/**
    * This file Copyright (c) 2020 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.field.converter;
  
  import info.magnolia.ui.field.DateFieldDefinition;
  
  import java.time.LocalDate;
  import java.time.LocalDateTime;
  import java.time.ZoneId;
  import java.time.format.DateTimeFormatter;
  import java.time.temporal.Temporal;
  import java.util.Date;
  import java.util.Locale;
  import java.util.Optional;
  
  import javax.inject.Inject;
  
  import com.vaadin.data.Converter;
  import com.vaadin.data.Result;
  import com.vaadin.data.ValueContext;
  import com.vaadin.data.converter.LocalDateTimeToDateConverter;
  import com.vaadin.data.converter.LocalDateToDateConverter;
  
  /**
   * Custom converter for DateField. Needs to handle conversion between Temporal and Date as well as String to Temporal
   * for correct handling of default value.
   *
   * Converter needs access to DateFieldDefinition in order to decide which of LocalDate and LocalDateTime should be used.
   */
  public class DateConverter implements Converter<Temporal, Object> {
  
      private final ZoneId zoneId = ZoneId.systemDefault();
      private final DateFieldDefinition definition;
  
      @Inject
      public DateConverter(DateFieldDefinition definition) {
          this.definition = definition;
      }
  
      @Override
      public Result<Object> convertToModel(Temporal value, ValueContext valueContext) { // Temporal (LocalDate or LocalDateTime) to Date
          if (value instanceof LocalDate) {
              return Result.ok(Date.from(((LocalDate) value).atStartOfDay(zoneId).toInstant()));
          }
          return Result.ok(Optional.ofNullable(value)
                  .map(nonNullDateTime -> Date.from(((LocalDateTime) nonNullDateTime).atZone(zoneId).toInstant()))
                  .orElse(null));
      }
  
      @Override
      public Temporal convertToPresentation(Object value, ValueContext valueContext) { // Date (or String) to Temporal (LocalDate or LocalDateTime)
          if (value == null) {
              return null;
          }
  
          if (value instanceof String) {
              return asTemporal((String) value);
          }
  
          Converter converter = definition.isTime() ?
                  new LocalDateTimeToDateConverter(zoneId) :
                  new LocalDateToDateConverter(zoneId);
  
          return (Temporal) converter.convertToPresentation(value, valueContext);
      }
  
      private Temporal asTemporal(String defaultValue) {
          if (DateFieldDefinition.NOW.equalsIgnoreCase(defaultValue)) {
             return definition.isTime() ? LocalDateTime.now() : LocalDate.now();
         }
 
         if (definition.isTime()) {
             return LocalDateTime.parse(defaultValue, DateTimeFormatter.ofPattern(definition.getDateFormat() + " " + definition.getTimeFormat(), Locale.ENGLISH));
         } else {
             return LocalDate.parse(defaultValue, DateTimeFormatter.ofPattern(definition.getDateFormat(), Locale.ENGLISH));
         }
     }
 }