package nl.tudelft.simulation.dsol.swing.introspection.gui;
   
   import java.awt.Component;
   import java.lang.ref.WeakReference;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.List;
   import java.util.Timer;
   import java.util.TimerTask;
  
  /**
   * provides a timed update mechanism for components. <br>
   * copyright (c) 2002-2021 <a href="https://simulation.tudelft.nl">Delft University of Technology</a>. <br>
   * BSD-style license. See <a href="https://https://simulation.tudelft.nl/dsol/docs/latest/license.html" target="_blank"> DSOL License</a>. <br>
   * @author <a href="https://www.linkedin.com/in/peterhmjacobs">Peter Jacobs</a>.
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>.
   * @author Niels Lang.
   * @since 1.5
   */
  public class UpdateTimer extends TimerTask
  {
      /** the tables to update. */
      @SuppressWarnings("unchecked")
      private WeakReference<Component>[] components = new WeakReference[0];
  
      /** the timer. */
      private Timer timer = null;
  
      /** the period for this timer. */
      private long period = 300L;
  
      /**
       * constructs a new UpdateTimer.
       * @param period long; the period in milliseconds
       */
      public UpdateTimer(final long period)
      {
          super();
          this.period = period;
      }
  
      /**
       * adds a component to the list.
       * @param component Component; the component
       */
      @SuppressWarnings("unchecked")
      public synchronized void add(final Component component)
      {
          List<WeakReference<Component>> arrayList = new ArrayList<WeakReference<Component>>(Arrays.asList(this.components));
          arrayList.add(new WeakReference<Component>(component));
          this.components = arrayList.toArray(new WeakReference[arrayList.size()]);
          // The first table added
          if (this.timer == null)
          {
              this.timer = new Timer(true);
              this.timer.scheduleAtFixedRate(this, 0L, this.period);
          }
      }
  
      /**
       * removes a component from a list.
       * @param component Component; the component
       */
      public synchronized void remove(final Component component)
      {
          for (int i = (this.components.length - 1); i > -1; i--)
          {
              if (this.components[i].get().equals(component))
              {
                  this.remove(this.components[i]);
              }
          }
      }
  
      /**
       * removes a reference from a list.
       * @param reference WeakReference&lt;Component&gt;; the reference
       */
      @SuppressWarnings("unchecked")
      private synchronized void remove(final WeakReference<Component> reference)
      {
          List<WeakReference<Component>> arrayList = new ArrayList<WeakReference<Component>>(Arrays.asList(this.components));
          arrayList.remove(reference);
          this.components = arrayList.toArray(new WeakReference[arrayList.size()]);
          if (this.components.length == 0)
          {
              // The last component is removed. Let's cancel the timer
              this.timer.cancel();
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public void run()
      {
          for (int i = (this.components.length - 1); i > -1; i--)
          {
              Component component = this.components[i].get();
              if (component != null)
             {
                 component.repaint();
             }
             else
             {
                 this.remove(this.components[i]);
             }
         }
     }
 }