package org.apidesign.apifest08.test;

import java.util.Calendar;

import java.util.Date;

import java.util.GregorianCalendar;

import java.util.TimeZone;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.CurrencyValue;

import org.apidesign.apifest08.currency.ExchangeRateValue;

/** 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 {

    public Task4Test(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:

    //

    /** 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 <AmountType, IdentifierType> Convertor<AmountType, IdentifierType> limitTo(Convertor<AmountType, IdentifierType> old, Date from, Date till) {

        return old.limitConvertor(from, till);

    }

    public void testCompositionOfLimitedConvertors() throws Exception {

        Calendar cal = new GregorianCalendar(TimeZone.getTimeZone("GMT"));

        cal.clear();

        cal.set(2008, 9, 1, 0, 0);

        Date d1 = cal.getTime(); // 2008-10-01 0:00 GMT

        cal.set(2008, 9, 2, 0, 0);

        Date d2 = cal.getTime(); // 2008-10-02 0:00 GMT

        cal.set(2008, 9, 3, 0, 0);

        Date d3 = cal.getTime(); // 2008-10-03 0:00 GMT

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

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

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

        );

        CurrencyValue<Double, String> result;

        // convert $5 to CZK using c:

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

        try {

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

            fail("Should not convert");

        } catch (Exception e) {

        }

        // convert $8 to CZK using c:

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

        try {

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

            fail("Should not convert");

        } catch (Exception e) {

        }

        // convert 1003CZK to USD using c:

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

        try {

            c.convert("USD", CurrencyValue.getCurrencyValue(1003d, "CZK"));

            fail("Should not convert");

        } catch (Exception e) {

        }

        // convert 16CZK using c:

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

        try {

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

            fail("Should not convert");

        } catch (Exception e) {

        }

        // convert 500SKK to CZK using c:

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

        try {

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

            fail("Should not convert");

        } catch (Exception e) {

        }

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

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

        cal.set(2008, 9, 1, 6, 0);

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

        assertEquals(CurrencyValue.getCurrencyValue(85d, "CZK"), result);

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

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

        cal.set(2008, 9, 1, 6, 0);

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

        assertEquals(CurrencyValue.getCurrencyValue(136d, "CZK"), result);

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

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

        cal.set(2008, 9, 1, 6, 0);

        result = c.convert("USD", CurrencyValue.getCurrencyValue(1003d, "CZK"), cal.getTime());

        assertEquals(CurrencyValue.getCurrencyValue(59d, "USD"), result);

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

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

        cal.set(2008, 9, 2, 9, 0);

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

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

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

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

        cal.set(2008, 9, 2, 9, 0);

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

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

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

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

        cal.set(2008, 9, 1, 6, 0);

        try {

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

            fail("Should not convert");

        } catch (Exception e) {

        }

    }

    /** 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<Double, String> createSKKtoCZK2() {

        return Convertor.getConvertorDoubleString(

                ExchangeRateValue.getExchangeRate(

                    CurrencyValue.getCurrencyValue(100d, "SKK"),

                    CurrencyValue.getCurrencyValue(90d, "CZK")));

    }

    public void testDateConvetorWithTwoDifferentRates() throws Exception {

        Calendar cal = new GregorianCalendar(TimeZone.getTimeZone("GMT"));

        cal.clear();

        cal.set(2008, 9, 1, 0, 0);

        Date d1 = cal.getTime(); // 2008-10-01 0:00 GMT

        cal.set(2008, 9, 2, 0, 0);

        Date d2 = cal.getTime(); // 2008-10-02 0:00 GMT

        cal.set(2008, 9, 3, 0, 0);

        Date d3 = cal.getTime(); // 2008-10-03 0:00 GMT

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

            limitTo(createSKKtoCZK2(), d1, d2),

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

        );

        CurrencyValue<Double, String> result;

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

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

        cal.set(2008, 9, 2, 9, 0);

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

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

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

        // assertEquals("Result is 450 CZK");

        cal.set(2008, 9, 1, 6, 0);

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

        assertEquals(CurrencyValue.getCurrencyValue(450d, "CZK"), result);

    }

}