package org.apidesign.apifest08.currency;

 import java.math.BigDecimal;

 import java.math.RoundingMode;

 /**

  * This class encapsulates settings for currency conversion

  * We can use it eg. for uptime options etc. in future versions

  *

  * @author Ladislav Vitasek

  */

 final public class ConversionProperties {

     private final ConversionRatioProvider conversionRatioProvider;

     private final RoundingMode roundingMode;

     /**

      * Returns conversion constants - conversion operation is invertable

      * Default

      */

     private final static class FixedBidirectionalRatioConversion implements ConversionRatioProvider {

         private final BigDecimal currency1ToCurrency2Constant;

         private final BigDecimal currency2ToCurrency1Constant;

         private static final int SCALE_MAX_DEFAULT = 20;

         /**

          * Constructor

          * @param ratioConstant fixed ratio constant

          * @param mode math rounding mode

          * @throws IllegalArgumentException if conversion value is <= 0

          */

         private FixedBidirectionalRatioConversion(BigDecimal ratioConstant, RoundingMode mode) {

             if (ratioConstant.compareTo(BigDecimal.ZERO) <= 0)

                 throw new IllegalArgumentException("Conversion value cannot be <= 0");

             this.currency1ToCurrency2Constant = ratioConstant;

             this.currency2ToCurrency1Constant = BigDecimal.ONE.setScale(SCALE_MAX_DEFAULT).divide(ratioConstant, mode);

         }

         public BigDecimal getCurrency1ToCurrency2Constant() {

             return currency1ToCurrency2Constant;

         }

         public BigDecimal getCurrency2ToCurrency1Constant() {

             return currency2ToCurrency1Constant;

         }

     }

     /**

      * Returns new instance Conversion properties - fixed conversion ratio - both directions

      * Default max scale is set to 20

      *

      * @param conversionConstant value of constant for conversion

      * @param roundingMode       math rounding mode

      * @return new instance of ConversionProperties class

      * @throws IllegalArgumentException if conversion constant is <= 0 

      * @see org.apidesign.apifest08.currency.ConversionProperties.FixedBidirectionalRatioConversion

      */

     public static ConversionProperties create(BigDecimal conversionConstant, RoundingMode roundingMode) {

         return create(new FixedBidirectionalRatioConversion(conversionConstant, roundingMode), roundingMode);

     }

     /**

      * Returns new instance Conversion properties

      *

      * @param conversionRatioProvider provider for conversion constants

      * @param roundingMode       math rounding mode

      * @return new instance of ConversionProperties class

      */

     public static ConversionProperties create(ConversionRatioProvider conversionRatioProvider, RoundingMode roundingMode) {

         if (conversionRatioProvider == null || roundingMode == null)

             throw new NullPointerException();

         return new ConversionProperties(conversionRatioProvider, roundingMode);

     }

     /**

      * Returns new instance Conversion properties with values set to conversionConstant=BigDecimal.ONE

      * and roundingMode=RoundingMode.HALF_EVEN

      * 

      * Conversion is bidirectional.

      *

      * @return

      */

     public static ConversionProperties createDefault() {

         return create(BigDecimal.ONE, RoundingMode.HALF_EVEN);

     }

     private ConversionProperties(ConversionRatioProvider conversionRatioProvider, RoundingMode roundingMode) {

         this.conversionRatioProvider = conversionRatioProvider;

         this.roundingMode = roundingMode;

     }

     public RoundingMode getRoundingMode() {

         return roundingMode;

     }

     public ConversionRatioProvider getConversionRatioProvider() {

         return conversionRatioProvider;

     }

 }