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>

lib/service/python_worker.ex

@@ -0,0 +1,65 @@
+defmodule Mobilizon.PythonWorker do
+  @moduledoc """
+  Genserver to handle an instance of Python handling the calls to `Mobilizon.PythonPort`.
+  """
+
+  use GenServer
+  use Export.Python
+
+  alias Mobilizon.PythonPort
+
+  @spec start_link(any) :: :ignore | {:error, any} | {:ok, pid}
+  def start_link(_) do
+    GenServer.start_link(__MODULE__, [], name: __MODULE__)
+  end
+
+  @spec init(any) :: {:ok, %{python_pid: pid}}
+  def init(_) do
+    path = Path.join([:code.priv_dir(:mobilizon), "python"])
+    pid = PythonPort.python_instance(path)
+
+    {:ok, %{python_pid: pid}}
+  end
+
+  def terminate(_reason, %{python_pid: pid}) do
+    Python.stop(pid)
+  end
+
+  @spec generate_pdf(String.t()) :: any
+  def generate_pdf(html) do
+    GenServer.call(__MODULE__, %{html: html, format: :pdf})
+  end
+
+  @spec generate_ods(String.t()) :: any
+  def generate_ods(data) do
+    GenServer.call(__MODULE__, %{data: data, format: :ods})
+  end
+
+  @spec has_module(String.t()) :: any
+  def has_module(module) do
+    GenServer.call(__MODULE__, %{module: module})
+  end
+
+  @spec handle_call(
+          %{html: String.t(), format: :pdf} | %{data: String.t(), format: :ods},
+          any(),
+          map()
+        ) :: {:reply, String.t(), map()}
+  def handle_call(%{html: html, format: :pdf}, _from, %{python_pid: pid} = state) do
+    res = PythonPort.call_python(pid, "pdf", "generate", [html])
+
+    {:reply, res, state}
+  end
+
+  def handle_call(%{data: data, format: :ods}, _from, %{python_pid: pid} = state) do
+    res = PythonPort.call_python(pid, "ods", "generate", [data])
+
+    {:reply, res, state}
+  end
+
+  def handle_call(%{module: module}, _from, %{python_pid: pid} = state) do
+    res = PythonPort.call_python(pid, "module", "has_package", [module])
+
+    {:reply, res, state}
+  end
+end