package org.apidesign.apifest08.test;

import java.math.BigDecimal;

import java.util.Currency;

import java.util.Set;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.ConvertorFactory;

import org.apidesign.apifest08.currency.InvalidConversionException;

/** There are many currencies around the world and many banks manipulate

 * with more than one or two at the same time. As banks are usually the

 * best paying clients, which is true even in case of your Convertor API,

 * it is reasonable to listen to their requests.

 * <p>

 * The quest for today is to enhance your existing convertor API to hold

 * information about many currencies and allow conversions between any of them.

 * Also, as conversion rates for diferent currencies usually arise from various

 * bank departments, there is another important need. There is a need to

 * compose two convertors into one by merging all the information about

 * currencies they know about.

 */

public class Task2Test 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 Task2Test(String testName)

    {

        super(testName);

    }

    @Override

    protected void setUp() 

        throws Exception

    {

    }

    @Override

    protected void tearDown() 

        throws Exception

    {

    }

    // As in Task1Test, keep in mind, that there are three parts

    // of the whole system:

    // 1. there is someone who knows the current exchange rate

    // 2. there is someone who wants to do the conversion

    // 3. there is the API between 1. and 2. which allows them to communicate

    // 

    // Please backward compatibly enhance your existing API to support following

    // usecases:

    //

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

     *  SKK. Make 100 SKK == 75 CZK. This is method for the group of users that

     *  knows the exchange rate, and needs to use the API to create objects

     *  with the exchange rate. Anyone shall be ready to call this method without

     *  any other method being called previously. The API itself shall know

     *  nothing about any rates, before this method is called.

     */

    public static Convertor createTripleConvertor() {

        // Rates: 1USD = 15CZK

        // Rates: 1USD = 20SKK

        // Rates: 75CZK = 100SKK

        Convertor c = ConvertorFactory.mergeConvertors(

            ConvertorFactory.getConvertor(USD, BigDecimal.ONE, CZK, BigDecimal.valueOf(15.00)),

            ConvertorFactory.getConvertor(USD, BigDecimal.ONE, SKK, BigDecimal.valueOf(20.00))

        );

        return c;

    }

    /** Define convertor that understands three currencies. Use it.

     */

    public void testConvertorForUSDandCZKandSKK() throws Exception {

        Convertor c = createTripleConvertor();

        // convert $5 to CZK using c:

        // assertEquals("Result is 75 CZK");

        assertEquals(new BigDecimal("75.00"), c.convert(USD, CZK, BigDecimal.valueOf(5.00)));

        // convert $5 to SKK using c:

        // assertEquals("Result is 100 SKK");

        assertEquals(new BigDecimal("100.00"), c.convert(USD, SKK, BigDecimal.valueOf(5.00)));

        // convert 200SKK to CZK using c:

        // assertEquals("Result is 150 CZK");

        assertEquals(new BigDecimal("150.00"), c.convert(SKK, CZK, BigDecimal.valueOf(200.00)));

        // convert 200SKK to USK using c:

        // assertEquals("Result is 10 USD");

        assertEquals(new BigDecimal("10.00"), c.convert(SKK, USD, BigDecimal.valueOf(200.00)));

    }

    /** Merge all currency rates of convertor 1 with convertor 2.

     * Implement this using your API, preferably this method just delegates

     * into some API method which does the actual work, without requiring

     * API clients to code anything complex.

     */

    public static Convertor merge(Convertor one, Convertor two) {

        return ConvertorFactory.mergeConvertors(one, two);

    }

    /** Join the convertors from previous task, Task1Test and show that it

     * can be used to do reasonable conversions.

     */

    public void testConvertorComposition() throws Exception {

        Convertor c = merge(

            Task1Test.createCZKtoUSD(),

            Task1Test.createSKKtoCZK()

        );

        // convert $5 to CZK using c:

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

        assertEquals(new BigDecimal("85.00"), c.convert(USD, CZK, BigDecimal.valueOf(5.00)));

        // convert $8 to CZK using c:

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

        assertEquals(new BigDecimal("136.00"), c.convert(USD, CZK, BigDecimal.valueOf(8.00)));

        // convert 1003CZK to USD using c:

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

        assertEquals(new BigDecimal("59.00"), c.convert(CZK, USD, BigDecimal.valueOf(1003.00)));

        // convert 16CZK using c:

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

        assertEquals(new BigDecimal("20.00"), c.convert(CZK, SKK, BigDecimal.valueOf(16.00)));

        // convert 500SKK to CZK using c:

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

        assertEquals(new BigDecimal("400.00"), c.convert(SKK, CZK, BigDecimal.valueOf(500.00)));

    }

    public void testGetCurrencies()

    {

        Convertor c = merge(

            Task1Test.createCZKtoUSD(),

            Task1Test.createSKKtoCZK()

        );

        Set<Currency> currencies;

        currencies = c.getCurrencies();        

        assertEquals(3, currencies.size());

        assertTrue(currencies.contains(Currency.getInstance("SKK")));

        assertTrue(currencies.contains(Currency.getInstance("CZK")));

        assertTrue(currencies.contains(Currency.getInstance("USD")));

    }

    public void testGetConverstionRate()

        throws InvalidConversionException

    {

        Convertor c = merge(

            Task1Test.createCZKtoUSD(),

            Task1Test.createSKKtoCZK()

        );

        assertEquals(1.0,        c.getConversionRate(USD, USD).doubleValue(), 0.0000000000000001);

        assertEquals(17.0,       c.getConversionRate(USD, CZK).doubleValue(), 0.0000000000000001);

        assertEquals(21.25,      c.getConversionRate(USD, SKK).doubleValue(), 0.0000000000000001);

        assertEquals(1.0 / 17.0, c.getConversionRate(CZK, USD).doubleValue(), 0.0000000000000001);

        assertEquals(1.0,        c.getConversionRate(CZK, CZK).doubleValue(), 0.0000000000000001);

        assertEquals(1.25,       c.getConversionRate(CZK, SKK).doubleValue(), 0.0000000000000001);

        assertEquals(0.04705882352941176, c.getConversionRate(SKK, USD).doubleValue(), 0.0000000000000001);

        assertEquals(0.8,                 c.getConversionRate(SKK, CZK).doubleValue(), 0.0000000000000001);

        assertEquals(1.0,                 c.getConversionRate(SKK, SKK).doubleValue(), 0.0000000000000001);

    }

}