module FFaker::PhoneNumber

def area_code
  # The North American Numbering Plan (NANP) does not permit the digits 0
  # and 1 as the leading digit of an area code.
  # https://en.wikipedia.org/wiki/List_of_North_American_Numbering_Plan_area_codes
  loop do
    rand_area_code = rand(201..999)
    return rand_area_code unless rand_area_code % 100 == 11
  end
end

def exchange_code
  # The North American Numbering Plan (NANP) does not permit the digits 0
  # and 1 as the leading digit of the exchange code.
  # https://en.wikipedia.org/wiki/North_American_Numbering_Plan#Numbering_system
  area_code
end

def imei(serial_number = nil)
  # IMEI Format:
  # AA-BBBBBB-CCCCCC-D
  characters = Array.new(15, 0)
  rbi_codes  = %w[01 10 30 33 35 44 45 49 50 51 52 53 54 86 91 98 99]
  serial_number ||= rand(0...1_000_000)
  serial_number = format('%06d', serial_number).chars.map(&:to_i)
  first_two_chars = fetch_sample(rbi_codes)
  characters[0, 2] = first_two_chars.chars.map(&:to_i)
  # serial number part
  2.upto(7) do |current_position|
    characters[current_position] = fetch_sample((0..9).to_a)
  end
  8.upto(13) do |current_position|
    characters[current_position] = serial_number[current_position - 8]
  end
  current_checksum = characters.reverse.each_with_index.inject(0) do |sum, (digit, i)|
    digit *= 2 if i.odd?
    digit -= 9 if digit > 9
    sum + digit
  end
  final_digit = (10 - (current_checksum % 10)) % 10
  characters[14] = final_digit
  characters.join
end

def phone_calling_code
  fetch_sample(PHONE_CALLING_CODE)
end

def phone_number
  FFaker.numerify case rand(0..19)
                  when 0 then "#{area_code}-#{exchange_code}-#### x#####"
                  when 1 then "#{area_code}-#{exchange_code}-#### x####"
                  when 2 then "#{area_code}-#{exchange_code}-#### x###"
                  when 3..4 then "#{area_code}-#{exchange_code}-####"
                  when 5 then "#{area_code}.#{exchange_code}.#### x#####"
                  when 6 then "#{area_code}.#{exchange_code}.#### x####"
                  when 7 then "#{area_code}.#{exchange_code}.#### x###"
                  when 8..9 then "#{area_code}.#{exchange_code}.####"
                  when 10 then "(#{area_code})#{exchange_code}-#### x#####"
                  when 11 then "(#{area_code})#{exchange_code}-#### x####"
                  when 12 then "(#{area_code})#{exchange_code}-#### x###"
                  when 13..14 then "(#{area_code})#{exchange_code}-####"
                  when 15 then "1-#{area_code}-#{exchange_code}-#### x#####"
                  when 16 then "1-#{area_code}-#{exchange_code}-#### x####"
                  when 17 then "1-#{area_code}-#{exchange_code}-#### x###"
                  when 18..19 then "1-#{area_code}-#{exchange_code}-####"
                  end
end

def short_phone_number
  FFaker.numerify("#{area_code}-#{exchange_code}-####")
end