/*
    GNU GENERAL PUBLIC LICENSE
    Copyright (C) 2006 The Lobo Project

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public
    License as published by the Free Software Foundation; either
    verion 2 of the License, or (at your option) any later version.

    This program 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.

    You should have received a copy of the GNU General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Contact info: lobochief@users.sourceforge.net
 */
/*
 * Created on Mar 31, 2005
 */
package org.lobobrowser.async;

import java.util.EventObject;

import javax.swing.SwingUtilities;

import org.lobobrowser.util.EventDispatch;
import org.lobobrowser.util.GenericEventListener;

/**
 * @author J. H. S.
 */
public class AsyncResultImpl<TResult> implements AsyncResult<TResult> {
  private final EventDispatch evtResult = new EventDispatch();
  private TResult result;
  private Throwable exception;
  private boolean hasResult = false;

  /*
   * (non-Javadoc)
   *
   * @see
   * org.xamjwg.dom.AsyncResult#addResultListener(org.xamjwg.dom.AsyncResultListener
   * )
   */
  public void addResultListener(final AsyncResultListener<TResult> listener) {
    synchronized (this) {
      if (this.hasResult) {
        if (this.exception != null) {
          final Throwable exception = this.exception;
          SwingUtilities.invokeLater(() -> {
            // Invoke holding no locks
            final AsyncResultEvent<Throwable> are = new AsyncResultEvent<>(AsyncResultImpl.this, exception);
            listener.exceptionReceived(are);
          });

        } else {
          final TResult result = this.result;
          SwingUtilities.invokeLater(() -> {
            // Invoke holding no locks
            final AsyncResultEvent<TResult> are = new AsyncResultEvent<>(AsyncResultImpl.this, result);
            listener.resultReceived(are);
          });
        }
      }
      evtResult.addListener(new EventListenerWrapper<>(listener));
    }
  }

  /*
   * (non-Javadoc)
   *
   * @see
   * org.xamjwg.clientlet.AsyncResult#removeResultListener(org.xamjwg.clientlet
   * .AsyncResultListener)
   */
  public void removeResultListener(final AsyncResultListener<TResult> listener) {
    this.evtResult.removeListener(new EventListenerWrapper<>(listener));
  }

  /*
   * (non-Javadoc)
   *
   * @see org.xamjwg.clientlet.AsyncResult#signal()
   */
  public void signal() {
    synchronized (this) {
      if (this.hasResult) {
        if (this.exception != null) {
          final Throwable exception = this.exception;
          SwingUtilities.invokeLater(() -> {
            // Invoke holding no locks
            final AsyncResultEvent<Throwable> are = new AsyncResultEvent<>(AsyncResultImpl.this, exception);
            evtResult.fireEvent(are);
          });

        } else {
          final TResult result = this.result;
          SwingUtilities.invokeLater(() -> {
            // Invoke holding no locks
            final AsyncResultEvent<TResult> are = new AsyncResultEvent<>(AsyncResultImpl.this, result);
            evtResult.fireEvent(are);
          });
        }
      }
    }
  }

  public void setResult(final TResult result) {
    synchronized (this) {
      this.result = result;
      this.hasResult = true;
      SwingUtilities.invokeLater(() -> evtResult.fireEvent(new AsyncResultEvent<>(AsyncResultImpl.this, result)));
    }
  }

  public void setException(final Throwable exception) {
    synchronized (this) {
      this.exception = exception;
      this.hasResult = true;
      SwingUtilities.invokeLater(() -> evtResult.fireEvent(new AsyncResultEvent<>(AsyncResultImpl.this, exception)));
    }
  }

  private static class EventListenerWrapper<TR> implements GenericEventListener {
    private final AsyncResultListener<TR> listener;

    /**
     * @param listener
     */
    public EventListenerWrapper(final AsyncResultListener<TR> listener) {
      super();
      this.listener = listener;
    }

    public void processEvent(final EventObject event) {
      // Invoke holding no locks
      final AsyncResultEvent<?> are = (AsyncResultEvent<?>) event;
      if (are.getResult() instanceof Exception) {
        @SuppressWarnings("unchecked")
        final AsyncResultEvent<Throwable> areException = (AsyncResultEvent<Throwable>) are;
        this.listener.exceptionReceived(areException);
      } else {
        @SuppressWarnings("unchecked")
        final AsyncResultEvent<TR> areResult = (AsyncResultEvent<TR>) are;
        this.listener.resultReceived(areResult);
      }
    }

    @Override
    public boolean equals(final Object other) {
      if (!(other instanceof EventListenerWrapper)) {
        return false;
      }
      final EventListenerWrapper<?> elw = (EventListenerWrapper<?>) other;
      return java.util.Objects.equals(elw.listener, this.listener);
    }

    @Override
    public int hashCode() {
      return this.listener.hashCode();
    }
  }
}