module Adhearsion
  module VoIP
    module DSL
      # In Ruby, a number with a leading zero such as 023.45 or 023 does not evaluate as expected.
      # In the case of the float 023.45, you get a syntax error. In the case of 023 the number is
      # parsed as being in octal form and the number 19 is returned. 
      #
      # In Adhearsion, various strings that are entirely numeric might start with zero and that zero
      # should be preserved when converting that string of numbers into a number. The numerical string 
      # retains the zero while still allowing it to be compared to other numbers.
      #
      # [[I think this leading zero thing is only part of the reason that NumericalString exists. I'm 
      # currently writing tests for this leading zero stuff so I thought I'd dump some of my assumptions
      # about it here in the documentation.]]
      class NumericalString
        class << self
          def starts_with_leading_zero?(string)
            string.to_s[/^0\d+/]
          end
        end

        (instance_methods - %w"__id__ __send__ __real_num __real_string").each do |m|
          undef_method m
        end

        attr_reader :__real_num, :__real_string

        def initialize(str)
          @__real_string = str.to_s
          @__real_num = str.to_i if @__real_string =~ /^\d+$/
        end

        def method_missing(name, *args, &block)
          @__real_string.__send__ name, *args, &block
        end

        def respond_to?(m)
          @__real_string.respond_to?(m) || m == :__real_num || m == :__real_string
        end

      end

      # The PhoneNumber class is used by one object throughout Adhearsion: the AGI
      # "extension" variable. Using some clevery Ruby hackery, the Extension class allows
      # dialplan writers to use the best of Fixnum and String usage such as
      #
      # - Dialing international numbers
      # - Using a regexp in a case statement for "extension"
      # - Using a numerical range against extension -- e.g. (100...200)
      # - Using the thousands separator
      class PhoneNumber < NumericalString

        # Checks against a pattern identifying US local numbers (i.e numbers
        # without an area code seven digits long)
        def us_local_number?() to_s =~ Adhearsion::VoIP::Constants::US_LOCAL_NUMBER end

        # Checks against a pattern identifying US domestic numbers.
        def us_national_number?() to_s =~ Adhearsion::VoIP::Constants::US_NATIONAL_NUMBER end

        # Checks against a pattern identifying an ISN number. See http://freenum.org
        # for more info.
        def isn?() to_s =~ Adhearsion::VoIP::Constants::ISN end

        # Useful for dialing those 1-800-FUDGEME type numbers with letters in them. Letters
        # in the argument will be converted to their appropriate keypad key.
        def self.from_vanity str
          str.gsub(/\W/, '').upcase.tr('A-Z', '22233344455566677778889999')
        end

      end

    end
  end
end

# These monkey patches are necessary for the NumericalString to work, unfortunately.
class Class
  def alias_method_once(new_name, old_name)
    unless instance_methods.include?(new_name.to_s)
      alias_method(new_name, old_name)
    end
  end
end

[Object, Range, class << String; self; end].each do |klass|
  klass.alias_method_once(:pre_modified_threequal, :===)
end

class Object
  def ===(arg)
    if arg.respond_to? :__real_string
      arg = arg.__real_num if kind_of?(Numeric) || kind_of?(Range)
      pre_modified_threequal arg
    else
      pre_modified_threequal arg
    end
  end
end

class Range
  alias_method_once(:original_threequal, :===)
  def ===(arg)
    if (arg.respond_to? :__real_string) &&  !arg.__real_num.nil?
      arg = arg.__real_num
      original_threequal arg
    else
      original_threequal arg
    end
  end
end

class << String
  alias_method_once(:original_threequal, :===)
  def ===(arg)
    arg.respond_to?(:__real_string) || original_threequal(arg)
  end
end