simongregory/glued

# encoding: utf-8

# Deserialises the manifest
#
class F4M
  NAMESPACE = 'http://ns.adobe.com/f4m/1.0'

  attr_reader :duration,
              :bootstrap_info,
              :base_ref,
              :media_filename,
              :media

  def initialize(url, data)
    xml = Nokogiri::XML(data)

    namespace = xml.root.namespace.href rescue 'not found'
    fail "Invalid manifest namespace. It was #{namespace} but should have been #{NAMESPACE}" unless namespace == NAMESPACE

    xml.remove_namespaces!

    stream_type = xml.xpath('//streamType').first.text rescue 'unknown'
    fail 'Only recorded streams are supported.' unless stream_type == 'recorded'

    @duration = xml.xpath('//duration').first.text.to_i

    b64_bootstrap_info = xml.xpath('//bootstrapInfo').first.text
    @bootstrap_info = Base64.strict_decode64(b64_bootstrap_info)

    media_nodes = xml.xpath('/manifest[1]/media')
    @media = find_highest_bitrate(media_nodes)
    @media_filename = @media.at_css('@url').value

    @base_ref = url.split('/').slice(0...-1).join('/') # can be specified in xml
  end

  def find_highest_bitrate(list)
    rates = []
    list.each do |media|
      br = media.at_css('@bitrate').value.to_i
      rates[br] = media
    end

    rates.reject { |e| e.nil? }.pop
  end
end