package org.apidesign.apifest08.test;

import java.util.Currency;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.ConversionRate;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.IllegalRequestSubtypeException;

import org.apidesign.apifest08.currency.MonetaryAmount;

import org.apidesign.apifest08.currency.TableConvertor;

/** 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 {

    }

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

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

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

    // 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

        final TableConvertor convertor = new TableConvertor();

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

        final MonetaryAmount amountInCZK = new MonetaryAmount( 15, CZK );

        final MonetaryAmount amountInSKK = new MonetaryAmount( 20, SKK );

        convertor.putIntoTable( new ConversionRate( amountInCZK, amountInUSD ) );

        convertor.putIntoTable( new ConversionRate( amountInUSD, amountInCZK ) );

        convertor.putIntoTable( new ConversionRate( amountInSKK, amountInUSD ) );

        convertor.putIntoTable( new ConversionRate( amountInUSD, amountInSKK ) );

        convertor.putIntoTable( new ConversionRate( amountInSKK, amountInCZK ) );

        convertor.putIntoTable( new ConversionRate( amountInCZK, amountInSKK ) );

        return new ContractImposingDelegatingConvertor( convertor ).test();

    }

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

     */

    public void testConvertorForUSDandCZKandSKK() throws Exception {

        final Convertor c = createTripleConvertor();

        // 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 75 CZK");

        assertNotNull( a1 );

        assertEquals( 75.0, a1.getAmount().doubleValue() );

        assertEquals( CZK, a1.getCurrency() );

        // convert $5 to SKK using c:

        final Convertor.ConversionResult r2 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 5, USD ), SKK ) );

        final MonetaryAmount a2 = r2.getNetAmount();

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

        assertNotNull( a2 );

        assertEquals( 100.0, a2.getAmount().doubleValue() );

        assertEquals( SKK, a2.getCurrency() );

        // convert 200SKK to CZK using c:

        final Convertor.ConversionResult r3 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 200, SKK ), CZK ) );

        final MonetaryAmount a3 = r3.getNetAmount();

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

        assertNotNull( a3 );

        assertEquals( 150.0, a3.getAmount().doubleValue() );

        assertEquals( CZK, a3.getCurrency() );

        // convert 200SKK to USK using c:

        final Convertor.ConversionResult r4 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 200, SKK ), USD ) );

        final MonetaryAmount a4 = r4.getNetAmount();

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

        assertNotNull( a4 );

        assertEquals( 10.0, a4.getAmount().doubleValue() );

        assertEquals( USD, a4.getCurrency() );

    }

    /** 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( final Convertor one, final Convertor two ) {

        return new Convertor() {

            public ConversionResult convert( ConversionRequest req ) throws IllegalRequestSubtypeException {

                final ConversionResult res1 = one.convert( req );

                final ConversionResult res2 = two.convert( req );

                if ( res1.getNetAmount() != null ) {

                    if ( res2.getNetAmount() != null ) {

                        // TODO check if they arrive at the same thing

                        return res1;

                    } else {

                        return res1;

                    }

                } else {

                    if ( res2.getNetAmount() != null ) {

                        return res2;

                    } else {

                        // neither converts

                        return new ConversionResult( null );

                    }                    

                }

            }

        };

    }

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

     * can be used to do reasonable conversions.

     */

    public void testConvertorComposition() throws Exception {

        final Convertor c = merge(

            Task1Test.createCZKtoUSD(),

            Task1Test.createSKKtoCZK()

        );

        // 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 85 CZK");

        assertNotNull( a1 );

        assertEquals( 85.0, a1.getAmount().doubleValue() );

        assertEquals( CZK, a1.getCurrency() );

        // convert $8 to CZK

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

        final MonetaryAmount a2 = r2.getNetAmount();

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

        assertNotNull( a2 );

        assertEquals( 136.0, a2.getAmount().doubleValue() );

        assertEquals( CZK, a2.getCurrency() );

        // convert 1003CZK to USD

        final Convertor.ConversionResult r3 = c.convert( new Convertor.ConversionRequest( new MonetaryAmount( 1003, CZK ), USD ) );

        final MonetaryAmount a3 = r3.getNetAmount();

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

        assertNotNull( a3 );

        assertEquals( 59.0, a3.getAmount().doubleValue() );

        assertEquals( USD, a3.getCurrency() );

        // 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() );

    }

}