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TenIO is a java NIO (Non-blocking I/O) based server specifically designed for multiplayer games. It supports UDP and TCP transports which are handled by Netty for high-speed network transmission. This is the engine module for the game related handlers of the framework.

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/*
The MIT License

Copyright (c) 2016-2021 kong 

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package com.tenio.engine.fsm.entity;

import com.tenio.engine.fsm.Component;
import com.tenio.engine.fsm.MessageDispatcher;

/**
 * Check out the
 * FSM
 * for more details.
 *
 * @param  the state template
 */
public final class FsmComponent extends Component {

  private final MessageDispatcher dispatcher;
  /**
   * The current state, see {@link State}.
   */
  private State currentState;
  /**
   * A record of the last state the agent was in, see {@link State}.
   */
  private State previousState;
  /**
   * This is called every time the FSM is updated, see {@link State}.
   */
  private State globalState;

  /**
   * Initialization.
   *
   * @param dispatcher the dispatcher
   * @param entity     the entity
   */
  public FsmComponent(final MessageDispatcher dispatcher, T entity) {
    super(entity);
    this.dispatcher = dispatcher;
    currentState = null;
    previousState = null;
    globalState = null;
  }

  public MessageDispatcher getDispatcher() {
    return dispatcher;
  }

  @Override
  public void update(double delta) {
    // if a global state exists, call its execute method, else do nothing
    if (globalState != null) {
      globalState.execute(entity);
    }

    // same for the current state
    if (currentState != null) {
      currentState.execute(entity);
    }
  }

  /**
   * Handling messages.
   *
   * @param message the sending message
   * @return true if success, false otherwise
   */
  public boolean handleMessage(Telegram message) {
    // First see if the current state is valid and that it can handle
    // the message
    if (currentState != null && currentState.onMessage(entity, message)) {
      return true;
    }

    // If not, and if a global state has been implemented, send
    // the message to the global state
    return globalState != null && globalState.onMessage(entity, message);
  }

  /**
   * Change to the another state.
   *
   * @param state the new state
   */
  public void changeState(State state) {
    // keep a record of the previous state
    previousState = currentState;

    // call the exit method of the existing state
    currentState.exit(entity);

    // change state to the new state
    currentState = state;

    // call the entry method of the new state
    currentState.enter(entity);
  }

  /**
   * Change state back to the previous state.
   */
  public void revertToPreviousState() {
    changeState(previousState);
  }

  /**
   * Check if it is in a particular state or not.
   *
   * @param state the confirming state
   * @return true if the current state's type is equal to the type of the parameter's class
   */
  public boolean isInState(State state) {
    return currentState.getClass() == state.getClass();
  }

  public State getCurrentState() {
    return currentState;
  }

  /**
   * Use these methods to initialize the FSM.
   *
   * @param state the first state
   */
  public void setCurrentState(State state) {
    currentState = state;
  }

  public State getGlobalState() {
    return globalState;
  }

  /**
   * The global state is called in every processing.
   *
   * @param state the corresponding state
   */
  public void setGlobalState(State state) {
    globalState = state;
  }

  public State getPreviousState() {
    return previousState;
  }

  /**
   * Set the previous state.
   *
   * @param state the corresponding state
   */
  public void setPreviousState(State state) {
    previousState = state;
  }

  /**
   * Only be used during debugging to grab the name of the current state.
   *
   * @return the name of current state
   */
  public String getNameOfCurrentState() {
    return currentState.getClass().getName();
  }
}