Refactoring of Application module

lib/mobilizon.ex

@@ -9,4 +9,80 @@ defmodule Mobilizon do
   Mobilizon relies on `Guardian` for auth and `Geo`/Postgis for geographical
   information.
   """
+
+  use Application
+
+  import Cachex.Spec
+
+  alias Mobilizon.Config
+  alias Mobilizon.Service.Export.{Feed, ICalendar}
+
+  @name Mix.Project.config()[:name]
+  @version Mix.Project.config()[:version]
+
+  @spec named_version :: String.t()
+  def named_version, do: "#{@name} #{@version}"
+
+  @spec user_agent :: String.t(:w)
+  def user_agent do
+    info = "#{MobilizonWeb.Endpoint.url()} <#{Config.get([:instance, :email], "")}>"
+
+    "#{named_version()}; #{info}"
+  end
+
+  @spec start(:normal | {:takeover, node} | {:failover, node}, term) ::
+          {:ok, pid} | {:ok, pid, term} | {:error, term}
+  def start(_type, _args) do
+    children = [
+      # supervisors
+      Mobilizon.Storage.Repo,
+      MobilizonWeb.Endpoint,
+      # workers
+      Guardian.DB.Token.SweeperServer,
+      Mobilizon.Service.Federator,
+      cachex_spec(:feed, 2500, 60, 60, &Feed.create_cache/1),
+      cachex_spec(:ics, 2500, 60, 60, &ICalendar.create_cache/1),
+      cachex_spec(:activity_pub, 2500, 3, 15)
+    ]
+
+    opts = [strategy: :one_for_one, name: Mobilizon.Supervisor]
+
+    Supervisor.start_link(children, opts)
+  end
+
+  @spec config_change(keyword, keyword, [atom]) :: :ok
+  def config_change(changed, _new, removed) do
+    MobilizonWeb.Endpoint.config_change(changed, removed)
+
+    :ok
+  end
+
+  @spec cachex_spec(atom, integer, integer, integer, function | nil) :: Supervisor.child_spec()
+  defp cachex_spec(name, limit, default, interval, fallback \\ nil) do
+    %{
+      id: :"cache_#{name}",
+      start:
+        {Cachex, :start_link,
+         [
+           name,
+           Keyword.merge(cachex_options(limit, default, interval), fallback_options(fallback))
+         ]}
+    }
+  end
+
+  @spec cachex_options(integer, integer, integer) :: keyword
+  defp cachex_options(limit, default, interval) do
+    [
+      limit: limit,
+      expiration:
+        expiration(
+          default: :timer.minutes(default),
+          interval: :timer.seconds(interval)
+        )
+    ]
+  end
+
+  @spec fallback_options(function | nil) :: keyword
+  defp fallback_options(nil), do: []
+  defp fallback_options(fallback), do: [fallback: fallback(default: fallback)]
 end