class ContentService
  DEFAULT_PROTOCOL = 'https'.freeze
  SOCKET_ERRORS = [EOFError, IOError, Errno::ECONNABORTED, Errno::ECONNRESET,
      Errno::EPIPE, Errno::EINVAL].freeze

  def self.query(path, payload)
    retry_once_on_socket_error do
      ConnectionManager.ensure_started(uri)
      request = build_request(path, payload)
      response = ConnectionManager.connection.request(request)
      MultiJson.load(response.body)
    end
  end

  class << self
    private

    def retry_once_on_socket_error
      retried = false
      begin
        yield
      rescue *SOCKET_ERRORS
        raise if retried
        ConnectionManager.ensure_finished
        retried = true
        retry
      end
    end

    def build_request(path, payload)
      request = Net::HTTP::Post.new("#{uri.path}/#{path}".squeeze('/'), request_headers)
      request.basic_auth(config['login'], config['api_key'])
      request.body = MultiJson.dump(payload)
      request
    end

    def uri
      url = config['url']
      url = "#{DEFAULT_PROTOCOL}://#{url}" unless url.match /^http/
      URI.parse(url)
    end

    def request_headers
      headers = {
        'Content-Type' => 'application/json',
        'Accept' => 'application/json',
        'User-Agent' => user_agent,
      }
      if http_host = config['http_host']
        headers['Host'] = http_host
      end
      headers
    end

    def config
      RailsConnector::Configuration.content_service
    end

    def user_agent
      @user_agent ||= (
        gem_info = Gem.loaded_specs["infopark_cloud_connector"]
        "#{gem_info.name}-#{gem_info.version}"
      )
    end
  end

  module ConnectionManager
    def self.connection
      @connection
    end

    def self.connection=(conn)
      @connection = conn
    end

    def self.ensure_started(uri)
      return if @connection && @connection.started?
      conn = Net::HTTP.new(uri.host, uri.port)
      if uri.scheme == 'https'
        conn.use_ssl = true
        conn.verify_mode = OpenSSL::SSL::VERIFY_PEER
      end
      retry_twice_on_socket_error { conn.start }
      @connection = conn
    end

    def self.ensure_finished
      @connection.finish if @connection && @connection.started?
      @connection = nil
    end

    class << self
      private

      def retry_twice_on_socket_error
        attempt = 0
        begin
          yield
        rescue *ContentService::SOCKET_ERRORS
          raise if attempt == 2
          attempt += 1
          retry
        end
      end
    end
  end
end