package org.apidesign.apifest08.currency;

import java.math.BigDecimal;

public class ConvertorFactory {

    public static Convertor getConvertor(CurrencyType from, CurrencyType to) {

        if (from == CurrencyType.CZK && to == CurrencyType.USD) {

             return new BasicConvertor(new BigDecimal(17));

        } else if (from == CurrencyType.SKK && to == CurrencyType.CZK) {

            double rate = 0.8d;

            return new BasicConvertor(new BigDecimal(rate));

        }

        throw new UnsupportedOperationException("Conversion not supported now");

    }

    private static class BasicConvertor implements Convertor {

        private final BigDecimal conversionRate;

        BasicConvertor(BigDecimal conversionRate) {

            this.conversionRate = conversionRate;

        }

        @Override

        public long convertTo(long amount) {

            return (long) (conversionRate.doubleValue() * amount);

        }

        @Override

        public long convertFrom(long amount) {

            return (long) (amount / conversionRate.doubleValue());

        }

    }

}