/* Class Grading
 * Created by Brendan Curran-Johnson
 * Made in COMP3040
 * Calculates a persons Grade
 */

import javax.swing.*; //needed for JOptionPane
import java.lang.Math;//needed for Min Max

public class Grade 
{

	public static void main (String args[]) 
	{
		// These variables are used for input
		String input;
		int grade;
		
		// Get Number grade
		input = JOptionPane.showInputDialog(null, "Please enter the grade");

		// Convert string to int
		//number grades can have decimal places, so read in as a double first to avoid errors
		//Hopefully your teacher is nice like this program and rounds grades instead of truncating them
		grade = (int)Math.round(Double.parseDouble(input));

		//This is the heart of the program. The great thing about chars is that you can
		//add and subtract int values from them. This means you can decrement the letter
		//grade for every threshhold value, and the grade will go from F -> A.
		char letter = 'F';

		//D
		//This code, convoluted as it may be, is the trick for actually working out whether
		//the grade should be decremented. You can't conditionally subtract something from
		//the grade (without using conditional statements, which you haven't learned yet),
		//so you have to manipulate values so that you are subtracting 0 if the grade is
		//less than a D, and 1 if the grade is atleast a D (technically, for a D, you will
		//use the values 0 or 2, as there is no E grade, but for the other cases, you will
		//use the values 0 or 1)
		
		int temp = grade - 49;//50% is a D. right now, temp will be <= 0  if the grade is less
		//than a D, and >= 1 if the grade is atleast a D
		
		//make all values greater than 1 equal to 1
		temp = Math.min(1,temp); //temp is 1 if grade is a D or better, otherwise, it is 0-
		
		//make all values less than 0  equal to 0
		temp = Math.max(0,temp); //temp is 1 if grade is a D or better, otherwise, it is 0
		
		//subtract temp from letter to turn the grade into an F or D
		letter -= temp*2; //The times 2 is because there isn't an E in the letter grade system

		//Getting plusses to show up is slightly more tricky than letter grades, but the
		//basic concept is the same. We are going to start with the plus value showing up
		//as a space, and if the person's grade warrants a plus, we will increment the character
		//to a +. We are going to use 4 plus values (D+, C+, B+, A+), and if the grade is within
		//the correct range for that value, it will equal 1, otherwise it will equal zero.
		//Later, we will add the 4 values together. This will result in 1 if there needs to be
		//a plus, and 0 otherwise.
		char plus = ' ';

		//D+
		//We have to check two things, is the grade above a D, and is the grade below a C. the
		//'easy' way to do this is to have a counter value that we increment if the grade is above
		//a D, and decrement if the grade is below a C. This way, the value will only = 1 if the
		//grade is in range
		int dp = 0;
		temp = grade - 54; //55% is a D+. righ now, temp will be <= 0 if the grade is lesss
		//than a D+, and >= 1 if the grade is atleast a D+

		//make all values greater than 1 equal to 1
		temp = Math.min(1,temp); //temp is 1 if grade is a D+ or better, otherwise, it is 0-
		
		//make all values less than 0  equal to 0
		temp = Math.max(0,temp); //temp is 1 if grade is a D+ or better, otherwise, it is 0
		
		//increment D+
		dp += temp;

		//C
		temp = grade - 59; //60% = C
	
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		
		letter -= temp; //Decrement grade
		dp	-= temp; //Decrement D+
		
		//c+
		int cp = 0;
		temp = grade - 64; //65% = C+
		
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		cp += temp; //increment C+
		
		//B
		temp = grade - 69; //70% = B
		
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		
		letter -= temp; //Decrement grade
		cp	-= temp; //Decrement C+
		
		//B+
		int bp = 0;
		temp = grade - 74; //75% = B+
		
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		bp += temp; //increment B+

		//A
		temp = grade - 79; //80% = A
		
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		
		letter -= temp; //Decrement grade
		bp	-= temp; //Decrement B+
		
		//A+
		int ap = 0;
		temp = grade - 89; //90% = A+
		
		temp = Math.min(1,temp); //make all values greater than 1 equal to 1
		temp = Math.max(0,temp); //make all values less than 0  equal to 0
		ap += temp; //increment A+. A+ will never be decremented, it is the highest grade

		//calculate whether a plus is needed
		int isPlus = ap + bp + cp + dp;

		//More fun with adding and subtracting chars. In this case we are working
		//out the gap between + and the space character. We multiply by 1 or 0, and
		//then add it to plus, so that it is only incremented if a plus is warrented
		plus += ('+' - ' ')*isPlus;

		//output solution
		System.out.println(grade + "% is equal to: " + letter + plus);
		//there will be a space after the letter grade if it is not a +, you can fix
		//this by replacing ' ' with the number 0 (the ascii value for the null char)
		//when plus is created and incremented. This sample code doesn't do this
		//merely because you might not have learned about null characters yet, and
		//this code is confusing enough without values you've never seen before
	}
}