package sut;

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

import java.io.*;

public class Cal
{
public 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
//               day1 and day2 must be in an acceptable range (e.g., 1-31 for January, 1-29 for February)  	
//***********************************************************
   int numDays = 0;
  
   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
}