/**
    * 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 info.magnolia.ui.api.i18n.I18NAuthoringSupport;
  import info.magnolia.ui.field.AbstractSelectFieldDefinition;
  import info.magnolia.ui.field.ComplexPropertyDefinition;
  import info.magnolia.ui.form.OptionDefinition;
  import info.magnolia.ui.form.SwitchableFormDefinition;
  import info.magnolia.ui.field.factory.FormFieldFactory;
  import info.magnolia.ui.framework.databinding.view.EditorView;
  import info.magnolia.ui.framework.datasource.DatasourceComponent;
  import info.magnolia.ui.framework.datasource.components.PropertySetFactory;
  import info.magnolia.ui.framework.datasource.impl.FixedSizeDatasourceDefinition;
  
  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.Converter;
  import com.vaadin.data.Result;
  import com.vaadin.data.ValueContext;
  import com.vaadin.ui.AbstractSingleSelect;
  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 AbstractSingleSelect<OptionDefinition> optionsField;
      private Binder<T> binder;
  
      private Layout layout = new VerticalLayout();
  
      @Inject
      public SwitchableFormView(SwitchableFormDefinition<T> definition, ItemProviderStrategy<T> itemProviderStrategy, Locale locale, FormFieldFactory formFieldFactory, @DatasourceComponent 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() {
         optionsField = formFieldFactory.createField(definition.getField(), locale);
 
         layout.addComponent(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);
             EditorView<T> subForm = getViewProvider().create(formDefinition);
             subForms.put(formDefinition.getName(), Pair.of(subForm, subFormProviderStrategy));
         });
 
         binder = ConfiguredBinder.withPropertySet(propertySetFactory.fromFieldDefinitions(Collections.singletonList(definition.getField()), locale));
         binder.forField(optionsField)
                 .withConverter(new StringToOptionDefinitionConverter(definition.getField()))
                 .bind(resolvePropertyNameByLocale(definition.getField().getName(), locale, definition.getField().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.getSelectedItem().isPresent()) {
             defaultSelectedOptionDefinition().ifPresent(optionsField::setSelectedItem);
         }
 
         optionsField.getSelectedItem().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);
 
         optionsField.getSelectedItem().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 optionsField.getSelectedItem()
                 .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;
     }
 
     private static class StringToOptionDefinitionConverter implements Converter<OptionDefinition, String> {
 
         private final AbstractSelectFieldDefinition<OptionDefinition, FixedSizeDatasourceDefinition> definition;
 
         public StringToOptionDefinitionConverter(AbstractSelectFieldDefinition<OptionDefinition, FixedSizeDatasourceDefinition> definition) {
             this.definition = definition;
         }
 
         @Override
         public Result<String> convertToModel(OptionDefinition optionDefinition, ValueContext context) {
             return Optional.ofNullable(optionDefinition).map(OptionDefinition::getValue).map(Result::ok).orElse(Result.ok(null));
         }
 
         @Override
         public OptionDefinition convertToPresentation(String optionValue, ValueContext context) {
             return Optional.ofNullable(optionValue).map(value -> definition.getDatasource()
                     .getOptions()
                     .stream()
                     .filter(optionDefinition -> value.equals(optionDefinition.getValue()))
                     .findFirst()
                     .orElse(null)
             ).orElse(null);
         }
     }
 }