/**
    * This file Copyright (c) 2018 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.framework.databinding;
  
  import static java.util.Collections.singletonList;
  
  import info.magnolia.ui.api.i18n.I18NAuthoringSupport;
  import info.magnolia.ui.field.AbstractSelectFieldDefinition;
  import info.magnolia.ui.field.ComplexPropertyDefinition;
  import info.magnolia.ui.field.factory.FieldBinder;
  import info.magnolia.ui.field.factory.FieldFactory;
  import info.magnolia.ui.field.factory.FormFieldFactory;
  import info.magnolia.ui.form.OptionDefinition;
  import info.magnolia.ui.form.SwitchableFormDefinition;
  import info.magnolia.ui.framework.databinding.view.EditorView;
  import info.magnolia.ui.framework.datasource.components.PropertySetFactory;
  import info.magnolia.ui.framework.datasource.impl.FixedSizeDatasourceDefinition;
  import info.magnolia.ui.framework.ioc.UiContextBoundComponentProvider;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Optional;
  
  import javax.inject.Inject;
  
  import org.apache.commons.lang3.tuple.Pair;
  
  import com.vaadin.data.Binder;
  import com.vaadin.data.BinderValidationStatus;
  import com.vaadin.data.HasValue;
  import com.vaadin.ui.Component;
  import com.vaadin.ui.Layout;
  import com.vaadin.ui.VerticalLayout;
  
  /**
   * Special kind of form that allows to switch between multiple views using selection field.
   * Only selected sub-form is written upon saving the changes.
   *
   * @param <T> item type.
   */
  public class SwitchableFormView<T> implements EditorView<T> {
  
      private final SwitchableFormDefinition<T> definition;
      private final ItemProviderStrategy<T> itemProviderStrategy;
      private final Locale locale;
      private final FormFieldFactory formFieldFactory;
      private final PropertySetFactory<T> propertySetFactory;
      private final I18NAuthoringSupport i18NAuthoringSupport;
  
      private Map<String, Pair<EditorView<T>, ItemProviderStrategy<T>>> subForms = new HashMap<>();
      private HasValue<OptionDefinition> optionsField;
      private Binder<T> binder;
  
      private Layout layout = new VerticalLayout();
  
      @Inject
      public SwitchableFormView(SwitchableFormDefinition<T> definition, ItemProviderStrategy<T> itemProviderStrategy, Locale locale, FormFieldFactory formFieldFactory, PropertySetFactory<T> propertySetFactory, I18NAuthoringSupport i18NAuthoringSupport) {
          this.definition = definition;
          this.itemProviderStrategy = itemProviderStrategy;
          this.locale = locale;
          this.formFieldFactory = formFieldFactory;
          this.propertySetFactory = propertySetFactory;
          this.i18NAuthoringSupport = i18NAuthoringSupport;
  
          initialize();
     }
 
     private void initialize() {
         AbstractSelectFieldDefinition<OptionDefinition, FixedSizeDatasourceDefinition> fieldDefinition = definition.getField();
         UiContextBoundComponentProvider componentProvider = getComponentProvider().inChildContext(fieldDefinition);
 
         FieldFactory<OptionDefinition> fieldFactory = componentProvider.newInstance(fieldDefinition.getFactoryClass());
         optionsField = fieldFactory.createField();
 
         layout.addComponent((Component) optionsField);
 
         optionsField.addValueChangeListener(e -> {
             if (e.getOldValue() == null || e.getOldValue() == null) {
                 return;
             }
 
             EditorView<T> oldView = subForm(e.getOldValue());
             EditorView<T> newView = subForm(e.getValue());
 
             layout.replaceComponent(oldView.asVaadinComponent(), newView.asVaadinComponent());
         });
 
         definition.getForms().forEach(formDefinition -> {
             ItemProviderStrategy<T> subFormProviderStrategy = create(((ComplexPropertyDefinition<T>) formDefinition).getItemProvider(), formDefinition, itemProviderStrategy);
             subForms.put(formDefinition.getName(), Pair.of(create(formDefinition), subFormProviderStrategy));
         });
 
         binder = Binder.withPropertySet(propertySetFactory.fromFieldDefinitions(singletonList(fieldDefinition), locale));
         FieldBinder<OptionDefinition> fieldBinder = componentProvider.newInstance(fieldDefinition.getFieldBinderClass());
 
         fieldBinder.configureBinding(fieldDefinition, binder.forField(optionsField))
                 .bind(resolvePropertyNameByLocale(fieldDefinition.getName(), locale, fieldDefinition.isI18n()));
     }
 
     private String resolvePropertyNameByLocale(String name, Locale locale, boolean isI18nProperty) {
         if (isI18nProperty && !i18NAuthoringSupport.isDefaultLocale(locale)) {
             return i18NAuthoringSupport.deriveLocalisedPropertyName(name, locale);
         }
         return name;
     }
 
     @Override
     public void populate(T item) {
         binder.readBean(item);
 
         if (optionsField.getValue() == null) {
             defaultSelectedOptionDefinition().ifPresent(optionsField::setValue);
         }
 
         Optional.ofNullable(optionsField.getValue()).ifPresent(optionDefinition -> {
             EditorView<T> subForm = subForm(optionDefinition);
             subFormItemProvider(optionDefinition).read().ifPresent(subForm::populate);
             layout.addComponent(subForm.asVaadinComponent());
         });
     }
 
     private Optional<OptionDefinition> defaultSelectedOptionDefinition() {
         return Optional.ofNullable(definition.getField().getDefaultValue());
     }
 
     @Override
     public void write(T item) {
         binder.writeBeanIfValid(item);
 
         Optional.ofNullable(optionsField.getValue()).ifPresent(selectedOptionDefinition ->
                 subFormItemProvider(selectedOptionDefinition).read().ifPresent(t -> subForm(selectedOptionDefinition).write(t)));
     }
 
     private ItemProviderStrategy<T> subFormItemProvider(OptionDefinition selectedItem) {
         return subForms.get(selectedItem.getValue()).getValue();
     }
 
     @Override
     public List<BinderValidationStatus<?>> validate() {
         return Optional.ofNullable(optionsField.getValue())
                 .map(this::subForm)
                 .map(EditorView::validate)
                 .orElseGet(Collections::emptyList);
     }
 
     private EditorView<T> subForm(OptionDefinition selectedOptionDefinition) {
         return subForms.get(selectedOptionDefinition.getValue()).getKey();
     }
 
     @Override
     public Component getLayout(Locale locale) {
         return layout;
     }
 
     @Override
     public Component asVaadinComponent() {
         return layout;
     }
 }