unfurl

defmodule Unfurl.Fetcher do
  @moduledoc """
  A module for fetching body data for a given url
  """
  use Tesla
  plug(Tesla.Middleware.FollowRedirects, max_redirects: 3)

  import Untangle

  alias Unfurl.Oembed

  @json_library Application.get_env(:unfurl, :json_library, Jason)

  @doc """
  Fetches a url and extracts the body
  """
  @spec fetch(String.t(), List.t()) :: {:ok, String.t(), Integer.t()} | {:error, Atom.t()}
  def fetch(url, opts \\ [])

  def fetch(url, opts) when is_binary(url) do
    URI.parse(url)
    |> fetch(opts)
  end

  def fetch(%URI{} = url, opts) do
    case url do
      %URI{host: nil, path: nil} ->
        warn(url, "expected a valid URI, but got")
        {:error, :invalid_uri}

      %URI{scheme: "doi"} ->
        {:error, :invalid_uri}

      %URI{scheme: nil, host: nil, path: host_detected_as_path} ->
        do_fetch("http://#{url}", opts)

      %URI{} ->
        do_fetch(to_string(url), opts)
    end
  end

  defp do_fetch(url, opts \\ []) when is_binary(url) do
    case get(url, opts) do
      {:ok, %{body: body, status: status_code}} -> {:ok, body, status_code}
      other -> other
    end
  rescue
    e in ArgumentError -> error(e)
  end
end