defmodule Pow.UUID do
@moduledoc """
Module to generate UUID binary.
The token generation code is pulled from
https://github.com/elixir-ecto/ecto/blob/v2.2.10/lib/ecto/uuid.ex#L1, and is
under Apache 2 license.
"""
@doc """
Generates a UUID binary.
"""
@spec generate :: binary()
def generate, do: encode(bingenerate())
defp bingenerate do
<<u0::48, _::4, u1::12, _::2, u2::62>> = :crypto.strong_rand_bytes(16)
<<u0::48, 4::4, u1::12, 2::2, u2::62>>
end
defp encode(<< a1::4, a2::4, a3::4, a4::4,
a5::4, a6::4, a7::4, a8::4,
b1::4, b2::4, b3::4, b4::4,
c1::4, c2::4, c3::4, c4::4,
d1::4, d2::4, d3::4, d4::4,
e1::4, e2::4, e3::4, e4::4,
e5::4, e6::4, e7::4, e8::4,
e9::4, e10::4, e11::4, e12::4 >>) do
<< e(a1), e(a2), e(a3), e(a4), e(a5), e(a6), e(a7), e(a8), ?-,
e(b1), e(b2), e(b3), e(b4), ?-,
e(c1), e(c2), e(c3), e(c4), ?-,
e(d1), e(d2), e(d3), e(d4), ?-,
e(e1), e(e2), e(e3), e(e4), e(e5), e(e6), e(e7), e(e8), e(e9), e(e10), e(e11), e(e12) >>
end
defp e(0), do: ?0
defp e(1), do: ?1
defp e(2), do: ?2
defp e(3), do: ?3
defp e(4), do: ?4
defp e(5), do: ?5
defp e(6), do: ?6
defp e(7), do: ?7
defp e(8), do: ?8
defp e(9), do: ?9
defp e(10), do: ?a
defp e(11), do: ?b
defp e(12), do: ?c
defp e(13), do: ?d
defp e(14), do: ?e
defp e(15), do: ?f
end