defmodule Numverify do
  @moduledoc """
  Verify numbers through the [Numverify](http://numverify.com/) API.

  A valid Numverify API key must be used to do anything. It can either be in the
  application configuration under `:key` or as an environment variable under the
  name of `NUMVERIFY_KEY`.
  """

  alias Numverify.Gateway

  @doc """
  Validate the given `opts`, a map of inputs to the API.

  A `number` field must be present.

  Refer to the Numverify [documentation](https://numverify.com/documentation) for
  more information.
  """
  @spec validate(map) :: {:ok, map} | {:error, integer, String.t}
  def validate(opts) do
    url = "validate?#{opts |> URI.encode_query}"

    url
    |> Gateway.get
    |> process_response
  end

  @doc """
  Returns a map of countries and their telephone codes.
  """
  @spec countries :: {:ok, map}
  def countries do
    "countries"
    |> Gateway.get
    |> process_response
  end

  @doc """
  Convenience function to quickly test the validity of a number.

  Returns `true` if the number is valid, `false` if not, and `nil` if there was
  an error.
  """
  @spec is_valid?(integer | String.t) :: boolean
  def is_valid?(number) do
    case validate(%{number: number}) do
      {:ok, body} ->
        Map.get(body, "valid") || false
      {:error, _, _} ->
        nil
    end
  end

  defp process_response({:ok, %{body: body}}) do
    process_body(body)
  end

  defp process_response({:error, _}) do
    {:error, "There was an error with your request. Please try again."}
  end

  defp process_body(%{"error" => body}) do
    {:error, body["code"], body["info"]}
  end

  defp process_body(body), do: {:ok, body}
end