package org.apidesign.apifest08.test;

import java.util.Currency;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.exceptions.UnknownConvertorException;

/** 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 {

    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

    	// set exchange rates

    	Convertor.setConvertorRates(Currency.getInstance("USD"), Currency.getInstance("CZK"), 15, 1);

    	Convertor.setConvertorRates(Currency.getInstance("USD"), Currency.getInstance("SKK"), 20, 1);

    	Convertor.setConvertorRates(Currency.getInstance("SKK"), Currency.getInstance("CZK"), 75, 100);

        // create new instance

        Convertor convertor = null;

        try {

          convertor = Convertor.getConvertorInstance(Currency.getInstance("USD"), Currency.getInstance("SKK"), Currency.getInstance("CZK"));

        } catch (UnknownConvertorException e) {

          e.printStackTrace();

        }

    	return convertor;

    }

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

     */

    public void testConvertorForUSDandCZKandSKK() throws Exception {

        Convertor c = createTripleConvertor();

        // convert $5 to CZK using c:

        double result = c.convert(5d, Currency.getInstance("USD"), Currency.getInstance("CZK"));

        assertEquals("Result is not 75 CZK", 75.0, result);

        // convert $5 to SKK using c:

        result = c.convert(5d, Currency.getInstance("USD"), Currency.getInstance("SKK"));

        assertEquals("Result is not 100 SKK", 100.0, result);

        // convert 200SKK to CZK using c:

        result = c.convert(200d, Currency.getInstance("SKK"), Currency.getInstance("CZK"));

        assertEquals("Result is not 150 CZK", 150.0, result);

        // convert 200SKK to USK using c:

        result = c.convert(200d, Currency.getInstance("SKK"), Currency.getInstance("USD"));

        assertEquals("Result is not 10 USD", 10.0, result);

    }

    /** 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 one.merge(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:

        double result = c.convert(5d, Currency.getInstance("USD"), Currency.getInstance("CZK"));

        assertEquals("Result is not 85 CZK", 85.0, result);

        // convert $8 to CZK using c:

        result = c.convert(8d, Currency.getInstance("USD"), Currency.getInstance("CZK"));

        assertEquals("Result is not 136 CZK", 136.0, result);

        // convert 1003CZK to USD using c:

        result = c.convert(1003d, Currency.getInstance("CZK"), Currency.getInstance("USD"));

        assertEquals("Result is not 59 USD", 59.0, result);

        // convert 16CZK using c:

        result = c.convert(16d, Currency.getInstance("CZK"), Currency.getInstance("SKK"));

        assertEquals("Result is not 20 SKK", 20.0, result);

        // convert 500SKK to CZK using c:

        result = c.convert(500d, Currency.getInstance("SKK"), Currency.getInstance("CZK"));

        assertEquals("Result is not 400 CZK", 400.0, result);

    }

}