package org.apidesign.apifest08.currency;

import java.math.BigDecimal;

import java.util.Currency;

import java.util.HashMap;

import java.util.Map;

/**

 * Default factory for convertors. Basically it just keeps exchange rates for given currency combinations.

 * @author lukas

 *

 */

class DefaultConvertorFactory {

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

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

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

	private Map<String, Convertor> convertorMap = new HashMap<String, Convertor>();

	public 	DefaultConvertorFactory()

	{

		addConvertor(CZK,USD,BigDecimal.valueOf(17),BigDecimal.valueOf(1));

		addConvertor(CZK,SKK,BigDecimal.valueOf(80),BigDecimal.valueOf(100));

	}

	private void addConvertor(Currency sourceCurrency, Currency destinationCurrency, BigDecimal sourceEquivalent, BigDecimal destinationEquivalent) {

		DefaultConvertor convertor = new DefaultConvertor(sourceEquivalent, destinationEquivalent, sourceCurrency, destinationCurrency);

		convertorMap.put(getConvertorKey(sourceCurrency, destinationCurrency), convertor);

		convertorMap.put(getConvertorKey(destinationCurrency, sourceCurrency), convertor.revert());

	}

	public Convertor getConvertor(Currency sourceCurrency, Currency destinationCurrency) throws UnsupportedConversionException

	{

		String convertorKey = getConvertorKey(sourceCurrency, destinationCurrency);

		Convertor result = convertorMap.get(convertorKey);

		if (result!=null)

		{

			return result;

		}

		else

		{

			throw new UnsupportedConversionException("Conversion from "+sourceCurrency+" to "+destinationCurrency+" is not supported");

		}

	}

	private String getConvertorKey(Currency sourceCurrency,	Currency destinationCurrency) {

		return sourceCurrency.getCurrencyCode()+destinationCurrency.getCurrencyCode();

	}

}