package org.apidesign.apifest08.currency;

 import org.apidesign.apifest08.currency.ExchangeRateProvider.ExchangeRateRequest;

 import org.apidesign.apifest08.currency.ExchangeRateProvider.ExchangeRateResponse;

 /**

  * Exchange rate data source.

  * 

  * @author ked

  */

 public final class ExchangeRateDataSource<AmountType, IdentifierType> {

   private final IdentifierType currencyAIdentifier;

   private final IdentifierType currencyBIdentifier;

   private final ExchangeRateProvider<AmountType, IdentifierType> exchangeRateProvider;

   private ExchangeRateDataSource(

       IdentifierType currencyAIdentifier,

       IdentifierType currencyBIdentifier,

       ExchangeRateProvider<AmountType, IdentifierType> exchangeRateProvider) {

         if (currencyAIdentifier == null ||

             currencyBIdentifier == null ||

             currencyAIdentifier.equals(currencyBIdentifier)) {

                 throw new IllegalArgumentException("Inappropriate exchange rates' identifiers!");

         }

   this.currencyAIdentifier = currencyAIdentifier;

     this.currencyBIdentifier = currencyBIdentifier;

     this.exchangeRateProvider = exchangeRateProvider;

   }

   public IdentifierType getCurrencyAIdentifier() {

     return currencyAIdentifier;

   }

   public IdentifierType getCurrencyBIdentifier() {

     return currencyBIdentifier;

   }

   public ExchangeRateValue<AmountType, IdentifierType> getExchangeRate() {

     ExchangeRateRequest<AmountType, IdentifierType> request =

         new ExchangeRateRequest<AmountType, IdentifierType>();

     ExchangeRateResponse<AmountType, IdentifierType> response =

         new ExchangeRateResponse<AmountType, IdentifierType>();

     request.setCurrencyAIdentifier(currencyAIdentifier);

     request.setCurrencyBIdentifier(currencyBIdentifier);

     exchangeRateProvider.getExchangeRate(request, response);

     if (response.getExchangeRate().getCurrencyA().getIdentifier().equals(currencyAIdentifier) &&

         response.getExchangeRate().getCurrencyB().getIdentifier().equals(currencyBIdentifier)) {

       return response.getExchangeRate();

     } else {

       throw new IllegalStateException("Data source's provider returned inappropriate exchange rate!");

     }

   }

   public static <AmountType, IdentifierType> ExchangeRateDataSource<AmountType, IdentifierType> getExchangeRateDataSource(

       IdentifierType currencyAIdentifier,

       IdentifierType currencyBIdentifier,

       ExchangeRateProvider<AmountType, IdentifierType> exchangeRateProvider) {

     return new ExchangeRateDataSource<AmountType, IdentifierType>(

         currencyAIdentifier,

         currencyBIdentifier,

         exchangeRateProvider);

   }

   @Override

   public boolean equals(Object obj) {

     if (obj == null) {

       return false;

     }

     if (getClass() != obj.getClass()) {

       return false;

     }

     final ExchangeRateDataSource other =

         (ExchangeRateDataSource) obj;

     if (this.currencyAIdentifier != other.currencyAIdentifier &&

         (this.currencyAIdentifier == null || !this.currencyAIdentifier.equals(other.currencyAIdentifier))) {

       return false;

     }

     if (this.currencyBIdentifier != other.currencyBIdentifier &&

         (this.currencyBIdentifier == null || !this.currencyBIdentifier.equals(other.currencyBIdentifier))) {

       return false;

     }

     if (this.exchangeRateProvider != other.exchangeRateProvider &&

         (this.exchangeRateProvider == null || !this.exchangeRateProvider.equals(other.exchangeRateProvider))) {

       return false;

     }

     return true;

   }

   @Override

   public int hashCode() {

     int hash = 7;

     hash = 83 * hash + (this.currencyAIdentifier != null ? this.currencyAIdentifier.hashCode() : 0);

     hash = 83 * hash + (this.currencyBIdentifier != null ? this.currencyBIdentifier.hashCode() : 0);

     hash = 83 * hash + (this.exchangeRateProvider != null ? this.exchangeRateProvider.hashCode() : 0);

     return hash;

   }

 }