Build CSV from subscriber list

lib/pleroma/user/mailing_list.ex

@@ -0,0 +1,43 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.User.MailingList do
+  @moduledoc """
+  Functions for generating email lists from local users.
+  """
+  import Ecto.Query
+
+  alias Pleroma.Repo
+  alias Pleroma.User
+
+  defp subscribers_query do
+    User.Query.build(%{
+      local: true,
+      is_active: true,
+      is_approved: true,
+      is_confirmed: true,
+      accepts_newsletter: true
+    })
+    |> where([u], not is_nil(u.email))
+  end
+
+  def generate_csv do
+    subscribers_query()
+    |> generate_csv()
+  end
+
+  def generate_csv(query) do
+    query
+    |> Repo.all()
+    |> Enum.map(&build_row/1)
+    |> build_csv()
+  end
+
+  defp build_row(%User{email: email}), do: email
+
+  defp build_csv(lines) do
+    ["Email Address" | lines]
+    |> Enum.join("\n")
+  end
+end

test/pleroma/user/mailing_list_test.exs

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+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.User.MailingListTest do
+  alias Pleroma.User.MailingList
+
+  use Pleroma.DataCase
+
+  import Pleroma.Factory
+
+  test "generate_csv/0" do
+    user1 = insert(:user)
+    user2 = insert(:user)
+    user3 = insert(:user)
+
+    expected = """
+    Email Address
+    #{user1.email}
+    #{user2.email}
+    #{user3.email}\
+    """
+
+    assert MailingList.generate_csv() == expected
+  end
+end