module JsonApiClient
  module Parsers
    class Parser
      class << self
        def parse(klass, response)
          data = response.body
          ResultSet.new.tap do |result_set|
            result_set.record_class = klass
            result_set.uri = response.env[:url]
            handle_data(result_set, data)
            handle_errors(result_set, data)
            handle_meta(result_set, data)
            handle_links(result_set, data)
            handle_pagination(result_set, data)
            handle_included(result_set, data)
          end
        end

        private

        def handle_data(result_set, data)
          # all data lives under the "data" attribute
          results = data.fetch("data", [])

          # we will treat everything as an Array
          results = [results] unless results.is_a?(Array)
          result_set.concat(results.map{|res| result_set.record_class.load(res)})
        end

        def handle_errors(result_set, data)
          result_set.errors = ErrorCollector.new(data.fetch("errors", []))
        end

        def handle_meta(result_set, data)
          result_set.meta = MetaData.new(data.fetch("meta", {}))
        end

        def handle_links(result_set, data)
          result_set.links = Linking::TopLevelLinks.new(result_set.record_class, data.fetch("links", {}))
        end

        def handle_pagination(result_set, data)
          result_set.pages = result_set.record_class.paginator.new(result_set, data.fetch("links", {}))
        end

        def handle_included(result_set, data)
          included = Linking::IncludedData.new(result_set.record_class, data.fetch("included", []))
          result_set.each do |res|
            res.linked_data = included
          end
        end
      end
    end
  end
end