defmodule PhoneVerification.Provider.Authy do
  @behaviour PhoneVerification.Provider

  @base_url "https://api.authy.com/protected/json/phones/verification/"

  @supported_keys [:phone_number, :country_code, :via, :locale, :code_length, :custom_code]
  @impl true
  def start(params) do
    request(:post, "start", transform_params(params, @supported_keys))
  end

  @supported_keys [:phone_number, :country_code, :verification_code]
  @impl true
  def check(params) do
    request(:get, "check", transform_params(params, @supported_keys))
  end

  defp request(method, action, params) do
    with {:ok, %HTTPoison.Response{body: body}} <-
           HTTPoison.request(
             method,
             @base_url <> action,
             "",
             headers(),
             params: params
           ),
         {:ok, body} <- config(:json_codec).decode(body) do
      parse_body(body)
    else
      _ -> %{message: "Service unavailable", code: 503}
    end
  end

  defp parse_body(%{"success" => true, "message" => message}) do
    {:ok, %{message: message}}
  end

  defp parse_body(%{"success" => false, "message" => message, "error_code" => error_code}) do
    {:error, %{message: message, code: error_code}}
  end

  defp transform_params(%{phone_number: phone_number} = params, supported_keys) do
    params
    |> Map.merge(convert_phone_number(phone_number))
    |> Map.take(supported_keys)
  end

  defp convert_phone_number(%{
         country_code: country_code,
         subscriber_number: subscriber_number
       }) do
    %{
      country_code: country_code,
      phone_number: subscriber_number
    }
  end

  defp headers() do
    ["X-Authy-API-Key": config(:api_key)]
  end

  defp config(key) do
    __MODULE__
    |> PhoneVerification.config()
    |> Keyword.fetch!(key)
  end
end