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 fixed exchange rate which does not depend

 * on date (method {@link #getExchangeRate()} ).

 * 

 * Date dependend exchange rate to be implemented.

 * 

 * @author arnostvalicek

 */

public class ExchangeRateProvider {

    BigDecimal fromValue, toValue;

    ConvertorCurrency fromCurrency, toCurrency;

    Map exchangeRateMap = new HashMap();

    /**

     * 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.fromValue = fromValue;

        this.toValue = toValue;

        this.fromCurrency = fromCurrency;

        this.toCurrency = 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();

        return provider;

    }

    /**

     * Add new exchange rate to <code></code> to this 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>

     * 

     * @param fromCurrency Source currency.

     * @param fromValue Valye for from currency.

     * @param toCurrency Target currency.

     * @param toValue Value for target currency.

     */

    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 map2 = (Map) exchangeRateMap.get(fromCurrency);

        if (map2==null) {

            map2 = new HashMap();

            exchangeRateMap.put(fromCurrency, map2);

        }

        ExchangeRate rate = new ExchangeRate(fromValue, toValue);

        map2.put(toCurrency, rate);

    }

    /**

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

     * @return Returns exchange rate.

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

     */

    public ExchangeRate getExchangeRate() {

        return new ExchangeRate(fromValue, toValue);

    }

    /**

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

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

     */

    public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

        return getExchangeRateImpl(fromCurrency, toCurrency);

    }

    /**

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

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

     */

    public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

       ExchangeRate rate = getExchangeRateImpl(fromCurrency, toCurrency);

       if (rate==null) {

           ExchangeRate revertedRate = getExchangeRateImpl(toCurrency, fromCurrency);

           if (revertedRate!=null) {

            rate = ExchangeRate.createRevertedRate(revertedRate);

           }

       }

       return rate;

    }

    /**

     * 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) {

        return new ExchangeRate(fromValue, toValue);

    }

    ConvertorCurrency getFromCurrency() {

        return fromCurrency;

    }

    ConvertorCurrency getToCurrency() {

        return toCurrency;

    }

    private ExchangeRate getExchangeRateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {

        if (fromValue != null && toValue != null && fromCurrency.equals(this.fromCurrency) && toCurrency.equals(this.toCurrency)) {

            return new ExchangeRate(fromValue, toValue);

        }

        //return new ExchangeRate(fromValue, toValue);

        Map map2 = (Map) exchangeRateMap.get(fromCurrency);

        if (map2 == null) {

            return null;

        }

        ExchangeRate result = (ExchangeRate) map2.get(toCurrency);

        return result;

    }

}