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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Upload.Filter.AnonymizeFilename do
   6   @moduledoc """
   7   Replaces the original filename with a pre-defined text or randomly generated string.
   8
   9   Should be used after `Pleroma.Upload.Filter.Dedupe`.
  10   """
  11   @behaviour Pleroma.Upload.Filter
  12
  13   alias Pleroma.Config
  14   alias Pleroma.Upload
  15
  16   def filter(%Upload{name: name} = upload) do
  17     extension = List.last(String.split(name, "."))
  18     name = predefined_name(extension) || random(extension)
  19     {:ok, %Upload{upload | name: name}}
  20   end
  21
  22   @spec predefined_name(String.t()) :: String.t() | nil
  23   defp predefined_name(extension) do
  24     with name when not is_nil(name) <- Config.get([__MODULE__, :text]),
  25          do: String.replace(name, "{extension}", extension)
  26   end
  27
  28   defp random(extension) do
  29     string =
  30       10
  31       |> :crypto.strong_rand_bytes()
  32       |> Base.url_encode64(padding: false)
  33
  34     string <> "." <> extension
  35   end
  36 end