japod@23: package org.apidesign.apifest08.currency;
japod@23: 
japod@23: import java.math.BigDecimal;
japod@23: import java.math.MathContext;
japod@23: import java.math.RoundingMode;
japod@23: 
japod@23: /** Convertor able to convert amount from one currency to other currency.
japod@41:  * <p>
japod@41:  * Conversion method are:
japod@41:  * <ul>
japod@41:  * <li>{@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal)} - convert using exchange rate specified in exchange rate provide. <em>Do not try use reverted excahnage rate</em>. 
japod@41:  * <li>{@link #convertWithReversibleRates(ConvertorCurrency, ConvertorCurrency, BigDecimal)} - convert using exchange rate specified in exchange rate provide. <em>Try use reverted excahnage rate</em>. 
japod@41:  * </ul>
japod@23:  * 
japod@23:  * Exchange rate is provided by {@link ExchangeRateProvider}.
japod@23:  */
japod@23: public class Convertor {
japod@41:     private Convertor[] convertors;
japod@41: 
japod@41:     /** Create new <code>Convertor</code> as merge of provided convertors. Merged convertor will use
japod@41:      * provided convertors to convert between currencies.
japod@41:      * <p>
japod@41:      * Only one should be able to provide conversion between currencies. If more than one convertos
japod@41:      * are able to convert currency, one of conversions will be used (it is not defined which).
japod@41:      * 
japod@41:      * @since version 2
japod@41:      * @param convertors Convertor used to create merge-convertor.
japod@41:      * @return Returns new convertor instance.
japod@41:      */
japod@41:     public static Convertor createConvertorAsMerge(Convertor[] convertors) {
japod@41:         return new Convertor(convertors);
japod@41:     }
japod@41:     
japod@41:     boolean remainderAllowed = true; //if false, remained is not allowed (should be true ideally, but can't handle it now)
japod@23:     ExchangeRateProvider exchangeRateProvider; 
japod@23:     
japod@41:     /** Create simle convertor.
japod@41:      */
japod@23:     private Convertor() {
japod@41:         this.convertors=new Convertor[0];
japod@41:     }
japod@41:     
japod@41:     /** Create merge convertor.
japod@41:      */            
japod@41:     private Convertor(Convertor[] convertors) {
japod@41:         this.convertors = convertors;       
japod@23:     }
japod@23:     
japod@23:     /**
japod@41:      * Create new <code>Convertor</code> using <code>ExchangeRateProvider</code>.
japod@23:      * 
japod@23:      * @param exchangeRateProvider {@link ExchangeRateProvider} used to get exchange rate.
japod@23:      * 
japod@23:      * @return Returns <code>Convertor</code> which can be used to convert money.
japod@41:      * @since version1
japod@23:      */
japod@23:     public static Convertor createConvertor(ExchangeRateProvider exchangeRateProvider) {
japod@23:         Convertor c = new Convertor();
japod@23: 
japod@23:         c.exchangeRateProvider = exchangeRateProvider;
japod@23:         return c;
japod@23:     }
japod@23:     
japod@23:     /**
japod@23:      * Convert <code>amount</code> from <code>fromCurrency</code> to <code>toCurrency</code> as specified
japod@23:      * in <code>ExchangeRateProvider</code>.
japod@23:      * 
japod@23:      * @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
japod@23:      * @return Return <code>ConversionResult</code> which holds conversion result.
japod@41:      * @since version1
japod@41:      * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
japod@23:      */
japod@23:     public ConversionResult convert(BigDecimal amount) {
japod@41:         return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, false,false);
japod@23:     }
japod@23:     
japod@23:     /**
japod@23:      * Convert <code>amount</code> from <code>toCurrency</code> to <code>fromCurrency</code> as specified
japod@23:      * in <code>ExchangeRateProvider</code>. This is <em>reverted</em> order than suggested by  names of currency fields in <code>ExchangeRate</code>.
japod@23:      * 
japod@23:      * @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
japod@23:      * @return Return <code>ConversionResult</code> which holds conversion result.
japod@41:      * @since version1
japod@41:      * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
japod@23:      */
japod@23:     public ConversionResult convertBack(BigDecimal amount) {
japod@41:         return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, true,false);
japod@23:     }
japod@23: 
japod@41:     private ConversionResult convertUsingSimpleConvertor(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, boolean reversibleExRate, BigDecimal amount, boolean convertBack) throws ConversionNotSupportedException, RuntimeException {
japod@23:         ConversionResult result = new ConversionResult();
japod@41: 
japod@41:         //ExchangeRate rate = exchangeRateProvider.getExchangeRate();
japod@41:         ExchangeRate rate;
japod@41:         if (reversibleExRate) {
japod@41:             rate = exchangeRateProvider.getReversibleExchangeRate(fromCurrency, toCurrency);
japod@41:         } else {
japod@41:             rate = exchangeRateProvider.getExchangeRate(fromCurrency, toCurrency);
japod@23:         }
japod@41:         if (rate == null) {
japod@41:             return null;
japod@23:         }
japod@23:         
japod@41:         int fromFranctionDigits = fromCurrency.getDefaultFractionDigits();
japod@41:         int toFractionDigits = toCurrency.getDefaultFractionDigits();
japod@41: 
japod@41:         if (toFractionDigits != 2) {
japod@41:             throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getToCurrency() + " has " + toFractionDigits + " defaultFractionDigits");
japod@23:         }
japod@41:         if (fromFranctionDigits != 2) {
japod@41:             throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getFromCurrency() + " has " + fromFranctionDigits + " defaultFractionDigits");
japod@41:         }
japod@41: 
japod@41:         if (amount.signum() == -1) {
japod@41:             throw new RuntimeException("Can convert only non-negative value, current value is " + amount);
japod@41:         }
japod@41: 
japod@41: 
japod@23:         MathContext context = new MathContext(0, RoundingMode.DOWN);
japod@41: 
japod@23:         BigDecimal from;
japod@23:         BigDecimal to;
japod@23:         if (convertBack) {
japod@23:             //converting in reverted way
japod@23:             to = rate.getFromValue();
japod@23:             from = rate.getToValue();
japod@23:         } else {
japod@41:             //converting in normal way
japod@23:             from = rate.getFromValue();
japod@23:             to = rate.getToValue();
japod@23:         }
japod@23: 
japod@23:         BigDecimal amountCent = amount.movePointRight(2);
japod@41: 
japod@41:         final BigDecimal multiplied = amountCent.multiply(to, context);
japod@41:         BigDecimal[] division = multiplied.divideAndRemainder(from, context);
japod@23: 
japod@23:         if (!remainderAllowed && !(BigDecimal.ZERO.equals(division[1]))) {
japod@41:             throw new RuntimeException("Remained is not allowed - remaining amount is " + division[1] + " cents");
japod@23:         } else {
japod@23:             result.setRemainder(BigDecimal.ZERO);
japod@23:         }
japod@41: 
japod@41:         final BigDecimal converted = division[0].movePointLeft(2);
japod@23:         result.setConverted(converted);
japod@23:         //result.setRemainder(...);
japod@23:         return result;
japod@23:     }
japod@41:     
japod@41: 
japod@41:     private ConversionResult convertValue(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,BigDecimal amount, boolean convertBack,boolean reversibleExRate) throws RuntimeException {
japod@41:         //result.setRemainder(...);
japod@41:         if (convertors.length==0) {
japod@41:             return convertUsingSimpleConvertor(fromCurrency, toCurrency, reversibleExRate, amount, convertBack);
japod@41:         } else {
japod@41:             ConversionResult result = null;
japod@41:             for (int i = 0;i<convertors.length;i++) {
japod@41:                 Convertor subConvertor = convertors[i];
japod@41:                 result = subConvertor.convertValue(fromCurrency, toCurrency, amount, convertBack, reversibleExRate);
japod@41:                 if (result!=null) {
japod@41:                     break;
japod@41:                 }
japod@41:             }
japod@41:             return result;
japod@41:         }
japod@41:     }
japod@41:     
japod@41:     /**
japod@41:      * Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
japod@41:      * <p>
japod@41:      * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
japod@41:      * This method is using only exchange rate from->to and not trying to use reverted excange rate to->from.
japod@41:      * 
japod@41:      * @param fromCurrency Source currency to convert from.
japod@41:      * @param toCurrency Target currency to convert to.
japod@41:      * @param value Value in source currency which should be converted.
japod@41:      * @return Return conversion result.
japod@41:      * @since version2
japod@41:      * @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code> is not supported.
japod@41:      */
japod@41:     public ConversionResult convert(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
japod@41:         ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false);
japod@41:         if (result==null) {
japod@41:             //throw new ConversionNotSupportedException("Conversion from " + fromCurrency + " to " + toCurrency + " is not supported");
japod@41:             throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),false);
japod@41:         }
japod@41:         return result;
japod@41:     }
japod@41:     
japod@41:     /**
japod@41:      * Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
japod@41:      * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
japod@41:      * <p>
japod@41:      *  This method is using only exchange rate from->to and if not found, it is trying to use reverted excange rate to->from.
japod@41:      * 
japod@41:      * @param fromCurrency Source currency to convert from.
japod@41:      * @param toCurrency Target currency to convert to.
japod@41:      * @param value Value in source currency which should be converted.
japod@41:      * @return Return conversion result.
japod@41:      * @since version2
japod@41:      * @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code> 
japod@41:      *         is not supported and neither conversion from <code>toCurrency</code> to <code>fromCurrency</code> is not supported.
japod@41:      */
japod@41:     public ConversionResult convertWithReversibleRates(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
japod@41:         ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true);
japod@41:         if (result==null) {
japod@41:             //throw new ConversionNotSupportedException("Neither onversion nor reverted conversion from " + fromCurrency + " to " + toCurrency + "  is not supported,");
japod@41:             throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),true);
japod@41:         }
japod@41:         return result;
japod@41:     }
japod@41:     
japod@23: }