/projects/rssowl-2.0.5/org.rssowl.core/src/org/rssowl/core/util/DateUtils.java

/*   **********************************************************************  **

 **   Copyright notice                                                       **

 **                                                                          **

 **   (c) 2005-2009 RSSOwl Development Team                                  **

 **   http://www.rssowl.org/                                                 **

 **                                                                          **

 **   All rights reserved                                                    **

 **                                                                          **

 **   This program and the accompanying materials are made available under   **

 **   the terms of the Eclipse Public License v1.0 which accompanies this    **

 **   distribution, and is available at:                                     **

 **   http://www.rssowl.org/legal/epl-v10.html                               **

 **                                                                          **

 **   A copy is found in the file epl-v10.html and important notices to the  **

 **   license from the team is found in the textfile LICENSE.txt distributed **

 **   in this package.                                                       **

 **                                                                          **

 **   This copyright notice MUST APPEAR in all copies of the file!           **

 **                                                                          **

 **   Contributors:                                                          **

 **     RSSOwl Development Team - initial API and implementation             **

 **                                                                          **

 **  **********************************************************************  */



package org.rssowl.core.util;



import org.eclipse.core.runtime.Assert;

import org.rssowl.core.persist.INews;



import java.text.DateFormat;

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Date;

import java.util.List;

import java.util.Locale;

import java.util.TimeZone;



/**

 * Utility Class for working with <code>Dates</code>.

 *

 * @author bpasero

 */

public class DateUtils {



  /** 1 Day in Millis */

  public static final long DAY = 24L * 60L * 60L * 1000L;



  /** 1 Week in Millis */

  public static final long WEEK = 7 * DAY;



  /* An array of custom date formats */

  private static final DateFormat[] CUSTOM_DATE_FORMATS;



  /* The Default Timezone to be used */

  private static final TimeZone TIMEZONE = TimeZone.getTimeZone("UTC"); //$NON-NLS-1$



  /**

   * @return A Calendar instance with the time being Today with a Time of

   * 0:00:00

   */

  public static Calendar getToday() {

    Calendar today = Calendar.getInstance();

    today.set(Calendar.HOUR_OF_DAY, 0);

    today.set(Calendar.MINUTE, 0);

    today.set(Calendar.SECOND, 0);

    today.set(Calendar.MILLISECOND, 0);



    return today;

  }



  /**

   * Returns the first Date-Field from the given News that is not NULL. Tries

   * Modified-Date, Publish-Date, and Received-Date. The latter one is never

   * NULL so this Method will never return NULL at all.

   *

   * @param news The News to get the Date from.

   * @return Either Modified-Date, Publish-Date or Received-Date if the formers

   * are NULL.

   */

  public static Date getRecentDate(INews news) {

    if (news.getModifiedDate() != null)

      return news.getModifiedDate();



    if (news.getPublishDate() != null)

      return news.getPublishDate();



    return news.getReceiveDate();

  }



  /**

   * Works like getRecentData(INews news) with the difference of returning the

   * most recent date from a List of News.

   *

   * @param news A List of News to get the most recent Date from.

   * @return Either Modified-Date, Publish-Date or Received-Date from the most

   * recent News.

   */

  public static Date getRecentDate(List<INews> news) {

    Assert.isTrue(!news.isEmpty());



    Date mostRecentDate = null;

    for (INews newsitem : news) {

      Date date = getRecentDate(newsitem);

      if (mostRecentDate == null || date.after(mostRecentDate))

        mostRecentDate = date;

    }



    return mostRecentDate;

  }



  /**

   * Tries different date formats to parse against the given string

   * representation to retrieve a valid Date object.

   *

   * @param strdate Date as String

   * @return Date The parsed Date

   */

  public static Date parseDate(String strdate) {



    /* Return in case the string date is not set */

    if (strdate == null || strdate.length() == 0)

      return null;



    Date result = null;

    strdate = strdate.trim();

    if (strdate.length() > 10) {



      /* Open: deal with +4:00 (no zero before hour) */

      if ((strdate.substring(strdate.length() - 5).indexOf("+") == 0 || strdate.substring(strdate.length() - 5).indexOf("-") == 0) && strdate.substring(strdate.length() - 5).indexOf(":") == 2) { //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

        String sign = strdate.substring(strdate.length() - 5, strdate.length() - 4);

        strdate = strdate.substring(0, strdate.length() - 5) + sign + "0" + strdate.substring(strdate.length() - 4); //$NON-NLS-1$

      }



      String dateEnd = strdate.substring(strdate.length() - 6);



      /*

       * try to deal with -05:00 or +02:00 at end of date replace with -0500 or

       * +0200

       */

      if ((dateEnd.indexOf("-") == 0 || dateEnd.indexOf("+") == 0) && dateEnd.indexOf(":") == 3) { //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$

        if (!"GMT".equals(strdate.substring(strdate.length() - 9, strdate.length() - 6))) { //$NON-NLS-1$

          String oldDate = strdate;

          String newEnd = dateEnd.substring(0, 3) + dateEnd.substring(4);

          strdate = oldDate.substring(0, oldDate.length() - 6) + newEnd;

        }

      }

    }



    /* Try to parse the date */

    int i = 0;

    while (i < CUSTOM_DATE_FORMATS.length) {

      try {



        /*

         * This Block needs to be synchronized, because the parse-Method in

         * SimpleDateFormat is not Thread-Safe.

         */

        synchronized (CUSTOM_DATE_FORMATS[i]) {

          return CUSTOM_DATE_FORMATS[i].parse(strdate);

        }

      } catch (ParseException e) {

        i++;

      } catch (NumberFormatException e) {

        i++;

      }

    }

    return result;

  }



  /** Initialize the array of common date formats and formatter */

  static {



    /* Create Date Formats */

    final String[] possibleDateFormats = {



        /* RFC 1123 with 2-digit Year */

        "EEE, dd MMM yy HH:mm:ss z", //$NON-NLS-1$



        /* RFC 1123 with 4-digit Year */

        "EEE, dd MMM yyyy HH:mm:ss z", //$NON-NLS-1$



        /* RFC 1123 with no Timezone */

        "EEE, dd MMM yy HH:mm:ss", //$NON-NLS-1$



        /* Variant of RFC 1123 */

        "EEE, MMM dd yy HH:mm:ss", //$NON-NLS-1$



        /* RFC 1123 with no Seconds */

        "EEE, dd MMM yy HH:mm z", //$NON-NLS-1$



        /* Variant of RFC 1123 */

        "EEE dd MMM yyyy HH:mm:ss", //$NON-NLS-1$



        /* RFC 1123 with no Day */

        "dd MMM yy HH:mm:ss z", //$NON-NLS-1$



        /* RFC 1123 with no Day or Seconds */

        "dd MMM yy HH:mm z", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:ssZ", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:ss'Z'", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:sszzzz", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:ss z", //$NON-NLS-1$



        /* ISO 8601 */

        "yyyy-MM-dd'T'HH:mm:ssz", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:ss.SSSz", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HHmmss.SSSz", //$NON-NLS-1$



        /* ISO 8601 slightly modified */

        "yyyy-MM-dd'T'HH:mm:ss", //$NON-NLS-1$



        /* ISO 8601 w/o seconds */

        "yyyy-MM-dd'T'HH:mmZ", //$NON-NLS-1$



        /* ISO 8601 w/o seconds */

        "yyyy-MM-dd'T'HH:mm'Z'", //$NON-NLS-1$



        /* RFC 1123 without Day Name */

        "dd MMM yyyy HH:mm:ss z", //$NON-NLS-1$



        /* RFC 1123 without Day Name and Seconds */

        "dd MMM yyyy HH:mm z", //$NON-NLS-1$



        /* Simple Date Format */

        "yyyy-MM-dd", //$NON-NLS-1$



        /* Simple Date Format */

        "MMM dd, yyyy" //$NON-NLS-1$

    };



    /* Create the dateformats */

    CUSTOM_DATE_FORMATS = new SimpleDateFormat[possibleDateFormats.length];



    for (int i = 0; i < possibleDateFormats.length; i++) {

      CUSTOM_DATE_FORMATS[i] = new SimpleDateFormat(possibleDateFormats[i], Locale.ENGLISH);

      CUSTOM_DATE_FORMATS[i].setTimeZone(TIMEZONE);

    }

  }

}