package org.apidesign.apifest08.currency;

import java.math.BigDecimal;

import java.util.Currency;

import java.util.Set;

/**

 * Convert between two currencies.

 *

 * @author D'Arcy Smith

 * @version 1.1

 */

class ConvertorImpl

    implements ExchangeRateConvertor

{

    /**

     */

    private final ExchangeRate rate;

    /**

     * Constructs a convertor with the specified currencies.

     * 

     * @param a the currency to convert from.

     * @param aRate the exchage rage between from and to.

     * @param b the currency to convert to.

     * @param bRate the exchage rage between to and from.

     * @throws IllegalArgumentException if either any of the arguments are null or if either rate <= 0.

     */

    public ConvertorImpl(final ExchangeRate r)

    {

        if(r == null)

        {

            throw new IllegalArgumentException("r cannot be null");

        }

        rate = r;

    }

    /**

     * Convert an amount from one currency to another.

     * 

     * @param from the currency to convert from.

     * @param to the currency to convert to.

     * @param amount the amount to convert.

     * @return the converted amount.

     * @throws IllegalArgumentException if any of the arguments are null.

     * @throws InvalidConversionException if either from or to are not equal to the currencies passed to the constructor.

     */

    public BigDecimal convert(final Currency   from,

                              final Currency   to,

                              final BigDecimal amount)

        throws InvalidConversionException

    {

        return (rate.convert(from, to, amount));

    }

    /**

     * Check to see if converting between the two currencies is possible.

     * 

     * @param from the currency to convert from.

     * @param to the currency to convert to.

     * @return true if the conversion is possible.

     * @throws IllegalArgumentException if either from or to are null.

     */

    public boolean canConvert(final Currency from, final Currency to)

    {

        return (rate.canConvert(from, to));

    }

    /**

     * Get the currencies that the convertor supports.

     * 

     * @return the supported currencies.

     */

    public Set<Currency> getCurrencies()

    {

        return (rate.getCurrencies());

    }

    /**

     * Get the conversion rate between two currencies.

     * 

     * @param from the currency to convert from.

     * @param to the currency to convert to.

     * @return the conversion rate between the two currencies.

     * @throws InvalidConversionException if canConvert would return false.

     * @throws IllegalArgumentException if either from or to are null.

     */

    public BigDecimal getConversionRate(final Currency from, 

                                        final Currency to)

        throws InvalidConversionException

    {                

        return (rate.getConversionRate(from, to));

    }

    /**

     * Check to see if two ConvertorImpls are equal.

     *

     * @param obj the object to check

     * @return if the ConvertorImpls are not the same (cuyrrencies and rates).

     */

    @Override

    public boolean equals(Object obj)

    {

        if (obj == null)

        {

            return false;

        }

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

        {

            return false;

        }

        final ConvertorImpl other = (ConvertorImpl) obj;

        return (rate.equals(other.rate));

    }

    /**

     * Get the hashCode of the Convertor.

     *

     * @return the hashCode of the convertor.

     */

    @Override

    public int hashCode()

    {

        return (rate.hashCode());

    }

    /**

     * Get the currencyCode of both currencies.

     *

     * @return the currency codes of both currencies.

     */

    @Override

    public String toString()

    {

        return (rate.getCurrencyA().getCurrencyCode() + " to " + rate.getCurrencyB().getCurrencyCode());

    }

    public ExchangeRate getExchangeRate()

    {

        return (rate);

    }

}