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);

    }

}