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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.Uploaders.Uploader do
   6   import Pleroma.Web.Gettext
   7
   8   @moduledoc """
   9   Defines the contract to put and get an uploaded file to any backend.
  10   """
  11
  12   @doc """
  13   Instructs how to get the file from the backend.
  14
  15   Used by `Pleroma.Plugs.UploadedMedia`.
  16   """
  17   @type get_method :: {:static_dir, directory :: String.t()} | {:url, url :: String.t()}
  18   @callback get_file(file :: String.t()) :: {:ok, get_method()}
  19
  20   @doc """
  21   Put a file to the backend.
  22
  23   Returns:
  24
  25   * `:ok` which assumes `{:ok, upload.path}`
  26   * `{:ok, spec}` where spec is:
  27     * `{:file, filename :: String.t}` to handle reads with `get_file/1` (recommended)
  28
  29     This allows to correctly proxy or redirect requests to the backend, while allowing to migrate backends without breaking any URL.
  30   * `{url, url :: String.t}` to bypass `get_file/2` and use the `url` directly in the activity.
  31   * `{:error, String.t}` error information if the file failed to be saved to the backend.
  32   * `:wait_callback` will wait for an http post request at `/api/pleroma/upload_callback/:upload_path` and call the uploader's `http_callback/3` method.
  33
  34   """
  35   @type file_spec :: {:file | :url, String.t()}
  36   @callback put_file(Pleroma.Upload.t()) ::
  37               :ok | {:ok, file_spec()} | {:error, String.t()} | :wait_callback
  38
  39   @callback delete_file(file :: String.t()) :: :ok | {:error, String.t()}
  40
  41   @callback http_callback(Plug.Conn.t(), Map.t()) ::
  42               {:ok, Plug.Conn.t()}
  43               | {:ok, Plug.Conn.t(), file_spec()}
  44               | {:error, Plug.Conn.t(), String.t()}
  45   @optional_callbacks http_callback: 2
  46
  47   @spec put_file(module(), Pleroma.Upload.t()) :: {:ok, file_spec()} | {:error, String.t()}
  48   def put_file(uploader, upload) do
  49     case uploader.put_file(upload) do
  50       :ok -> {:ok, {:file, upload.path}}
  51       :wait_callback -> handle_callback(uploader, upload)
  52       {:ok, _} = ok -> ok
  53       {:error, _} = error -> error
  54     end
  55   end
  56
  57   defp handle_callback(uploader, upload) do
  58     :global.register_name({__MODULE__, upload.path}, self())
  59
  60     receive do
  61       {__MODULE__, pid, conn, params} ->
  62         case uploader.http_callback(conn, params) do
  63           {:ok, conn, ok} ->
  64             send(pid, {__MODULE__, conn})
  65             {:ok, ok}
  66
  67           {:error, conn, error} ->
  68             send(pid, {__MODULE__, conn})
  69             {:error, error}
  70         end
  71     after
  72       callback_timeout() -> {:error, dgettext("errors", "Uploader callback timeout")}
  73     end
  74   end
  75
  76   defp callback_timeout do
  77     case Mix.env() do
  78       :test -> 1_000
  79       _ -> 30_000
  80     end
  81   end
  82 end