//interface file for a simple date class
#ifndef DATE_H
#define DATE_H

#include <iostream>
using namespace std;

#include <utility>                // this provides != <= > >= when == and < 
using namespace std::rel_ops;     // are defined

// date class declaration
class Date
{
   public:
      Date ();                            // default constructor creates today
      Date(int yr, int mon, int day);     // constructor - creates mon day, yr
   
      Date& operator= (int);              // assign date with form yyyymmdd
   
      // input/output member methods
      
      void read(istream& iStr);           // read a date
                                          // acceptable formats are
                                          //    yyyy/mm/dd
                                          //    yyyy-mm-dd
                                          //    yyyy:mm:dd
                                          // a date may not contain any spaces
      void read();                        // prompt for and read a date
      
      void print(ostream& oStr) const;    // print in format yyyy/mm/dd
      void print() const;                 // print in format month dd, yyyy
                                          // to standard out
   
      // accessor functions
      int year() const;                      
      int month() const;
      int day () const;
   
      // increment & decrement functions
      Date operator++();                  // add one day Pre-increment
      Date operator++(int);               // add one day Post-increment
      Date operator--();                  // subtract one day Pre-decrement
      Date operator--(int);               // subtract one day Post-decrement

      void addYear(int=1);                // add/sub years 
      void addMonth(int=1);               // add/sub months
      void addWeek(int=1);                // add/sub weeks
      void addDay(int=1);                 // add/sub days
   
      // provide the == and < comparison overloads
      bool operator==(const Date&) const;
      bool operator<(const Date&) const;
   
      // static functions - for the class - not available to specific instances
      static bool leapYear(int yr);       // is yr a leap year?  
      static Date today();                // returns todays date
      static int daysIn(int month, int yr); // returns # of days in a month
   
   private:            
      int yy, mm, dd;                     // data members
   
      // helper functions
      bool setDate(int yr, int mm, int day); // set the date to this day    
      static bool validDate(int yr, int month, int day); // ensure validity

      // lowest valid year for this type of calendar 
      static const int baseYear = 1582;
};

// non-member insertion and extraction overloads
istream& operator>>(istream&, Date&);
ostream& operator<<(ostream&, const Date&);

#endif