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;

import org.apidesign.apifest08.currency.IExchangeRateEngine;

/** The exchange rates are not always the same. They are changing. Day by day,

 * hour by hour, minute by minute. For every bank it is important to always

 * have the actual exchange rate available in the system. That is why let's

 * create a pluggable convertor that will always have up to date value of its

 * exchange rate.

 * <p>

 * The quest for today is to allow 3rd party developer to write a convertor

 * that adjusts its exchange rate everytime it is queried. This convertor is

 * written by independent vendor, the vendor knows only your Convertor API,

 * he does not know how the whole system looks and how the convertor is supposed

 * to be used.

 */

public class Task3Test extends TestCase {

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

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

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

    public Task3Test(String testName) {

        super(testName);

    }

    @Override

    protected void setUp() throws Exception {

    }

    @Override

    protected void tearDown() throws Exception {

    }

    // Backward compatibly enhance your existing API to support following

    // usecases:

    //

    /** Without knowing anything about the surrounding system, write an

     * implementation of convertor that will return different rates everytime

     * it is queried. Convert USD to CZK and vice versa. Start with the rate of

     * 1USD = 16CZK and adjust it in favor of CZK by 0.01 CZK with every query.

     * As soon as you reach 1USD = 15CZK adjust it by 0.01 CZK in favor of USD

     * until you reach 1USD = 16CZK

     *

     * @return new instance of "online" USD and CZK convertor starting with rate 1USD = 16CZK

     */

    public static Convertor createOnlineCZKUSDConvertor() {

        // initial rate: 1USD = 16CZK

        // 2nd query 1USD = 15.99CZK

        // 3rd query 1USD = 15.98CZK

        // until 1USD = 15.00CZK

        // then 1USD = 15.01CZK

        // then 1USD = 15.02CZK

        // and so on and on up to 1USD = 16CZK

        // and then another round to 15, etc.

        IExchangeRateEngine engine = BouncingExchangeRateEngine.create(

                currencyUSD,  new BigDecimal(1),

                currencyCZK, 

                new BigDecimal(16),new BigDecimal(15),

                new BigDecimal("-0.01"));

        ExchangeRateProvider exRateProvider = ExchangeRateProvider.createExchangeRateProvider(engine);

        Convertor convertor = Convertor.createConvertor(exRateProvider);

        return convertor;

    }

    public void testFewQueriesForOnlineConvertor() {

        Convertor c = createOnlineCZKUSDConvertor();

        doFewQueriesForOnlineConvertor(c);

    }

    static void doFewQueriesForOnlineConvertor(Convertor c) {

        // convert $5 to CZK using c:

        assertEquals("Result is 80 CZK", new BigDecimal("80.00"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(5)).getConverted());

        // convert $8 to CZK using c:

        assertEquals("Result is 127.92 CZK", new BigDecimal("127.92"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(8)).getConverted());

        // convert $1 to CZK using c:

        assertEquals("Result is 15.98 CZK", new BigDecimal("15.98"), c.convertWithReversibleRates(currencyUSD, currencyCZK, new BigDecimal(1)).getConverted());

        // convert 15.97CZK to USD using c:

        assertEquals("Result is 15.98 CZK", new BigDecimal("1.00"), c.convertWithReversibleRates(currencyCZK, currencyUSD , new BigDecimal("15.97")).getConverted());

    }

    /** Join the convertors and show they behave sane.

     */

    public void testOnlineConvertorComposition() throws Exception {

        Convertor c = Task2Test.merge(

            createOnlineCZKUSDConvertor(),

            Task1Test.createSKKtoCZK()

        );

        // convert 16CZK to SKK using c:

        assertEquals("Result is 20 CZK", 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());

        doFewQueriesForOnlineConvertor(c);

    }

//    public void testBouncing() {

//        Convertor c=createOnlineCZKUSDConvertor();

//        

//        IExchangeRateEngine engine = BouncingExchangeRateEngine.create(

//                currencyUSD,  new BigDecimal(1),

//                currencyCZK, 

//                new BigDecimal("16.00"),new BigDecimal("15.00"),

//                new BigDecimal("-0.01"));        

//        

//        for (int i=0;i<300;i++) {

//            System.out.println(engine.getExchangeRate(currencyUSD, currencyCZK).getToValue());

//        }

//    }

}