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/***********************************************************************************************************************
 *
 * blueMarine Metadata - open source media workflow
 * Copyright (C) 2007-2011 by Tidalwave s.a.s. (http://www.tidalwave.it)
 *
 ***********************************************************************************************************************
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations under the License.
 *
 ***********************************************************************************************************************
 *
 * WWW: http://bluemarine.tidalwave.it
 * SCM: https://kenai.com/hg/bluemarine~metadata-src
 *
 **********************************************************************************************************************/
package it.tidalwave.metadata.text;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import java.util.StringTokenizer;
import java.text.DecimalFormat;
import java.text.FieldPosition;
import java.text.ParseException;

/*******************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 ******************************************************************************/
public class EVFormat extends DecimalFormat
  {
    public static enum Fractions
      {
        STANDARD("1/6", "1/3", "1/2", "2/3", "5/6"),
        UNICODE("\u2159", "\u2153", "\u00bd", "\u2154", "\u215A");

        @Nonnull
        private final String[] strings;
        
        private Fractions (@Nonnull final String ... strings)
          {
            this.strings = strings;
          }

        @Nonnull
        public String getString (@Nonnegative final int i)
          {
            return strings[i];
          }
      }
            
    private static final long serialVersionUID = 7069052345876458L;

    private static final int[] NUMERATORS = { 1, 1, 1, 2, 5 };
    
    private static final int[] DENUMERATORS = { 6, 3, 2, 3, 6 };

    private Fractions fractions;

    public EVFormat()
      {
        this( Fractions.STANDARD);
      }
            
    public EVFormat (@Nonnull final Fractions fractions)
      {
        this.fractions = fractions;
      }

    @Nonnull
    public Fractions getFractions() 
      {
        return fractions;
      }

    public void setFractions (@Nonnull final Fractions fractions)
      {
        this.fractions = fractions;
      }
    
    @Override
    @Nonnull
    public StringBuffer format (@Nonnegative final long number,
                                @Nonnull final StringBuffer result,
                                @Nonnull final FieldPosition fieldPosition)
      {
        return format((double)number, result, fieldPosition);
      }
    
    @Override
    @Nonnull
    public StringBuffer format (@Nonnegative final double number,
                                @Nonnull final StringBuffer toAppendTo,
                                @Nonnull final FieldPosition fieldPosition)
      {
        final StringBuilder s = new StringBuilder();

        if (number == 0)
          {
            s.append("0");
          }

        else
          {
            if (number > 0)
              {
                s.append("+");
              }

            if (number < 0)
              {
                s.append("-");
              }

            final double abs = Math.abs(number);
            final int integer = (int)Math.floor(abs);
            final double fractional = abs - integer;

            if (integer != 0)
              {
                s.append(integer);
                s.append(" ");
              }
            
            s.append(getFractionText(fractional));
          }

        toAppendTo.append(s.toString().trim());
        toAppendTo.append(" EV");

        return toAppendTo;
      }

    @Override
    @Nonnull
    public Number parse (@CheckForNull String s)
        throws ParseException
      {
        if (s != null)
          {
            s = s.replaceAll("EV$", "").trim();
          }
        
        if ((s == null) || s.equals("") || s.equals("0"))
          {
            return Double.valueOf(0); // FIXME
          }

        StringTokenizer st = new StringTokenizer(s.substring(1), " ");
        final String maybeIntegerPart = st.nextToken().trim();
        double d = 0;
        String fractionalPart = null;
        
        if (!maybeIntegerPart.contains("/"))
          {
            d = Double.parseDouble(maybeIntegerPart);
            
            if (st.hasMoreTokens())
              {
                fractionalPart = st.nextToken();
              }
          }
        else
          {
            fractionalPart = maybeIntegerPart;  
          }

        if (fractionalPart != null)
          {
            st = new StringTokenizer(fractionalPart, "/");
            d += (Double.parseDouble(st.nextToken()) / Double.parseDouble(st.nextToken()));
          }

        if (s.charAt(0) == '-')
          {
            d = -d;
          }

        return Double.valueOf(d);
      }

    @Nonnull
    private String getFractionText (@Nonnegative final double value)
      {
        for (int i = 0; i < NUMERATORS.length; i++)
          {
            if (Math.abs((value * DENUMERATORS[i]) - NUMERATORS[i]) < 0.01)
              {
                return fractions.getString(i);
              }
          }

        return "";
      }
  }