package org.apidesign.apifest08.test;

 import java.math.BigDecimal;

 import java.util.Currency;

 import org.apidesign.apifest08.currency.ConvertorFactory;

 import org.apidesign.apifest08.currency.ExtendedConvertor;

 import org.apidesign.apifest08.currency.Money;

 import org.apidesign.apifest08.currency.MoneyImpl;

 /**

  * Third party implementation of the convertor. IT IS NOT THREAD SAFE.

  * @author lukas

  *

  */

 class OnlineConvertor implements ExtendedConvertor {

 	private static final BigDecimal LOWER_LIMIT = BigDecimal.valueOf(15);

 	private static final BigDecimal HIGHER_LIMIT = BigDecimal.valueOf(16);

 	private static final Currency USD = Currency.getInstance("USD");

 	private static final Currency CZK = Currency.getInstance("CZK");

 	private static final MoneyImpl ONE_USD = new MoneyImpl(1,USD);

 	private ExtendedConvertor wrappedConvertor = ConvertorFactory.createConvertor(ONE_USD, new MoneyImpl(16, CZK));

 	private BigDecimal increment = new BigDecimal("-0.01");

 	public boolean isConversionSupported(Currency from, Currency to) {

 		return wrappedConvertor.isConversionSupported(from, to);

 	}

 	public Money convert(Money amount, Currency destinationCurrency)

 			throws IllegalArgumentException {

 		Money result = wrappedConvertor.convert(amount, destinationCurrency);

 		updateConvertor();

 		return result;

 	}

 	/**

 	 * Prepares convertor for the next conversion.

 	 */

 	private void updateConvertor() {

 		BigDecimal currentRate = wrappedConvertor.convert(ONE_USD, CZK).getAmount();

 		BigDecimal newRate = currentRate.add(increment);

 		if (LOWER_LIMIT.compareTo(newRate)==0 || HIGHER_LIMIT.compareTo(newRate)==0)

 		{

 			increment = increment.negate();

 		}

 		wrappedConvertor = ConvertorFactory.createConvertor(ONE_USD, new MoneyImpl(newRate, CZK));

 	}

 }