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;

  }

}