# DateValue.java

    /*
    ** Module   :DateValue.java
    ** Abstract :Date value holder.
    **
    ** Copyright (c) 2005-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- -T- --JPRM-- ----------------Description-----------------
    ** 001 SIY 20050218 ADD  @20017  Created initial version
    ** 002 SIY 20050310 CHG  @20356  Organized imports and reordered methods.
    **                               Fixed format string.
    **                               Fixed month calculation.
    **                               Fixed equals();
    ** 003 SIY 20050323 CHG  @20470  Fixed formatting.
    ** 004 SIY 20050325 CHG  @20493  Fixed format string.
    ** 005 SIY 20050328 CHG  @20576  Added "implements Comparable" and cleared
    **                               milliseconds field.
    ** 006 NVS 20050426 CHG  @20890  Class implements Serializable interface.
    ** 007 SIY 20050429 CHG  @21009  Fixed formatting.
    ** 008 EVL 20160223              Javadoc fixes to make compatible with Oracle Java 8 for
    **                               Solaris 10.
    ** 009 IAS 20160331              Moved non-threadsafe format field to ThreadLocal
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.directory;

    import java.text.DateFormat;
    import java.text.FieldPosition;
    import java.text.ParsePosition;
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.Date;
    import java.io.Serializable;

    /**
     * The main purpose of this class is to hold date value for storing/saving it
     * in the Directory. Also it allows to distinguish types during processing
     * (this is not so simple for java.util.Date and derivatives). For the
     * convenience it can be easily converted to/from java.util.Date class.
     *
     * @author  SIY
     * @version 1.0
     */
    public class DateValue
       implements Comparable, Serializable
    {
       /**
        * Format used for <code>DateValue</code> &lt;-&gt; <code>String</code>
        * conversion.
        */
       private static final ThreadLocal<SimpleDateFormat> format =
             new ThreadLocal<SimpleDateFormat>()
       {
           @Override
           protected SimpleDateFormat initialValue()
           {
               return new SimpleDateFormat("yyyy-MM-dd");
           }
       };

       /** Internal instance of the Calendar */
       private Calendar calendar;

       /**
        * Construct an instance for the current date.
        */
       public DateValue()
       {
          calendar = Calendar.getInstance();
          enforceTime(calendar.getTime());
       }

       /**
        * Construct new instance from the instance of the <code>Date</code>.
        *
        * @param   other
        *          An instance which is used as a source of the information.
        */
       public DateValue(Date other)
       {
          calendar = Calendar.getInstance();
          enforceTime(other);
       }

       /**
        * Construct new instance from the other instance of the
        * <code>DateValue</code>.
        *
        * @param   other
        *          An instance which is used as a source of the information.
        */
       public DateValue(DateValue other)
       {
          calendar = Calendar.getInstance();
          enforceTime(other.getDate());
       }

       /**
        * Construct an instance for specified date.
        *
        * @param   year
        *          Year value for the new instance.
        * @param   month
        *          Month value for the new instance.
        * @param   day
        *          Day of the month value for the new instance.
        */
       public DateValue(int year, int month, int day)
       {
          calendar = Calendar.getInstance();
          calendar.set(year, month - 1, day, 0, 0, 0);
          enforceTime(calendar.getTime());
       }

       /**
        * Parse <code>String</code> like YYYYMMDD and create an instance of
        * <code>DateValue</code>.
        *
        * @param   str
        *          Source string.
        * @return  new <code>DateValue</code> instance or <code>null</code> if
        *          source string does not contain properly formatted date.
        */
       public static DateValue valueOf(String str)
       {
          try
          {
             return new DateValue(format.get().parse(str, new ParsePosition(0)));
          }
          catch (Exception e)
          {
             return null;
          }
       }

       /**
        * Compares this instance with instance of <code>Date</code> for
        * ordering.
        *
        * @param   other
        *          The instance of <code>Date</code> to be compared.
        * @return  <code>0</code> if dates are equal; a value less than
        *          <code>0</code> if this instance date is before date of the
        *          passed parameter; a value greater than <code>0</code> if this
        *          instance date is after date of the parameter.
        */
       public int compareTo(Date other)
       {
          return calendar.getTime().compareTo(other);
       }

       /**
        * Compares two instances for ordering.
        *
        * @param   other
        *          The instance to be compared.
        * @return  <code>0</code> if instances are equal; a value less than
        *          <code>0</code> if this instance date is before date of the
        *          instance passed as a parameter; a value greater than
        *          <code>0</code> if this instance date is after date of the
        *          instance passed as a parameter.
        */
       public int compareTo(DateValue other)
       {
          return calendar.getTime().compareTo(other.getDate());
       }

       /**
        * Compare this instance with other object.
        *
        * @param   other
        *          The instance of <code>Date</code> to be compared.
        * @return  <code>0</code> if dates are equal; a value less than
        *          <code>0</code> if this instance date is before date of the
        *          passed parameter; a value greater than <code>0</code> if this
        *          instance date is after date of the parameter.
        * @throws  ClassCastException
        *          if argument is not instance of <code>Date</code> or
        *          <code>DateValue</code>.
        */
       public int compareTo(Object other)
       {
          if (other instanceof Date)
             return calendar.getTime().compareTo((Date)other);

          return compareTo((DateValue)other);
       }

       /**
        * Compares two objects for equality. Calls <code>Calendar.equals()</code>
        * or <code>Date.equals()</code> if possible. Otherwise return
        * <code>false</code>.
        *
        * @param   o
        *          Object to compare with.
        * @return  <code>true</code> if instances are equal and
        *          <code>false</code> otherwise.
        */
       public boolean equals(Object o)
       {
          if (o instanceof DateValue || o instanceof Calendar)
          {
             Calendar other;

             if (o instanceof DateValue)
                other = ((DateValue)o).calendar;
             else
                other = (Calendar)o;

             if (calendar.get(Calendar.YEAR) == other.get(Calendar.YEAR)
                && calendar.get(Calendar.MONTH) == other.get(Calendar.MONTH)
                && calendar.get(Calendar.DATE) == other.get(Calendar.DATE))
             {
                return true;
             }
             return false;
          }

          if (o instanceof Date)
             return getDate().equals(o);

          return false;
       }

       /**
        * Return current value represented as an instance of <code>Date</code>.
        *
        * @return  an instance of <code>java.util.Date</code>.
        */
       public Date getDate()
       {
          return calendar.getTime();
       }

       /**
        * Return a hash code for the instance. Use <code>Date.hashCode()</code>
        * for real computation.
        *
        * @return  hash code for the instance.
        */
       public int hashCode()
       {
          return calendar.getTime().hashCode();
       }

       /**
        * Set current value using instance of <code>Date</code> as a source.
        *
        * @param   date
        *          Source instance of <code>Date</code> to get values from.
        */
       public void setDate(Date date)
       {
          enforceTime(date);
       }

       /**
        * Convert <code>DateValue</code> instance into <code>String</code>.
        *
        * @return  string in format YYYYMMMDD.
        */
       public String toString()
       {
          StringBuffer buf = new StringBuffer();

          format.get().format(getDate(), buf, new FieldPosition(DateFormat.YEAR_FIELD));

          return buf.toString();
       }

       /**
        * This method performs all necessary steps to enforce DateValue instance
        * to contain only date, without time part.
        *
        * @param   input
        *          <code>Date</code> instance to set information from.
        */
       private void enforceTime(Date input)
       {
          //Make sure that time part is set to 0
          calendar.setTime(input);
          calendar.set(Calendar.HOUR_OF_DAY, 0);
          calendar.set(Calendar.MINUTE, 0);
          calendar.set(Calendar.SECOND, 0);
          calendar.set(Calendar.MILLISECOND, 0);
       }
    }