package org.apidesign.apifest08.test;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.ConvertorFactory;

import org.apidesign.apifest08.currency.CurrencyRate;

import org.apidesign.apifest08.currency.Rate;

/** The exchange rates are not always the same. They are changing. Day by day,

 * hour by hour, minute by minute. For every bank it is important to always

 * have the actual exchange rate available in the system. That is why let's

 * create a pluggable convertor that will always have up to date value of its

 * exchange rate.

 * <p>

 * The quest for today is to allow 3rd party developer to write a convertor

 * that adjusts its exchange rate everytime it is queried. This convertor is

 * written by independent vendor, the vendor knows only your Convertor API,

 * he does not know how the whole system looks and how the convertor is supposed

 * to be used.

 */

public class Task3Test extends TestCase {

    public Task3Test(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:

    //

    /** Without knowing anything about the surrounding system, write an

     * implementation of convertor that will return different rates everytime

     * it is queried. Convert USD to CZK and vice versa. Start with the rate of

     * 1USD = 16CZK and adjust it in favor of CZK by 0.01 CZK with every query.

     * As soon as you reach 1USD = 15CZK adjust it by 0.01 CZK in favor of USD

     * until you reach 1USD = 16CZK

     *

     * @return new instance of "online" USD and CZK convertor starting with rate 1USD = 16CZK

     */

    public static Convertor createOnlineCZKUSDConvertor() {

        // initial rate: 1USD = 16CZK

        // 2nd query 1USD = 15.99CZK

        // 3rd query 1USD = 15.98CZK

        // until 1USD = 15.00CZK

        // then 1USD = 15.01CZK

        // then 1USD = 15.02CZK

        // and so on and on up to 1USD = 16CZK

        // and then another round to 15, etc.

        CurrencyRate onlineCurrencyRate = new CurrencyRate() {

            private int usdAmount = 100;

            private int czkAmount = 1600;

            private boolean up = false;

            public String getCurrency1() {

                return "USD";

            }

            public String getCurrency2() {

                return "CZK";

            }

            public Rate getRate() { //return Rate according to online status

                Rate rate = new Rate(usdAmount, czkAmount);

                if (up) {

                    if (czkAmount < 1600) {

                        czkAmount++;

                    } else {

                        up = false;

                        czkAmount--;

                    }

                } else { //down

                    if (czkAmount > 1500) {

                        czkAmount--;

                    } else {

                        up = true;

                        czkAmount++;

                    }

                }

                return rate;

            }

        };

        return ConvertorFactory.newInstance().createConvertor(onlineCurrencyRate);

    }

    public void testFewQueriesForOnlineConvertor() {

        Convertor c = createOnlineCZKUSDConvertor();

        doFewQueriesForOnlineConvertor(c);

    }

    static void doFewQueriesForOnlineConvertor(Convertor c) {

        // convert $5 to CZK using c:

        //assertEquals("Result is 80 CZK");

        assertEquals("Result is 80 CZK", 80.0, c.convert("USD", "CZK", 5), 0.001);

        // convert $8 to CZK using c:

        //assertEquals("Result is 127.92 CZK");

        assertEquals("Result is 127.92 CZK", 127.92, c.convert("USD", "CZK", 8), 0.001);

        // convert $1 to CZK using c:

        //assertEquals("Result is 15.98 CZK");

        assertEquals("Result is 15.98 CZK", 15.98, c.convert("USD", "CZK", 1), 0.001);

        // convert 15.97CZK to USD using c:

        //assertEquals("Result is 1$");

        assertEquals("Result is 1$", 1.0, c.convert("CZK", "USD", 15.97), 0.001);

    }

    /** Join the convertors and show they behave sane.

     */

    public void testOnlineConvertorComposition() throws Exception {

        Convertor c = Task2Test.merge(

            createOnlineCZKUSDConvertor(),

            Task1Test.createSKKtoCZK()

        );

        // convert 16CZK to SKK using c:

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

        assertEquals("Result is 20 SKK", 20.0, c.convert("CZK", "SKK", 16), 0.001);

        // convert 500SKK to CZK using c:

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

        assertEquals("Result is 400 CZK", 400.0, c.convert("SKK", "CZK", 500), 0.001);

        doFewQueriesForOnlineConvertor(c);

    }

}