package org.apidesign.apifest08.test;

 import java.math.BigDecimal;

 import java.util.Currency;

 import junit.framework.TestCase;

 import org.apidesign.apifest08.currency.Convertor;

 import org.apidesign.apifest08.currency.InvalidConversionException;

 import org.apidesign.apifest08.currency.OnlineConvertor;

 /** 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 final static Currency CZK;

     private final static Currency SKK;

     private final static Currency USD;

     static

     {

         CZK = Currency.getInstance("CZK");

         SKK = Currency.getInstance("SKK");

         USD = Currency.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

      * @throws InvalidConversionException 

      */

     public static Convertor createOnlineCZKUSDConvertor() 

         throws InvalidConversionException

     {

         final Convertor convertor;

         convertor = new OnlineConvertor(USD,

                                         CZK,

                                         new TestExchangeRateFinder(new BigDecimal("15.00"), 

                                                                    new BigDecimal("16.00"),

                                                                    new BigDecimal("16.00"),

                                                                    new BigDecimal("0.01"),

                                                                    new BigDecimal("-0.01")));

         // 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;

     }

     public void testFewQueriesForOnlineConvertor() 

         throws InvalidConversionException

     {

         Convertor c = createOnlineCZKUSDConvertor();

         doFewQueriesForOnlineConvertor(c);

     }

     static void doFewQueriesForOnlineConvertor(Convertor c) 

         throws InvalidConversionException            

     {

         BigDecimal amount;

         // convert $5 to CZK using c:

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

         amount = c.convert(USD, CZK, new BigDecimal("5.00"));

         assertEquals(new BigDecimal("80.00"), amount);

         // convert $8 to CZK using c:

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

         amount = c.convert(USD, CZK, new BigDecimal("8.00"));

         assertEquals(new BigDecimal("127.92"), amount);

         // convert $1 to CZK using c:

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

         amount = c.convert(USD, CZK, new BigDecimal("1.00"));

         assertEquals(new BigDecimal("15.98"), amount);

         // convert 15.97CZK to USD using c:

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

         amount = c.convert(CZK, USD, new BigDecimal("15.97"));

         assertEquals(new BigDecimal("1.00"), amount);

     }

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

      */

     public void testOnlineConvertorComposition() throws Exception {

         BigDecimal amount;

         Convertor c = Task2Test.merge(

             createOnlineCZKUSDConvertor(),

             Task1Test.createSKKtoCZK()

         );

         // convert 16CZK to SKK using c:

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

         amount = c.convert(CZK, SKK, new BigDecimal("16.00"));

         assertEquals(new BigDecimal("20.00"), amount);

         // convert 500SKK to CZK using c:

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

         amount = c.convert(SKK, CZK, new BigDecimal("500.00"));

         assertEquals(new BigDecimal("400.00"), amount);

         doFewQueriesForOnlineConvertor(c);

     }

 }