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/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.scenes.scene2d;

/** An Action is used with an {@link Actor} and modifes the Actor's attributes over time.
 * 
 * @author mzechner */
public abstract class Action {

	protected OnActionCompleted listener = null;

	/** Sets the {@link Actor} of this action. Will be called when the Action is added to an Actor via {@link Actor#action(Action)}
	 * before any other call to this interface.
	 * 
	 * @param actor the actor. */
	public abstract void setTarget (Actor actor);

	/** @return the {@link Actor} this action targets. */
	public abstract Actor getTarget ();

	/** Apply the action.
	 * 
	 * @param delta delta time in seconds */
	public abstract void act (float delta);

	/** @return whether the action is done or not */
	public abstract boolean isDone ();

	/** Called by the owner of the action when it can release all its resources, e.g. put itself back into a pool. */
	public void finish () {
		if (listener != null) {
			listener.completed(this);
		}
	}

	/** Calls the {@link OnActionCompleted} listener and sets it to null so it won't be called again. */
	public void callActionCompletedListener () {
		if (listener != null) {
			listener.completed(this);
		}
		listener = null;
	}

	/** Creates a copy of this action. The action must be in a state independent of the original and one must be able to call
	 * {@link #setTarget(Actor)} on it without any side effects. */
	public abstract Action copy ();

	/** Sets the listener to be invoked when the action is finished.
	 * @param listener
	 * @return this */
	public Action setCompletionListener (final OnActionCompleted listener) {
		this.listener = listener;
		return this;
	}

	/** @return the {@link OnActionCompleted} listener or null. */
	public OnActionCompleted getCompletionListener () {
		return listener;
	}

	/** Sets the Action back to a vanilla state. */
	public void reset () {
		listener = null;
	}

}