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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2021 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   @mix_env Mix.env()
   9
  10   @moduledoc """
  11   Defines the contract to put and get an uploaded file to any backend.
  12   """
  13
  14   @doc """
  15   Instructs how to get the file from the backend.
  16
  17   Used by `Pleroma.Web.Plugs.UploadedMedia`.
  18   """
  19   @type get_method :: {:static_dir, directory :: String.t()} | {:url, url :: String.t()}
  20   @callback get_file(file :: String.t()) :: {:ok, get_method()}
  21
  22   @doc """
  23   Put a file to the backend.
  24
  25   Returns:
  26
  27   * `:ok` which assumes `{:ok, upload.path}`
  28   * `{:ok, spec}` where spec is:
  29     * `{:file, filename :: String.t}` to handle reads with `get_file/1` (recommended)
  30
  31     This allows to correctly proxy or redirect requests to the backend, while allowing to migrate backends without breaking any URL.
  32   * `{url, url :: String.t}` to bypass `get_file/2` and use the `url` directly in the activity.
  33   * `{:error, String.t}` error information if the file failed to be saved to the backend.
  34   * `: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.
  35
  36   """
  37   @type file_spec :: {:file | :url, String.t()}
  38   @callback put_file(upload :: struct()) ::
  39               :ok | {:ok, file_spec()} | {:error, String.t()} | :wait_callback
  40
  41   @callback delete_file(file :: String.t()) :: :ok | {:error, String.t()}
  42
  43   @callback http_callback(Plug.Conn.t(), Map.t()) ::
  44               {:ok, Plug.Conn.t()}
  45               | {:ok, Plug.Conn.t(), file_spec()}
  46               | {:error, Plug.Conn.t(), String.t()}
  47   @optional_callbacks http_callback: 2
  48
  49   @spec put_file(module(), upload :: struct()) :: {:ok, file_spec()} | {:error, String.t()}
  50   def put_file(uploader, upload) do
  51     case uploader.put_file(upload) do
  52       :ok -> {:ok, {:file, upload.path}}
  53       :wait_callback -> handle_callback(uploader, upload)
  54       {:ok, _} = ok -> ok
  55       {:error, _} = error -> error
  56     end
  57   end
  58
  59   defp handle_callback(uploader, upload) do
  60     :global.register_name({__MODULE__, upload.path}, self())
  61
  62     receive do
  63       {__MODULE__, pid, conn, params} ->
  64         case uploader.http_callback(conn, params) do
  65           {:ok, conn, ok} ->
  66             send(pid, {__MODULE__, conn})
  67             {:ok, ok}
  68
  69           {:error, conn, error} ->
  70             send(pid, {__MODULE__, conn})
  71             {:error, error}
  72         end
  73     after
  74       callback_timeout() -> {:error, dgettext("errors", "Uploader callback timeout")}
  75     end
  76   end
  77
  78   defp callback_timeout do
  79     case @mix_env do
  80       :test -> 1_000
  81       _ -> 30_000
  82     end
  83   end
  84 end