package org.apidesign.apifest08.test;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.CurrencyValue;

/** Finish the Convertor API, and then write bodies of methods inside

 * of this class to match the given tasks. To fullfil your task, use the

 * API define in the <code>org.apidesign.apifest08.currency</code> package.

 * Do not you reflection, or other hacks as your code

 * shall run without any runtime permissions.

 */

public class Task1Test extends TestCase {

    public Task1Test(String testName) {

        super(testName);

    }

    @Override

    protected void setUp() throws Exception {

    }

    @Override

    protected void tearDown() throws Exception {

    }

    //

    // Imagine 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 design such API

    //

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

     *  USD. Make 1 USD == 17 CZK. This is a method provided for #1 group -

     *  e.g. those that know the exchange rate. They somehow need to create

     *  the objects from the API and tell them the exchange rate. The API itself

     *  knows nothing about any rates, before the createCZKtoUSD method is called.

     *

     * Creation of the convertor shall not require subclassing of any class

     * or interface on the client side.

     *

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

     */

    public static Convertor<Double, String> createCZKtoUSD() {

        return Convertor.getConvertorDoubleString(

                CurrencyValue.getCurrencyValue(1d, "USD"),

                CurrencyValue.getCurrencyValue(17d, "CZK")

        );

    }

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

     *  SKK. Make 100 SKK == 80 CZK. Again this is method for the #1 group -

     *  it 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.

     *

     * Creation of the convertor shall not require subclassing of any class

     * or interface on the client side.

     * 

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

     */

    public static Convertor<Double, String> createSKKtoCZK() {

        return Convertor.getConvertorDoubleString(

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

                CurrencyValue.getCurrencyValue(80d, "CZK")

        );

    }

    //

    // now the methods for group #2 follow:

    // this group knows nothing about exchange rates, but knows how to use

    // the API to do conversions. It somehow (by calling one of the factory

    // methods) gets objects from the API and uses them to do the conversions.

    //

    /** Use the convertor from <code>createCZKtoUSD</code> method and do few conversions

     * with it.

     */

    public void testCurrencyCZKUSD() throws Exception {

        Convertor<Double, String> c = createCZKtoUSD();

        CurrencyValue<Double, String> result;

        // convert $5 to CZK using c:

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

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

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

        // convert $8 to CZK

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

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

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

        // convert 1003CZK to USD

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

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

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

    }

    /** Use the convertor from <code>createSKKtoCZK</code> method and do few conversions

     * with it.

     */

    public void testCurrencySKKCZK() throws Exception {

        Convertor<Double, String> c = createSKKtoCZK();

        CurrencyValue<Double, String> result;

        // convert 16CZK using c:

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

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

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

        // convert 500SKK to CZK

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

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

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

    }

    /** Verify that the CZK to USD convertor knows nothing about SKK.

     */

    public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {

        Convertor<Double, String> c = createCZKtoUSD();

        try {

            // convert $5 to SKK, the API shall say this is not possible

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

            fail("Should not convert");

        } catch (Exception e) {

        }

        try {

            // convert 500 SKK to CZK, the API shall say this is not possible

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

            fail("Should not convert");

        } catch (Exception e) {

        }

    }

    /** Verify that the CZK to SKK convertor knows nothing about USD.

     */

    public void testCannotConvertToUSDwithSKKCZKConvertor() throws Exception {

        Convertor<Double, String> c = createSKKtoCZK();

        try {

            // convert $5 to SKK, the API shall say this is not possible

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

            fail("Should not convert");

        } catch (Exception e) {

        }

        try {

            // convert 500 CZK to USD, the API shall say this is not possible

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

            fail("Should not convert");

        } catch (Exception e) {

        }

    }

}