package org.apidesign.apifest08.test;

 import java.math.BigDecimal;

 import java.util.Currency;

 import org.apidesign.apifest08.currency.ExchangeRate;

 import org.apidesign.apifest08.currency.ExchangeRateFinder;

 class TestExchangeRateFinder

     implements ExchangeRateFinder

 {

     private final BigDecimal min;

     private final BigDecimal max;

     private final BigDecimal stepUp;

     private final BigDecimal stepDown;

     private BigDecimal step;

     private BigDecimal rate;

     private boolean firstCall;

     TestExchangeRateFinder(final BigDecimal mn,

                            final BigDecimal mx,

                            final BigDecimal start,

                            final BigDecimal up,

                            final BigDecimal down)

     {

         min       = mn;

         max       = mx;

         rate      = start;

         stepUp    = up;

         stepDown  = down;

         firstCall = true;

     }

     public ExchangeRate findRate(Currency a, Currency b) 

     {

         final ExchangeRate value;

         if(rate.equals(max))

         {

             step = stepDown;

         }

         else if(rate.equals(min))

         {

             step = stepUp;

         }

         value = new ExchangeRate(a, b, BigDecimal.ONE, rate);

         if(firstCall)

         {

             firstCall = false;

         }

         else

         {

             rate = rate.add(step);

         }

         return (value);

     }

 }