# frozen_string_literal: true

# Implementa rollups recursivos
module RecursiveRollup
  extend ActiveSupport::Concern

  included do
    private

    # Genera un rollup recursivo en base al período anterior y aplica una
    # operación.
    #
    # @param :name [String]
    # @param :interval_previous [String]
    # @param :interval [String]
    # @param :operation [Symbol]
    # @param :dimensions [Hash]
    # @param :beginning [Time]
    # @return [Rollup]
    def recursive_rollup(name:, interval_previous:, interval:, dimensions:, beginning:, operation: :sum)
      Rollup.where(name: name, interval: interval_previous, dimensions: dimensions)
            .where('time >= ?', beginning.try(:"beginning_of_#{interval}"))
            .group(*dimensions_to_jsonb_query(dimensions))
            .rollup(name, interval: interval, update: true) do |rollup|
              rollup.try(operation, :value)
            end
    end

    # Reducir las estadísticas calculadas aplicando un rollup sobre el
    # intervalo más amplio.
    #
    # @param :name [String]
    # @param :operation [Symbol]
    # @param :dimensions [Hash]
    # @return [nil]
    def reduce_rollup(name:, dimensions:, operation: :sum)
      Stat::INTERVALS.reduce do |previous, current|
        recursive_rollup(name: name,
                         interval_previous: previous,
                         interval: current,
                         dimensions: dimensions,
                         beginning: beginning_of_interval,
                         operation: operation)

        # Devolver el intervalo actual
        current
      end

      nil
    end

    # @param :dimensions [Hash]
    # @return [Array]
    def dimensions_to_jsonb_query(dimensions)
      dimensions.keys.map do |key|
        "dimensions->'#{key}'"
      end
    end
  end
end