# Clear global environment
rm(list = ls())
# Set highscore = 0 before the quiz
highscore <- 0

# User inputs: 
# max.number = maximum number for calculations (e.g. if max.number = 10, you will calculate with numbers from 1 to 10)
# questions.number = number of questions per quiz

QUIZ <- function(max.number, questions.number) {
  
  # Introduction
  print("=== Hello, welcome to the Math Quiz! ===", quote = F)
  cat("\n")
  
  # Set points to 0 before each quiz
  counter <- 0
  
  # Produces multiple questions (based on questions.number)
  for (i in 1:questions.number) {
    
    # Chose random number for x and y 
    x <- sample(1:max.number, 1)
    y <- sample(1:max.number, 1)
    
    # Chose either 1 for plus or 2 for minus randomly 
    operator.chooser <- sample(1:2, 1)
    
    # Print the question, wait for user input and check if it is correct
    if (operator.chooser == 1) {
      print(c(x, "+", y), quote = F)
      answer <- readline(prompt = "Answer:")
      if (answer == x + y) {
        print("Correct")
        
        # + 1 point if answer was correct
        counter <- counter + 1 
      } else {
        print ("Wrong")
      }
    }
    
    # Same for substractions 
    else {
      print(c(x, "-", y), quote = F)
      answer <- readline(prompt = "Answer:")
      if (answer == x - y) {
        print("Correct!", quote = F)
        counter <- counter + 1
      } else {
        print ("Wrong!", quote = F)
      }
    }
    
    # Print the current number of points 
    print(c("Points:", counter), quote = F)
  }
  
  # In the end: Print the final number of points 
  cat("\n")
  print(c("Finished! Your final points: ", counter), quote = F)
  
  # Keep track of your highscore 
  if(counter > highscore) {
    
    # Saves highscore outside of function, so it's valid for all runs of the function
    highscore <<- counter 
    print(c("Congratulations, you beat the highscore! New highscore: ", highscore), quote = F)
  } else {
    print(c("The highscore is", highscore), quote = F)
  }
}