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));

	}

}