Add blurhash support to backend

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/upload/filter/analyze_metadata.ex

@@ -0,0 +1,47 @@
+# Portions of this file are derived from Pleroma:
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+# Upstream: https://git.pleroma.social/pleroma/pleroma/-/blob/develop/lib/pleroma/upload/filter/analyze_metadata.ex
+
+defmodule Mobilizon.Web.Upload.Filter.AnalyzeMetadata do
+  @moduledoc """
+  Extracts metadata about the upload, such as width/height
+  """
+  require Logger
+  alias Mobilizon.Web.Upload
+
+  @behaviour Mobilizon.Web.Upload.Filter
+
+  @spec filter(Upload.t()) ::
+          {:ok, :filtered, Upload.t()} | {:ok, :noop} | {:error, String.t()}
+  def filter(%Upload{tempfile: file, content_type: "image" <> _} = upload) do
+    image =
+      file
+      |> Mogrify.open()
+      |> Mogrify.verbose()
+
+    upload =
+      upload
+      |> Map.put(:width, image.width)
+      |> Map.put(:height, image.height)
+      |> Map.put(:blurhash, get_blurhash(file))
+
+    {:ok, :filtered, upload}
+  rescue
+    e in ErlangError ->
+      Logger.warn("#{__MODULE__}: #{inspect(e)}")
+      {:ok, :noop}
+  end
+
+  def filter(_), do: {:ok, :noop}
+
+  defp get_blurhash(file) do
+    case :eblurhash.magick(to_charlist(file)) do
+      {:ok, blurhash} ->
+        to_string(blurhash)
+
+      _ ->
+        nil
+    end
+  end
+end

lib/web/upload/upload.ex

@@ -73,12 +73,9 @@ defmodule Mobilizon.Web.Upload do
          {:ok, upload} <- Filter.filter(opts.filters, upload),
          {:ok, url_spec} <- Uploader.put_file(opts.uploader, upload) do
       {:ok,
-       %{
-         name: Map.get(opts, :description) || upload.name,
-         url: url_from_spec(upload, opts.base_url, url_spec),
-         content_type: upload.content_type,
-         size: upload.size
-       }}
+       upload
+       |> Map.put(:name, Map.get(opts, :description) || upload.name)
+       |> Map.put(:url, url_from_spec(upload, opts.base_url, url_spec))}
     else
       {:error, error} ->
         Logger.error(