DateFormatter.java

/*
** Module   : DateFormatter.java
** Abstract : Format Progress date objects.
**
** Copyright (c) 2021, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description---------------------------------
** 001 VVT 20210413 Created initial version.
**     VVT 20210426 The class API re-designed.
**     VVT 20210428 Import statements fixed.
**     VVT 20210624 Javadoc fixed
**     VVT 20210917 Javadoc fixed. 
*/
/*
** 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.
**
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**     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.
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*/
package com.goldencode.p2j.util;

import java.text.NumberFormat;

import com.goldencode.p2j.ui.client.format.*;

/**
 * Progress date formatter.
 * 
 */
public class DateFormatter
extends DateFormatParser
{
   /**
    * The constructor.
    * 
    * @param value
    *        the date instance to format
    * @param format
    *        the date format to use
    * @param order
    *        The date component order spec: array of 3 elements. Values can be {@link date#YEAR},
    *        {@link date#MONTH},  or {@link date#DAY}.
    */
   public DateFormatter(final date value, final String format, final byte[] order)
   {
      this.value = value;
      this.format = format;
      this.order = order;
   }

   /** The date to format */
   private final date value;
   
   /** The output formatted value collector */
   private final StringBuilder sb = new StringBuilder();
   
   /** The date format, used for error reporting. */
   private final String format;
   
   /** Set to true when the first "value cannot be formatted" error is occurred.
    * This deferred value error handling is required to assert the format is always parsed completely,
    * and any format errors are reported first, to match the OE behavior. */
   private boolean deferredValueError;

   /** The date component order spec: array of 3 elements. Values can be {@link date#YEAR},
    *  {@link date#MONTH},  or {@link date#DAY} */
   private final byte[] order;
   
   /**
    * Format date using the specified format string.
    * 
    * @return the formatted date
    */
   public String format()
   {
      sb.setLength(0);
      parse(format);
      if (deferredValueError)
      {
         DisplayFormat.genValueCannotBeDisplayedError(value.toStringExport(), format);
         return null;
      }
      
      return sb.toString();
   }

   /**
    * The the year component of the date spec.
    * <p>
    * Note: the length of the first date component <b>can be zero</b>.
    * 
    * @param startIdx
    *        the component start index, zero based
    * @param endIdx
    *        the component end index, zero based, exclusive
    */
   protected void visitYear(final int startIdx, final int endIdx)
   {
      // this method can be called from the parse method
      // with no value provided.

      // If the year spec is empty, just do nothing
      if (deferredValueError || value == null || startIdx == endIdx)
      {
         return;
      }

      final int len = endIdx - startIdx;
      final String yr = toYearString(len);
      if (yr == null)
      {
         deferredValueError = true;
         return;
      }

      sb.append(yr);
   }

   /**
    * The the month component of the date spec.
    * <p>
    * Note: the length of the component <b>can be zero</b>.
    * 
    * @param startIdx
    *        the component start index, zero based
    * @param endIdx
    *        the component end index, zero based, exclusive
    */
   protected void visitMonth(final int startIdx, final int endIdx)
   {
      // this method can be called from the parse method
      // with no value provided.
      if (deferredValueError || value == null)
      {
         return;
      }

      formatDayOrMonth(startIdx, endIdx, value.getMonth());
   }

   /**
    * The day component of the date spec.
    * <p>
    * Note: the length of the component <b>can be zero</b>.
    * 
    * @param startIdx
    *        the component start index, zero based
    * @param endIdx
    *        the component end index, zero based, exclusive
    */
   protected void visitDay(final int startIdx, final int endIdx)
   {
      // this method can be called from the parse method
      // with no value provided.
      if (deferredValueError || value == null)
      {
         return;
      }

      formatDayOrMonth(startIdx, endIdx, value.getDay());
   }

   /**
    * Dispatch the date component to a matching callback.
    * 
    * @param componentIndex
    *        the number of the component in the format spec
    * @param startIdx
    *        the component start index, zero based
    * @param endIdx
    *        the component end index, zero based, exclusive
    */
   @Override
   protected final void visitDateComponent(final int componentIndex, final int startIdx,
            final int endIdx)
   {
      switch (order[componentIndex])
      {
         case date.YEAR:
            visitYear(startIdx, endIdx);
            break;
         case date.MONTH:
            visitMonth(startIdx, endIdx);
            break;
         case date.DAY:
            visitDay(startIdx, endIdx);
            break;
         default:
      }
   }

   /**
    * The first date component separator was parsed: one of '.', '-' or '/'.
    * <p>
    * Subclasses are expected to overload this method,
    * default implementation does nothing.
    * <p>
    * Note: if date format has no separators, this callback is never called.
    * 
    * @param sep
    *        the first separator character
    */
   @Override
   protected void visitSep1(final char sep)
   {
      sb.append(sep);
   }

   /**
    * The second date component separator was parsed: one of '.', '-' or '/'.
    * <p>
    * Subclasses are expected to overload this method,
    * default implementation does nothing.
    * <p>
    * Note: if date format has no separators, this callback is never called.
    * 
    * @param sep
    *        the second separator character
    */
   @Override
   protected void visitSep2(final char sep)
   {
      sb.append(sep);
   }

   /**
    * Format day or month component.
    * 
    * @param startIdx
    *        the component start index in the format string
    * @param endIdx
    *        the component end index in the format string
    * @param number
    *        the value to format
    */
   private void formatDayOrMonth(final int startIdx, final int endIdx, final int number)
   {
      if (deferredValueError)
      {
         return;
      }
      
      final int len = endIdx - startIdx;
      if (len == 0 || (len == 1 && number > 9))
      {
         deferredValueError = true;
         return;
      }

      sb.append(formatField(number, len));
   }

   /**
    * Generate a string representation of the year based on the unusual
    * rules of the Progress 4GL.
    * 
    * @param    max
    *           Specifies the maximum number of output characters. If the
    *           result cannot fit into this number of characters, then
    *           a <code>null</code> string will be returned. As a special
    *           case, years within the Y2K window will be truncated to
    *           1 (if possible without losing data) or 2 characters if
    *           max is set to these values respectively.  All other values
    *           must 'naturally' fit inside the maximum.
    *           
    * @return   The formatted string or <code>null</code> if the result is
    *           too large to fit.
    */
   private String toYearString(final int max)
   {
      // make sure the laws of logic hold
      assert max >= 1;
      final int yy = value.getYear();

      // if we have a negative number, we can only pad up to min - 1 chars
      // except when force is enabled
      final int actual = yy >= 0 ? max : max - 1;

      final String year = formatField(yy, actual);

      // non-export mode windowing allows truncation
      if (value.inY2KWindow() && max < 3)
      {
         // even truncation doesn't help if we lose data
         if ((yy % 100) > 9 && max == 1)
         {
            return null;
         }

         // truncate
         if (year.length() > max)
         {
            return year.substring(year.length() - max);
         }

         return year;
      }

      // test if we fit
      return year.length() > max ? null : year;
   }

   /**
    * Format one date component.
    * 
    * @param number
    *        the number to format
    * @param minimumLen
    *        the minimum number of digits
    */
   private final static String formatField(final int number, final int minimumLen)
   {
      final NumberFormat nf = NumberFormat.getInstance();
      nf.setGroupingUsed(false);
      nf.setMinimumIntegerDigits(minimumLen);
      return nf.format(number);
   }
}