/**
    * This file Copyright (c) 2010-2017 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.vaadin.gwt.client.tabsheet.widget;
  
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.event.ActiveTabChangedEvent;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.event.ShowAllTabsEvent;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.event.ShowAllTabsHandler;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.event.TabCloseEvent;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.event.TabCloseEventHandler;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.tab.widget.MagnoliaTabLabel;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.tab.widget.MagnoliaTabWidget;
  import info.magnolia.ui.vaadin.gwt.client.tabsheet.util.CollectionUtil;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  
  import com.google.gwt.core.client.Scheduler.ScheduledCommand;
  import com.google.gwt.dom.client.NativeEvent;
  import com.google.gwt.event.dom.client.ClickEvent;
  import com.google.gwt.event.dom.client.ClickHandler;
  import com.google.gwt.user.client.DOM;
  import com.google.gwt.user.client.Element;
  import com.google.gwt.user.client.ui.ComplexPanel;
  import com.google.gwt.user.client.ui.DialogBox;
  import com.google.gwt.user.client.ui.MenuBar;
  import com.google.gwt.user.client.ui.MenuItem;
  import com.google.gwt.user.client.ui.SimplePanel;
  import com.google.gwt.user.client.ui.Widget;
  import com.google.web.bindery.event.shared.EventBus;
  import com.vaadin.client.ui.VButton;
  
  /**
   * A bar that contains the tab labels and controls the switching between tabs.
   */
  public class TabBarWidget extends ComplexPanel {
  
      private static final String SINGLE_TAB_CLASS_NAME = "single-tab";
  
      private final List<MagnoliaTabLabel> tabLabels = new LinkedList<>();
  
      private final Element tabContainer = DOM.createElement("ul");
  
      private final EventBus eventBus;
  
      private VShellShowAllTabLabel showAllTab;
  
      private final HiddenTabsPopup hiddenTabsPopup;
  
      private MagnoliaTabLabel activeTab;
  
      public TabBarWidget(EventBus eventBus) {
          this.eventBus = eventBus;
          setElement(tabContainer);
          setStyleName("nav");
          addStyleDependentName("tabs");
  
          hiddenTabsPopup = new HiddenTabsPopup(eventBus);
          add(hiddenTabsPopup, tabContainer);
          bindHandlers();
      }
  
      public void reArrangeTabVisibility() {
          if (tabLabels.isEmpty()) {
              return;
         }
         // Is this ever possible?
         if (activeTab == null) {
             activeTab = tabLabels.get(0);
         }
 
         // Reset hidden-tabs popup
         hiddenTabsPopup.setVisible(true);
         int toggleWidth = hiddenTabsPopup.getOffsetWidth();
         int availableWidth = tabContainer.getOffsetWidth();
 
         // 1. Active tab is always visible, count its width first
         activeTab.setVisible(true);
         availableWidth -= activeTab.getOffsetWidth();
 
         // 2. Account for show-all tab if needed
         if (showAllTab != null) {
             availableWidth -= showAllTab.getOffsetWidth();
         }
 
         // Collect every tab's width (we'll have to know anyway)
         Map<MagnoliaTabLabel, Integer> tabWidths = new HashMap<>();
         for (MagnoliaTabLabel tab : tabLabels) {
             if (tab == activeTab) {
                 continue;
             }
             tab.setVisible(true);
             tabWidths.put(tab, tab.getOffsetWidth());
         }
 
         // 3. Squeeze all other tabs from start to end, as many as width allows
         Iterator<MagnoliaTabLabel> it = tabLabels.iterator();
         boolean outOfSpace = false;
         while (it.hasNext()) {
             MagnoliaTabLabel tab = it.next();
             // Active tab is already accounted for, don't hide it
             if (tab == activeTab) {
                 continue;
             }
             if (!outOfSpace) {
                 int width = tabWidths.get(tab);
                 int maxWidth = Collections.max(tabWidths.values());
                 // Either I have enough space for the next tab and it's the last one
                 if ((!it.hasNext() && availableWidth >= width)
                         // Either I need enough space for the widest of the next tabs, plus the toggle
                         // Why widest? The tab bar may have to accommodate it, not necessarily now, but maybe when switching.
                         || (maxWidth + toggleWidth <= availableWidth)) {
                     tabWidths.remove(tab);
                     availableWidth -= width;
                     continue;
                 } else {
                     outOfSpace = true;
                 }
             }
             // If we're there we've run out of space
             tab.setVisible(false);
         }
 
         // 4. Compute content of the hidden tabs popup
         hiddenTabsPopup.hide();
         hiddenTabsPopup.menubar.clearItems();
         it = tabLabels.iterator();
         while (it.hasNext()) {
             MagnoliaTabLabel tab = it.next();
             if (!tab.isVisible()) {
                 hiddenTabsPopup.addTabLabel(tab);
             }
         }
         hiddenTabsPopup.showControlIfNeeded();
     }
 
     private void bindHandlers() {
         eventBus.addHandler(ActiveTabChangedEvent.TYPE, new ActiveTabChangedEvent.Handler() {
             @Override
             public void onActiveTabChanged(final ActiveTabChangedEvent event) {
                 final MagnoliaTabWidget tab = event.getTab();
                 final MagnoliaTabLabel label = tab.getLabel();
                 if (label != null) {
                     for (final MagnoliaTabLabel tabLabel : tabLabels) {
                         tabLabel.removeStyleName("active");
                     }
                     label.addStyleName("active");
                     showAll(false);
                     activeTab = label;
                     hiddenTabsPopup.menuWrapper.hide();
                     if (!label.isVisible()) {
                         reArrangeTabVisibility();
                     }
                 }
             }
         });
 
         eventBus.addHandler(TabCloseEvent.TYPE, new TabCloseEventHandler() {
             @Override
             public void onTabClosed(TabCloseEvent event) {
                 final MagnoliaTabLabel tabLabel = event.getTab().getLabel();
                 boolean wasActive = tabLabel.getStyleName().contains("active");
                 if (wasActive) {
                     final MagnoliaTabLabel nextLabel = getNextLabel(tabLabel);
                     if (nextLabel != null) {
                         nextLabel.addStyleName("active");
                         activeTab = nextLabel;
                     }
                 }
                 tabLabels.remove(tabLabel);
                 remove(tabLabel);
                 updateSingleTabStyle();
                 reArrangeTabVisibility();
             }
         });
 
         eventBus.addHandler(ShowAllTabsEvent.TYPE, new ShowAllTabsHandler() {
 
             @Override
             public void onShowAllTabs(ShowAllTabsEvent event) {
                 for (final MagnoliaTabLabel tabLabel : tabLabels) {
                     tabLabel.removeStyleName("active");
                 }
                 showAll(true);
             }
         });
     }
 
     protected MagnoliaTabLabel getNextLabel(final MagnoliaTabLabel label) {
         return CollectionUtil.getNext(tabLabels, label);
     }
 
     public void addTabLabel(MagnoliaTabLabel label) {
         label.setEventBus(eventBus);
         if (!tabLabels.contains(label)) {
             tabLabels.add(label);
             // Keep hidden-tabs toggle and show-all button last in the DOM when inserting labels.
             insert(label, tabContainer, tabLabels.size() - 1, true);
             updateSingleTabStyle();
         }
     }
 
     public void updateSingleTabStyle() {
         if (tabLabels.size() <= 1) {
             tabContainer.addClassName(SINGLE_TAB_CLASS_NAME);
         } else {
             tabContainer.removeClassName(SINGLE_TAB_CLASS_NAME);
         }
     }
 
     public void addShowAllTab(boolean showAll, String label) {
         if (showAll && showAllTab == null) {
             showAllTab = new VShellShowAllTabLabel(label);
             add(showAllTab, getElement());
         } else if (!showAll && showAllTab != null) {
             remove(showAllTab);
             showAllTab = null;
         }
         reArrangeTabVisibility();
     }
 
     private class VShellShowAllTabLabel extends SimplePanel {
 
         private final VButton textWrapper = new VButton();
 
         public VShellShowAllTabLabel(String label) {
             super(DOM.createElement("li"));
             addStyleName("show-all");
             textWrapper.getElement().setInnerHTML(label);
             textWrapper.getElement().setClassName("tab-title");
             this.add(textWrapper);
         }
 
         @Override
         protected void onLoad() {
             super.onLoad();
             bindHandlers();
         }
 
         private void bindHandlers() {
             addDomHandler(new ClickHandler() {
                 @Override
                 public void onClick(ClickEvent event) {
                     onClickGeneric(event.getNativeEvent());
                 }
             }, ClickEvent.getType());
 
             textWrapper.addClickHandler(new ClickHandler() {
                 @Override
                 public void onClick(ClickEvent event) {
                     textWrapper.setFocus(false);
                     onClickGeneric(event.getNativeEvent());
                 }
             });
         }
 
         private void onClickGeneric(NativeEvent nativeEvent) {
             eventBus.fireEvent(new ShowAllTabsEvent());
             nativeEvent.stopPropagation();
         }
 
     }
 
     /**
      * The toggle display the hidden-tabs popup upon click.
      */
     static class HiddenTabsPopup extends Widget {
 
         private final DialogBox menuWrapper = new DialogBox(true);
         private final HiddenTabsMenuBar menubar = new HiddenTabsMenuBar();
         private final EventBus eventBus;
 
         public HiddenTabsPopup(EventBus eventBus) {
             this.eventBus = eventBus;
 
             setElement(DOM.createElement("li"));
             addStyleName("icon-arrow2_e");
             addStyleName("hidden-tabs-popup-button");
             menuWrapper.add(menubar);
             menuWrapper.setStyleName("context-menu-wrapper");
 
             // Initially hide the component
             setVisible(false);
         }
 
         @Override
         protected void onLoad() {
             super.onLoad();
             bindHandlers();
         }
 
         public void addTabLabel(final MagnoliaTabLabel label) {
             final MenuItem item = menubar.addItem(label.getCaption(), new ScheduledCommand() {
                 @Override
                 public void execute() {
                     menuWrapper.hide();
                     eventBus.fireEvent(new ActiveTabChangedEvent(label.getTab()));
                 }
             });
             item.addStyleName("menu-item");
         }
 
         private void bindHandlers() {
             addDomHandler(new ClickHandler() {
                 @Override
                 public void onClick(ClickEvent event) {
                     event.preventDefault();
                     event.stopPropagation();
                     menuWrapper.setPopupPosition(getAbsoluteLeft() + getOffsetWidth(), getAbsoluteTop());
                     menuWrapper.show();
                 }
 
             }, ClickEvent.getType());
         }
 
         public void hide() {
             menuWrapper.hide();
             setVisible(false);
         }
 
         public void showControlIfNeeded() {
             setVisible(!menubar.isEmpty());
         }
 
         private class HiddenTabsMenuBar extends MenuBar {
 
             public HiddenTabsMenuBar() {
                 super(true);
                 setStyleName("context-menu");
                 addStyleName("hidden-tabs-menu");
             }
 
             public boolean isEmpty() {
                 return super.getItems().isEmpty();
             }
         }
     }
 
     public void showAll(boolean showAll) {
         if (showAllTab != null) {
             if (showAll) {
                 showAllTab.addStyleName("active");
             } else {
                 if (showAllTab.getStyleName().contains("active")) {
                     showAllTab.removeStyleName("active");
                 }
             }
         }
     }
 
 }