package org.apidesign.apifest08.currency;

 import java.math.BigDecimal;

 import java.util.Date;

 import java.util.HashMap;

 import java.util.Map;

 /**

  * Exchange rate provider. Provides  exchange rate for two currencies (method {@link #getExchangeRate(ConvertorCurrency, ConvertorCurrency)} ).

  * <p>

  * Several method can be created to create <code>ExchangeRateProvider</code>:

  * <ul>

  * <li>{@link #createExchangeRateProvider() } - create <em>simple</em> exchange rate provider using fixed echange rate.

  * <li>{@link #createExchangeRateProvider(IExchangeRateEngine) } - create exchange rate provider using custom {@link IExchangeRateEngine}.

  * <li>{@link #createDateExchangeRateProvider(IDateExchangeRateEngine) } - create exchange rate provider using custom {@link IDateExchangeRateEngine}.

  * </ul>

  * <p>

  * Date dependend exchange rate to be implemented.

  * 

  * @author arnostvalicek

  */

 public class ExchangeRateProvider {

     IExchangeRateEngine exrateEngine;

     IDateExchangeRateEngine dateExrateEngine;

     /**

      * Simple constructor for <code>ExchangeRateProviderM</code> which can provide fixed exchange rate.

      * 

      * Describes conversion <em>from ONE</em> to <em>to ONE</em> currency.

      * 

      * @param fromValue From value. BigDecimal value, precision should be set to currency precision.

      * @param fromCurrency From currency.

      * @param toValue To value. BigDecimal value, precision should be set to currency precision.

      * @param toCurrency To currency.

      * @deprecated deprecated since task2. Use {@link #createExchangeRateProvider() } instead of this constructor.

      */

     public ExchangeRateProvider(BigDecimal fromValue, ConvertorCurrency fromCurrency, BigDecimal toValue, ConvertorCurrency toCurrency) {

         this.exrateEngine = FixedOneExchangeRateEngine.createEngine(fromValue, fromCurrency, toValue, toCurrency);

     }

     private ExchangeRateProvider() {

     }

     /**

      * Static method to create new exchange rate provider. This exchange rate provider does not contain

      * any exchange rates (this is difference to public constructor).

      * @return New <code>ExchangeRateProvider</code>

      */

     public static ExchangeRateProvider createExchangeRateProvider() {

         ExchangeRateProvider provider = new ExchangeRateProvider();

         provider.exrateEngine = FixedExchangeRateEngine.createEngine();

         return provider;

     }

     /**

      * Static method to create exchange rate provider which is using provided <code>IExchangeRateEngine</code>. This exchange rate provider is using

      * <code>IExchangeRateEngine</code> to get actual exchange rate.

      * @param exchangeRateEngine <code>IExchangeRateEngine</code> used to get exchange rate.

      * @return Returns instance of <code>ExchangeRateProvider</code>

      */

     public static ExchangeRateProvider createExchangeRateProvider(IExchangeRateEngine exchangeRateEngine) {

         ExchangeRateProvider provider = new ExchangeRateProvider();

         provider.exrateEngine = exchangeRateEngine;

         return provider;

     }

     /**

      * Static method to create exchange rate provider which is using provided <code>IExIDateExchangeRateEnginechangeRateEngine</code>. This exchange rate provider is using

      * <code>IExchangeRateEngine</code> to get actual exchange rate.

      * @param exchangeRateEngine <code>IDateExchangeRateEngine</code> used to get exchange rate.

      * @return Returns instance of <code>ExchangeRateProvider</code>

      */

     public static ExchangeRateProvider createDateExchangeRateProvider(IDateExchangeRateEngine exchangeRateEngine) {

         ExchangeRateProvider provider = new ExchangeRateProvider();

         provider.dateExrateEngine = exchangeRateEngine;

         return provider;

     }

     /**

      * Add new exchange rate to <code></code> to this <em>simple</em> exchange rate provider.

      * <p>

      * Example of specifiing conversion rate: 100 SKK == 80 CZK:<br>

      * <code>addFixedCurencyRate(ConvertorCurrency.getInstance("SKK"), new BigDecimal(100), ConvertorCurrency.getInstance("CZK"),  new BigDecimal(80));</code>

      * <p>

      * This method may be used <em>only</em> when <code>ExchangeRateProvider</code> is created using {@link #createExchangeRateProvider() } - creating exchange rate provider without external <code>IExchangeRateEngine</code>.

      * 

      * @param fromCurrency Source currency.

      * @param fromValue Valye for from currency.

      * @param toCurrency Target currency.

      * @param toValue Value for target currency.

      * @throws IllegalStateException Throws exception when adding fixed currency rate to exchange rate provider which is not created using {@link #createExchangeRateProvider() }.

      */

     public synchronized void addFixedCurencyRate(ConvertorCurrency fromCurrency, BigDecimal fromValue, ConvertorCurrency toCurrency, BigDecimal toValue) {

         if (exrateEngine instanceof FixedExchangeRateEngine) {

             ((FixedExchangeRateEngine) exrateEngine).addFixedCurencyRate(fromCurrency, fromValue, toCurrency, toValue);

         } else {

             throw new IllegalStateException("Cuurency rate can be added only to ExchangeRateProvider created with FixedExchangeRateEngine - using method createExchangeRateProvider()");

         }

     }

     /**

      * Get fixed exange rate for currencies (from->to).

      * @return Returns exchange rate.

      * @deprecated deprecated since task2. Use {@link #getExchangeRate(ConvertorCurrency, ConvertorCurrency) }

      */

     public ExchangeRate getExchangeRate() {

         //works only for FixedExchangeRateEngine

         if (exrateEngine instanceof FixedOneExchangeRateEngine) {

             FixedOneExchangeRateEngine engine = (FixedOneExchangeRateEngine) exrateEngine;

             return new ExchangeRate(engine.getFromValue(), engine.getToValue());

         } else {

             throw new IllegalStateException("Method supported only for MinimalFixedExchangeRateEngine. This method is deprecated");

         }

     }

     /**

      * Get fixed exange rate for currencies (from->to).

      * @param fromCurrency Source currency.

      * @param toCurrency Target currency.

      * @return Returns exchange rate or <code>null</code> if exchange rate not found.

      */

     public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

         return getExchangeRateImpl(fromCurrency, toCurrency,null);

     }

     /**

      * Get exange rate for currencies (from->to) for date.

      * @param fromCurrency Source currency.

      * @param toCurrency Target currency.

      * @param date Conversion date.

      * @return Returns exchange rate or <code>null</code> if exchange rate not found.

      */

     public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date) {

         return getExchangeRateImpl(fromCurrency, toCurrency,date);

     }

     /**

      * Get fixed exange rate for currencies (from->to) or reversed exchange rate (to->from).

      * @param fromCurrency Source currency.

      * @param toCurrency Target currency.

      * @return Returns exchange rate or <code>null</code> if exchange rate not found.

      */

     public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

         return getReversibleExrateImpl(fromCurrency, toCurrency,null);

     }

     /**

      * Get exange rate for currencies (from->to) or reversed exchange rate (to->from) for date.

      * @param fromCurrency Source currency.

      * @param toCurrency Target currency.

      * @param date Conversion date.

      * @return Returns exchange rate or <code>null</code> if exchange rate not found.

      */

     public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date) {

         return getReversibleExrateImpl(fromCurrency, toCurrency, date);

     }

     /**

      * Get exchange rate for currencies (from->to) based on provided date.

      * @param date Date for which exchange rate should be provided.

      * @return Returns exchange rate 

      * @deprecated deprecated since task2. No real implementation in version2.

      */

     public ExchangeRate getExchangeRate(Date date) {

         //works only for FixedExchangeRateEngine

         if (exrateEngine instanceof FixedOneExchangeRateEngine) {

             FixedOneExchangeRateEngine engine = (FixedOneExchangeRateEngine) exrateEngine;

             return new ExchangeRate(engine.getFromValue(), engine.getToValue());

         } else {

             throw new IllegalStateException("Method supported only for FixedOneExchangeRateEngine. This method is deprecated");

         }

     }

     ConvertorCurrency getFromCurrency() {

         if (exrateEngine instanceof FixedOneExchangeRateEngine) {

             FixedOneExchangeRateEngine engine = (FixedOneExchangeRateEngine) exrateEngine;

             return engine.getFromCurrency();

         } else {

             throw new IllegalStateException("Method supported only for FixedOneExchangeRateEngine. This method is deprecated");

         }

     }

     ConvertorCurrency getToCurrency() {

         if (exrateEngine instanceof FixedOneExchangeRateEngine) {

             FixedOneExchangeRateEngine engine = (FixedOneExchangeRateEngine) exrateEngine;

             return engine.getToCurrency();

         } else {

             throw new IllegalStateException("Method supported only for FixedOneExchangeRateEngine. This method is deprecated");

         }

     }

     private ExchangeRate getReversibleExrateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,Date date) {

         ExchangeRate rate = getExchangeRateImpl(fromCurrency, toCurrency, date);

         if (rate == null) {

             ExchangeRate revertedRate = getExchangeRateImpl(toCurrency, fromCurrency, date);

             if (revertedRate != null) {

                 rate = ExchangeRate.createRevertedRate(revertedRate);

             }

         }

         return rate;

     }    

     private ExchangeRate getExchangeRateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,Date date) {

         ExchangeRate result;

         if (exrateEngine!=null) {

             result = exrateEngine.getExchangeRate(fromCurrency, toCurrency);

         } else if (dateExrateEngine!=null) {

             result = dateExrateEngine.getExchangeRate(fromCurrency, toCurrency, date);

         } else {

             throw new IllegalStateException("No exchange rate engine provided");

         }

         return result;

     }

     private static class FixedOneExchangeRateEngine implements IExchangeRateEngine {

         BigDecimal fromValue;

         ConvertorCurrency fromCurrency;

         BigDecimal toValue;

         ConvertorCurrency toCurrency;

         private FixedOneExchangeRateEngine(BigDecimal fromValue, ConvertorCurrency fromCurrency, BigDecimal toValue, ConvertorCurrency toCurrency) {

             this.fromValue = fromValue;

             this.toValue = toValue;

             this.fromCurrency = fromCurrency;

             this.toCurrency = toCurrency;

         }

         /**

          * Create IExchangeRateEngine conveting from <code>fromCurrency</code> to <code>toCurrency</code>

          * with echange rate <code>fromValue:toValue</code>

          * @param fromValue

          * @param fromCurrency

          * @param toValue

          * @param toCurrency

          * @return Returns instance of <code>FixedOneExchangeRateEngine</code>.

          */

         private static IExchangeRateEngine createEngine(BigDecimal fromValue, ConvertorCurrency fromCurrency, BigDecimal toValue, ConvertorCurrency toCurrency) {

             return new FixedOneExchangeRateEngine(fromValue, fromCurrency, toValue, toCurrency);

         }

         private BigDecimal getFromValue() {

             return fromValue;

         }

         private BigDecimal getToValue() {

             return toValue;

         }

         private ConvertorCurrency getFromCurrency() {

             return fromCurrency;

         }

         private ConvertorCurrency getToCurrency() {

             return toCurrency;

         }

         public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

             if (!fromCurrency.equals(this.fromCurrency)) {

                 return null;

             }

             if (!toCurrency.equals(this.toCurrency)) {

                 return null;

             }

             return new ExchangeRate(fromValue, toValue);

         }

     }

     /**

      * Exchange rate engine able to hold several fixed exchange rates.

      * 

      * @author arnostvalicek

      */

     private static class FixedExchangeRateEngine implements IExchangeRateEngine {

         private Map<ConvertorCurrency, Map<ConvertorCurrency, ExchangeRate>> exchangeRateMap = new HashMap<ConvertorCurrency, Map<ConvertorCurrency, ExchangeRate>>();

         private FixedExchangeRateEngine() {

         }

         /**

          * Create instance of <code>FixedExchangeRateEngine</code>.

          * @return Returns instance of <code>FixedExchangeRateEngine</code>.

          */

         public static IExchangeRateEngine createEngine() {

             return new FixedExchangeRateEngine();

         }

         public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

             Map<ConvertorCurrency,ExchangeRate> map2 = exchangeRateMap.get(fromCurrency);

             if (map2 == null) {

                 return null;

             }

             ExchangeRate result = map2.get(toCurrency);

             return result;

         }

         public synchronized void addFixedCurencyRate(ConvertorCurrency fromCurrency, BigDecimal fromValue, ConvertorCurrency toCurrency, BigDecimal toValue) {

             if (fromValue == null) {

                 throw new NullPointerException("fromValue can't be null");

             }

             if (toValue == null) {

                 throw new NullPointerException("toValue can't be null");

             }

             Map<ConvertorCurrency,ExchangeRate> map2 = exchangeRateMap.get(fromCurrency);

             if (map2 == null) {

                 map2 = new HashMap<ConvertorCurrency,ExchangeRate>();

                 exchangeRateMap.put(fromCurrency, map2);

             }

             ExchangeRate rate = new ExchangeRate(fromValue, toValue);

             map2.put(toCurrency, rate);

         }

     }

 }