//  Friday13.m  Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2013-07-15  Objective-C version of this file was created.
//  2013-07-15  Last modification.

#include  <stdio.h>
#import   <Foundation/Foundation.h>
#import   "class_isodate_oc.h"

int main( void )
{
   NSAutoreleasePool* autorelease_pool = [ [ NSAutoreleasePool alloc ] init ] ;

   char  given_date_as_c_string[ 20 ] ;

   printf( "\n This program can print you a list of 10 dates"
           "\n that are Fridays and 13th days of a month."
           "\n Please, type in a date from which you want"
           "\n the calculation to begin. Type in the date"
           "\n in form YYYY-MM-DD:  "  ) ;

   scanf( "%s", given_date_as_c_string ) ;
   
   NSString* given_date_as_nsstring =
   
      [ NSString stringWithUTF8String: given_date_as_c_string ] ;

   ISODate*  date_to_increment =
            [ [ ISODate alloc ] init_with_string: given_date_as_nsstring ] ;

   int   number_of_friday13_dates_to_print  =  10 ;

   printf( "\n It is a common belief that you may have"
           "\n bad luck on the following dates:\n" ) ;

   while ( number_of_friday13_dates_to_print  >  0 )
   {
      while ( [ date_to_increment index_for_day_of_week ]  !=  4  ||
              [ date_to_increment day ]  !=  13   )
      {
         [ date_to_increment increment ] ;
      }

      // Now we have found a date that is Friday the 13th.
      // Let's print the date.

      NSString* text_to_print = [ NSString stringWithFormat:
                                    @"\n    %@, %@",
                                    date_to_increment,
                                    [ date_to_increment get_day_of_week ]
                                ] ;
      
      printf( "%s", [ text_to_print UTF8String ] ) ;

      [ date_to_increment increment ] ;
      number_of_friday13_dates_to_print  --  ;
   }

   printf( "\n\n" ) ;

   [ autorelease_pool drain ] ;
}

/*  Here is a sample compilation and execution of this program:

user$ gcc Friday13.m -o runnablefile.out -framework Foundation
user$ ./runnablefile.out
 
 This program can print you a list of 10 dates
 that are Fridays and 13th days of a month.
 Please, type in a date from which you want
 the calculation to begin. Type in the date
 in form YYYY-MM-DD:  2013-07-15

 It is a common belief that you may have
 bad luck on the following dates:

    2013-09-13, Friday
    2013-12-13, Friday
    2014-06-13, Friday
    2015-02-13, Friday
    2015-03-13, Friday
    2015-11-13, Friday
    2016-05-13, Friday
    2017-01-13, Friday
    2017-10-13, Friday
    2018-04-13, Friday

*/