# NumberFormatter.java

    /*
    ** Module   : NumberFormatter.java
    ** Abstract : Format Progress numbers.
    **
    ** Copyright (c) 2021-2022, Golden Code Development Corporation.
    **
    ** -#- -I- --Number-- ---------------------------------Description---------------------------------
    ** 001 VVT 20210426 Created initial version.
    **     VVT 20210624 Javadoc fixed
    **     TJD 20220504 Java 11 compatibility minor changes
    */
    /*
    ** 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.util;

    import java.math.*;

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

    /**
     * Format Progress numbers.
     *
     */
    public class NumberFormatter
    extends NumberFormatParser
    {
       /** Collector for the output formatted value */
       private StringBuilder sb;

       /** The value being formatted */
       private final BigDecimal value;

       /** {@code true} if we are formatting a negative number. */
       private final boolean isNegative;

       /** The left (integer) part of the formatted number */
       private final String leftDigits;

       /** The right (fraction) part of the formatted number */
       private final String rightDigits;

       /** Set to {@code true} by if any of {@link #visitLeftDigits(int, int)} or
        * {@link #visitRightDigits(int, int, int)} callbacks was called */
       private boolean digitsVisited;

       /** Set to {@code true} by {@link #visitSign(int, int)} digits callback */
       private boolean signVisited;

       /** The format string, used for error reporting from callbacks */
       private final String format;

       /** Any error related to a value being formatted occurred before the format parse is complete.
        * This value is used to defer processing of value-related error until format string is
        * completely parsed, and all format-related errors processed. */
       private Runnable deferredError = null;

       /**
        * The constructor.
        *
        * @param value
        *        the value to format
        * @param fmt
        *        the format string
        */
       public NumberFormatter(final BigDecimal value, final String fmt)
       {
          this.value = value;
          final String full = value.abs().toString();
          final int pos = full.indexOf('.');
          if (pos < 0)
          {
             // no decimal point
             leftDigits = full;
             rightDigits = "";
          }
          else
          {
             // standard case
             leftDigits = full.substring(0, pos);
             rightDigits = full.substring(pos + 1);
          }

          this.isNegative = value.signum() < 0;
          this.format = fmt;
       }

       /**
        * Do the formatting.
        *
        * @return the formatted number
        */
       public final String format()
       {
          sb = new StringBuilder();
          parse(format);
          final String result = sb.toString();

          if (isNegative && !signVisited)
          {
             DisplayFormat.genValueCannotBeDisplayedError(value.toString(), format);
             // FIXME: generate string of question marks?
             return "";
          }

          if (deferredError != null)
          {
             deferredError.run();
          }

          return result;
       }

       /**
        * A fill character was parsed.
        *
        * @param c
        *        the character
        */
       @Override
       protected void visitFillChar(final char c)
       {
          if (deferredError != null)
          {
             return;
          }

          sb.append(c);
       }

       /**
        * A sign spec was parsed.
        *
        * Sign specs are: '+', '-', '(', ')', DR, CR and DB.
        *
        * @param startIdx
        *        the section start index in format string, zero-based, inclusive
        * @param endIdx
        *        the section end index in format string, zero-based, exclusive
        */
       @Override
       protected void visitSign(final int startIdx, final int endIdx)
       {
          if (deferredError != null)
          {
             return;
          }

          signVisited = true;
          switch (endIdx - startIdx)
          {
             case 1:
                // single format character
                final char in;
                final char c = format.charAt(startIdx);
                switch (c)
                {
                   case '+':
                      in = isNegative ? '-' : '+';
                      break;

                   case '-':
                      if (isNegative)
                      {
                         in = '-';
                         break;
                      }

                      if (!digitsVisited)
                      {
                         // If we are on left, insert spaces to the beginning of the output.
                         // Test the next format character: if 'z'
                         if (endIdx == format.length())
                         {
                            // Id we are at the end of the format string, then format is invalid:
                            // no digits. Just return and let the format parser handle this error.
                            return;
                         }

                         final char nextChar = format.charAt(endIdx);
                         if (nextChar == '>')
                         {
                            sb.insert(0, ' ');
                            return;
                         }
                      }

                      in = ' ';
                      break;

                   case '(':
                   case ')':
                      in = isNegative ? c : ' ';
                      break;

                   default:
                      // Should never happen
                      throw new ErrorConditionException(-1, "Invalid sign character");
                }

                sb.append(in);
                break;

             case 2:
                // two-character spec: DR, CR, DB
                sb.append(isNegative ? format.substring(startIdx, endIdx) : "  ");
                break;

             default:
                // Should never happen
                throw new ErrorConditionException(-1, "Invalid sign specification");
          }
       }

       /**
        * Non-empty left digits section was parsed.
        *
        * @param startIdx
        *        the section start index in format string, zero-based, inclusive
        * @param endIdx
        *        the section end index in format string, zero-based, exclusive
        */
       @Override
       protected void visitLeftDigits(final int startIdx, final int endIdx)
       {
          digitsVisited = true;
          int insertionPoint = sb.length();

          int formatIdx = endIdx - 1;
          int valueIdx = leftDigits.length() - 1;
          for (;; formatIdx--)
          {
             final boolean inLeadingZeroes = valueIdx < 0;
             if (formatIdx < startIdx && inLeadingZeroes)
             {
                return;
             }

             if (formatIdx < 0)
             {
                setDeferredError(leftDigits);
                return;
             }

             char formatChar = format.charAt(formatIdx);

             if (!inLeadingZeroes)
             {
                if (formatChar == ',')
                {
                   sb.insert(insertionPoint, ',');
                   continue;
                }

                if (formatIdx < startIdx)
                {
                   if (formatChar == '+')
                   {
                      insertionPoint--;
                      sb.deleteCharAt(insertionPoint);
                   }
                   else
                   {
                      setDeferredError(leftDigits);
                      return;
                   }
                }

                sb.insert(insertionPoint, leftDigits.charAt(valueIdx--));
                continue;
             }

             // If we are here, we are in leading zeroes

             // If a comma is preceded by 'z' or '>', it acts as the
             // preceding character, so just replace comma to the preceding character.
             if (formatChar == ',' && formatIdx > 0)
             {
                final char preceding = format.charAt(formatIdx - 1);
                switch (preceding)
                {
                   case '>':
                   case 'z':
                   case 'Z':
                   case '*':
                      formatChar = preceding;
                      break;

                   default:
                }
             }

             if (formatChar == ',')
             {
                sb.insert(insertionPoint, ',');
                continue;
             }

             final char insertChar;
             switch (formatChar)
             {
                case '9':
                   insertChar = '0';
                   break;

                case '*':
                   insertChar = '*';
                   break;

                case 'z':
                case 'Z':
                   insertChar = ' ';
                   break;

                case '>':
                   // We are inserting spaces to the beginning of the output.
                   sb.insert(0, ' ');
                   continue;

                case '(':
                   insertChar = isNegative ? '(' : ' ';
                   break;

                default:
                   // Should never happen
                   throw new ErrorConditionException(-1, "Invalid digit");
             }

             sb.insert(insertionPoint, insertChar);
          }
       }

       /**
        * Right digits section was parsed (may be empty).
        *
        * @param startIdx
        *        the section start index in format string, zero-based, inclusive
        * @param endIdx
        *        the section end index in format string, zero-based, exclusive
        * @param separators
        *        the number of digit separator ',' character in right digits
        */
       @Override
       protected void visitRightDigits(final int startIdx, final int endIdx, final int separators)
       {
          if (deferredError != null)
          {
             return;
          }

          digitsVisited = true;
          sb.append('.');
          if (startIdx == endIdx)
          {
             // Special case, check it here to prevent endless loop below
             return;
          }

          // Test if all fraction digits will fit, otherwise round the value

          // The number of outstanding digits
          final int unfitDigits = rightDigits.length() - (endIdx - startIdx - separators);
          final String src;
          if (unfitDigits > 0)
          {
             // If we are here, then some digits do not fit, do rounding and repeat
             final BigDecimal rounded = value.setScale(value.scale() - unfitDigits,
                      RoundingMode.HALF_UP);

             final String roundedString = rounded.toString();
             final int dotIdx = roundedString.indexOf('.');
             assert dotIdx >= 0;
             src = roundedString.substring(dotIdx + 1);
          }
          else
          {
             src = rightDigits;
          }

          final int srcLength = src.length();
          int digitsIdx = 0;

          for (int fmtIdx = startIdx; fmtIdx < endIdx; fmtIdx++)
          {
             final char fmtChar = format.charAt(fmtIdx);
             if (fmtChar == ',')
             {
                sb.append(',');
                continue;
             }

             if (digitsIdx < srcLength)
             {
                final int nextChar = src.charAt(digitsIdx++);
                sb.append((char) nextChar);
                continue;
             }

             switch (fmtChar)
             {
                case '9':
                   sb.append('0');
                   break;

                case '<':
                   break;

                default:
                   // Must never be here
                   throw new ErrorConditionException(-1, "");
             }
          }
       }

       /**
        * Set the deferred error action.
        * <p>
        * Implementation should call this method only once when the first value-related
        * error is detected.
        *
        * @param reportedValue
        *        the value as string to use in the error message
        */
       private final void setDeferredError(final String reportedValue)
       {
          // Implementation should assert we never set it twice
          assert deferredError == null;

          deferredError = () -> DisplayFormat.genValueCannotBeDisplayedError(reportedValue, format);
       }
    }