package org.apidesign.apifest08.currency;

 import java.util.ArrayList;

 import java.util.List;

 public final class ConvertorFactory {

     //Singleton

     private static ConvertorFactory thisFactory = new ConvertorFactory();    

     private ConvertorFactory() {};    

     public static ConvertorFactory newInstance() { //ehm, mistake - it should be named getInstance

         return thisFactory;

     }        

     public Convertor createConvertor(String currency1, String currency2, Rate rate) {

         return new Convertor(currency1, currency2, rate);

     }

     public Convertor createConvertor(String currency1, String currency2, int amount1, int amount2) {

         return new Convertor(currency1, currency2, new Rate(amount1, amount2));

     }

     public Convertor createConvertor(String currency1, String currency2, double amount1, double amount2) {

         return new Convertor(currency1, currency2, new Rate(amount1, amount2));

     }

     public Convertor createConvertor(String currency1, String currency2, double rate) {

         return new Convertor(currency1, currency2, new Rate(rate));

     }

     public Convertor createConvertor(CurrencyRate currencyRate) {

         return new Convertor(currencyRate);

     }

     public Convertor createConvertor(CurrencyRate ... currencyRates) {

         return new Convertor(currencyRates);

     }

     public Convertor mergeConvertors(Convertor ... convertors) {

         if (convertors == null) {

             throw new IllegalArgumentException("Parameter cannot be null.");

         }

         if (convertors.length == 0) {

             throw new IllegalArgumentException("Convertors cannot be empty.");

         }

         List<CurrencyRate> currRates = new ArrayList<CurrencyRate>();

         List<Pair<String,String>> currPairs = new ArrayList<Pair<String,String>>();

         for (Convertor convertor : convertors) {

             if (convertor == null) {

                 throw new IllegalArgumentException("Parameter cannot be null.");                

             }

             for (CurrencyRate currRate : convertor.getCurrencyRates()) {

                 Pair<String,String> currPair = new Pair<String,String>(currRate.getCurrency1(), currRate.getCurrency2());

                 if (currPairs.contains(currPair)) {

                     throw new IllegalArgumentException("Cannot merge - convertors contain same currency rates.");

                 }

                 currPairs.add(currPair);

                 currRates.add(currRate);

             }

         }

         return new Convertor(currRates.toArray(new CurrencyRate[0]));

     }

 }