rss2_parser.ex

defmodule Feedme.Parsers.RSS2 do
  alias Feedme.Feed
  alias Feedme.Entry
  alias Feedme.MetaData
  alias Feedme.Image
  alias Feedme.Enclosure

  def valid?(document) do
    has_version = document
                  |> XmlNode.first("/rss")
                  |> XmlNode.attr("version") == "2.0"

    has_one_channel = document
                      |> XmlNode.first("/rss/channel") != nil

    Enum.all? [ has_version, has_one_channel ]
  end

  def parse(document) do
    %Feed{meta: parse_meta(document), entries: parse_entries(document)}
  end

  def parse_meta(document) do
    # struct will be filled
    meta_data = %MetaData{}

    # image like fields has their own structs and they need special threatment
    skip_fields = [:image, :skip_hours, :skip_days]

    # Structs are basically Maps
    [_ | string_fields] = Map.keys(meta_data)
                          |> Enum.reject(&Enum.member?(skip_fields, &1))

    channel = XmlNode.first(document, "/rss/channel")
    get_text = fn(name) -> XmlNode.text_for_node(channel, name) end

    # try to read all string typed fields from xml into struct
    meta_data = Enum.reduce string_fields, meta_data, fn(key, meta_data) ->
      Map.put meta_data, key, get_text.(key)
    end

    # TODO: read special fields like image
    

    meta_data
  end

  defp parse_image(node) do
    # TODO: parse image node
  end

  def parse_entries(document) do
    entries = XmlNode.all(document, "/rss/channel/item")

    Enum.map entries, &parse_entry(&1)
  end

  def parse_entry(node) do
      title = XmlNode.text_for_node(node, "title")
      link = XmlNode.text_for_node(node, "link")
      description = XmlNode.text_for_node(node, "description")

      %Entry{title: title, link: link, description: description}
  end
end