# HG changeset patch
# User japod@localhost
# Date 1223331577 -7200
# Node ID 3a18aae85c9e96707f75d6b2de9446079c1bd712
# Parent  80f2d8751f356e0d3a4057a01a46f8f8e8d0889b
adding solution02 for task2

diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/src/org/apidesign/apifest08/currency/CompositeConvertor.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task2/solution02/src/org/apidesign/apifest08/currency/CompositeConvertor.java	Tue Oct 07 00:19:37 2008 +0200
@@ -0,0 +1,75 @@
+package org.apidesign.apifest08.currency;
+
+import java.io.Serializable;
+import java.util.Arrays;
+import java.util.Currency;
+
+/**
+ * Convertor that is composed from other convertors. 
+ * @author lukas
+ *
+ */
+class CompositeConvertor implements ExtendedConvertor, Serializable {
+
+	private static final long serialVersionUID = -2702026568249130055L;
+	
+	private final ExtendedConvertor[] convertors;
+
+
+	public CompositeConvertor(ExtendedConvertor... convertors) {
+		this.convertors = convertors.clone();
+		for (ExtendedConvertor convertor: this.convertors)
+		{
+			if (convertor==null)
+			{
+				throw new NullPointerException("One of the convertors to be merged is null");
+			}
+		}
+	}
+
+	/**
+	 * Returns true if the composite contains convertor that supports given conversion.
+	 */
+	public boolean isConversionSupported(Currency from, Currency to) {
+		return findConvertorFor(from, to)!=null;
+	}
+
+
+	/**
+	 * If the composite contains convertor that supports given conversion, delegates to its convert method.
+	 * Throws {@link IllegalArgumentException} convertor supporting given conversion is not found. 
+	 */
+	public Money convert(Money amount, Currency destinationCurrency) throws IllegalArgumentException {
+		ExtendedConvertor convertor = findConvertorFor(amount.getCurrency(), destinationCurrency);
+		if (convertor!=null)
+		{
+			return convertor.convert(amount, destinationCurrency);
+		}
+		throw new IllegalArgumentException("Conversion not supported. Can not convert to "+destinationCurrency+".");
+	}
+	
+	/**
+	 * Finds convertor for given currencies. If not found, returns null. 
+	 * @param from
+	 * @param to
+	 * @return
+	 */
+	ExtendedConvertor findConvertorFor(Currency from, Currency to) {
+		//does linear search, in the future can cache the results.
+		for (ExtendedConvertor convertor:convertors)
+		{
+			if (convertor.isConversionSupported(from, to))
+			{
+				return convertor;
+			}
+		}
+		return null;
+	}
+	
+
+	@Override
+	public String toString() {
+		return getClass().getName()+" converts "+Arrays.toString(convertors);
+	}
+
+}
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/src/org/apidesign/apifest08/currency/ConvertorFactory.java
--- a/task2/solution02/src/org/apidesign/apifest08/currency/ConvertorFactory.java	Tue Oct 07 00:17:07 2008 +0200
+++ b/task2/solution02/src/org/apidesign/apifest08/currency/ConvertorFactory.java	Tue Oct 07 00:19:37 2008 +0200
@@ -22,9 +22,24 @@
 	 * @param destinationEquivalent
 	 * @return
 	 */
-	public static final Convertor createConvertor(Money sourceEquivalent, Money destinationEquivalent)
+	public static final ExtendedConvertor createConvertor(Money sourceEquivalent, Money destinationEquivalent)
 	{
-		return new DefaultConvertor(sourceEquivalent.getAmount(), destinationEquivalent.getAmount(), sourceEquivalent.getCurrency(), destinationEquivalent.getCurrency());
+		return mergeConvertors(
+				new DefaultConvertor(sourceEquivalent, destinationEquivalent),
+				new DefaultConvertor(destinationEquivalent ,sourceEquivalent)
+		);
+	}
+	
+	/**
+	 * Merges convertors. The resulting convertor has ability to do all conversions that its underlying 
+	 * convertors could do. No consistency validation is done, inconsistent input will result in a convertor with
+	 * inconsistent behavior.
+	 * @param convertors
+	 * @return
+	 */
+	public static final ExtendedConvertor mergeConvertors(ExtendedConvertor... convertors)
+	{
+		return new CompositeConvertor(convertors);
 	}
 	
 
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/src/org/apidesign/apifest08/currency/DefaultConvertor.java
--- a/task2/solution02/src/org/apidesign/apifest08/currency/DefaultConvertor.java	Tue Oct 07 00:17:07 2008 +0200
+++ b/task2/solution02/src/org/apidesign/apifest08/currency/DefaultConvertor.java	Tue Oct 07 00:19:37 2008 +0200
@@ -11,9 +11,9 @@
  * @author lukas
  *
  */
-class DefaultConvertor implements Convertor, Serializable {
+class DefaultConvertor implements ExtendedConvertor, Serializable {
 
-	private static final long serialVersionUID = -1754789142402148099L;
+	private static final long serialVersionUID = 6660014633685135034L;
 
 	/**
 	 * Equivalent in source currency.
@@ -29,20 +29,20 @@
 	
 	private final Currency destinationCurrency;
 	
-	public DefaultConvertor(BigDecimal sourceEquivalent, BigDecimal destinationEquivalent, Currency sourceCurrency, Currency destinationCurrency) {
+	public DefaultConvertor(Money sourceEquivalent, Money destinationEquivalent) {
 		super();
-		if (BigDecimal.ZERO.compareTo(sourceEquivalent)==0)
+		if (BigDecimal.ZERO.compareTo(sourceEquivalent.getAmount())==0)
 		{
 			throw new IllegalArgumentException("Source equivalent amount can not be 0.");
 		}
-		if (BigDecimal.ZERO.compareTo(destinationEquivalent)==0)
+		if (BigDecimal.ZERO.compareTo(destinationEquivalent.getAmount())==0)
 		{
 			throw new IllegalArgumentException("Destination equivalent amount can not be 0.");
 		}
-		this.sourceEquivalent = sourceEquivalent;
-		this.destinationEquivalent = destinationEquivalent;
-		this.sourceCurrency = sourceCurrency;
-		this.destinationCurrency = destinationCurrency;
+		this.sourceEquivalent = sourceEquivalent.getAmount();
+		this.destinationEquivalent = destinationEquivalent.getAmount();
+		this.sourceCurrency = sourceEquivalent.getCurrency();
+		this.destinationCurrency = destinationEquivalent.getCurrency();
 	}
 	
 	public Money convert(Money amount, Currency destinationCurrency) {
@@ -54,10 +54,6 @@
 		{
 			throw new NullPointerException("destionationCurrency is null");
 		}
-		if (isConversionInOpositeDirection(amount, destinationCurrency))
-		{
-			return revert().convert(amount, destinationCurrency);
-		}
 		if (!amount.getCurrency().equals(getSourceCurrency()))
 		{
 			throw new IllegalArgumentException("Can not convert from "+amount.getCurrency()+". Converts between "+getSourceCurrency()+" and "+getDestinationCurrency());
@@ -70,20 +66,9 @@
 		BigDecimal destinationAmount = sourceAmount.multiply(destinationEquivalent).divide(sourceEquivalent, 2, RoundingMode.HALF_UP);
 		return new MoneyImpl(destinationAmount, getDestinationCurrency());
 	}
-
-	/**
-	 * Returns true, if the conversion is in oposit direction.
-	 * @param amount
-	 * @param destinationCurrency
-	 * @return
-	 */
-	private boolean isConversionInOpositeDirection(Money amount,	Currency destinationCurrency) {
-		return amount.getCurrency().equals(getDestinationCurrency()) && destinationCurrency.equals(getSourceCurrency());
-	}
-
-
-	public Convertor revert() {
-		return new DefaultConvertor(destinationEquivalent, sourceEquivalent, destinationCurrency, sourceCurrency);
+	
+	public boolean isConversionSupported(Currency from, Currency to) {
+		return sourceCurrency.equals(from) && destinationCurrency.equals(to);
 	}
 
 	public BigDecimal getSourceEquivalent() {
@@ -107,58 +92,4 @@
 		return getClass().getName()+" converts "+getSourceCurrency()+" to "+getDestinationCurrency()+" "
 			+getSourceCurrency()+getSourceEquivalent()+"="+getDestinationCurrency()+getDestinationEquivalent();
 	}
-
-	@Override
-	public int hashCode() {
-		final int prime = 31;
-		int result = 1;
-		result = prime
-				* result
-				+ ((destinationCurrency == null) ? 0 : destinationCurrency
-						.hashCode());
-		result = prime
-				* result
-				+ ((destinationEquivalent == null) ? 0 : destinationEquivalent
-						.hashCode());
-		result = prime * result
-				+ ((sourceCurrency == null) ? 0 : sourceCurrency.hashCode());
-		result = prime
-				* result
-				+ ((sourceEquivalent == null) ? 0 : sourceEquivalent.hashCode());
-		return result;
-	}
-
-	@Override
-	public boolean equals(Object obj) {
-		if (this == obj)
-			return true;
-		if (obj == null)
-			return false;
-		if (!(obj instanceof DefaultConvertor))
-			return false;
-		DefaultConvertor other = (DefaultConvertor) obj;
-		if (destinationCurrency == null) {
-			if (other.destinationCurrency != null)
-				return false;
-		} else if (!destinationCurrency.equals(other.destinationCurrency))
-			return false;
-		if (destinationEquivalent == null) {
-			if (other.destinationEquivalent != null)
-				return false;
-		} else if (!destinationEquivalent.equals(other.destinationEquivalent))
-			return false;
-		if (sourceCurrency == null) {
-			if (other.sourceCurrency != null)
-				return false;
-		} else if (!sourceCurrency.equals(other.sourceCurrency))
-			return false;
-		if (sourceEquivalent == null) {
-			if (other.sourceEquivalent != null)
-				return false;
-		} else if (!sourceEquivalent.equals(other.sourceEquivalent))
-			return false;
-		return true;
-	}
-
-
 }
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/src/org/apidesign/apifest08/currency/ExtendedConvertor.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task2/solution02/src/org/apidesign/apifest08/currency/ExtendedConvertor.java	Tue Oct 07 00:19:37 2008 +0200
@@ -0,0 +1,18 @@
+package org.apidesign.apifest08.currency;
+
+import java.util.Currency;
+
+/**
+ * Extended convertor interface. 
+ * @author lukas
+ *
+ */
+public interface ExtendedConvertor extends Convertor {
+	/**
+	 * Returns true if given conversion is supported.
+	 * @param from
+	 * @param to
+	 * @return
+	 */
+	public boolean isConversionSupported(Currency from, Currency to);
+}
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/src/org/apidesign/apifest08/currency/MoneyImpl.java
--- a/task2/solution02/src/org/apidesign/apifest08/currency/MoneyImpl.java	Tue Oct 07 00:17:07 2008 +0200
+++ b/task2/solution02/src/org/apidesign/apifest08/currency/MoneyImpl.java	Tue Oct 07 00:19:37 2008 +0200
@@ -15,7 +15,7 @@
 	private final BigDecimal amount;
 	
 	private final Currency currency;
-
+	
 	public MoneyImpl(BigDecimal amount, Currency currency) {
 		if (amount==null) throw new NullPointerException("Amount is null");
 		if (currency==null) throw new NullPointerException("Currency is null"+currency);
@@ -23,6 +23,8 @@
 		this.currency = currency;
 	}
 	
+	
+	
 	public MoneyImpl(long amount, Currency currency) {
 		this(BigDecimal.valueOf(amount), currency);
 	}
@@ -30,6 +32,37 @@
 	public MoneyImpl(double amount, Currency currency) {
 		this(BigDecimal.valueOf(amount), currency);
 	}
+	
+	/**
+	 * Factory method.
+	 * @param amount
+	 * @param currency
+	 * @return
+	 */
+	public static final Money money(BigDecimal amount, Currency currency)
+	{
+		return new MoneyImpl(amount, currency);
+	}
+	/**
+	 * Factory method.
+	 * @param amount
+	 * @param currency
+	 * @return
+	 */
+	public static final Money money(long amount, Currency currency)
+	{
+		return new MoneyImpl(amount, currency);
+	}
+	/**
+	 * Factory method.
+	 * @param amount
+	 * @param currency
+	 * @return
+	 */
+	public static final Money money(double amount, Currency currency)
+	{
+		return new MoneyImpl(amount, currency);
+	}
 
 	/**
 	 * Returns amount.
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/test/org/apidesign/apifest08/currency/CompositeConvertorTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task2/solution02/test/org/apidesign/apifest08/currency/CompositeConvertorTest.java	Tue Oct 07 00:19:37 2008 +0200
@@ -0,0 +1,56 @@
+package org.apidesign.apifest08.currency;
+
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
+import static junit.framework.Assert.fail;
+import static org.apidesign.apifest08.test.Task1Test.CZK;
+import static org.apidesign.apifest08.test.Task1Test.SKK;
+import static org.apidesign.apifest08.test.Task1Test.USD;
+
+import org.junit.Test;
+
+public class CompositeConvertorTest {
+	private static final ExtendedConvertor USD_CZK_CONVERTOR = ConvertorFactory.createConvertor(new MoneyImpl(1,USD), new MoneyImpl(17,CZK));
+	private static final ExtendedConvertor SKK_CZK_CONVERTOR = ConvertorFactory.createConvertor(new MoneyImpl(100,SKK), new MoneyImpl(80,CZK));
+
+	@Test
+	public void testCompose()
+	{
+		ExtendedConvertor convertor = new CompositeConvertor(USD_CZK_CONVERTOR, SKK_CZK_CONVERTOR);
+		assertTrue(convertor.isConversionSupported(CZK, SKK));
+		assertTrue(convertor.isConversionSupported(CZK, USD));
+		assertFalse(convertor.isConversionSupported(SKK, USD));
+		assertEquals(new MoneyImpl(10,SKK), convertor.convert(new MoneyImpl(8,CZK), SKK));
+		assertEquals(new MoneyImpl(2,USD), convertor.convert(new MoneyImpl(34,CZK), USD));
+		try
+		{
+			convertor.convert(new MoneyImpl(34,SKK), USD);
+			fail("Exception expected");
+		}
+		catch(IllegalArgumentException e)
+		{
+			assertTrue("Ok", true);
+		}
+	}
+	@Test
+	public void testEmpty()
+	{
+		ExtendedConvertor convertor = new CompositeConvertor();
+		assertFalse(convertor.isConversionSupported(SKK, USD));
+		try
+		{
+			convertor.convert(new MoneyImpl(34,SKK), USD);
+			fail("Exception expected");
+		}
+		catch(IllegalArgumentException e)
+		{
+			assertTrue("Ok", true);
+		}
+	}
+	@Test(expected=NullPointerException.class)
+	public void testCreateNull()
+	{
+		new CompositeConvertor(USD_CZK_CONVERTOR, null);
+	}
+}
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/test/org/apidesign/apifest08/test/ConvertorTest.java
--- a/task2/solution02/test/org/apidesign/apifest08/test/ConvertorTest.java	Tue Oct 07 00:17:07 2008 +0200
+++ b/task2/solution02/test/org/apidesign/apifest08/test/ConvertorTest.java	Tue Oct 07 00:19:37 2008 +0200
@@ -1,13 +1,16 @@
 package org.apidesign.apifest08.test;
 
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
 import static org.apidesign.apifest08.test.Task1Test.CZK;
+import static org.apidesign.apifest08.test.Task1Test.SKK;
 import static org.apidesign.apifest08.test.Task1Test.USD;
-import static org.junit.Assert.assertEquals;
 
 import java.math.BigDecimal;
 
-import org.apidesign.apifest08.currency.Convertor;
 import org.apidesign.apifest08.currency.ConvertorFactory;
+import org.apidesign.apifest08.currency.ExtendedConvertor;
 import org.apidesign.apifest08.currency.Money;
 import org.apidesign.apifest08.currency.MoneyImpl;
 import org.junit.Test;
@@ -15,7 +18,7 @@
 
 public class ConvertorTest {
 
-	private static final Convertor CZK_TO_USD_CONVERTOR = ConvertorFactory.createConvertor(new MoneyImpl(17,CZK), new MoneyImpl(1,USD));
+	private static final ExtendedConvertor CZK_TO_USD_CONVERTOR = ConvertorFactory.createConvertor(new MoneyImpl(17,CZK), new MoneyImpl(1,USD));
 	@Test
 	public void testConvertSmall()
 	{
@@ -29,4 +32,13 @@
 		Money converted = CZK_TO_USD_CONVERTOR.convert(new MoneyImpl(0.01,USD),CZK);
 		assertEquals(new MoneyImpl(new BigDecimal("0.17"),CZK),converted);
 	}
+	@Test
+	public void testSupports()
+	{
+		assertTrue(CZK_TO_USD_CONVERTOR.isConversionSupported(USD,CZK));
+		assertTrue(CZK_TO_USD_CONVERTOR.isConversionSupported(CZK,USD));
+		assertFalse(CZK_TO_USD_CONVERTOR.isConversionSupported(CZK,CZK));
+		assertFalse(CZK_TO_USD_CONVERTOR.isConversionSupported(CZK,SKK));
+		
+	}
 }
diff -r 80f2d8751f35 -r 3a18aae85c9e task2/solution02/test/org/apidesign/apifest08/test/Task2Test.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task2/solution02/test/org/apidesign/apifest08/test/Task2Test.java	Tue Oct 07 00:19:37 2008 +0200
@@ -0,0 +1,119 @@
+package org.apidesign.apifest08.test;
+
+import static org.apidesign.apifest08.currency.ConvertorFactory.createConvertor;
+import static org.apidesign.apifest08.currency.ConvertorFactory.mergeConvertors;
+import static org.apidesign.apifest08.currency.MoneyImpl.money;
+import static org.apidesign.apifest08.test.Task1Test.CZK;
+import static org.apidesign.apifest08.test.Task1Test.SKK;
+import static org.apidesign.apifest08.test.Task1Test.USD;
+import junit.framework.TestCase;
+
+import org.apidesign.apifest08.currency.Convertor;
+import org.apidesign.apifest08.currency.ExtendedConvertor;
+
+/** 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
+	   return mergeConvertors(
+			   createConvertor(money(1, USD),  money(15, CZK)),
+			   createConvertor(money(1, USD),  money(20, SKK)),
+			   createConvertor(money(75, CZK), money(100, SKK))
+       );
+    }
+
+    /** Define convertor that understands three currencies. Use it.
+     */
+    public void testConvertorForUSDandCZKandSKK() throws Exception {
+        Convertor c = createTripleConvertor();
+
+        // convert $5 to CZK using c:
+        assertEquals("Result is 75 CZK", money(75, CZK),c.convert(money(5,USD), CZK));
+
+        // convert $5 to SKK using c:
+        assertEquals("Result is 100 SKK", money(100, SKK),c.convert(money(5,USD), SKK));
+
+        // convert 200SKK to CZK using c:
+        assertEquals("Result is 150 CZK", money(150, CZK),c.convert(money(200,SKK), CZK));
+
+        // convert 200SKK to USK using c:
+        assertEquals("Result is 10 USD", money(10, USD),c.convert(money(200,SKK), USD));
+    }
+
+    /** 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 mergeConvertors((ExtendedConvertor)one, (ExtendedConvertor)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:
+        assertEquals("Result is 85 CZK", money(85, CZK),c.convert(money(5,USD), CZK));
+
+        // convert $8 to CZK using c:
+        assertEquals("Result is 136 CZK", money(136, CZK),c.convert(money(8,USD), CZK));
+
+        // convert 1003CZK to USD using c:
+        assertEquals("Result is 59 USD", money(59, USD),c.convert(money(1003,CZK), USD));
+
+        // convert 16CZK using c:
+        assertEquals("Result is 20 SKK", money(20, SKK),c.convert(money(16,CZK), SKK));
+
+        // convert 500SKK to CZK using c:
+        assertEquals("Result is 400 CZK", money(400, CZK),c.convert(money(500,SKK), CZK));
+
+    }
+}