# HG changeset patch
# User Jaroslav Tulach <jaroslav.tulach@apidesign.org>
# Date 1224257508 -7200
# Node ID 20d332739f60c856e82a585b310ca1540576200e
# Parent  f711ecd374f348a14acaf6fb036d9d644f8978be
Solution 13 for task4

diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/ConversionNotSupportedException.java
--- a/task4/solution13/src/org/apidesign/apifest08/currency/ConversionNotSupportedException.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/ConversionNotSupportedException.java	Fri Oct 17 17:31:48 2008 +0200
@@ -46,9 +46,9 @@
     public String toString() {
         if (from!=null && to !=null) {
           if (reversed) {
-             return "Neither onversion nor reverted conversion from " + from + " to " + to + "  is not supported,"; 
+             return "Neither conversion nor reverted conversion from " + from + " to " + to + " is supported,"; 
           }  else {
-             return "Conversion from " + from + " to " + to + "  is not supported,"; 
+             return "Conversion from " + from + " to " + to + " is not supported,"; 
           }
         } else {
             return super.toString();
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/ConversionResult.java
--- a/task4/solution13/src/org/apidesign/apifest08/currency/ConversionResult.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/ConversionResult.java	Fri Oct 17 17:31:48 2008 +0200
@@ -46,4 +46,11 @@
         this.remainder = remainder;
     }
 
+    @Override
+    public String toString() {
+        return getClass().getSimpleName()+": converter:"+getConverted()+", remainder:"+getRemainder();
+    }
+    
+    
+
 }
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/Convertor.java
--- a/task4/solution13/src/org/apidesign/apifest08/currency/Convertor.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/Convertor.java	Fri Oct 17 17:31:48 2008 +0200
@@ -3,6 +3,7 @@
 import java.math.BigDecimal;
 import java.math.MathContext;
 import java.math.RoundingMode;
+import java.util.Date;
 
 /** Convertor able to convert amount from one currency to other currency.
  * <p>
@@ -20,6 +21,11 @@
  */
 public class Convertor {
     private Convertor[] convertors;
+    private IDateProviderEngine dateProvider;
+    boolean remainderAllowed = true; //if false, remained is not allowed (should be true ideally, but can't handle it now)
+    private ExchangeRateProvider exchangeRateProvider;
+    private Date fromDate;
+    private Date toDate;
 
     /** Create new <code>Convertor</code> as merge of provided convertors. Merged convertor will use
      * provided convertors to convert between currencies.
@@ -32,21 +38,26 @@
      * @return Returns new convertor instance.
      */
     public static Convertor createConvertorAsMerge(Convertor[] convertors) {
+        for (int i=0;i<convertors.length;i++) {
+            if (convertors[i]==null) {
+                throw new NullPointerException("Convertor at index "+i+" can't be null");
+            }
+        }
         return new Convertor(convertors);
     }
     
-    boolean remainderAllowed = true; //if false, remained is not allowed (should be true ideally, but can't handle it now)
-    ExchangeRateProvider exchangeRateProvider; 
     
     /** Create simle convertor.
      */
     private Convertor() {
+        setDateProvider(DateProvider.createCurrentDateProvider());
         this.convertors=new Convertor[0];
     }
     
     /** Create merge convertor.
      */            
     private Convertor(Convertor[] convertors) {
+        this();
         this.convertors = convertors;       
     }
     
@@ -75,7 +86,7 @@
      * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
      */
     public ConversionResult convert(BigDecimal amount) {
-        return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, false,false);
+        return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, false,false,null);
     }
     
     /**
@@ -88,32 +99,36 @@
      * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
      */
     public ConversionResult convertBack(BigDecimal amount) {
-        return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, true,false);
+        return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, true,false,null);
     }
 
-    private ConversionResult convertUsingSimpleConvertor(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, boolean reversibleExRate, BigDecimal amount, boolean convertBack) throws ConversionNotSupportedException, RuntimeException {
-        ConversionResult result = new ConversionResult();
+    private ConversionResult convertUsingSimpleConvertor(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, boolean reversibleExRate, BigDecimal amount, boolean convertBack,Date date) throws ConversionNotSupportedException, RuntimeException {
+        if (date == null) {
+            date = dateProvider.getCurrentDate();
+        }
 
-        //ExchangeRate rate = exchangeRateProvider.getExchangeRate();
         ExchangeRate rate;
         if (reversibleExRate) {
-            rate = exchangeRateProvider.getReversibleExchangeRate(fromCurrency, toCurrency);
+            rate = exchangeRateProvider.getReversibleExchangeRate(fromCurrency, toCurrency, date);
         } else {
-            rate = exchangeRateProvider.getExchangeRate(fromCurrency, toCurrency);
+            rate = exchangeRateProvider.getExchangeRate(fromCurrency, toCurrency, date);
         }
         if (rate == null) {
             return null;
         }
+        ConversionResult result = new ConversionResult();
         
         int fromFranctionDigits = fromCurrency.getDefaultFractionDigits();
         int toFractionDigits = toCurrency.getDefaultFractionDigits();
+        
+        int usedFractionDigits = Math.max(fromFranctionDigits, toFractionDigits);
 
-        if (toFractionDigits != 2) {
-            throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getToCurrency() + " has " + toFractionDigits + " defaultFractionDigits");
-        }
-        if (fromFranctionDigits != 2) {
-            throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getFromCurrency() + " has " + fromFranctionDigits + " defaultFractionDigits");
-        }
+        //if (toFractionDigits != 2) {
+        //    throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + toCurrency + " has " + toFractionDigits + " defaultFractionDigits");
+        //}
+        //if (fromFranctionDigits != 2) {
+        //    throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + fromCurrency + " has " + fromFranctionDigits + " defaultFractionDigits");
+        //}
 
         if (amount.signum() == -1) {
             throw new RuntimeException("Can convert only non-negative value, current value is " + amount);
@@ -134,7 +149,7 @@
             to = rate.getToValue();
         }
 
-        BigDecimal amountCent = amount.movePointRight(toFractionDigits);
+        BigDecimal amountCent = amount.movePointRight(usedFractionDigits);
 
         final BigDecimal multiplied = amountCent.multiply(to, context);
         BigDecimal[] division = multiplied.divideAndRemainder(from, context);
@@ -142,26 +157,33 @@
         if (!remainderAllowed && !(BigDecimal.ZERO.equals(division[1]))) {
             throw new RuntimeException("Remained is not allowed - remaining amount is " + division[1] + " cents");
         } else {
-            result.setRemainder(BigDecimal.ZERO);
+            result.setRemainder(BigDecimal.ZERO.setScale(fromFranctionDigits));
         }
 
-        BigDecimal converted = division[0].movePointLeft(toFractionDigits);
-        converted = converted.setScale(toFractionDigits); //XXX ugly
+        BigDecimal converted = division[0].movePointLeft(usedFractionDigits);
+        converted = converted.setScale(toFractionDigits,RoundingMode.DOWN); //XXX ugly
         result.setConverted(converted);
-        //result.setRemainder(...);
+        BigDecimal[] convertedInBase = converted.multiply(from).divideAndRemainder(to);
+        BigDecimal x2 = convertedInBase[0].add(convertedInBase[1]);
+        BigDecimal remainder = amount.subtract(x2);
+        result.setRemainder(remainder);
+        //System.out.println("ConvertedInBase="+Arrays.asList(convertedInBase)+":"+x2 +" ("+amount+") ["+converted+"] <"+from+","+to+"> ->"+remainder);
         return result;
     }
     
 
-    private ConversionResult convertValue(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,BigDecimal amount, boolean convertBack,boolean reversibleExRate) throws RuntimeException {
+    private ConversionResult convertValue(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,BigDecimal amount, boolean convertBack,boolean reversibleExRate,Date date) throws RuntimeException {
         //result.setRemainder(...);
+        if (!dateIsInLimit(date)) {
+            return null;
+        }        
         if (convertors.length==0) {
-            return convertUsingSimpleConvertor(fromCurrency, toCurrency, reversibleExRate, amount, convertBack);
+            return convertUsingSimpleConvertor(fromCurrency, toCurrency, reversibleExRate, amount, convertBack,date);
         } else {
             ConversionResult result = null;
             for (int i = 0;i<convertors.length;i++) {
                 Convertor subConvertor = convertors[i];
-                result = subConvertor.convertValue(fromCurrency, toCurrency, amount, convertBack, reversibleExRate);
+                result = subConvertor.convertValue(fromCurrency, toCurrency, amount, convertBack, reversibleExRate,date);
                 if (result!=null) {
                     break;
                 }
@@ -175,6 +197,8 @@
      * <p>
      * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
      * This method is using only exchange rate from->to and not trying to use reverted excange rate to->from.
+     * <p>
+     * This method is using date from <code>IDateProviderEngine</code> to get exchange rate (see {@link #getDateProvider() }.
      * 
      * @param fromCurrency Source currency to convert from.
      * @param toCurrency Target currency to convert to.
@@ -184,19 +208,40 @@
      * @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code> is not supported.
      */
     public ConversionResult convert(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
-        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false);
+        Date defaultDate = dateProvider.getCurrentDate();
+        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false,defaultDate);
         if (result==null) {
             //throw new ConversionNotSupportedException("Conversion from " + fromCurrency + " to " + toCurrency + " is not supported");
             throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),false);
         }
         return result;
     }
+    /**
+     * Same as {@link #convert(ConvertorCurrency, ConvertorCurrency, java.math.BigDecimal)} but using provided rate instead of
+     * <code>IDateProviderEngine</code>.
+     * 
+     * @param fromCurrency Source currency to convert from.
+     * @param toCurrency Target currency to convert to.
+     * @param value Value in source currency which should be converted.
+     * @return Return conversion result.
+     * @param date Conversion date
+     * @return Return conversion result.
+     */
+    public ConversionResult convert(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value, Date date) {
+        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false,date);
+        if (result==null) {
+            throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),false);
+        }
+        return result;
+    }    
     
     /**
      * Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
      * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
      * <p>
      *  This method is using only exchange rate from->to and if not found, it is trying to use reverted excange rate to->from.
+     * <p>
+     * This method is using date from <code>IDateProviderEngine</code> to get exchange rate (see {@link #getDateProvider() }.
      * 
      * @param fromCurrency Source currency to convert from.
      * @param toCurrency Target currency to convert to.
@@ -207,7 +252,8 @@
      *         is not supported and neither conversion from <code>toCurrency</code> to <code>fromCurrency</code> is not supported.
      */
     public ConversionResult convertWithReversibleRates(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
-        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true);
+        Date defaultDate = dateProvider.getCurrentDate();
+        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true,defaultDate);
         if (result==null) {
             //throw new ConversionNotSupportedException("Neither onversion nor reverted conversion from " + fromCurrency + " to " + toCurrency + "  is not supported,");
             throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),true);
@@ -215,4 +261,75 @@
         return result;
     }
     
+    /**
+     * Same as {@link #convertWithReversibleRates(ConvertorCurrency, ConvertorCurrency, java.math.BigDecimal)} but using provided rate instead of
+     * <code>IDateProviderEngine</code>.
+     * 
+     * @param fromCurrency Source currency to convert from.
+     * @param toCurrency Target currency to convert to.
+     * @param value Value in source currency which should be converted.
+     * @return Return conversion result.
+     * @param date Conversion date
+     * @return Return conversion result.
+     */
+    public ConversionResult convertWithReversibleRates(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value, Date date) {
+        ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true,date);
+        if (result==null) {
+            throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),true);
+        }
+        return result;
+    }
+    
+    private boolean dateIsInLimit(Date date) {
+        boolean result;
+//        if (date==null) {
+//          result = true;  
+//        } else 
+        if (fromDate == null && toDate == null) {
+            result = true;
+        } else if (fromDate.getTime()<=date.getTime() && date.getTime()<=toDate.getTime()) {
+            result = true;
+        } else {
+            result = false;
+        }
+        
+        return result;
+    }
+    
+    
+    public void limitAllowedDates(Date from, Date till) {
+        if (from==null) {
+            throw new NullPointerException("from Date can't be null");
+        }
+        if (till==null) {
+            throw new NullPointerException("till Date can't be null");
+        }
+        if (from.getTime()>till.getTime()) {
+            throw new IllegalArgumentException("From date "+from+" must be before tii date "+till);
+        }
+        this.fromDate = from;
+        this.toDate = till;
+    }
+    
+
+    /** Return current date provider.
+     * @return Returns current date provider.
+     */
+    public IDateProviderEngine getDateProvider() {
+        return dateProvider;
+    }
+
+    
+    /**
+     * Set date provider. Date provider is used to get "current date". Current date 
+     * is used by methods {@link #convert(ConvertorCurrency, ConvertorCurrency, java.math.BigDecimal)} and  
+     * {@link #convertWithReversibleRates(ConvertorCurrency, ConvertorCurrency, java.math.BigDecimal)}.
+     * 
+     * @param dateProvider Date provider which should be used by Convertor.
+     */
+    public void setDateProvider(IDateProviderEngine dateProvider) {
+        this.dateProvider = dateProvider;
+    }
+    
+    
 }
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/ConvertorCurrency.java
--- a/task4/solution13/src/org/apidesign/apifest08/currency/ConvertorCurrency.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/ConvertorCurrency.java	Fri Oct 17 17:31:48 2008 +0200
@@ -12,22 +12,38 @@
  * @author arnostvalicek
  */
 public class ConvertorCurrency {
+    private String currencyCode;
+    private int fractionDigits;
 
-    private Currency currency;
-
-    private void setJavaCurrency(Currency javaCurrency) {
-        this.currency = javaCurrency;
-    }
 
     /**
-     * Static method providing instance of <code>ConvertorCurrency</code> base of currency code.
+     * Static method providing instance of <code>ConvertorCurrency</code> based on currency code.
+     * <p>
+     * <code>currencyCode</code> is one of codes supported by Java class {@link java.util.Currency}.
      * 
      * @param currencyCode Code of required currency.
      * @return Returns required <code>ConvertorCurrency</code>
      */
     public static ConvertorCurrency getInstance(String currencyCode) {
         ConvertorCurrency convertorCurrency = new ConvertorCurrency();
-        convertorCurrency.setJavaCurrency(Currency.getInstance(currencyCode));
+        Currency currency = Currency.getInstance(currencyCode);
+        convertorCurrency.setCurrencyCode(currency.getCurrencyCode());
+        convertorCurrency.setDefaultFractionDigits(currency.getDefaultFractionDigits());
+        return convertorCurrency;
+    }
+    
+    /**
+     * Static method providing instance of <code>ConvertorCurrency</code> base of currency code.
+     * 
+     * @param currencyCode Code of required currency.
+     * @param fractionDigits Number of fraction digits for currency.
+     * @return Returns required <code>ConvertorCurrency</code>
+     * @since version4
+     */
+    public static ConvertorCurrency getInstance(String currencyCode, int fractionDigits) {
+        ConvertorCurrency convertorCurrency = new ConvertorCurrency();
+        convertorCurrency.setCurrencyCode(currencyCode);
+        convertorCurrency.setDefaultFractionDigits(fractionDigits);
         return convertorCurrency;
     }
 
@@ -36,7 +52,23 @@
      * @return Returns the default number of fraction digits used with this currency.
      */
     public int getDefaultFractionDigits() {
-        return currency.getDefaultFractionDigits();
+        return fractionDigits;
+    }
+    
+    private void setDefaultFractionDigits(int value) {
+        this.fractionDigits = value;
+    }
+    
+    /**
+     * Get currency code.
+     * @return Returns currency code.
+     */
+    public String getCurrencyCode() {
+        return currencyCode;
+    }
+    
+    private void setCurrencyCode(String value) {
+        currencyCode = value;
     }
 
     @Override
@@ -44,7 +76,7 @@
         boolean result;
         if (obj instanceof ConvertorCurrency) {
             ConvertorCurrency that = (ConvertorCurrency) obj;
-            result = currency.equals(that.currency);
+            result = getCurrencyCode().equals(that.getCurrencyCode())  && getDefaultFractionDigits()==that.getDefaultFractionDigits();
         } else {
             result = false;
         }
@@ -53,18 +85,13 @@
 
     @Override
     public int hashCode() {
-        return currency==null ? 47/*??*/ : currency.hashCode();
+        return currencyCode==null ? 47/*??*/ : currencyCode.hashCode();
     }
-    
-    
-    
+        
 
     @Override
     public String toString() {
-        return  "ConvertorCurrency[" + (currency != null ? currency.toString() : "NO-BASE-CURRENCY")+"]";
+        return  "ConvertorCurrency[" + (currencyCode != null ? currencyCode : "NO-BASE-CURRENCY")+"]";
     }
-    
-    String getCurrencyCode() {
-        return currency.getCurrencyCode();
-    }
-}
+   
+}
\ No newline at end of file
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/DateProvider.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/DateProvider.java	Fri Oct 17 17:31:48 2008 +0200
@@ -0,0 +1,36 @@
+package org.apidesign.apifest08.currency;
+
+import java.util.Date;
+
+/**
+ * Provider for current date.
+ * 
+ * @author arnostvalicek
+ * @since version4.
+ */
+public class DateProvider {
+    private DateProvider() {
+        
+    }
+    
+    /**
+     * Create date provider based on current system time.
+     * @see     java.lang.System#currentTimeMillis()
+     */    
+    public static IDateProviderEngine createCurrentDateProvider() {
+        return new CurrentDateProvider();
+    }
+    
+    /**
+     * Date provider based on current system time.
+     * @see     java.lang.System#currentTimeMillis()
+     */
+    private static class CurrentDateProvider implements IDateProviderEngine {
+
+        public Date getCurrentDate() {
+            return new Date();
+        }
+        
+    }
+
+}
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java
--- a/task4/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java	Fri Oct 17 17:31:48 2008 +0200
@@ -12,6 +12,7 @@
  * <ul>
  * <li>{@link #createExchangeRateProvider() } - create <em>simple</em> exchange rate provider using fixed echange rate.
  * <li>{@link #createExchangeRateProvider(IExchangeRateEngine) } - create exchange rate provider using custom {@link IExchangeRateEngine}.
+ * <li>{@link #createDateExchangeRateProvider(IDateExchangeRateEngine) } - create exchange rate provider using custom {@link IDateExchangeRateEngine}.
  * </ul>
  * <p>
  * Date dependend exchange rate to be implemented.
@@ -21,6 +22,7 @@
 public class ExchangeRateProvider {
 
     IExchangeRateEngine exrateEngine;
+    IDateExchangeRateEngine dateExrateEngine;
     
     /**
      * Simple constructor for <code>ExchangeRateProviderM</code> which can provide fixed exchange rate.
@@ -62,6 +64,18 @@
         provider.exrateEngine = exchangeRateEngine;
         return provider;
     }
+    
+    /**
+     * Static method to create exchange rate provider which is using provided <code>IExIDateExchangeRateEnginechangeRateEngine</code>. This exchange rate provider is using
+     * <code>IExchangeRateEngine</code> to get actual exchange rate.
+     * @param exchangeRateEngine <code>IDateExchangeRateEngine</code> used to get exchange rate.
+     * @return Returns instance of <code>ExchangeRateProvider</code>
+     */
+    public static ExchangeRateProvider createDateExchangeRateProvider(IDateExchangeRateEngine exchangeRateEngine) {
+        ExchangeRateProvider provider = new ExchangeRateProvider();
+        provider.dateExrateEngine = exchangeRateEngine;
+        return provider;
+    }
 
     /**
      * Add new exchange rate to <code></code> to this <em>simple</em> exchange rate provider.
@@ -103,25 +117,44 @@
 
     /**
      * Get fixed exange rate for currencies (from->to).
+     * @param fromCurrency Source currency.
+     * @param toCurrency Target currency.
      * @return Returns exchange rate or <code>null</code> if exchange rate not found.
      */
     public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
-        return getExchangeRateImpl(fromCurrency, toCurrency);
+        return getExchangeRateImpl(fromCurrency, toCurrency,null);
+    }
+    
+    /**
+     * Get exange rate for currencies (from->to) for date.
+     * @param fromCurrency Source currency.
+     * @param toCurrency Target currency.
+     * @param date Conversion date.
+     * @return Returns exchange rate or <code>null</code> if exchange rate not found.
+     */
+    public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date) {
+        return getExchangeRateImpl(fromCurrency, toCurrency,date);
     }
 
     /**
      * Get fixed exange rate for currencies (from->to) or reversed exchange rate (to->from).
+     * @param fromCurrency Source currency.
+     * @param toCurrency Target currency.
      * @return Returns exchange rate or <code>null</code> if exchange rate not found.
      */
     public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
-        ExchangeRate rate = getExchangeRateImpl(fromCurrency, toCurrency);
-        if (rate == null) {
-            ExchangeRate revertedRate = getExchangeRateImpl(toCurrency, fromCurrency);
-            if (revertedRate != null) {
-                rate = ExchangeRate.createRevertedRate(revertedRate);
-            }
-        }
-        return rate;
+        return getReversibleExrateImpl(fromCurrency, toCurrency,null);
+    }
+    
+    /**
+     * Get exange rate for currencies (from->to) or reversed exchange rate (to->from) for date.
+     * @param fromCurrency Source currency.
+     * @param toCurrency Target currency.
+     * @param date Conversion date.
+     * @return Returns exchange rate or <code>null</code> if exchange rate not found.
+     */
+    public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date) {
+        return getReversibleExrateImpl(fromCurrency, toCurrency, date);
     }
 
     /**
@@ -157,9 +190,28 @@
             throw new IllegalStateException("Method supported only for FixedOneExchangeRateEngine. This method is deprecated");
         }
     }
+    
 
-    private ExchangeRate getExchangeRateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
-        ExchangeRate result = exrateEngine.getExchangeRate(fromCurrency, toCurrency);
+    private ExchangeRate getReversibleExrateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,Date date) {
+        ExchangeRate rate = getExchangeRateImpl(fromCurrency, toCurrency, date);
+        if (rate == null) {
+            ExchangeRate revertedRate = getExchangeRateImpl(toCurrency, fromCurrency, date);
+            if (revertedRate != null) {
+                rate = ExchangeRate.createRevertedRate(revertedRate);
+            }
+        }
+        return rate;
+    }    
+
+    private ExchangeRate getExchangeRateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,Date date) {
+        ExchangeRate result;
+        if (exrateEngine!=null) {
+            result = exrateEngine.getExchangeRate(fromCurrency, toCurrency);
+        } else if (dateExrateEngine!=null) {
+            result = dateExrateEngine.getExchangeRate(fromCurrency, toCurrency, date);
+        } else {
+            throw new IllegalStateException("No exchange rate engine provided");
+        }
         return result;
     }
 
@@ -224,7 +276,7 @@
      */
     private static class FixedExchangeRateEngine implements IExchangeRateEngine {
 
-        private Map exchangeRateMap = new HashMap();
+        private Map<ConvertorCurrency, Map<ConvertorCurrency, ExchangeRate>> exchangeRateMap = new HashMap<ConvertorCurrency, Map<ConvertorCurrency, ExchangeRate>>();
 
         private FixedExchangeRateEngine() {
         }
@@ -238,15 +290,14 @@
         }
 
         public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
-            Map map2 = (Map) exchangeRateMap.get(fromCurrency);
+            Map<ConvertorCurrency,ExchangeRate> map2 = exchangeRateMap.get(fromCurrency);
             if (map2 == null) {
                 return null;
             }
-            ExchangeRate result = (ExchangeRate) map2.get(toCurrency);
+            ExchangeRate result = map2.get(toCurrency);
             return result;
         }
 
-        @SuppressWarnings("unchecked")
         public synchronized void addFixedCurencyRate(ConvertorCurrency fromCurrency, BigDecimal fromValue, ConvertorCurrency toCurrency, BigDecimal toValue) {
             if (fromValue == null) {
                 throw new NullPointerException("fromValue can't be null");
@@ -254,9 +305,9 @@
             if (toValue == null) {
                 throw new NullPointerException("toValue can't be null");
             }
-            Map map2 = (Map) exchangeRateMap.get(fromCurrency);
+            Map<ConvertorCurrency,ExchangeRate> map2 = exchangeRateMap.get(fromCurrency);
             if (map2 == null) {
-                map2 = new HashMap();
+                map2 = new HashMap<ConvertorCurrency,ExchangeRate>();
                 exchangeRateMap.put(fromCurrency, map2);
             }
 
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/IDateExchangeRateEngine.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/IDateExchangeRateEngine.java	Fri Oct 17 17:31:48 2008 +0200
@@ -0,0 +1,21 @@
+package org.apidesign.apifest08.currency;
+
+import java.util.Date;
+
+/**
+ * Interface for exchange rate engine using dates.
+ * 
+ * @author arnostvalicek
+ */
+public interface IDateExchangeRateEngine {
+    /**
+     * Get exchange rate for conversion from <code>fromCurrency</code> to <code>toCurrency</code> at <code>date</code>.
+     * 
+     * @param fromCurrency From currency.
+     * @param toCurrency To currency.
+     * @param date Conversion date.
+     * @return Returns <code>ExchangeRate</code> if exchange rate is known or <code>null</code> if exchanger rate is not known.
+     */
+    public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date);
+
+}
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/src/org/apidesign/apifest08/currency/IDateProviderEngine.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution13/src/org/apidesign/apifest08/currency/IDateProviderEngine.java	Fri Oct 17 17:31:48 2008 +0200
@@ -0,0 +1,19 @@
+package org.apidesign.apifest08.currency;
+
+import java.util.Date;
+
+/**
+ * Date provider - provides current date.
+ * @see DateProvider#createCurrentDateProvider() 
+ * @see Convertor#setDateProvider(IDateProviderEngine) 
+ * @author arnostvalicek
+ * @since version4
+ */
+public interface IDateProviderEngine {
+    /**
+     * Get current date.
+     * @return Return current date.
+     */
+    public Date getCurrentDate();
+
+}
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/test/org/apidesign/apifest08/test/ConvertorWithDateExchangeRateTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution13/test/org/apidesign/apifest08/test/ConvertorWithDateExchangeRateTest.java	Fri Oct 17 17:31:48 2008 +0200
@@ -0,0 +1,109 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.apidesign.apifest08.test;
+
+import java.math.BigDecimal;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import junit.framework.TestCase;
+import org.apidesign.apifest08.currency.ConversionResult;
+import org.apidesign.apifest08.currency.Convertor;
+import org.apidesign.apifest08.currency.ConvertorCurrency;
+import org.apidesign.apifest08.currency.ExchangeRate;
+import org.apidesign.apifest08.currency.ExchangeRateProvider;
+import org.apidesign.apifest08.currency.IDateExchangeRateEngine;
+import org.apidesign.apifest08.currency.IDateProviderEngine;
+
+/**
+ *
+ * @author arnostvalicek
+ */
+public class ConvertorWithDateExchangeRateTest extends TestCase {
+
+    private static ConvertorCurrency CZK = ConvertorCurrency.getInstance("CZK");
+    private static ConvertorCurrency SKK = ConvertorCurrency.getInstance("SKK");
+    private static ConvertorCurrency USD = ConvertorCurrency.getInstance("USD");
+    private SimpleDateFormat df;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        df = new SimpleDateFormat("yyyy-MM-dd HH:mm zzzz");
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        super.tearDown();
+        df = null;
+    }
+
+    private IDateExchangeRateEngine createDateEngine() {
+        IDateExchangeRateEngine engine = new IDateExchangeRateEngine() {
+
+            public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, Date date) {
+                int day = date.getDay();
+                if (day >= 1 && day <= 5) {
+                    //weekday
+                    return new ExchangeRate(new BigDecimal(1), new BigDecimal(2));
+                } else {
+                    //weekend
+                    return new ExchangeRate(new BigDecimal(1), new BigDecimal(3));
+                }
+            }
+        };
+        return engine;
+    }
+
+    private Convertor createConvertor() {
+        ExchangeRateProvider exchangeRateProvider = ExchangeRateProvider.createDateExchangeRateProvider(createDateEngine());
+        Convertor c = Convertor.createConvertor(exchangeRateProvider);
+        return c;
+    }
+
+    public void testConvertuUsingDifferentRatesForDays() throws ParseException {
+        Convertor c = createConvertor();
+        {
+            Date d1 = df.parse("2008-10-15 9:00 GMT");  //Wednesday
+            ConversionResult resultWeekday = c.convert(CZK, SKK, new BigDecimal("2.3"), d1);
+            assertEquals("Weekday conversion", new BigDecimal("4.60"), resultWeekday.getConverted());
+        }
+        {
+            Date d1 = df.parse("2008-10-18 9:00 GMT");  //Saturday
+            ConversionResult resultWeekday = c.convert(CZK, SKK, new BigDecimal("2.3"), d1);
+            assertEquals("Weekday conversion", new BigDecimal("6.90"), resultWeekday.getConverted());
+        }
+    }
+
+    public void testConvertUsingDifferenDefaultDay() throws ParseException {
+        class MyDateProvider implements IDateProviderEngine {
+
+            private Date date;
+
+            void setDate(Date date) {
+                this.date = date;
+            }
+
+            public Date getCurrentDate() {
+                return date;
+            }
+        }
+
+        Convertor c = createConvertor();
+        MyDateProvider dp = new MyDateProvider();
+        c.setDateProvider(dp);
+
+        {
+            dp.setDate(df.parse("2008-10-15 9:00 GMT")); //Wednesday
+            ConversionResult resultWeekday = c.convert(CZK, SKK, new BigDecimal("2.3"));
+            assertEquals("Weekday conversion", new BigDecimal("4.60"), resultWeekday.getConverted());
+        }
+        {
+            dp.setDate(df.parse("2008-10-18 9:00 GMT"));  //Saturday
+            ConversionResult resultWeekday = c.convert(CZK, SKK, new BigDecimal("2.3"));
+            assertEquals("Weekday conversion", new BigDecimal("6.90"), resultWeekday.getConverted());
+        }
+    }
+}
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/test/org/apidesign/apifest08/test/RemainderTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution13/test/org/apidesign/apifest08/test/RemainderTest.java	Fri Oct 17 17:31:48 2008 +0200
@@ -0,0 +1,80 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+package org.apidesign.apifest08.test;
+
+import java.math.BigDecimal;
+import java.text.SimpleDateFormat;
+import junit.framework.TestCase;
+import org.apidesign.apifest08.currency.ConversionResult;
+import org.apidesign.apifest08.currency.Convertor;
+import org.apidesign.apifest08.currency.ConvertorCurrency;
+import org.apidesign.apifest08.currency.ExchangeRateProvider;
+
+/**
+ *
+ * @author arnostvalicek
+ */
+public class RemainderTest extends TestCase {
+    private static ConvertorCurrency CZK = ConvertorCurrency.getInstance("CZK");
+    private static ConvertorCurrency SKK = ConvertorCurrency.getInstance("SKK");
+    private static ConvertorCurrency USD = ConvertorCurrency.getInstance("USD");
+    private SimpleDateFormat df;
+    
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        df = new SimpleDateFormat("yyyy-MM-dd HH:mm zzzz");
+        
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        super.tearDown();
+    }
+    
+    public void testRemainder1() {
+        Convertor c = Task2Test.createUsdToSkkConvertor();
+        {
+            final BigDecimal convertedValue = new BigDecimal("12.34");
+            ConversionResult result = c.convertWithReversibleRates(SKK,USD,convertedValue);
+            //System.out.println("Result = "+result);
+            assertEquals("Converted", new BigDecimal("0.61"),result.getConverted());
+            assertEquals("Remainder", new BigDecimal("0.14"),result.getRemainder());
+            
+            ConversionResult resultBack = c.convertWithReversibleRates(USD, SKK, result.getConverted());
+            assertEquals("Conversion back", convertedValue, resultBack.getConverted().add(result.getRemainder()));
+            
+        }
+        {
+            ConversionResult result = c.convertWithReversibleRates(SKK,USD,new BigDecimal("20.00"));
+            //System.out.println("Result = "+result);
+        }
+    
+        {
+            ConversionResult result = c.convertWithReversibleRates(USD,SKK,new BigDecimal("1.00"));
+            //System.out.println("Result = "+result);
+        }
+        
+    }
+    
+    public void testRemainderStripCents() {
+        ConvertorCurrency CZK_cents=ConvertorCurrency.getInstance("CZK", 2);
+        ConvertorCurrency CZK_nocents=ConvertorCurrency.getInstance("CZK", 0);
+        
+        
+        ExchangeRateProvider exchangeRateProvider = ExchangeRateProvider.createExchangeRateProvider();
+        exchangeRateProvider.addFixedCurencyRate(CZK_cents, new BigDecimal(1), CZK_nocents, new BigDecimal(1));
+        
+        Convertor c = Convertor.createConvertor(exchangeRateProvider);
+        
+        ConversionResult result = c.convertWithReversibleRates(CZK_cents, CZK_nocents, new BigDecimal("2.34"));
+        assertEquals("Converted",new BigDecimal("2"),result.getConverted());
+        assertEquals("Remainder",new BigDecimal("0.34"),result.getRemainder());
+    }
+    
+    
+
+}
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/test/org/apidesign/apifest08/test/Task1Test.java
--- a/task4/solution13/test/org/apidesign/apifest08/test/Task1Test.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/test/org/apidesign/apifest08/test/Task1Test.java	Fri Oct 17 17:31:48 2008 +0200
@@ -78,35 +78,35 @@
             // convert $1 to CZK using c:
             ConversionResult result = convertCzkUsd.convertBack(new BigDecimal(1));
             assertEquals("Result is 17 CZK", new BigDecimal("17.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", new BigDecimal("00.00").setScale(2), result.getRemainder());
         }
 
         {
             // convert 17CKZ to $ using c:
             ConversionResult result = convertCzkUsd.convert(new BigDecimal(17));
             assertEquals("Result is 1 $", new BigDecimal("1.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", new BigDecimal("00.00").setScale(2), result.getRemainder());
         }
 
         {
             // convert $5 to CZK using c:
             ConversionResult result = convertCzkUsd.convertBack(new BigDecimal(5));
             assertEquals("Result is 85 CZK", new BigDecimal("85.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", BigDecimal.ZERO.setScale(2), result.getRemainder());
         }
         
         {
             // convert $8 to CZK
             ConversionResult result = convertCzkUsd.convertBack(new BigDecimal(8));
             assertEquals("Result is 136 CZK", new BigDecimal("136.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", BigDecimal.ZERO.setScale(2), result.getRemainder());
         }
 
         {
             // convert 1003CZK to USD
             ConversionResult result = convertCzkUsd.convert(new BigDecimal(1003));
             assertEquals("Result is 59 USD", new BigDecimal("59.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", BigDecimal.ZERO.setScale(2), result.getRemainder());
         }
     }
 
@@ -136,14 +136,14 @@
             // convert 500SKK to CZK
             ConversionResult result = convertSkkCzk.convert(new BigDecimal(500));
             assertEquals("Result is 400 CZK", new BigDecimal("400.00"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());            
+            assertEquals("No Remainer", BigDecimal.ZERO.setScale(2), result.getRemainder());            
         }
         
         {
             // convert 501SKK to CZK
             ConversionResult result = convertSkkCzk.convert(new BigDecimal(501));
             assertEquals("Result is 400 CZK", new BigDecimal("400.80"), result.getConverted());
-            assertEquals("No Remainer", BigDecimal.ZERO, result.getRemainder());
+            assertEquals("No Remainer", BigDecimal.ZERO.setScale(2), result.getRemainder());
             
         }
     }
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/test/org/apidesign/apifest08/test/Task2Test.java
--- a/task4/solution13/test/org/apidesign/apifest08/test/Task2Test.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/test/org/apidesign/apifest08/test/Task2Test.java	Fri Oct 17 17:31:48 2008 +0200
@@ -38,7 +38,7 @@
     
     public static Convertor createUsdToSkkConvertor() {
         ConvertorCurrency fromCurrency = currencyUSD;
-        ConvertorCurrency toCurrency = currencyUSD;
+        ConvertorCurrency toCurrency = currencySKK;
         ExchangeRateProvider exchangeRateProvider = new ExchangeRateProvider(new BigDecimal(1), fromCurrency, new BigDecimal(20), toCurrency);
         
         return Convertor.createConvertor(exchangeRateProvider);
diff -r f711ecd374f3 -r 20d332739f60 task4/solution13/test/org/apidesign/apifest08/test/Task4Test.java
--- a/task4/solution13/test/org/apidesign/apifest08/test/Task4Test.java	Sat Oct 11 23:46:05 2008 +0200
+++ b/task4/solution13/test/org/apidesign/apifest08/test/Task4Test.java	Fri Oct 17 17:31:48 2008 +0200
@@ -1,8 +1,13 @@
 package org.apidesign.apifest08.test;
 
+import java.math.BigDecimal;
+import java.text.SimpleDateFormat;
 import java.util.Date;
 import junit.framework.TestCase;
+import org.apidesign.apifest08.currency.ConversionNotSupportedException;
 import org.apidesign.apifest08.currency.Convertor;
+import org.apidesign.apifest08.currency.ConvertorCurrency;
+import org.apidesign.apifest08.currency.ExchangeRateProvider;
 
 /** The exchange rates are not always the same. They are changing. However
  * as in order to predict the future, one needs to understand own past. That is
@@ -18,16 +23,26 @@
  * System.currentTimeMillis() as default date.
  */
 public class Task4Test extends TestCase {
+    private static ConvertorCurrency CZK = ConvertorCurrency.getInstance("CZK");
+    private static ConvertorCurrency SKK = ConvertorCurrency.getInstance("SKK");
+    private static ConvertorCurrency USD = ConvertorCurrency.getInstance("USD");
+    private SimpleDateFormat df;
+    
+    
     public Task4Test(String testName) {
         super(testName);
     }
 
     @Override
     protected void setUp() throws Exception {
+        super.setUp();
+        df = new SimpleDateFormat("yyyy-MM-dd HH:mm zzzz");
     }
 
     @Override
     protected void tearDown() throws Exception {
+        super.tearDown();
+        df = null;
     }
 
     // Backward compatibly enhance your existing API to support following
@@ -45,19 +60,22 @@
      * @return new convertor
      */
     public static Convertor limitTo(Convertor old, Date from, Date till) {
-        return null;
+        Convertor c = Convertor.createConvertorAsMerge(new Convertor[]{old});
+        c.limitAllowedDates(from, till);
+        return c;
     }
 
 
     public void testCompositionOfLimitedConvertors() throws Exception {
-        if (Boolean.getBoolean("ignore.failing")) {
-            // implement me! then delete this if statement
-            return;
-        }
+//        if (Boolean.getBoolean("ignore.failing")) {
+//            // implement me! then delete this if statement
+//            return;
+//        }
+        
 
-        Date d1 = null; // 2008-10-01 0:00 GMT
-        Date d2 = null; // 2008-10-02 0:00 GMT
-        Date d3 = null; // 2008-10-03 0:00 GMT
+        Date d1 = df.parse("2008-10-01 0:00 GMT");
+        Date d2 = df.parse("2008-10-02 0:00 GMT");
+        Date d3 = df.parse("2008-10-03 0:00 GMT");
         
         Convertor c = Task2Test.merge(
             limitTo(Task1Test.createCZKtoUSD(), d1, d2),
@@ -66,36 +84,81 @@
 
         // convert $5 to CZK using c:
         // cannot convert as no rate is applicable to current date
+        try {
+          c.convert(USD, CZK, new BigDecimal(5));
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
 
         // convert $8 to CZK using c:
         // cannot convert as no rate is applicable to current date
+        try {
+          c.convert(USD, CZK, new BigDecimal(8));
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
+        
 
         // convert 1003CZK to USD using c:
         // cannot convert as no rate is applicable to current date
+        try {
+          c.convert(CZK, USD, new BigDecimal(1003));
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
 
         // convert 16CZK using c:
         // cannot convert as no rate is applicable to current date
+        // ???
+        try {
+          c.convert(CZK, USD, new BigDecimal(16));
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
 
         // convert 500SKK to CZK using c:
         // cannot convert as no rate is applicable to current date
+        try {
+          c.convert(SKK, CZK, new BigDecimal(500));
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
+        
 
         // convert $5 to CZK using c at 2008-10-01 6:00 GMT:
         // assertEquals("Result is 85 CZK");
+        assertEquals("Result is 85 CZK", new BigDecimal("85.00"), c.convertWithReversibleRates(USD, CZK , new BigDecimal("5"),df.parse("2008-10-01 6:00 GMT")).getConverted());        
 
         // convert $8 to CZK using c at 2008-10-01 6:00 GMT:
         // assertEquals("Result is 136 CZK");
+        assertEquals("Result is 136 CZK", new BigDecimal("136.00"), c.convertWithReversibleRates(USD, CZK , new BigDecimal("8"),df.parse("2008-10-01 6:00 GMT")).getConverted());        
 
         // convert 1003CZK to USD using c at 2008-10-01 6:00 GMT:
         // assertEquals("Result is 59 USD");
+        assertEquals("Result is 59 USD", new BigDecimal("59.00"), c.convertWithReversibleRates(CZK, USD , new BigDecimal("1003"),df.parse("2008-10-01 6:00 GMT")).getConverted());        
 
         // convert 16CZK using c at 2008-10-02 9:00 GMT:
         // assertEquals("Result is 20 SKK");
+        assertEquals("Result is 20 SKK", new BigDecimal("20.00"), c.convertWithReversibleRates(CZK, SKK , new BigDecimal("16"),df.parse("2008-10-02 9:00 GMT")).getConverted());        
 
         // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:
         // assertEquals("Result is 400 CZK");
+        assertEquals("Result is 400 SKK", new BigDecimal("400.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-02 9:00 GMT")).getConverted());        
 
         // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:
         // cannot convert as no rate is applicable to current date
+        try {
+          c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-01 6:00 GMT")).getConverted();        
+          fail();        
+        } catch (ConversionNotSupportedException e) {
+            //exception expected
+        }
+
     }
 
     /** Create convertor that understands two currencies, CZK and
@@ -104,18 +167,17 @@
      * @return prepared convertor ready for converting SKK to CZK and CZK to SKK
      */
     public static Convertor createSKKtoCZK2() {
-        return null;
+        ExchangeRateProvider exchangeRateProvider = ExchangeRateProvider.createExchangeRateProvider();
+        exchangeRateProvider.addFixedCurencyRate(SKK, new BigDecimal("100.00"), CZK, new BigDecimal("90.00"));
+        Convertor c  = Convertor.createConvertor(exchangeRateProvider);
+        return c;
     }
 
     public void testDateConvetorWithTwoDifferentRates() throws Exception {
-        if (Boolean.getBoolean("ignore.failing")) {
-            // implement me! then delete this if statement
-            return;
-        }
 
-        Date d1 = null; // 2008-10-01 0:00 GMT
-        Date d2 = null; // 2008-10-02 0:00 GMT
-        Date d3 = null; // 2008-10-03 0:00 GMT
+        Date d1 = df.parse("2008-10-01 0:00 GMT");
+        Date d2 = df.parse("2008-10-02 0:00 GMT");
+        Date d3 = df.parse("2008-10-03 0:00 GMT");
 
         Convertor c = Task2Test.merge(
             limitTo(createSKKtoCZK2(), d1, d2),
@@ -123,10 +185,10 @@
         );
 
         // convert 500SKK to CZK using c at 2008-10-02 9:00 GMT:
-        // assertEquals("Result is 400 CZK");
+        assertEquals("Result is 400 CZK", new BigDecimal("400.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-02 9:00 GMT")).getConverted());        
 
         // convert 500SKK to CZK using c at 2008-10-01 6:00 GMT:
-        // assertEquals("Result is 450 CZK");
+        assertEquals("Result is 450 CZK", new BigDecimal("450.00"), c.convertWithReversibleRates(SKK, CZK , new BigDecimal("500"),df.parse("2008-10-01 9:00 GMT")).getConverted());        
     }
 
 }