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);

     }

 }