+ def preview(conn, %{"sig" => sig64, "url" => url64}) do
+ with {_, true} <- {:enabled, MediaProxy.preview_enabled?()},
+ {:ok, url} <- MediaProxy.decode_url(sig64, url64),
+ :ok <- MediaProxy.verify_request_path_and_url(conn, url) do
+ handle_preview(conn, url)
+ else
+ {:enabled, false} ->
+ send_resp(conn, 404, Plug.Conn.Status.reason_phrase(404))
+
+ {:error, :invalid_signature} ->
+ send_resp(conn, 403, Plug.Conn.Status.reason_phrase(403))
+
+ {:wrong_filename, filename} ->
+ redirect(conn, external: MediaProxy.build_preview_url(sig64, url64, filename))
+ end
+ end
+
+ defp handle_preview(conn, url) do
+ with {:ok, %{status: status} = head_response} when status in 200..299 <-
+ Tesla.head(url, opts: [adapter: [timeout: preview_head_request_timeout()]]) do
+ content_type = Tesla.get_header(head_response, "content-type")
+ handle_preview(content_type, conn, url)
+ else
+ {_, %{status: status}} ->
+ send_resp(conn, :failed_dependency, "Can't fetch HTTP headers (HTTP #{status}).")
+
+ {:error, :recv_response_timeout} ->
+ send_resp(conn, :failed_dependency, "HEAD request timeout.")
+
+ _ ->
+ send_resp(conn, :failed_dependency, "Can't fetch HTTP headers.")
+ end
+ end
+
+ defp thumbnail_max_dimensions(params) do
+ config = Config.get([:media_preview_proxy], [])
+
+ thumbnail_max_width =
+ if w = params["thumbnail_max_width"] do
+ String.to_integer(w)
+ else
+ Keyword.fetch!(config, :thumbnail_max_width)
+ end
+
+ thumbnail_max_height =
+ if h = params["thumbnail_max_height"] do
+ String.to_integer(h)
+ else
+ Keyword.fetch!(config, :thumbnail_max_height)
+ end
+
+ {thumbnail_max_width, thumbnail_max_height}
+ end
+
+ defp thumbnail_binary(url, body, params) do
+ {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions(params)
+
+ with true <- Config.get([:media_preview_proxy, :enable_eimp]),
+ {:ok, [type: image_type, width: source_width, height: source_height]} <-
+ :eimp.identify(body),
+ scale_factor <-
+ Enum.max([source_width / thumbnail_max_width, source_height / thumbnail_max_height]),
+ {:ok, thumbnail_binary} =
+ :eimp.convert(body, image_type, [
+ {:scale, {round(source_width / scale_factor), round(source_height / scale_factor)}}
+ ]) do
+ {:ok, thumbnail_binary}
+ else
+ _ ->
+ mogrify_dimensions = "#{thumbnail_max_width}x#{thumbnail_max_height}"
+
+ with {:ok, path} <- MogrifyHelper.store_as_temporary_file(url, body),
+ %Mogrify.Image{} <-
+ MogrifyHelper.in_place_resize_to_limit(path, mogrify_dimensions),
+ {:ok, thumbnail_binary} <- File.read(path),
+ _ <- File.rm(path) do
+ {:ok, thumbnail_binary}
+ else
+ _ -> :error
+ end
+ end
+ end