Donovic Doomsday

/*
 *  doomsday.c
 *  A program to test a function dayOfWeek which determines which
 *  day of the week a particular date falls on.
 *  (only for dates after the start of the Gregorian calendar).
 *
 *  Program stub created by Richard Buckland on 17/03/14
 *  This program by Tomas Donovic on 26/3/14
 *  Freely licensed under Creative Commons CC-BY-3.0
 *
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#define THURSDAY 0
#define FRIDAY   1
#define SATURDAY 2
#define SUNDAY   3
#define MONDAY   4
#define TUESDAY  5
#define WEDNESDAY 6

#define JAN_DOOMSDAY_LEAP 4
#define JAN_DOOMSDAY_COMMON 3
#define FEB_DOOMSDAY_COMMON 28
#define FEB_DOOMSDAY_LEAP 29
#define MARCH_DOOMSDAY 0
#define APRIL_DOOMSDAY 4
#define MAY_DOOMSDAY 9
#define JUNE_DOOMSDAY 6
#define JULY_DOOMSDAY 11
#define AUGUST_DOOMSDAY 8
#define SEPTEMBER_DOOMSDAY 5
#define OCTOBER_DOOMSDAY 10
#define NOVEMBER_DOOMSDAY 7
#define DECEMBER_DOOMSDAY 12

#define TRUE 1
#define FALSE 0
#define DAYS_PER_WEEK 7


int dayOfWeek (int doomsday, int leapYear, int month, int day);
int dateCalc (int doomsdate, int day, int doomsday);
int doomsdayCalc (int month, int leapYear);
int inputChecker (int doomsday, int LeapYear, int month, int day);


int main (int argc, char *argv[]) {
   assert (dayOfWeek (THURSDAY,  FALSE,  4,  4) == THURSDAY);
   assert (dayOfWeek (FRIDAY,    FALSE,  6,  6) == FRIDAY);
   assert (dayOfWeek (MONDAY,    FALSE,  8,  8) == MONDAY);
   assert (dayOfWeek (WEDNESDAY, FALSE, 10, 10) == WEDNESDAY);
   assert (dayOfWeek (FRIDAY,    FALSE, 12, 12) == FRIDAY);
   assert (dayOfWeek (THURSDAY,  FALSE,  9,  5) == THURSDAY);
   assert (dayOfWeek (FRIDAY,    FALSE,  5,  9) == FRIDAY);
   assert (dayOfWeek (SUNDAY,    FALSE,  7, 11) == SUNDAY);
   assert (dayOfWeek (TUESDAY,   FALSE, 11,  7) == TUESDAY);
   assert (dayOfWeek (WEDNESDAY, FALSE,  3,  7) == WEDNESDAY);

   assert (dayOfWeek (THURSDAY,  FALSE,  4,  5) == FRIDAY);
   assert (dayOfWeek (SATURDAY,  FALSE,  6,  5) == FRIDAY);
   assert (dayOfWeek (MONDAY,    FALSE,  8,  9) == TUESDAY);
   assert (dayOfWeek (WEDNESDAY, FALSE, 10,  9) == TUESDAY);
   assert (dayOfWeek (FRIDAY,    FALSE, 12, 20) == SATURDAY);
   assert (dayOfWeek (THURSDAY,  FALSE,  9,  9) == MONDAY);
   assert (dayOfWeek (FRIDAY,    FALSE,  5,  5) == MONDAY);
   assert (dayOfWeek (SUNDAY,    FALSE,  7,  7) == WEDNESDAY);
   assert (dayOfWeek (TUESDAY,   FALSE, 11, 11) == SATURDAY);
   assert (dayOfWeek (THURSDAY,  FALSE,  3, 30) == SATURDAY);

   assert (dayOfWeek (TUESDAY,   FALSE,  2,  28) == TUESDAY);
   assert (dayOfWeek (TUESDAY,   FALSE,  2,  27) == MONDAY);
   assert (dayOfWeek (THURSDAY,  FALSE,  1,  3)  == THURSDAY);
   assert (dayOfWeek (SATURDAY,  FALSE,  2,  1)  == SUNDAY);
   assert (dayOfWeek (0, 1, 7, 1) == 4);

   printf ("all tests passed - You are awesome!\n");
   return EXIT_SUCCESS;
}


// given the doomsday for a year, and whether or not it is a
// leap year, this function return the day of the week for any
// given month and day in the year.

int dayOfWeek (int doomsday, int leapYear, int month, int day) {

   int badInput = inputChecker (doomsday, leapYear, month, day);


   int doomsdateRes = doomsdayCalc(month, leapYear);
   int finResult = dateCalc(doomsdateRes, day, doomsday);
   int dayOfWeek = finResult;

//calls a bad run if input is bad.
   if(badInput == TRUE) {
      finResult = -99;
      }

   printf("%d\n",dayOfWeek);
   return dayOfWeek;
}

int inputChecker (int doomsday, int LeapYear, int month, int day) {

//Various tests to see if there is user input error.
   int flag = FALSE;
   if(doomsday > 7) {
      if(doomsday < 0) {
         flag = TRUE;
      }
      flag = TRUE;
   }
   if(LeapYear > 1) {
      if(LeapYear <0) {
      flag = TRUE;
      }
   flag = TRUE;
   }
   if(month>12) {
      if(month<1) {
         flag = TRUE;
      }
      flag = TRUE;
   }
   if(day>6) {
      if(day<0) {
         flag = TRUE;
      }
      flag = TRUE;
   }
   return flag;
}

int doomsdayCalc (int month, int leapYear) {

   int doomsdate;

 //Associates month with its doomsday

   if(month == 12) {
      doomsdate = DECEMBER_DOOMSDAY;
   }else if(month == 11) {
      doomsdate = NOVEMBER_DOOMSDAY;
   }else if(month == 10) {
      doomsdate = OCTOBER_DOOMSDAY;
   }else if(month == 9) {
      doomsdate = SEPTEMBER_DOOMSDAY;
   }else if(month == 8) {
      doomsdate = AUGUST_DOOMSDAY;
   }else if(month == 7) {
      doomsdate = JULY_DOOMSDAY;
   }else if(month == 6) {
      doomsdate = JUNE_DOOMSDAY;
   }else if(month == 5) {
      doomsdate = MAY_DOOMSDAY;
   }else if(month == 4) {
      doomsdate = APRIL_DOOMSDAY;
   }else if(month == 3) {
      doomsdate = MARCH_DOOMSDAY;
   }else if(month == 2) {
      if(leapYear == TRUE) {
         doomsdate = FEB_DOOMSDAY_LEAP;
      }else {
         doomsdate = FEB_DOOMSDAY_COMMON;
      }
   }else {
      if(leapYear == TRUE) {
         doomsdate = JAN_DOOMSDAY_LEAP;
      }else {
         doomsdate = JAN_DOOMSDAY_COMMON;
      }

   }
   return doomsdate;
}

int dateCalc (int doomsdate, int day, int doomsday){

   int intRem;
   int rem;
   int result;

   intRem = (day - doomsdate);
   rem = intRem % 7;
   if (rem < 0){
      rem = rem + 7;
    }
    result = (doomsday + rem) % 7;

    return result;
}