package org.apidesign.apifest08.test;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.CurrencyValue;

import org.apidesign.apifest08.currency.ExchangeRateDataSource;

import org.apidesign.apifest08.currency.ExchangeRateProvider;

import org.apidesign.apifest08.currency.ExchangeRateProvider.ExchangeRateRequest;

import org.apidesign.apifest08.currency.ExchangeRateProvider.ExchangeRateResponse;

import org.apidesign.apifest08.currency.ExchangeRateValue;

/** 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 {

    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<Double, String> 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.

        return Convertor.getConvertorDataSourceDoubleString(

                ExchangeRateDataSource.getExchangeRateDataSource(

                "USD", "CZK", new ExchangeRateProvider<Double, String>() {

            double currentRate = 16d;

            double step;

            public void getExchangeRate(ExchangeRateRequest<Double, String> request,

                    ExchangeRateResponse<Double, String> response) {

                if ((request.getCurrencyAIdentifier().equals("CZK") && request.getCurrencyBIdentifier().equals("USD")) ||

                        (request.getCurrencyAIdentifier().equals("USD") && request.getCurrencyBIdentifier().equals("CZK"))) {

                    response.setExchangeRate(ExchangeRateValue.getExchangeRate(

                            CurrencyValue.getCurrencyValue(1d, "USD"),

                            CurrencyValue.getCurrencyValue(currentRate, "CZK")));

                    if (currentRate == 16d) {

                        step = -0.01;

                    }

                    if (currentRate == 15d) {

                        step = 0.01;

                    }

                    currentRate += step;

                } else {

                    throw new IllegalArgumentException("No exchange rate for requested currencies!");

                }

            }

        }));

    }

    public void testFewQueriesForOnlineConvertor() {

        Convertor<Double, String> c = createOnlineCZKUSDConvertor();

        doFewQueriesForOnlineConvertor(c);

    }

    static void doFewQueriesForOnlineConvertor(Convertor<Double, String> c) {

        CurrencyValue<Double, String> result;

        // convert $5 to CZK using c:

        //assertEquals("Result is 80 CZK");

        result = c.convert("CZK", CurrencyValue.getCurrencyValue(5d, "USD"));

        assertEquals(CurrencyValue.getCurrencyValue(80d, "CZK"), result);

        // convert $8 to CZK using c:

        //assertEquals("Result is 127.92 CZK");

        result = c.convert("CZK", CurrencyValue.getCurrencyValue(8d, "USD"));

        assertEquals(CurrencyValue.getCurrencyValue(127.92d, "CZK"), result);

        // convert $1 to CZK using c:

        //assertEquals("Result is 15.98 CZK");

        result = c.convert("CZK", CurrencyValue.getCurrencyValue(1d, "USD"));

        assertEquals(CurrencyValue.getCurrencyValue(15.98d, "CZK"), result);

        // convert 15.97CZK to USD using c:

        //assertEquals("Result is 1$");

        result = c.convert("USD", CurrencyValue.getCurrencyValue(15.97d, "CZK"));

        assertEquals(CurrencyValue.getCurrencyValue(1d, "USD"), result);

    }

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

     */

    public void testOnlineConvertorComposition() throws Exception {

        Convertor<Double, String> c = Task2Test.merge(

                createOnlineCZKUSDConvertor(),

                Task1Test.createSKKtoCZK());

        CurrencyValue<Double, String> result;

        // convert 16CZK to SKK using c:

        // assertEquals("Result is 20 SKK");

        result = c.convert("SKK", CurrencyValue.getCurrencyValue(16d, "CZK"));

        assertEquals(CurrencyValue.getCurrencyValue(20d, "SKK"), result);

        // convert 500SKK to CZK using c:

        // assertEquals("Result is 400 CZK");

        result = c.convert("CZK", CurrencyValue.getCurrencyValue(500d, "SKK"));

        assertEquals(CurrencyValue.getCurrencyValue(400d, "CZK"), result);

        doFewQueriesForOnlineConvertor(c);

    }

}