module Memorandum

# File lib/memorandum.rb, line 4
def self.extended base
  base.send :include, InstanceMethods
end

# File lib/memorandum.rb, line 8
def memo *arguments
  name = arguments.pop
  flags = arguments

  memoized_statuses = memorandum_ivar_name MEMORANDUM_STATUSES, name
  memoized_values   = memorandum_ivar_name MEMORANDUM_VALUES,   name
  unmemoized_name   = "#{MEMORANDUM_UNMEMOIZED}_#{name}"

  access = find_access name

  alias_method unmemoized_name, name

  define_method name do |*args|
    statuses = memorandum_fetch memoized_statuses, Hash[]
    values   = memorandum_fetch memoized_values,   Hash[]

    unless statuses[args]
      value = send unmemoized_name, *args

      value = value.freeze              if flags.include? :freeze
      value = IceNine.deep_freeze value if flags.include? :deep_freeze

      values[args]   = value
      statuses[args] = true
    end

    values[args]
  end

  send access, name
  send access, unmemoized_name
end

# File lib/memorandum.rb, line 41
def memorandum_ivar_name name, method_name
  "@#{MEMORANDUM_MEMOIZED}_#{name}_for_#{method_name}".tap do |result|
    MEMORANDUM_SPECIAL_CHARACTERS.each do |special_character, replacement|
      result.gsub! special_character, replacement
    end
  end
end

# File lib/memorandum.rb, line 74
def find_access method_name
  case
  when private_instance_methods.include?(method_name.to_sym)   then :private
  when protected_instance_methods.include?(method_name.to_sym) then :protected
  when public_instance_methods.include?(method_name.to_sym)    then :public
  else :unknown
  end
end