code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.sdk.server.events.conversions;
  
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.TimeZone;
  
  import org.eclipse.milo.opcua.stack.core.BuiltinDataType;
  import org.eclipse.milo.opcua.stack.core.types.builtin.DateTime;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  final class DateTimeConversions {
  
      private DateTimeConversions() {}
  
      @NotNull
      static String dateTimeToString(@NotNull DateTime dt) {
          return dateToIso8601UtcString(dt.getJavaDate());
      }
  
      private static final DateFormat ISO_8601_UTC_DATE_FORMAT;
  
      static {
          ISO_8601_UTC_DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
          ISO_8601_UTC_DATE_FORMAT.setTimeZone(TimeZone.getTimeZone("UTC"));
      }
  
      private static String dateToIso8601UtcString(Date date) {
          synchronized (ISO_8601_UTC_DATE_FORMAT) {
              return ISO_8601_UTC_DATE_FORMAT.format(date);
          }
      }
  
      @Nullable
      static Object convert(@NotNull Object o, BuiltinDataType targetType, boolean implicit) {
          if (o instanceof DateTime) {
              DateTime d = (DateTime) o;
  
              return implicit ?
                  implicitConversion(d, targetType) :
                  explicitConversion(d, targetType);
          } else {
              return null;
          }
      }
  
      @Nullable
      static Object explicitConversion(@NotNull DateTime d, BuiltinDataType targetType) {
          //@formatter:off
          switch (targetType) {
              case String:    return dateTimeToString(d);
              default:        return implicitConversion(d, targetType);
          }
          //@formatter:on
      }
  
      @Nullable
      static Object implicitConversion(@NotNull DateTime d, BuiltinDataType targetType) {
          // no implicit conversions exist
          return null;
      }
  
  
  }
  