Add intensity recalculation task

lib/mix/tasks/recalculate_intensities.ex

@@ -0,0 +1,53 @@
+defmodule Mix.Tasks.RecalculateIntensities do
+  use Mix.Task
+
+  alias Philomena.Images.{Image, Thumbnailer}
+  alias Philomena.ImageIntensities.ImageIntensity
+  alias Philomena.Batch
+  alias Philomena.Repo
+
+  import Ecto.Query
+
+  @shortdoc "Recalculates all intensities for reverse search."
+  @requirements ["app.start"]
+  @impl Mix.Task
+  def run(_args) do
+    Batch.record_batches(Image, fn batch ->
+      batch
+      |> Stream.with_index()
+      |> Stream.each(fn {image, i} ->
+        image_file =
+          cond do
+            image.image_mime_type in ["image/png", "image/jpeg"] ->
+              Thumbnailer.image_file(image)
+
+            true ->
+              Path.join(Thumbnailer.image_thumb_dir(image), "rendered.png")
+          end
+
+        case System.cmd("image-intensities", [image_file]) do
+          {output, 0} ->
+            [nw, ne, sw, se] =
+              output
+              |> String.trim()
+              |> String.split("\t")
+              |> Enum.map(&String.to_float/1)
+
+            ImageIntensity
+            |> where(image_id: ^image.id)
+            |> Repo.update_all(set: [nw: nw, ne: ne, sw: sw, se: se])
+
+          _ ->
+            :err
+        end
+
+        if rem(i, 100) == 0 do
+          IO.write("\r#{image.id}")
+        end
+      end)
+      |> Stream.run()
+    end)
+
+    IO.puts("\nDone")
+  end
+end

lib/philomena/images/thumbnailer.ex

@@ -132,18 +132,18 @@ defmodule Philomena.Images.Thumbnailer do
     |> File.mkdir_p!()
   end
 
-  defp image_file(%Image{image: image}),
+  def image_file(%Image{image: image}),
     do: Path.join(image_file_root(), image)
 
-  defp image_thumb_dir(%Image{
+  def image_thumb_dir(%Image{
-         created_at: created_at,
+        created_at: created_at,
-         id: id,
+        id: id,
-         hidden_from_users: true,
+        hidden_from_users: true,
-         hidden_image_key: key
+        hidden_image_key: key
-       }),
+      }),
-       do: Path.join([image_thumbnail_root(), time_identifier(created_at), "#{id}-#{key}"])
+      do: Path.join([image_thumbnail_root(), time_identifier(created_at), "#{id}-#{key}"])
 
-  defp image_thumb_dir(%Image{created_at: created_at, id: id}),
+  def image_thumb_dir(%Image{created_at: created_at, id: id}),
     do: Path.join([image_thumbnail_root(), time_identifier(created_at), to_string(id)])
 
   defp image_url_base(%Image{created_at: created_at, id: id}, nil),