package org.apidesign.apifest08.test;

import java.math.BigDecimal;

import java.util.Currency;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.MonetaryAmount;

import org.apidesign.apifest08.currency.anothervendor.ZigZaggingBidirectionalConvertor;

/** 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 {

    }

    protected static final Currency CZK = Currency.getInstance( "CZK" );

    protected static final Currency SKK = Currency.getInstance( "SKK" );

    protected static final Currency USD = Currency.getInstance( "USD" );

    // 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.

        final MonetaryAmount oneUSD = new MonetaryAmount( 1, USD );

        final BigDecimal startAmount = new BigDecimal( 16 );

        final BigDecimal endAmount = new BigDecimal( 15 );

        final BigDecimal stepAmount = BigDecimal.ONE.movePointLeft( 2 ).negate();

        return new ContractImposingDelegatingConvertor( new ZigZaggingBidirectionalConvertor( oneUSD, CZK, startAmount, endAmount, stepAmount ) );

    }

    public void testFewQueriesForOnlineConvertor() {

        Convertor c = createOnlineCZKUSDConvertor();

        doFewQueriesForOnlineConvertor(c);

    }

    static void doFewQueriesForOnlineConvertor( final Convertor c ) {

        // convert $5 to CZK using c:

        final Convertor.ConversionResult r1 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), CZK ) );

        final MonetaryAmount a1 = r1.getNetAmount();

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

        assertNotNull( a1 );

        assertEquals( 80.0, a1.getAmount().doubleValue() );

        assertEquals( CZK, a1.getCurrency() );

        // convert $8 to CZK using c:

        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 8, USD ), CZK ) );

        final MonetaryAmount a2 = r2.getNetAmount();

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

        assertNotNull( a2 );

        assertEquals( 12792.0, a2.getAmount().movePointRight( 2 ).doubleValue() );

        assertEquals( CZK, a2.getCurrency() );

        // convert $1 to CZK using c:

        final Convertor.ConversionResult r3 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 1, USD ), CZK ) );

        final MonetaryAmount a3 = r3.getNetAmount();

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

        assertNotNull( a3 );

        assertEquals( 1598.0, a3.getAmount().movePointRight( 2 ).doubleValue() );

        assertEquals( CZK, a3.getCurrency() );

        // convert 15.97CZK to USD using c:

        final BigDecimal s4 = new BigDecimal( 1597 ).movePointLeft( 2 );

        final Convertor.ConversionResult r4 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( s4, CZK ), USD ) );

        final MonetaryAmount a4 = r4.getNetAmount();

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

        assertNotNull( a4 );

        assertEquals( 1.0, a4.getAmount().doubleValue() );

        assertEquals( USD, a4.getCurrency() );

    }

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

     */

    public void testOnlineConvertorComposition() throws Exception {

        final Convertor c = Task2Test.merge(

            createOnlineCZKUSDConvertor(),

            Task1Test.createSKKtoCZK()

        );

        // convert 16CZK using c:

        final Convertor.ConversionResult r4 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 16, CZK ), SKK ) );

        final MonetaryAmount a4 = r4.getNetAmount();

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

        assertNotNull( a4 );

        assertEquals( 20.0, a4.getAmount().doubleValue() );

        assertEquals( SKK, a4.getCurrency() );

        // convert 500SKK to CZK using c:

        final Convertor.ConversionResult r5 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 500, SKK ), CZK ) );

        final MonetaryAmount a5 = r5.getNetAmount();

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

        assertNotNull( a5 );

        assertEquals( 400.0, a5.getAmount().doubleValue() );

        assertEquals( CZK, a5.getCurrency() );

        doFewQueriesForOnlineConvertor(c);

    }

}