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| 1 | +defmodule CreditCard do |
| 2 | + @moduledoc """ |
| 3 | + Credit card validations library |
| 4 | + """ |
| 5 | + @card_types [ |
| 6 | + visa: ~r/^4[0-9]{12}(?:[0-9]{3})?$/, |
| 7 | + master_card: ~r/^5[1-5][0-9]{14}$/, |
| 8 | + maestro: ~r/(^6759[0-9]{2}([0-9]{10})$)|(^6759[0-9]{2}([0-9]{12})$)|(^6759[0-9]{2}([0-9]{13})$)/, |
| 9 | + diners_club: ~r/^3(?:0[0-5]|[68][0-9])[0-9]{11}$/, |
| 10 | + amex: ~r/^3[47][0-9]{13}$/, |
| 11 | + discover: ~r/^6(?:011|5[0-9]{2})[0-9]{12}$/, |
| 12 | + jcb: ~r/^(?:2131|1800|35\d{3})\d{11}$/ |
| 13 | + ] |
| 14 | + |
| 15 | + @test_numbers [ |
| 16 | + amex: ~w(378282246310005 371449635398431 378734493671000 ), |
| 17 | + diners_club: ~w(30569309025904 38520000023237 ), |
| 18 | + discover: ~w(6011000990139424 6011111111111117 ), |
| 19 | + master_card: ~w(5555555555554444 5105105105105100 ), |
| 20 | + visa: ~w( |
| 21 | + 4111111111111111 4012888888881881 4222222222222 |
| 22 | + 4005519200000004 4009348888881881 4012000033330026 |
| 23 | + 4012000077777777 4217651111111119 4500600000000061 |
| 24 | + 4000111111111115 ), |
| 25 | + jcb: ~w(3530111333300000 3566002020360505) |
| 26 | + ] |> Keyword.values |> List.flatten |
| 27 | + |
| 28 | + @opts %{ |
| 29 | + allowed_card_types: Keyword.keys(@card_types), |
| 30 | + test_numbers_are_valid: false |
| 31 | + } |
| 32 | + |
| 33 | + @type opts :: %{atom => String.t} |
| 34 | + @type validation_error :: {:error, :unrecognized_card_type} |
| 35 | + |
| 36 | + @doc """ |
| 37 | + Returns CreditCard options map. |
| 38 | + """ |
| 39 | + @spec new :: opts |
| 40 | + def new, do: @opts |
| 41 | + |
| 42 | + @doc """ |
| 43 | + Returns True if card matches the allowed card patterns. By default, |
| 44 | + the set of cards matched against are Amex, VISA, MasterCard, Discover, |
| 45 | + Diners Club and JCB. Otherwise, false |
| 46 | +
|
| 47 | + ## Examples |
| 48 | +
|
| 49 | + iex> CreditCard.valid?("4000111111111115") |
| 50 | + false |
| 51 | + """ |
| 52 | + @spec valid?(String.t, opts) :: boolean |
| 53 | + def valid?(number, opts \\ @opts) do |
| 54 | + case card_type(number) do |
| 55 | + {:error, _err_msg} -> |
| 56 | + false |
| 57 | + type when is_atom(type) -> |
| 58 | + valid_card? = (is_allowed_card_type?(number, opts) |
| 59 | + && verify_luhn(number)) |
| 60 | + valid_card? && |
| 61 | + (if opts[:test_numbers_are_valid] do |
| 62 | + true |
| 63 | + else |
| 64 | + !is_test_number(number) |
| 65 | + end) |
| 66 | + end |
| 67 | + end |
| 68 | + |
| 69 | + @doc """ |
| 70 | + Returns true if the validation options is set to recognize the card's class. |
| 71 | + Otherwise, false. |
| 72 | +
|
| 73 | + ## Examples |
| 74 | +
|
| 75 | + iex> CreditCard.is_allowed_card_type?("5555555555554444") |
| 76 | + true |
| 77 | + """ |
| 78 | + @spec is_allowed_card_type?(String.t, opts) :: boolean |
| 79 | + def is_allowed_card_type?(number, opts \\ @opts) do |
| 80 | + case card_type(number) do |
| 81 | + {:error, _err_msg} -> |
| 82 | + false |
| 83 | + type when is_atom(type) -> |
| 84 | + allowed? = (opts[:allowed_card_types] |
| 85 | + && (type in opts[:allowed_card_types])) |
| 86 | + if allowed?, do: true, else: false |
| 87 | + end |
| 88 | + end |
| 89 | + |
| 90 | + @doc """ |
| 91 | + Returns true if number is among the list of test credit card numbers |
| 92 | + ;otherwise, it returns false. |
| 93 | + """ |
| 94 | + @spec is_test_number(String.t) :: boolean |
| 95 | + def is_test_number(number) do |
| 96 | + strip(number) in @test_numbers |
| 97 | + end |
| 98 | + |
| 99 | + @doc """ |
| 100 | + Performs luhn check on the credit card number |
| 101 | + """ |
| 102 | + @spec verify_luhn(String.t) :: boolean |
| 103 | + def verify_luhn(number) do |
| 104 | + total = |
| 105 | + number |> strip |> String.reverse |> String.split("") |
| 106 | + |> Enum.reject(&(&1 == "")) |
| 107 | + |> Enum.reduce([0,0], fn x, acc -> |
| 108 | + n = String.to_integer(x) |
| 109 | + [acc_h, acc_t] = Enum.slice(acc, 0, 2) |
| 110 | + val = (if((rem(acc_t,2) == 1), do: rotate(n*2), else: n)) |
| 111 | + [acc_h + val, acc_t + 1|acc] |
| 112 | + end) |
| 113 | + |
| 114 | + rem(Enum.at(total,0),10) == 0 |
| 115 | + end |
| 116 | + |
| 117 | + @doc """ |
| 118 | + Returns the type of card |
| 119 | +
|
| 120 | + ## Examples |
| 121 | +
|
| 122 | + iex> CreditCard.card_type("3566002020360505") |
| 123 | + :jcb |
| 124 | + """ |
| 125 | + @spec card_type(String.t) :: atom | validation_error |
| 126 | + def card_type(number) do |
| 127 | + card_type = (Keyword.keys(@card_types) |
| 128 | + |> Enum.filter(&(card_is(strip(number), &1)))) |
| 129 | + case card_type do |
| 130 | + [h|_] -> h |
| 131 | + _ -> {:error, :unrecognized_card_type} |
| 132 | + end |
| 133 | + end |
| 134 | + |
| 135 | + @spec strip(String.t) :: String.t |
| 136 | + defp strip(number) do |
| 137 | + number |
| 138 | + |> String.split("") |
| 139 | + |> Enum.reject(&(&1 in ["", " "])) |
| 140 | + |> Enum.join("") |
| 141 | + end |
| 142 | + |
| 143 | + @spec card_is(String.t, atom) :: boolean |
| 144 | + def card_is(number, :visa) do |
| 145 | + @card_types[:visa] |> Regex.match?(number) |
| 146 | + end |
| 147 | + |
| 148 | + def card_is(number, :master_card) do |
| 149 | + @card_types[:master_card] |> Regex.match?(number) |
| 150 | + end |
| 151 | + |
| 152 | + def card_is(number, :maestro) do |
| 153 | + @card_types[:maestro] |> Regex.match?(number) |
| 154 | + end |
| 155 | + |
| 156 | + def card_is(number, :diners_club) do |
| 157 | + @card_types[:diners_club] |> Regex.match?(number) |
| 158 | + end |
| 159 | + |
| 160 | + def card_is(number, :discover) do |
| 161 | + @card_types[:discover] |> Regex.match?(number) |
| 162 | + end |
| 163 | + |
| 164 | + def card_is(number, :amex) do |
| 165 | + @card_types[:amex] |> Regex.match?(number) |
| 166 | + end |
| 167 | + |
| 168 | + def card_is(number, :jcb) do |
| 169 | + @card_types[:jcb] |> Regex.match?(number) |
| 170 | + end |
| 171 | + |
| 172 | + @spec rotate(String.t) :: String.t |
| 173 | + defp rotate(number) do |
| 174 | + if number > 9, do: number = rem(number,10) + 1 |
| 175 | + number |
| 176 | + end |
| 177 | +end |
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