/*
 * This file is part of the Illarion project.
 *
 * Copyright © 2015 - Illarion e.V.
 *
 * Illarion is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Illarion is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
package illarion.client.world.movement;

import illarion.common.types.ServerCoordinate;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

/**
 * This is the main interface of a movement handler. All movement systems have to use this one.
 *
 * @author Martin Karing <nitram@illarion.org>
 */
public interface MovementHandler {
    /**
     * Check if this movement handler is currently active.
     *
     * @return {@code true} in case this movement is currently active
     */
    boolean isActive();

    /**
     * Calling this function causes this handler to take over control over the movement.
     */
    void assumeControl();

    /**
     * Calling this function causes the handler to stop handling movement.
     *
     * @param transferAllowed {@code true} in case its okay to transfer the control to another handler right away.
     */
    void disengage(boolean transferAllowed);

    /**
     * Get the next step generated by this movement handler.
     *
     * @param currentLocation the current location of the player character once this next step takes effect
     * @return the next step or {@code null} in case no step is to be done
     */
    @Nullable
    StepData getNextStep(@Nonnull ServerCoordinate currentLocation);
}