package org.apidesign.apifest08.test;

import java.math.BigDecimal;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.ConvertorCurrency;

import org.apidesign.apifest08.currency.ExchangeRateProvider;

/** There are many currencies around the world and many banks manipulate

 * with more than one or two at the same time. As banks are usually the

 * best paying clients, which is true even in case of your Convertor API,

 * it is reasonable to listen to their requests.

 * <p>

 * The quest for today is to enhance your existing convertor API to hold

 * information about many currencies and allow conversions between any of them.

 * Also, as conversion rates for diferent currencies usually arise from various

 * bank departments, there is another important need. There is a need to

 * compose two convertors into one by merging all the information about

 * currencies they know about.

 */

public class Task2Test extends TestCase {

    private static ConvertorCurrency currencyCZK = ConvertorCurrency.getInstance("CZK");

    private static ConvertorCurrency currencySKK = ConvertorCurrency.getInstance("SKK");

    private static ConvertorCurrency currencyUSD = ConvertorCurrency.getInstance("USD");

    public Task2Test(String testName) {

        super(testName);

    }

    @Override

    protected void setUp() throws Exception {

    }

    @Override

    protected void tearDown() throws Exception {

    }

    public static Convertor createUsdToSkkConvertor() {

        ConvertorCurrency fromCurrency = currencyUSD;

        ConvertorCurrency toCurrency = currencyUSD;

        ExchangeRateProvider exchangeRateProvider = new ExchangeRateProvider(new BigDecimal(1), fromCurrency, new BigDecimal(20), toCurrency);

        return Convertor.createConvertor(exchangeRateProvider);

    }

    // As in Task1Test, keep in mind, that there are three parts

    // of the whole system:

    // 1. there is someone who knows the current exchange rate

    // 2. there is someone who wants to do the conversion

    // 3. there is the API between 1. and 2. which allows them to communicate

    // 

    // Please backward compatibly enhance your existing API to support following

    // usecases:

    //

    /** Create convertor that understands two currencies, CZK and

     *  SKK. Make 100 SKK == 75 CZK. This is method for the group of users that

     *  knows the exchange rate, and needs to use the API to create objects

     *  with the exchange rate. Anyone shall be ready to call this method without

     *  any other method being called previously. The API itself shall know

     *  nothing about any rates, before this method is called.

     */

    public static Convertor createTripleConvertor() {

        ExchangeRateProvider exRateProvider = ExchangeRateProvider.createExchangeRateProvider();

        // Rates: 1USD = 15CZK

        exRateProvider.addFixedCurencyRate(currencyUSD, new BigDecimal(1),currencyCZK,  new BigDecimal(15));

        // Rates: 1USD = 20SKK

        exRateProvider.addFixedCurencyRate(currencyUSD, new BigDecimal(1), currencySKK,  new BigDecimal(20));

        // Rates: 75CZK = 100SKK

        exRateProvider.addFixedCurencyRate(currencyCZK, new BigDecimal(75), currencySKK,  new BigDecimal(100));

        Convertor c = Convertor.createConvertor(exRateProvider);

        return c;

    }

    /** Define convertor that understands three currencies. Use it.

     */

    public void testConvertorForUSDandCZKandSKK() throws Exception {

        Convertor c = createTripleConvertor();

        // convert $5 to CZK using c:

        assertEquals("Result is 75 CZK",new BigDecimal("75.00"),c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(5)).getConverted());

        // convert $5 to SKK using c:

        assertEquals("Result is 100 SKK",new BigDecimal("100.00"),c.convertWithReversibleRates(currencyUSD, currencySKK, new BigDecimal(5)).getConverted());

        // convert 200SKK to CZK using c:

        assertEquals("Result is 150 CZK",new BigDecimal("150.00"),c.convertWithReversibleRates(currencySKK, currencyCZK, new BigDecimal(200)).getConverted());

        // convert 200SKK to USK using c:

        // assertEquals("Result is 10 USD");

    }

    /** Merge all currency rates of convertor 1 with convertor 2.

     * Implement this using your API, preferably this method just delegates

     * into some API method which does the actual work, without requiring

     * API clients to code anything complex.

     */

    public static Convertor merge(Convertor one, Convertor two) {

        return Convertor.createConvertorAsMerge(new Convertor[]{one, two});

    }

    /** Join the convertors from previous task, Task1Test and show that it

     * can be used to do reasonable conversions.

     */

    public void testConvertorComposition() throws Exception {

        Convertor c = merge(

            Task1Test.createCZKtoUSD(),

            Task1Test.createSKKtoCZK()

        );

        // convert $5 to CZK using c:

        assertEquals("Result is 85 CZK",new BigDecimal("85.00"),c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(5)).getConverted());

        // convert $8 to CZK using c:

        // assertEquals("Result is 136 CZK");

        assertEquals("Result is 136 CZK",new BigDecimal("136.00"),c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(8)).getConverted());

        // convert 1003CZK to USD using c:

        assertEquals("Result is 59 USD",new BigDecimal("59.00"),c.convertWithReversibleRates(currencyCZK, currencyUSD, new BigDecimal(1003)).getConverted());

        // convert 16CZK using c:

        assertEquals("Result is 20 SKK",new BigDecimal("20.00"),c.convertWithReversibleRates(currencyCZK, currencySKK, new BigDecimal(16)).getConverted());

        // convert 500SKK to CZK using c:

        assertEquals("Result is 400 CZK",new BigDecimal("400.00"),c.convertWithReversibleRates(currencySKK, currencyCZK, new BigDecimal(500)).getConverted());

    }

}