defmodule MicroservicesAuthorization do
  @moduledoc """
  Documentation for MicroservicesAuthorization.
  """
  defp get_json(filename) do
    with {:ok, body} <- File.read(filename), {:ok, json} <- Poison.decode(body), do: {:ok, json}
  end

  defp get_config_file do
    Mix.Project.get().project[:app]
    |> :code.priv_dir()
    |> Path.join(Application.get_env(:microservices_authorization, :config, ""))
  end

  def get_config do
    get_json(get_config_file())
  end

  def get_config_permissions do
    case get_config do
      {:ok, %{"permissions" => permissions}} ->
        permissions

      _ ->
        []
    end
  end

  def get_operation_permissions(operation) do
    Enum.reduce(get_config_permissions(), %{}, fn x, acc ->
      if operation == x["operation"] do
        Map.merge(x["roles"], acc)
      else
        acc
      end
    end)
  end

  def authorize(roles, operation) do
    operation_permissions = get_operation_permissions(operation)

    Enum.reduce(roles, false, fn role, acc ->
      case operation_permissions[role] do
        nil ->
          false

        result ->
          result
      end
    end)
  end
end