package org.apidesign.apifest08.currency;

import java.util.Date;

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 final Date validFrom;

    private final Date validTill;

    private ExchangeRateDataSource(

            IdentifierType currencyAIdentifier,

            IdentifierType currencyBIdentifier,

            ExchangeRateProvider<AmountType, IdentifierType> exchangeRateProvider,

            Date validFrom,

            Date validTill) {

        if (currencyAIdentifier == null ||

                currencyBIdentifier == null ||

                currencyAIdentifier.equals(currencyBIdentifier)) {

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

        }

        if (validFrom != null &&

                validTill != null &&

                !validTill.after(validFrom)) {

            throw new IllegalArgumentException("Inappropriate exchange rate validity!");

        }

        this.currencyAIdentifier = currencyAIdentifier;

        this.currencyBIdentifier = currencyBIdentifier;

        this.exchangeRateProvider = exchangeRateProvider;

        this.validFrom = validFrom;

        this.validTill = validTill;

    }

    public IdentifierType getCurrencyAIdentifier() {

        return currencyAIdentifier;

    }

    public IdentifierType getCurrencyBIdentifier() {

        return currencyBIdentifier;

    }

    ExchangeRateProvider<AmountType, IdentifierType> getExchangeRateProvider() {

        return exchangeRateProvider;

    }

    public Date getValidFrom() {

        return validFrom != null ? (Date) validFrom.clone() : null;

    }

    public Date getValidTill() {

        return validTill != null ? (Date) validTill.clone() : null;

    }

    public ExchangeRateValue<AmountType, IdentifierType> getExchangeRate() {

        return getExchangeRate(new Date()); // System.currentTimeMillis()

    }

    public ExchangeRateValue<AmountType, IdentifierType> getExchangeRate(Date instant) {

        ExchangeRateRequest<AmountType, IdentifierType> request =

                new ExchangeRateRequest<AmountType, IdentifierType>();

        ExchangeRateResponse<AmountType, IdentifierType> response =

                new ExchangeRateResponse<AmountType, IdentifierType>();

        request.setCurrencyAIdentifier(currencyAIdentifier);

        request.setCurrencyBIdentifier(currencyBIdentifier);

        request.setInstant(instant);

        exchangeRateProvider.getExchangeRate(request, response);

        ExchangeRateValue<AmountType, IdentifierType> result = response.getExchangeRate();

        if (result.getCurrencyA().getIdentifier().equals(currencyAIdentifier) &&

                result.getCurrencyB().getIdentifier().equals(currencyBIdentifier)) {

            return result;

        } 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 getExchangeRateDataSource(

                currencyAIdentifier,

                currencyBIdentifier,

                exchangeRateProvider,

                null,

                null);

    }

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

            IdentifierType currencyAIdentifier,

            IdentifierType currencyBIdentifier,

            ExchangeRateProvider<AmountType, IdentifierType> exchangeRateProvider,

            Date validFrom,

            Date validTill) {

        return new ExchangeRateDataSource<AmountType, IdentifierType>(

                currencyAIdentifier,

                currencyBIdentifier,

                exchangeRateProvider,

                validFrom,

                validTill);

    }

    @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;

        }

        if (this.validFrom != other.validFrom && (this.validFrom == null || !this.validFrom.equals(other.validFrom))) {

            return false;

        }

        if (this.validTill != other.validTill && (this.validTill == null || !this.validTill.equals(other.validTill))) {

            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;

    }

}