Export participants to different formats

* CSV
* PDF (requires Python dependency `weasyprint`)
* ODS (requires Python dependency `pyexcel_ods3`)

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

test/service/export/participants/pdf_test.exs

@@ -0,0 +1,62 @@
+defmodule Mobilizon.Service.Export.Participants.PDFTest do
+  use Mobilizon.DataCase
+
+  import Mobilizon.Factory
+
+  alias Mobilizon.Events.Event
+  alias Mobilizon.Service.Export.Participants.PDF
+
+  setup do
+    test_format?()
+  end
+
+  describe "export event participants to PDF" do
+    test "export basic infos" do
+      %Event{} = event = insert(:event)
+      insert(:participant, event: event, role: :creator)
+      insert(:participant, event: event, role: :participant)
+      insert(:participant, event: event, role: :not_approved)
+
+      set_exports(Mobilizon.Service.Export.Participants.CSV)
+
+      refute PDF.ready?()
+    end
+
+    test "enable the exporter" do
+      set_exports(Mobilizon.Service.Export.Participants.PDF)
+
+      %Event{} = event = insert(:event)
+      insert(:participant, event: event, role: :creator)
+      insert(:participant, event: event, role: :participant)
+      insert(:participant, event: event, role: :not_approved)
+
+      assert PDF.dependencies_ok?()
+      assert PDF.enabled?()
+      assert {:ok, path} = PDF.export(event)
+      assert File.exists?("uploads/exports/pdf/" <> path)
+      set_exports(Mobilizon.Service.Export.Participants.CSV)
+    end
+  end
+
+  @spec set_exports(module()) :: :ok
+  defp set_exports(module) do
+    Mobilizon.Config.put(:exports,
+      formats: [module]
+    )
+  end
+
+  @spec test_format? :: :ok | {:ok, skip: true}
+  defp test_format? do
+    case System.get_env("EXPORT_FORMATS") do
+      nil ->
+        {:ok, skip: true}
+
+      formats ->
+        if "pdf" in String.split(formats, ",") do
+          :ok
+        else
+          {:ok, skip: true}
+        end
+    end
+  end
+end