require 'faraday'

class RefreshConstituencyPartyJob < ApplicationJob

  HOST = "http://data.parliament.uk"

  ENDPOINT = "/membersdataplatform/services/mnis/members/query/House=Commons%7CIsEligible=true/"

  TIMEOUT = 5

  MEMBERS    = "//Members/Member"

   MP_ID      = "./@Member_Id"

  MP_NAME    = "./FullTitle"

  MP_PARTY   = "./Party"

  rescue_from StandardError do |exception|

    Appsignal.send_exception exception

  end

  def perform

    Constituency.find_each do |constituency|

      if member = members[constituency.mp_id]

        constituency.update!(party: member[:party])

      else

        constituency.update!(mp_id: nil, mp_name: nil, mp_date: nil, party: nil)

      end

    end

  end

  private

  def members

    @members ||= load_members

  end

  def load_members

    response = fetch_members

    if response.success?

      Hash[parse(response.body)]

    else

      {}

    end

  rescue Faraday::Error => e

    Appsignal.send_exception(e)

    return {}

  end

  def parse(body)

    xml = Nokogiri::XML(body)

    xml.xpath(MEMBERS).map do |node|

      [

        node.xpath(MP_ID).text,

        {}.tap { |attrs|

          attrs[:id]    = node.xpath(MP_ID).text

          attrs[:name]  = node.xpath(MP_NAME).text

          attrs[:party] = node.xpath(MP_PARTY).text

        }

      ]

    end

  end

  def faraday

    Faraday.new(HOST) do |f|

      f.response :follow_redirects

      f.response :raise_error

      f.adapter :net_http_persistent

    end

  end

  def fetch_members

    faraday.get(ENDPOINT) do |request|

      request.options[:timeout] = TIMEOUT

      request.options[:open_timeout] = TIMEOUT

    end

  end

end