feed_parser/lib/feed_parser.ex

defmodule FeedParser do
  @default_parsers [
    FeedParser.RSS2.Parser,
    FeedParser.Atom.Parser,
    FeedParser.JSONFeed.Parser,
    FeedParser.RSSInJSON.Parser
  ]

  @spec parse(data :: String.t(), content_type :: String.t(), parsers :: [module()]) ::
          {:ok, feed :: FeedParser.Feed.t()} | {:error, reason :: String.t()}
  def parse(data, content_type, parsers \\ @default_parsers) when is_binary(data) do
    parsers
    |> Enum.reduce_while(false, fn parser, acc ->
      case parser.accepts(data, content_type) do
        {true, result} ->
          {:halt, {parser, result}}

        _ ->
          {:cont, acc}
      end
    end)
    |> case do
      {parser, result} ->
        parser.parse_feed(result)

      false ->
        {:error, "no parser matched the given content type and data"}
    end
  end
end