// Introduction to Software Testing
// Authors: Paul Ammann & Jeff Offutt
// Chapters 8, 9; pages 226, 257
// Can be run from command line
// No JUnit tests at this time.

import java.io.*;

public class Cal
{
   public static int cal (int month1, int day1, int month2,
                          int day2, int year)
   {
   //***********************************************************
   // Calculate the number of Days between the two given days in
   // the same year.
   // preconditions : day1 and day2 must be in same year
   //               1 <= month1, month2 <= 12
   //               1 <= day1, day2 <= 31
   //               month1 <= month2
   //               The range for year: 1 ... 10000
   //***********************************************************
      int numDays;

      if (month2 == month1) // in the same month
         numDays  = day2 - day1;
      else
      {
         // Skip month 0.
         int daysIn[] = {0, 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
         // Are we in a leap year?
         int m4 = year % 4;
         int m100 = year % 100;
         int m400 = year % 400;
         if ((m4 != 0) || ((m100 == 0) && (m400 != 0)))
            daysIn[2] = 28;
         else
            daysIn[2] = 29;

         // start with days in the two months
         numDays = day2 + (daysIn[month1] - day1);

         // add the days in the intervening months
         for (int i = month1 + 1; i <= month2-1; i++)
            numDays = daysIn[i] + numDays;
      }
      return (numDays);
   }

   public static void main (String[] argv)
   {  // Driver program for cal
      int month1, day1, month2, day2, year;
      int T;

      System.out.println ("Enter month1: ");
      month1 = getN();
      System.out.println ("Enter day1: ");
      day1 = getN();
      System.out.println ("Enter month2: ");
      month2 = getN();
      System.out.println ("Enter day2: ");
      day2 = getN();
      System.out.println ("Enter year: ");
      year = getN();
   // preconditions : day1 and day2 must be in same year
   //               1 <= month1, month2 <= 12
   //               1 <= day1, day2 <= 31
   //               month1 <= month2
   //               The range for year: 1 ... 10000

      if ( (month1 < 1) || (month1 > 12) )
      {
         month1 = 1;
         System.out.println ("invalid month1, choosing 1.");
      }
      if ( (month2 < 1) || (month2 > 12) )
      {
         month2 = 1;
         System.out.println ("invalid month2, choosing 1.");
      }
      if ( (day1 < 1) || (day1 > 31) )
      {
         day1 = 1;
         System.out.println ("invalid day1, choosing 1.");
      }
      if ( (day2 < 1) || (day2 > 31) )
      {
         day2 = 1;
         System.out.println ("invalid day2, choosing 1.");
      }
      while ( month1 > month2 )
      {
         System.out.println ("month1 must be prior or equals to month2");
         System.out.println ("Enter month1: ");
         month1 = getN();
         System.out.println ("Enter month2: ");
         month2 = getN();
      }
      if ( (year < 1) || (year > 10000) )
      {
         year = 1;
         System.out.println ("invalid year, choosing 1.");
      }

      T = cal (month1, day1, month2, day2, year);

      System.out.println ("Result is: " + T);
   }

   // ====================================
   // Read (or choose) an integer
   private static int getN ()
   {
      int inputInt = 1;
      BufferedReader in = new BufferedReader (new InputStreamReader (System.in));
      String inStr;

      try
      {
         inStr    = in.readLine ();
         inputInt = Integer.parseInt(inStr);
      }
      catch (IOException e)
      {
         System.out.println ("Could not read input, choosing 1.");
      }
      catch (NumberFormatException e)
      {
         System.out.println ("Entry must be a number, choosing 1.");
      }

      return (inputInt);
   }  // end getN
}