ProtectionDecayer.java

package com.nicewuerfel.blockown.protection;

import com.nicewuerfel.blockown.Setting;
import com.nicewuerfel.blockown.Setting.PROTECTION;
import com.nicewuerfel.blockown.User;

import org.bukkit.OfflinePlayer;
import org.bukkit.plugin.Plugin;
import org.bukkit.scheduler.BukkitScheduler;
import org.bukkit.scheduler.BukkitTask;

import java.util.HashMap;
import java.util.Map;

import javax.annotation.Nonnull;

public class ProtectionDecayer implements Runnable {

  private final Setting setting;
  private final Protection protection;
  private final Plugin plugin;
  /**
   * Maps the UUID string of players to the last time they've been dropped.
   */
  private final Map<String, Long> checked;

  private BukkitTask schedulerTask = null;

  ProtectionDecayer(@Nonnull Setting setting, @Nonnull Protection protection,
                    @Nonnull Plugin plugin) {
    this.protection = protection;
    this.plugin = plugin;
    this.setting = setting;
    this.checked = new HashMap<>(plugin.getServer().getOfflinePlayers().length * 2);
  }

  /**
   * Schedules an possibly asynchronous cleanup after {@link PROTECTION#DECAY} which repeats every
   * 2* {@link PROTECTION#DECAY} hours.<br>
   * If {@link PROTECTION#DECAY} is 0, no task will be scheduled.<br>
   * Cancels all tasks created by previous calls to this method.
   */
  public void start() {
    schedule(getSetting().PROTECTION.DECAY * 3600);
  }

  /**
   * Cancels all ProtectionDecayer tasks. If this task is not scheduled, does nothing.
   */
  public void stop() {
    BukkitScheduler scheduler = plugin.getServer().getScheduler();
    if (schedulerTask != null) {
      if (scheduler.isQueued(schedulerTask.getTaskId())) {
        scheduler.cancelTask(schedulerTask.getTaskId());
      }
    }
    schedulerTask = null;
  }

  /**
   * Schedules this task after the given time in seconds. Doesn't schedule the task if delay is 0.
   *
   * @param delay the delay in seconds
   */
  private void schedule(long delay) {
    BukkitScheduler scheduler = plugin.getServer().getScheduler();
    stop();
    delay *= 20;
    if (delay != 0) {
      schedulerTask = scheduler.runTaskLaterAsynchronously(plugin, this, delay);
    }
  }

  @Override
  public void run() {
    long now = System.currentTimeMillis();
    for (OfflinePlayer player : plugin.getServer().getOfflinePlayers()) {
      String uuid = player.getUniqueId().toString();
      Long checkedTime = checked.get(player.getUniqueId().toString());
      if (checkedTime == null) {
        checkedTime = Long.valueOf(0);
      }
      if (player.getLastPlayed() > checkedTime) {
        if (now - player.getLastPlayed() > getSetting().PROTECTION.DECAY * 1000 * 3600) {
          User user = User.getInstance(player.getUniqueId());
          ProtectAction protectAction = new ProtectAction.Builder(user).drop().build();
          getProtection().enqueue(protectAction);
          checked.put(uuid, now);
        }
      }
    }
    schedule(getSetting().PROTECTION.DECAY * 2 * 3600);
  }

  private Protection getProtection() {
    return protection;
  }

  private Setting getSetting() {
    return setting;
  }

}