/*
    * DavMail POP/IMAP/SMTP/CalDav/LDAP Exchange Gateway
    * Copyright (C) 2010  Mickael Guessant
    *
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public License
    * as published by the Free Software Foundation; either version 2
    * of the License, or (at your option) any later version.
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  
  package davmail.util;
  
  import davmail.exception.DavMailException;
  
  import java.time.LocalDateTime;
  import java.time.ZoneId;
  import java.time.ZonedDateTime;
  import java.time.format.DateTimeFormatter;
  import java.time.format.DateTimeParseException;
  
  /**
   * Date related conversion methods
   */
  public class DateUtil {
      public static final String GRAPH_DATE_TIME = "yyyy-MM-dd'T'HH:mm:ss";
      public static final String CALDAV_DATE_TIME = "yyyyMMdd'T'HHmmss";
  
      public static String convertDateFormat(String sourceDate, String sourceFormat, String targetFormat) throws DavMailException {
          String targetDate = null;
          if (sourceDate != null) {
              try {
                  DateTimeFormatter parser = DateTimeFormatter.ofPattern(sourceFormat);
                  DateTimeFormatter formatter = DateTimeFormatter.ofPattern(targetFormat);
                  LocalDateTime localDateTime = LocalDateTime.parse(sourceDate, parser);
  
                  targetDate = localDateTime.format(formatter);
              } catch (DateTimeParseException e) {
                  throw new DavMailException("EXCEPTION_INVALID_DATE", sourceDate);
              }
          }
          return targetDate;
      }
  
      public static String convertToUTCDateFormat(String sourceDate, String sourceTimezone, String sourceFormat, String targetFormat) throws DavMailException {
          String targetDate = null;
          if (sourceDate != null && sourceTimezone != null) {
              try {
                  DateTimeFormatter parser = DateTimeFormatter.ofPattern(sourceFormat);
                  DateTimeFormatter formatter = DateTimeFormatter.ofPattern(targetFormat);
                  LocalDateTime localDateTime = LocalDateTime.parse(sourceDate, parser);
  
                  // Convert to UTC
                  ZonedDateTime zonedStart = localDateTime.atZone(ZoneId.of(sourceTimezone));
                  ZonedDateTime utcStartDate = zonedStart.withZoneSameInstant(ZoneId.of("UTC"));
                  targetDate = utcStartDate.format(formatter);
              } catch (DateTimeParseException e) {
                  throw new DavMailException("EXCEPTION_INVALID_DATE", sourceDate);
              }
          }
          return targetDate;
      }
  }