// SalesItem.h

#ifndef __SalesItem_h__
#define __SalesItem_h__

#include <iostream>

using namespace std;

// SalesItem starts here

class SalesItem
{
 private:
  string fISBN;
  unsigned int fUnitsSold;
  double fRevenue;

 public:
  // default constructor (initialization of built-in types)
  SalesItem() :
    fUnitsSold(0), fRevenue(0.0) {}

  SalesItem( const string& aBook ) :
    fISBN(aBook), fUnitsSold(0), fRevenue(0.0) {}
  SalesItem( istream& aIStream ) { aIStream >> *this; }

  // operators
  SalesItem& operator+=( const SalesItem& aRHS );

  // friends
  friend bool operator==( const SalesItem& aLeft, const SalesItem& aRight );
  friend istream& operator>>( istream& aIStream, SalesItem& aItem );
  friend ostream& operator<<( ostream& aOStream, const SalesItem& aItem );

  // read-only methods
  double getAveragePrice() const;
  bool hasSameISBN( const SalesItem& aRHS ) const;
};

// operators
SalesItem&
SalesItem::operator+=( const SalesItem& aRHS )
{
  fUnitsSold += aRHS.fUnitsSold;
  fRevenue += aRHS.fRevenue;
  return *this;
}

// friends
bool operator==( const SalesItem& aLeft, const SalesItem& aRight )
{
  return aLeft.fUnitsSold == aRight.fUnitsSold &&
         aLeft.fRevenue == aRight.fRevenue &&
         aLeft.hasSameISBN( aRight );
}

istream& operator>>( istream& aIStream, SalesItem& aItem )
{
  double lPrice;

  aIStream >> aItem.fISBN >> aItem.fUnitsSold >> lPrice;
  // check that the inputs succeeded
  if ( aIStream )
    {
      aItem.fRevenue = aItem.fUnitsSold * lPrice;
    }
  else
    {
      // reset to default state
      aItem = SalesItem();
    }
  return aIStream;
}

ostream& operator<<( ostream& aOStream, const SalesItem& aItem )
{
  aOStream << aItem.fISBN << "\t" << aItem.fUnitsSold << "\t"
           << aItem.fRevenue << "\t" << aItem.getAveragePrice();
  return aOStream;
}

// read-only methods

double SalesItem::getAveragePrice() const
{
  if ( fUnitsSold )
    {
      return fRevenue / fUnitsSold;
    }
  else
    {
      return 0;
    }
}

bool SalesItem::hasSameISBN( const SalesItem& aRHS ) const
{
  return fISBN == aRHS.fISBN;
}

#endif