/*
 * The MIT License
 * Copyright © 2014-2019 Ilkka Seppälä
 *
 * 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.iluwatar.gameloop;

/**
 * For fixed-step game loop, a certain amount of real time has elapsed since the
 * last turn of the game loop. This is how much game time need to be simulated for
 * the game’s “now” to catch up with the player’s.
 */
public class FixedStepGameLoop extends GameLoop {

  /**
   * 20 ms per frame = 50 FPS.
   */
  private static final long MS_PER_FRAME = 20;

  @Override
  protected void processGameLoop() {
    var previousTime = System.currentTimeMillis();
    var lag = 0L;
    while (isGameRunning()) {
      var currentTime = System.currentTimeMillis();
      var elapsedTime = currentTime - previousTime;
      previousTime = currentTime;
      lag += elapsedTime;

      processInput();

      while (lag >= MS_PER_FRAME) {
        update();
        lag -= MS_PER_FRAME;
      }

      render();
    }
  }

  protected void update() {
    controller.moveBullet(0.5f * MS_PER_FRAME / 1000);
  }
}
