package org.apidesign.apifest08.test;

import java.math.BigDecimal;

import java.text.SimpleDateFormat;

import java.util.Date;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.ConversionNotSupportedException;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.ConvertorCurrency;

import org.apidesign.apifest08.currency.ExchangeRateProvider;

/** The exchange rates are not always the same. They are changing. However

 * as in order to predict the future, one needs to understand own past. That is

 * why it is important to know the exchange rate as it was at any time during

 * the past.

 * <p>

 * Today's quest is to enhance the convertor API to deal with dates.

 * One shall be able to convert a currency at any date. Each currencies rate shall

 * be associated with a range between two Date objects. In order

 * to keep compatibility with old API that knew nothing about dates, the

 * rates associated then are applicable "for eternity". Any use of existing

 * convert methods that do not accept a Date argument, uses the current

 * System.currentTimeMillis() as default date.

 */

public class Task4Test extends TestCase {

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

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

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

    private SimpleDateFormat df;

    public Task4Test(String testName) {

        super(testName);

    }

    @Override

    protected void setUp() throws Exception {

        super.setUp();

        df = new SimpleDateFormat("yyyy-MM-dd HH:mm zzzz");

    }

    @Override

    protected void tearDown() throws Exception {

        super.tearDown();

        df = null;

    }

    // Backward compatibly enhance your existing API to support following

    // usecases:

    //

    /** Takes a convertor with any rates associated and creates new convertor

     * that returns the same values as the old one for time between from to till.

     * Otherwise it returns no results. This is just a helper method that

     * shall call some real one in the API.

     * 

     * @param old existing convertor

     * @param from initial date (inclusive)

     * @param till final date (exclusive)

     * @return new convertor

     */

    public static Convertor limitTo(Convertor old, Date from, Date till) {

        Convertor c = Convertor.createConvertorAsMerge(new Convertor[]{old});

        c.limitAllowedDates(from, till);

        return c;

    }

    public void testCompositionOfLimitedConvertors() throws Exception {

        Date d1 = df.parse("2008-10-01 0:00 GMT");

        Date d2 = df.parse("2008-10-02 0:00 GMT");

        Date d3 = df.parse("2008-10-03 0:00 GMT");

        Convertor c = Task2Test.merge(

            limitTo(Task1Test.createCZKtoUSD(), d1, d2),

            limitTo(Task1Test.createSKKtoCZK(), d2, d3)

        );

        // convert $5 to CZK using c:

        // cannot convert as no rate is applicable to current date

        try {

          c.convert(USD, CZK, new BigDecimal(5));

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

        // convert $8 to CZK using c:

        // cannot convert as no rate is applicable to current date

        try {

          c.convert(USD, CZK, new BigDecimal(8));

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

        // convert 1003CZK to USD using c:

        // cannot convert as no rate is applicable to current date

        try {

          c.convert(CZK, USD, new BigDecimal(1003));

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

        // convert 16CZK using c:

        // cannot convert as no rate is applicable to current date

        // ???

        try {

          c.convert(CZK, USD, new BigDecimal(16));

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

        // convert 500SKK to CZK using c:

        // cannot convert as no rate is applicable to current date

        try {

          c.convert(SKK, CZK, new BigDecimal(500));

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

        // convert $5 to CZK using c at 2008-10-01 6:00 GMT:

        // assertEquals("Result is 85 CZK");

        assertEquals("Result is 85 CZK", new BigDecimal("85.00"), c.convertWithReversibleRates(USD, CZK , new BigDecimal("5"),df.parse("2008-10-01 6:00 GMT")).getConverted());        

        // convert $8 to CZK using c at 2008-10-01 6:00 GMT:

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

        assertEquals("Result is 136 CZK", new BigDecimal("136.00"), c.convertWithReversibleRates(USD, CZK , new BigDecimal("8"),df.parse("2008-10-01 6:00 GMT")).getConverted());        

        // convert 1003CZK to USD using c at 2008-10-01 6:00 GMT:

        // assertEquals("Result is 59 USD");

        assertEquals("Result is 59 USD", new BigDecimal("59.00"), c.convertWithReversibleRates(CZK, USD , new BigDecimal("1003"),df.parse("2008-10-01 6:00 GMT")).getConverted());        

        // convert 16CZK using c at 2008-10-02 9:00 GMT:

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

        assertEquals("Result is 20 SKK", new BigDecimal("20.00"), c.convertWithReversibleRates(CZK, SKK , new BigDecimal("16"),df.parse("2008-10-02 9:00 GMT")).getConverted());        

        // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:

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

        assertEquals("Result is 400 SKK", new BigDecimal("400.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-02 9:00 GMT")).getConverted());        

        // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:

        // cannot convert as no rate is applicable to current date

        try {

          c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-01 6:00 GMT")).getConverted();        

          fail();        

        } catch (ConversionNotSupportedException e) {

            //exception expected

        }

    }

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

     *  SKK. Make 100 SKK == 90 CZK.

     *

     * @return prepared convertor ready for converting SKK to CZK and CZK to SKK

     */

    public static Convertor createSKKtoCZK2() {

        ExchangeRateProvider exchangeRateProvider = ExchangeRateProvider.createExchangeRateProvider();

        exchangeRateProvider.addFixedCurencyRate(SKK, new BigDecimal("100.00"), CZK, new BigDecimal("90.00"));

        Convertor c  = Convertor.createConvertor(exchangeRateProvider);

        return c;

    }

    public void testDateConvetorWithTwoDifferentRates() throws Exception {

        Date d1 = df.parse("2008-10-01 0:00 GMT");

        Date d2 = df.parse("2008-10-02 0:00 GMT");

        Date d3 = df.parse("2008-10-03 0:00 GMT");

        Convertor c = Task2Test.merge(

            limitTo(createSKKtoCZK2(), d1, d2),

            limitTo(Task1Test.createSKKtoCZK(), d2, d3)

        );

        // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:

        assertEquals("Result is 400 CZK", new BigDecimal("400.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-02 9:00 GMT")).getConverted());        

        // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:

        assertEquals("Result is 450 CZK", new BigDecimal("450.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-01 9:00 GMT")).getConverted());        

    }

}