attack/barometer-noaa

module Barometer
  class Noaa
    class Response
      class ForecastedWeather
        def initialize(payload)
          @payload = payload
          @predictions = Barometer::Response::PredictionCollection.new
        end

        def parse
          each_prediction do |prediction, index, shared_index|
            prediction.starts_at = start_times[index]
            prediction.ends_at = end_times[index]
            prediction.icon = icons[shared_index]
            prediction.condition = summaries[shared_index]
            prediction.pop = precipitations[index]
            prediction.high = [:imperial, high_temperatures[shared_index]]
            prediction.low = [:imperial, low_temperatures[shared_index]]
          end

          predictions
        end

        private

        attr_reader :payload, :predictions

        def total_forecasts
          high_temperatures.count * 2
        end

        def each_forecast
          (0...total_forecasts).each do |index|
            yield index, shared_index(index)
          end
        end

        def each_prediction
          each_forecast do |index, shared_index|
            predictions.build do |prediction|
              yield prediction, index, shared_index
            end
          end
        end

        def shared_index(index)
          (index / 2).floor
        end

        def times
          @times ||= payload.fetch('time_layout').detect{|layout| layout['layout_key'] == 'k-p12h-n14-2'}
        end

        def start_times
          @start_times ||= times['start_valid_time']
        end

        def end_times
          @end_times ||= times['end_valid_time']
        end

        def temperatures
          @temperatures ||= payload.fetch('parameters', 'temperature')
        end

        def high_temperatures
          @high_temperatures ||= temperatures.detect{|t| t['@type'] == 'maximum'}.fetch('value', [])
        end

        def low_temperatures
          @low_temperatures ||= temperatures.detect{|t| t['@type'] == 'minimum'}.fetch('value', [])
        end

        def precipitations
          @precipitations ||= payload.fetch('parameters', 'probability_of_precipitation', 'value').map(&:to_i)
        end

        def summaries
          @summaries ||= payload.fetch('parameters', 'weather', 'weather_conditions').map{|c| c['@weather_summary'] }
        end

        def icons
          @icons ||= payload.fetch('parameters', 'conditions_icon', 'icon_link').map{|l| l.match(/(\w*)\.[a-zA-Z]{3}$/)[1] }
        end
      end
    end
  end
end