open-pod/lib/podcast_feed/provider/archive/parser.ex

defmodule PodcastFeed.Provider.Archive.Parser do
  alias PodcastFeed.Utility.Format

  @extra_metadata_url "https://archive.org/download/{identifier}/metadata.json"
  @archive_metadata_url "http://archive.org/metadata/{identifier}"
  @download_url "https://archive.org/download/{identifier}/{filename}"

  @extra_metadata_defaults %{
    "link" => "",
    "image" => %{
      "url" => "",
      "title" => "",
      "link" => "",
    },
    "category" => "",
    "explicit" => "",
  }

  def by_identifier(identifier) do
    extra_metadata_json = fetch_extra_metadata(identifier)
    metadata_json = fetch_archive_metadata(identifier)
    parse(identifier, metadata_json, extra_metadata_json)
  end

  defp fetch_extra_metadata(identifier) do
    extra_metadata_url = Format.compile(@extra_metadata_url, identifier: identifier)
    parse_extra_metadata_response(:hackney.get(extra_metadata_url, [], "", [follow_redirect: true]))
  end

  defp parse_extra_metadata_response({:ok, 200, _headers, client_ref}) do
    {:ok, extra_metadata_json} = :hackney.body(client_ref)
    extra_metadata_json
    |> String.split("\n")
    |> Enum.join()
    |> Poison.decode!()
  end
  defp parse_extra_metadata_response(_), do: @extra_metadata_defaults

  defp fetch_archive_metadata(identifier) do
    metadata_url = Format.compile(@archive_metadata_url, identifier: identifier)
    {:ok, 200, _headers, client_ref} = :hackney.get(metadata_url, [], "", [follow_redirect: true, connect_timeout: 30000, recv_timeout: 30000])
    {:ok, metadata_json} = :hackney.body(client_ref)
    metadata_json |> Poison.decode!()
  end

  def parse(identifier, metadata = %{"files" => files}, extra) do
    extra = files
    |> fetch_cover(identifier)
    |> enrich_extra_metadata_with_cover(extra)

    %{podcast: podcast_data(metadata, extra), items: items_data(metadata, identifier)}
  end

  # cover is nil
  defp enrich_extra_metadata_with_cover(nil, extra), do: extra

  # cover is found and image is missing in the extra_metadata
  defp enrich_extra_metadata_with_cover(cover, extra = %{"image" => %{"url" => ""}}) do
    put_in(extra, ["image", "url"], cover)
  end

  # image is already set in the extra_metadata
  defp enrich_extra_metadata_with_cover(_cover, extra), do: extra

  defp podcast_data(%{"metadata" => metadata, "item_last_updated" => last_updated}, extra) do
    %{
      title: metadata["title"],
      description: metadata["description"],
      webmaster: metadata["uploader"],
      managingEditor: metadata["uploader"],
      owner: %{
        name: metadata["creator"],
        email: metadata["uploader"],
      },
      keywords: metadata["subject"],
      pubDate: metadata["publicdate"] |> NaiveDateTime.from_iso8601!() |> DateTime.from_naive!("Etc/UTC"),
      lastBuildDate: last_updated |> DateTime.from_unix!(:second),
      author: metadata["creator"],
      language: metadata["language"],
      image: %{
        url: extra["image"]["url"],
        title: extra["image"]["title"],
        link: extra["image"]["link"],
      },
      link: extra["link"],
      category: extra["category"],
      explicit: extra["explicit"],
    }
  end


  defp items_data(%{"files" => files}, identifier) do
    files
    |> filter_audio_files()
    |> Enum.map(fn f -> to_feed_item(f, identifier, files) end)
  end

  defp filter_audio_files(files) do
    files |> Enum.filter(fn f -> Map.get(f, "format") =~ ~r/MP3/i end) #FIXME:! mp3, ogg, boh
  end

  defp to_feed_item(file, identifier, files) do
    filename = Map.get(file, "name")
    %{
      title: file["title"],
      description: "",
      pubDate: file |> Map.get("mtime") |> Integer.parse() |> elem(0) |> DateTime.from_unix!(:second),
      link: download_url(identifier, filename),
      length: (file |> Map.get("length") |> Float.parse() |> elem(0)) |> trunc(),
      size: file |> Map.get("size"),
      summary: "",
      image: download_url(identifier, fetch_image_of_audio(filename, files)),
      keywords: file |> Map.take(["album", "artist", "genre"]) |> Map.values(),
      explicit: "no",
    }
  end

  defp fetch_cover(files, identifier) do
    filename = files
    |> Enum.filter(fn f -> f["source"] == "original" end)
    |> Enum.filter(fn f -> f["format"] == "JPEG" end) #FIXME:! jpg, png, gif
    |> List.first()
    |> case do
      nil -> nil
      file -> Map.get(file, "name")
    end

    download_url(identifier, filename)
  end

  defp fetch_image_of_audio(audio_file, files) do
    files
    |> Enum.filter(fn
      %{"format" => format, "source" => "derivative", "original" => ^audio_file} ->
        format =~ ~r/JPG|JPEG|PNG|GIF/i
      _ -> nil
    end)
    |> fetch_image_of_audio()
  end

  defp fetch_image_of_audio(image_files) when is_list(image_files), do: fetch_image_of_audio(List.first(image_files))
  defp fetch_image_of_audio(nil), do: nil
  defp fetch_image_of_audio(image_file), do: image_file |> Map.get("name", nil)

  defp download_url(_identifier, nil), do: nil
  defp download_url(identifier, filename) do
    Format.compile(@download_url, identifier: identifier, filename: filename) |> URI.encode()
  end
end