package junit.samples.money;
   
   import java.util.ArrayList;
   import java.util.List;
   
   /**
    * A MoneyBag defers exchange rate conversions. For example adding
    * 12 Swiss Francs to 14 US Dollars is represented as a bag
    * containing the two Monies 12 CHF and 14 USD. Adding another
   * 10 Swiss francs gives a bag with 22 CHF and 14 USD. Due to
   * the deferred exchange rate conversion we can later value a
   * MoneyBag with different exchange rates.
   *
   * A MoneyBag is represented as a list of Monies and provides
   * different constructors to create a MoneyBag.
   */
  public class MoneyBag implements IMoney {
      private List<Money> fMonies = new ArrayList<Money>(5);
  
      public static IMoney create(IMoney m1, IMoney m2) {
          MoneyBag result = new MoneyBag();
          m1.appendTo(result);
          m2.appendTo(result);
          return result.simplify();
      }
  
      public IMoney add(IMoney m) {
          return m.addMoneyBag(this);
      }
  
      public IMoney addMoney(Money m) {
          return MoneyBag.create(m, this);
      }
  
      public IMoney addMoneyBag(MoneyBag s) {
          return MoneyBag.create(s, this);
      }
  
      void appendBag(MoneyBag aBag) {
          for (Money each : aBag.fMonies) {
              appendMoney(each);
          }
      }
  
      void appendMoney(Money aMoney) {
          if (aMoney.isZero()) return;
          IMoney old = findMoney(aMoney.currency());
          if (old == null) {
              fMonies.add(aMoney);
              return;
          }
          fMonies.remove(old);
          Money sum = (Money) old.add(aMoney);
          if (sum.isZero()) {
              return;
          }
          fMonies.add(sum);
      }
  
      @Override
      public boolean equals(Object anObject) {
          if (isZero()) {
              if (anObject instanceof IMoney) {
                  return ((IMoney) anObject).isZero();
              }
          }
  
          if (anObject instanceof MoneyBag) {
              MoneyBag aMoneyBag = (MoneyBag) anObject;
              if (aMoneyBag.fMonies.size() != fMonies.size()) {
                  return false;
              }
  
              for (Money each : fMonies) {
                  if (!aMoneyBag.contains(each)) {
                      return false;
                  }
              }
              return true;
          }
          return false;
      }
  
      private Money findMoney(String currency) {
          for (Money each : fMonies) {
              if (each.currency().equals(currency)) {
                  return each;
              }
          }
          return null;
      }
  
      private boolean contains(Money m) {
          Money found = findMoney(m.currency());
          if (found == null) return false;
          return found.amount() == m.amount();
      }
  
      @Override
     public int hashCode() {
         int hash = 0;
         for (Money each : fMonies) {
             hash ^= each.hashCode();
         }
         return hash;
     }
 
     public boolean isZero() {
         return fMonies.size() == 0;
     }
 
     public IMoney multiply(int factor) {
         MoneyBag result = new MoneyBag();
         if (factor != 0) {
             for (Money each : fMonies) {
                 result.appendMoney((Money) each.multiply(factor));
             }
         }
         return result;
     }
 
     public IMoney negate() {
         MoneyBag result = new MoneyBag();
         for (Money each : fMonies) {
             result.appendMoney((Money) each.negate());
         }
         return result;
     }
 
     private IMoney simplify() {
         if (fMonies.size() == 1) {
             return fMonies.iterator().next();
         }
         return this;
     }
 
     public IMoney subtract(IMoney m) {
         return add(m.negate());
     }
 
     @Override
     public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("{");
         for (Money each : fMonies) {
             sb.append(each);
         }
         sb.append("}");
         return sb.toString();
     }
 
     public void appendTo(MoneyBag m) {
         m.appendBag(this);
     }
 }