discussion.rb

require 'faraday'
require 'json'

class Discussion
  class EngineUnreachableException < Exception; end

  # TODO: If the same article comes in via multiple sources, uniq it
  def self.of_articles(articles)
    articles.map { |article|
      self.for(article).map { |discussion|
        discussion.article = article
        discussion
      }
    }.flatten
  end

  def self.for(article)
    article.identifier_strings.map do |identifier_string|
      for_identifier(identifier_string)
    end.flatten.uniq_by(&:url)
  end

  def self.for_identifier(identifier_string)
    url = "#{PAPERNAUT_ENGINE_URL}/discussions.json?query=#{CGI.escape(identifier_string)}"
    response = get_http(url)
    discussion_hashes = JSON.parse(response.body)
    discussion_hashes.map { |hash| self.new(hash) }
  rescue JSON::ParserError => e
    raise EngineUnreachableException.new
  end

  attr_accessor :article

  def initialize(attributes)
    @attributes = attributes
  end

  def title
    if @attributes["title"] == @attributes["url"]
      guess_readable_title_from_url
    else
      @attributes["title"]
    end
  end

  def url
    @attributes["url"]
  end

  def identifier_strings
    @attributes["identifier_strings"] || []
  end

  private

  def guess_readable_title_from_url
    article_part = Addressable::URI.parse(url).path.split('/').last
    pagename = article_part.underscore.humanize
  end

  def hostname
    Addressable::URI.parse(url).host
  end

  def self.get_http(url)
    begin
      Faraday.get(url)
    rescue Faraday::Error::ConnectionFailed => e
      raise EngineUnreachableException.new
    end
  end
end