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/*******************************************************************************
 * Copyright 2014 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.ai.sched;

/** A {@code Scheduler} works by assigning a pot of execution time among a variety of tasks, based on which ones need the time.
 * 
 * Different AI tasks can and should be run at different frequencies. You can simply schedule some tasks to run every few frames
 * and other tasks to run more frequently, slicing up the overall AI and distributing it over time. It is a powerful technique for
 * making sure that the game doesn't take too much AI time overall.
 * 

 * The tasks that get called are passed timing information so they can decide when to stop running and return. However, note that
 * there is nothing to stop a task from running for as long as it wants. The scheduler trusts that they will be well behaved.
 * 

 * Notes:
 * 

 * Hierarchical Scheduling: {@code Scheduler} extends the {@link Schedulable} interface, allowing a scheduling system to
 * be run as a task by another scheduler. This technique is known as hierarchical scheduling. Also, it's worth noting that with a
 * hierarchical approach, there's no reason why the schedulers at different levels should be of the same kind. For instance, it is
 * possible to use a frequency-based scheduler for the whole game and priority-based schedulers for individual characters.
 * Level of Detail: On its own there is nothing that hierarchical scheduling provides that a single scheduler cannot
 * handle. It comes into its own when used in combination with level of detail (LOD) systems. Level of detail systems are behavior
 * selectors; they choose only one behavior to run. In a hierarchical structure this means that schedulers running the whole game
 * don't need to know which behavior each character is running. A flat structure would mean removing and registering behaviors
 * with the main scheduler each time.
 * 
 * 
 * @author davebaol */
public interface Scheduler extends Schedulable {

	/** Adds the {@code schedulable} to the list using the given {@code frequency} and a phase calculated by this scheduler.
	 * @param schedulable the task to schedule
	 * @param frequency the frequency */
	public void addWithAutomaticPhasing (Schedulable schedulable, int frequency);

	/** Adds the {@code schedulable} to the list using the given {@code frequency} and {@code phase}
	 * @param schedulable the task to schedule
	 * @param frequency the frequency
	 * @param phase the phase */
	public void add (Schedulable schedulable, int frequency, int phase);

}