defmodule ExKits.Crypto.Common do
  @moduledoc false
  @doc """
  md5
  """
  @spec md5(String.t()) :: binary()
  def md5(plaintext), do: :crypto.hash(:md5, plaintext)

  @doc """
  sha1
  """
  @spec sha(String.t()) :: binary()
  def sha(plaintext), do: :crypto.hash(:sha, plaintext)

  @doc """
  sha256
  """
  @spec sha256(String.t()) :: binary()
  def sha256(plaintext), do: :crypto.hash(:sha256, plaintext)

  @doc """
  generate random string
  ## Example

  iex(17)> Common.Crypto.random_string 16
  "2jqDlUxDuOt-qyyZ"
  """
  @spec random_string(integer()) :: String.t()
  def random_string(length) do
    length
    |> :crypto.strong_rand_bytes()
    |> Base.url_encode64()
    |> binary_part(0, length)
  end


  @doc """
  generate short random id

  ## Examples

  iex> generate_id("H")
  "H68203790HX446F"
  """
  @spec generate_id(String.t()) :: String.t()
  def generate_id(prefix) do
    mid =
      1..8
      |> Enum.map(fn _ -> Enum.random(0..9) end)
      |> Enum.join()

    "#{prefix}#{mid}#{gen_reference()}"
  end

  defp gen_reference() do
    min = String.to_integer("100000", 36)
    max = String.to_integer("ZZZZZZ", 36)

    max
    |> Kernel.-(min)
    |> :rand.uniform()
    |> Kernel.+(min)
    |> Integer.to_string(36)
  end
end