R/numeric_menu.R

In matiasandina/choices: User Friendly Interactive Choices

#' @title Numeric menu
#' @description This function allows the user to create numeric menus with ease for interaction with user. The menu is robust to selecting orders that are not available or are not numbers.
#' @param opts vector with options to be displayed on the menu
#' @param prompt character vector with the propmt (default to "Use numbers to select the option").
#' @usage numeric_menu(c("apple", "banana", "coconut"), "What would you like for dessert?")

#' @export
numeric_menu <- function(opts, prompt = NULL){

  if (is.null(prompt)) {
    prompt <- "Use numbers to select the option"
  }

  # prompt
  print_options(opts)
  prompt <- paste(as.character(prompt), ":> ")

  # ask for the first time
  ans <- readline(prompt = prompt)

  # validate and convert to numeric
  ans <- validate_input(ans, prompt)
  # Check if answer is within options
  ans <- within_options(ans, opts, prompt)

  # will this blow up with index error?
  selected_option <- opts[ans]

  return(selected_option)
}


print_options <- function(opts){
  message("+++++++++++++++++++++++++++++++")
  message("Please see your options below:")
  message("+++++++++++++++++++++++++++++++")
  message(paste0("Option ",
                 seq_len(length(opts)),
                 ") ",
                 opts,
                 "\n"))

}

within_options <- function(ans, opts, prompt){
  while (ans < 1 | ans > length(opts)) {
    message("Option is not valid. Choose again")
    ans <- readline(prompt = prompt)
  }
  ans <- validate_input(ans, prompt)
  return(ans)
}

validate_input <- function(ans, prompt){
  # while loop checking whether the input is valid
  # TODO: expand this to more categories?
  # Consider ensurer package?
  ans <- suppressWarnings(as.numeric(ans))

  while (is.na(ans)) {
    message("Your input is not valid, please enter a number.")
    ans <- readline(prompt = prompt)
    ans <- suppressWarnings(as.numeric(ans))
  }

  return(ans)
}