defmodule PortingTools.Mappings.Agent do
  use Agent, restart: :transient
  require Logger

  def start_link(_) do
    Agent.start_link(&init/0, name: __MODULE__)
  end

  def init() do
    Logger.info("Reading mappings")

    mappings =
      File.ls!("mappings")
      |> Stream.flat_map(&File.stream!("mappings/#{&1}"))
      |> Stream.map(&String.split(&1, ","))
      |> Enum.reduce(%{}, fn [remapped, orig | _], map ->
        Map.put(map, remapped, orig)
      end)

    Logger.info("Done reading mappings")
    mappings
  end

  def map(key) do
    Agent.get(__MODULE__, &Map.get(&1, key))
  end
end