elixir lessons

area_code.ex

defmodule AreaCode do
  @moduledoc """
  Returns map of provinces with corresponding area codes as a list
  """

  def codes_by_province do
    %{
    marbella: [822], badajoz: [ 824, 924], guipuzcoa: [843,943],
    navarra: [848, 948], granada: [858, 958], murcia: [868, 968], baleares: [871, 971],
    gerona: [872, 972], lerida: [ 873, 973], zaragoza: [876, 976],
    tarragona: [877, 977], pontevedra: [886, 986], madrid: [911, 912, 913, 914, 915, 916, 917, 918],
    segovia: [921], salamanca: [923], toledo: [925], ciudad_real: [926], caceres: [927],
    barcelona: [931, 932, 933, 934, 935, 936, 937, 938], la_rioja: [941], cantabria: [942],
    vizcaya: [944, 946], alava: [945], burgos: [947], guadalajara: [949], almeria: [950],
    malaga: [951, 952], jaen: [953], sevilla: [954, 955], cordoba: [957], huelva: [959],
    valencia: [960, 961, 962, 963], alicante: [965, 966],  albacete: [967], cuenca: [969],
    huesca: [974],  soria: [975], teruel: [978], palencia: [979], zamora: [980], lugo: [982],
    valladolid: [983], asturias: [984, 985], orense: [988]
    }
  end
end

phone_validator.ex

defmodule PhoneValidator do
  @moduledoc """
    Module for validating Spanish Phone Numbers, and also
    returns information about phone number type and can generate
    random valid phone numbers,
  """
  def digit_extension(n) do
    Enum.map(0..n, fn _i -> :rand.uniform(9) end)
  end

  def join_digits(list), do: Enum.join(list)

  def valid?(n), do: Regex.match?(~r/[6789]\d{8}/, n)

  def generate, do: 8 |> digit_extension() |> join_digits()

  def prefix(n), do: String.slice(n,0..2)

  def phone_type(n)  do
    cond do
      Regex.match?(~r/^80[1-9]|^90[1-9]/, prefix n) ->
        "premium"
      Regex.match?(~r/^800|^900/, prefix n) ->
        "toll-free"
      Regex.match?(~r/^[67]/, prefix n) ->
        "mobile"
      true ->
        "landline"
    end
  end

  def find_province(n) do
    require AreaCode
    area_code = Enum.filter AreaCode.codes_by_province, fn {key, value} ->
      Enum.member?(value, String.to_integer(prefix n))
    end
    area_code |> Keyword.keys
  end
end