package org.apidesign.apifest08.currency;

 import java.io.Serializable;

 import java.util.Arrays;

 import java.util.Currency;

 /**

  * Convertor that is composed from other convertors. 

  * @author lukas

  *

  */

 class CompositeConvertor implements ExtendedConvertor, Serializable {

 	private static final long serialVersionUID = -2702026568249130055L;

 	private final ExtendedConvertor[] convertors;

 	public CompositeConvertor(ExtendedConvertor... convertors) {

 		this.convertors = convertors.clone();

 		for (ExtendedConvertor convertor: this.convertors)

 		{

 			if (convertor==null)

 			{

 				throw new NullPointerException("One of the convertors to be merged is null");

 			}

 		}

 	}

 	/**

 	 * Returns true if the composite contains convertor that supports given conversion.

 	 */

 	public boolean isConversionSupported(Currency from, Currency to) {

 		return findConvertorFor(from, to)!=null;

 	}

 	/**

 	 * If the composite contains convertor that supports given conversion, delegates to its convert method.

 	 * Throws {@link IllegalArgumentException} convertor supporting given conversion is not found. 

 	 */

 	public Money convert(Money amount, Currency destinationCurrency) throws IllegalArgumentException {

 		ExtendedConvertor convertor = findConvertorFor(amount.getCurrency(), destinationCurrency);

 		if (convertor!=null)

 		{

 			return convertor.convert(amount, destinationCurrency);

 		}

 		throw new IllegalArgumentException("Conversion not supported. Can not convert to "+destinationCurrency+".");

 	}

 	/**

 	 * Finds convertor for given currencies. If not found, returns null. 

 	 * @param from

 	 * @param to

 	 * @return

 	 */

 	ExtendedConvertor findConvertorFor(Currency from, Currency to) {

 		//does linear search, in the future can cache the results.

 		for (ExtendedConvertor convertor:convertors)

 		{

 			if (convertor.isConversionSupported(from, to))

 			{

 				return convertor;

 			}

 		}

 		return null;

 	}

 	@Override

 	public String toString() {

 		return getClass().getName()+" converts "+Arrays.toString(convertors);

 	}

 }