//
// simplified program to compute letter grade based on:
//   maximum points (values "hardcoded" in program)
//   and student's points (entered by user)
//

// version using function to avoid repetitive code

// the next line is needed to avoid warnings with the newest Scala
// "comment it out" (insert a //) if you compile with an earlier version
import scala.io.StdIn._

val MaxExam1 = 100.0
val MaxExam2 = 200.0
val MaxHomework = 200.0

val exam1 = promptForNonNegativeDouble("exam1", MaxExam1)
val exam2 = promptForNonNegativeDouble("exam2", MaxExam2)
val homework = promptForNonNegativeDouble("homework", MaxHomework)

val average = (exam1 + exam2 + homework) / (MaxExam1 + MaxExam2 + MaxHomework)
println("average = " + average)

if (average >= .90) {
  println("A- or better")
}
else if (average >= .80) {
  println("B- or better") 
}
else if (average >= .70) {
  println("C- or better")
}
else if (average >= .60) {
  println("D- or better")
}
else {
  println("sorry, F")
}

// prompt for input, using name and perfectScore
// exit if value is < 0
def promptForNonNegativeDouble(name:String, perfectScore:Double) : Double = {
  println("enter points for " + name + " (max " + perfectScore + ")")
  val in = readDouble
  if (in < 0) {
    println("value must be >= 0")
    sys.exit(0)
  }
  in
}