# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Config.TransferTask do
  use Task

  alias Pleroma.ConfigDB
  alias Pleroma.Repo

  require Logger

  def start_link(_) do
    load_and_update_env()
    if Pleroma.Config.get(:env) == :test, do: Ecto.Adapters.SQL.Sandbox.checkin(Repo)
    :ignore
  end

  def load_and_update_env do
    with true <- Pleroma.Config.get(:configurable_from_database),
         true <- Ecto.Adapters.SQL.table_exists?(Repo, "config"),
         started_applications <- Application.started_applications() do
      # We need to restart applications for loaded settings take effect
      ConfigDB
      |> Repo.all()
      |> Enum.map(&update_env(&1))
      |> Enum.uniq()
      # TODO: some problem with prometheus after restart!
      |> Enum.reject(&(&1 in [:pleroma, nil, :prometheus]))
      |> Enum.each(&restart(started_applications, &1))
    end
  end

  defp update_env(setting) do
    try do
      key = ConfigDB.from_string(setting.key)
      group = ConfigDB.from_string(setting.group)
      value = ConfigDB.from_binary(setting.value)

      if group != :phoenix and key != :serve_endpoints do
        default = Pleroma.Config.Holder.config(group, key)

        merged_value =
          if can_be_merged?(default, value) do
            DeepMerge.deep_merge(default, value)
          else
            value
          end

        :ok = Application.put_env(group, key, merged_value)
        group
      end
    rescue
      e ->
        Logger.warn(
          "updating env causes error, key: #{inspect(setting.key)}, error: #{inspect(e)}"
        )

        nil
    end
  end

  defp restart(started_applications, app) do
    with {^app, _, _} <- List.keyfind(started_applications, app, 0),
         :ok <- Application.stop(app) do
      :ok = Application.start(app)
    else
      nil -> Logger.warn("#{app} is not started.")
      error -> Logger.warn(inspect(error))
    end
  end

  defp can_be_merged?(val1, val2) when is_map(val1) and is_map(val2), do: true

  defp can_be_merged?(val1, val2) when is_list(val1) and is_list(val2) do
    Keyword.keyword?(val1) and Keyword.keyword?(val2)
  end

  defp can_be_merged?(_val1, _val2), do: false
end