Sales_item.h

#pragma once

/*
 * // Copyright (c) 2025 Tanner Davison. All rights reserved
 *
 * Permission is granted for this code to be used for educational purposes in
 * association, given proper citation if and when posted or
 * reproduced. Any commercial use of this code requires the explicit written
 * permission of the publisher, Tanner Davison , a division of
 * Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *     The Davison Boys, llc.
 *     227 w thistle dr
 *     Ut, 84045
 *     email: tanner.davison@gmail.com
 */

/* This file defines the Sales_item class used in chapter 1.
 * The code used in this file will be explained in
 * Chapter 7 (Classes) and Chapter 14 (Overloaded Operators)
 */

#ifndef SALESITEM_H
// we're here only if SALESITEM_H has not yet been defined
#define SALESITEM_H

// Definition of Sales_item class and related functions goes here
#include <iomanip>
#include <iostream>
#include <string>

class Sales_item {
  friend std::istream &operator>>(std::istream &, Sales_item &);
  friend std::ostream &operator<<(std::ostream &, const Sales_item &);
  friend bool operator<(const Sales_item &, const Sales_item &);
  friend bool operator==(const Sales_item &, const Sales_item &);

public:
#if defined(IN_CLASS_INITS) && defined(DEFAULT_FCNS)
  Sales_item() = default;
#else
  Sales_item() : units_sold(0), revenue(0.0) {}
#endif
  Sales_item(const std::string &book)
      : bookNo(book), units_sold(0), revenue(0.0) {}
  Sales_item(std::istream &is) { is >> *this; }

public:
  // operations on Sales_item objects
  // member binary operator: left-hand operand bound to implicit this pointer
  Sales_item &operator+=(const Sales_item &);

  // operations on Sales_item objects
  std::string isbn() const { return bookNo; }
  double avg_price() const;
  // private members as before
private:
  std::string bookNo; // implicitly initialized to the empty string
#ifdef IN_CLASS_INITS
  unsigned units_sold = 0; // explicitly initialized
  double revenue = 0.0;
#else
  unsigned units_sold;
  double revenue;
#endif
};

// used in chapter 10
inline bool compareIsbn(const Sales_item &lhs, const Sales_item &rhs) {
  return lhs.isbn() == rhs.isbn();
}

// nonmember binary operator: must declare a parameter for each operand
Sales_item operator+(const Sales_item &, const Sales_item &);

inline bool operator==(const Sales_item &lhs, const Sales_item &rhs) {
  // must be made a friend of Sales_item
  return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue &&
         lhs.isbn() == rhs.isbn();
}

inline bool operator!=(const Sales_item &lhs, const Sales_item &rhs) {
  return !(lhs == rhs); // != defined in terms of operator==
}

// assumes that both objects refer to the same ISBN
Sales_item &Sales_item::operator+=(const Sales_item &rhs) {
  units_sold += rhs.units_sold;
  revenue += rhs.revenue;
  return *this;
}

// assumes that both objects refer to the same ISBN
Sales_item operator+(const Sales_item &lhs, const Sales_item &rhs) {
  Sales_item ret(lhs); // copy (|lhs|) into a local object that we'll return
  ret += rhs;          // add in the contents of (|rhs|)
  return ret;          // return (|ret|) by value
}

std::istream &operator>>(std::istream &in, Sales_item &s) {
  double price;
  in >> s.bookNo >> s.units_sold >> price;
  // check that the inputs succeeded
  if (in)
    s.revenue = s.units_sold * price;
  else
    s = Sales_item(); // input failed: reset object to default state
  return in;
}
// cat
std::ostream &operator<<(std::ostream &out, const Sales_item &s) {
  out << "ISBN: " << s.isbn() << "\nUnits sold: " << s.units_sold
      << "\nRevenue: $" << std::fixed << std::setprecision(2)
      << static_cast<float>(s.revenue) << "\nAvg price: $"
      << static_cast<float>(s.avg_price());
  return out;
}

double Sales_item::avg_price() const {
  if (units_sold)
    return revenue / units_sold;
  else
    return 0;
}
#endif