defmodule PotionIngredients.Plugs.AppToken do
  alias Plug.Conn

  def get_user(conn, opts) do
    secret = get_secret(opts)
    type_of_validation = get_validation_type(opts)

    try do
      signer = Joken.Signer.create("HS256", secret)

      headers = conn.req_headers

      {"app_token", app_token} = get_app_token(headers)

      app_token
      |> case do
        nil ->
          Conn.resp(conn, :forbidden, Poison.encode!(%{msg: "invalid.token", code: 009}))
          |> Conn.put_resp_content_type("application/json")
          |> Conn.halt()

        token ->
          get_user_from_token(token, signer, type_of_validation)
      end
      |> case do
        nil ->
          Conn.resp(conn, :forbidden, Poison.encode!(%{msg: "invalid.token", code: 009}))
          |> Conn.put_resp_content_type("application/json")
          |> Conn.halt()

        open_token ->
          Conn.put_req_header(conn, "app_token", Poison.encode!(open_token))
          |> Conn.put_req_header("original_app_token", app_token)
      end
    rescue
      _ ->
        Conn.resp(conn, :forbidden, Poison.encode!(%{msg: "invalid.token", code: 009}))
        |> Conn.put_resp_content_type("application/json")
        |> Conn.halt()
    end
  end

  def get_app_token(headers) do
    Enum.find(headers, fn {key, _header} -> key == "app_token" end)
  end

  defp get_secret(opts) do
    try do
      secret = get_opt!(opts, :secret)
      secret
    rescue
      _ -> nil
    end
  end

  defp get_opt!(opts, opt) do
    found =
      Enum.find(opts, fn o ->
        {key, _} = o
        key == opt
      end)

    case found do
      {_key, value} ->
        value

      _ ->
        raise(:not_found)
    end
  end

  defp get_validation_type(opts) do
    try do
      check = get_opt!(opts, :check)
      check
    rescue
      _ -> :validate
    end
  end

  defp get_user_from_token(token, signer, validation_type) do
    case validation_type do
      :validate ->
        PotionIngredients.Utils.Token.verify_and_validate(token, signer)
        |> case do
          {:ok, decoded} -> decoded
          _ -> nil
        end

      _ ->
        PotionIngredients.Utils.Token.verify(token, signer)
        |> case do
          {:ok, decoded} -> decoded
          _ -> nil
        end
    end
  end
end