Language detection

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

lib/pleroma/language/language_detector/fasttext.ex

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+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Language.LanguageDetector.Fasttext do
+  import Pleroma.Web.Utils.Guards, only: [not_empty_string: 1]
+
+  alias Pleroma.Language.LanguageDetector.Provider
+
+  @behaviour Provider
+
+  @impl Provider
+  def missing_dependencies do
+    if Pleroma.Utils.command_available?("fasttext") do
+      []
+    else
+      ["fasttext"]
+    end
+  end
+
+  @impl Provider
+  def configured?, do: not_empty_string(get_model())
+
+  @impl Provider
+  def detect(text) do
+    text_path = Path.join(System.tmp_dir!(), "fasttext-#{Ecto.UUID.generate()}")
+
+    File.write(text_path, text)
+
+    detected_language =
+      case System.cmd("fasttext", ["predict", get_model(), text_path]) do
+        {"__label__" <> language, _} ->
+          language |> String.trim()
+
+        _ ->
+          nil
+      end
+
+    File.rm(text_path)
+
+    detected_language
+  end
+
+  defp get_model do
+    Pleroma.Config.get([__MODULE__, :model])
+  end
+end

lib/pleroma/language/language_detector/provider.ex

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+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Language.LanguageDetector.Provider do
+  @callback missing_dependencies() :: [String.t()]
+
+  @callback configured?() :: boolean()
+
+  @callback detect(text :: String.t()) :: String.t() | nil
+end