class Gamefic::Props::MultipleChoice

def index
  return nil unless input
  @index ||= index_by_number || index_by_text
end

def index_by_number
  return input.to_i - 1 if input.match(/^\d+$/) && options[input.to_i - 1]
  nil
end

def index_by_text
  options.find_index { |opt| opt.casecmp?(input) }
end

def invalid_message
  @invalid_message ||= '"%<input>s" is not a valid choice.'
end

def number
  return nil unless index
  index + 1
end

def options
  @options ||= []
end

def selected?
  !!index
end

def selection
  return nil unless index
  options[index]
end