package org.apidesign.apifest08.currency;

 import java.math.BigDecimal;

 public class ConvertorFactory {

     public static Convertor getConvertor(CurrencyType from, CurrencyType to) {

         if (from == CurrencyType.CZK && to == CurrencyType.USD) {

              return new BasicConvertor(new BigDecimal(17));

         } else if (from == CurrencyType.SKK && to == CurrencyType.CZK) {

             double rate = 0.8d;

             return new BasicConvertor(new BigDecimal(rate));

         }

         throw new UnsupportedOperationException("Conversion not supported now");

     }

     private static class BasicConvertor implements Convertor {

         private final BigDecimal conversionRate;

         BasicConvertor(BigDecimal conversionRate) {

             this.conversionRate = conversionRate;

         }

         @Override

         public long convertTo(long amount) {

             return (long) (conversionRate.doubleValue() * amount);

         }

         @Override

         public long convertFrom(long amount) {

             return (long) (amount / conversionRate.doubleValue());

         }

     }

 }