content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.gwt.client.ui.input;
  
  import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
  import com.google.gwt.event.logical.shared.ValueChangeEvent;
  import com.google.gwt.event.logical.shared.ValueChangeHandler;
  import com.google.gwt.event.shared.EventHandler;
  import com.google.gwt.event.shared.GwtEvent;
  import com.google.gwt.event.shared.HandlerRegistration;
  import com.google.gwt.event.shared.SimpleEventBus;
  
  /**
   * This class coordinates multiple radio buttons and makes sure that when a radio button of a group is
   * selected, no other radio button of the same group is selected.<p>
   *
   * @since 8.0.0
   */
  public class CmsRadioButtonGroup implements HasValueChangeHandlers<String> {
  
      /** The event bus. */
      private transient SimpleEventBus m_eventBus;
  
      /** The currently selected radio button (null if none is selected). */
      private CmsRadioButton m_selectedButton;
  
      /** The object to which value change events should be fired. */
      private HasValueChangeHandlers<String> m_target;
  
      /**
       * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler)
       */
      public HandlerRegistration addValueChangeHandler(ValueChangeHandler<String> handler) {
  
          return addHandler(handler, ValueChangeEvent.getType());
      }
  
      /**
       * Deselects a selected radio button (if one is selected).<p>
       */
      public void deselectButton() {
  
          if (m_selectedButton != null) {
              if (m_selectedButton.isChecked()) {
                  m_selectedButton.setChecked(false);
              }
              m_selectedButton = null;
              ValueChangeEvent.fire(this, null);
          }
      }
  
      /**
       * @see com.google.gwt.event.shared.HasHandlers#fireEvent(com.google.gwt.event.shared.GwtEvent)
       */
      public void fireEvent(GwtEvent<?> event) {
  
          ensureHandlers().fireEventFromSource(event, this);
      }
  
      /**
       * Returns the currently selected button, or null if none is selected.<p>
       *
       * @return the selected button or null
       */
      public CmsRadioButton getSelectedButton() {
  
          return m_selectedButton;
      }
  
      /**
       * Selects a new button and deselects the previously selected one.<p>
       *
       * @param button the button which should be selected
       */
      public void selectButton(CmsRadioButton button) {
  
          if (m_selectedButton != button) {
              if (m_selectedButton != null) {
                  m_selectedButton.setChecked(false);
              }
              if (!button.isChecked()) {
                  button.setChecked(true);
              }
              m_selectedButton = button;
              if (m_target != null) {
                  ValueChangeEvent.fire(m_target, button.getName());
              }
              ValueChangeEvent.fire(this, button.getName());
          }
      }
  
      /**
       * Sets the new value change event target for this button group.<p>
       *
       * @param target the value change event target
       */
      public void setValueChangeTarget(HasValueChangeHandlers<String> target) {
  
          m_target = target;
      }
  
      /**
       * Adds this handler to the widget.
       *
       * @param <H> the type of handler to add
       * @param type the event type
       * @param handler the handler
       * @return {@link HandlerRegistration} used to remove the handler
       */
      protected final <H extends EventHandler> HandlerRegistration addHandler(final H handler, GwtEvent.Type<H> type) {
  
          return ensureHandlers().addHandlerToSource(type, this, handler);
      }
  
      /**
       * Lazy initializing the handler manager.<p>
       *
       * @return the handler manager
       */
      private SimpleEventBus ensureHandlers() {
  
          if (m_eventBus == null) {
              m_eventBus = new SimpleEventBus();
          }
          return m_eventBus;
      }
  
  }
  