+ 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 handle_preview("image/gif" = _content_type, conn, url) do
+ mediaproxy_url = url |> MediaProxy.url()
+
+ redirect(conn, external: mediaproxy_url)
+ end
+
+ defp handle_preview("image/" <> _ = _content_type, conn, url) do
+ handle_image_preview(conn, url)
+ end
+
+ defp handle_preview("video/" <> _ = _content_type, conn, url) do
+ mediaproxy_url = url |> MediaProxy.url()
+
+ redirect(conn, external: mediaproxy_url)
+ end
+
+ defp handle_preview(content_type, conn, _url) do
+ send_resp(conn, :unprocessable_entity, "Unsupported content type: #{content_type}.")
+ end