupplier;
+   private CompletableFuture<?> future;
 
    @Override
    public PathProgress perform(T movable, ObjectLayer layer, float dt) {
-      var future = futureSupplier.get();
+      if (future == null) {
+         future = futureSupplier.get();
+      }
 
       if (future.isCancelled() || future.isCompletedExceptionally()) {
          return PathProgress.SEGMENT_FAILED;

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

@@ -1,6 +1,7 @@
 package com.bartlomiejpluta.base.util.path;
 
 public enum PathProgress {
+   NOT_STARTED,
    ONGOING,
    SEGMENT_DONE,
    SEGMENT_FAILED,