Crystal Terminal Prompt Helper Functions

terminal_prompts.cr

def prompt_input(prompt_text, *, default = nil) : String
  print prompt_text
  if default
    print %[ (default: "], default, %[")]
  end
  print " "
  gets || default || ""
end

def prompt_integer_input(prompt_text)
  until (user_in = (prompt_input prompt_text).to_i?)
    puts "Input must be an integer!"
  end
  user_in
end

def prompt_enum_input(prompt_text, enum_type : Enum.class)
  until (user_in = enum_type.parse?(prompt_input prompt_text))
    puts "Input must be one of #{enum_type.values}!"
  end
  user_in
end

DATE_FORMAT = Time::Format.new "%Y%m%d", Time::Location.local

def prompt_date_input(prompt_text)
  date_input = nil
  until date_input
    begin
      user_in = prompt_input prompt_text

      date_input_parsed = DATE_FORMAT.parse user_in

      date_input = date_input_parsed
    rescue exception : Time::Format::Error | ArgumentError
      puts "Invalid date! Input valid year in YYYYMMDD format."
    end
  end
  date_input
end

def yes_no_to_boolean?(input_string)
  case input_string.downcase
  when "yes", "y"
    true
  when "no", "n"
    false
  else
    nil
  end
end

def prompt_yes_no_input(prompt_text)
  while (user_in = yes_no_to_boolean?(prompt_input prompt_text)).nil?
    puts %(Input must be one of ["yes", "y", "no", "n"]!)
  end
  user_in
end