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]));

    }

}