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.Convertor;

import org.apidesign.apifest08.currency.UnsupportedConversionException;

import static org.apidesign.apifest08.test.Currencies.*;

/** 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 Convertor limitTo(Convertor old, Date from, Date till) {

        return new Convertor(old, from, till);

    }

    public void testCompositionOfLimitedConvertors() throws Exception {

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

        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:

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//expected

        }

        // convert $8 to CZK using c:

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//expected

        }

        // convert 1003CZK to USD using c:

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//expected

        }

        // convert 16CZK using c:

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//expected

        }

        // convert 500SKK to CZK using c:

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//expected

        }

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

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

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

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

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

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

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

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

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

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

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

        try {

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

        	fail("cannot convert as no rate is applicable to current date");

        } catch(UnsupportedConversionException e) {

        	//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() {

    	return new Convertor(new BigDecimal("0.9"), SKK, CZK);

    }

    public void testDateConvetorWithTwoDifferentRates() throws Exception {

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

        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", 400, c.convert(new BigDecimal(500), SKK, CZK, df.parse("2008-10-02 9:00 GMT")).getValue().intValue());

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

        assertEquals("Result is 450 CZK", 450, c.convert(new BigDecimal(500), SKK, CZK, df.parse("2008-10-01 6:00 GMT")).getValue().intValue());

    }

}