panel/app/jobs/stat_collection_job.rb

# frozen_string_literal: true

# Genera resúmenes de información para poder mostrar estadísticas y se
# corre regularmente a sí misma.
class StatCollectionJob < PeriodicJob
  STAT_NAME = 'stat_collection_job'

  def perform(site_id:, once: true)
    @site = Site.find site_id

    scope.rollup('builds', **options)

    scope.rollup('space_used', **options) do |rollup|
      rollup.average(:bytes)
    end

    scope.rollup('build_time', **options) do |rollup|
      rollup.average(:seconds)
    end

    # XXX: Es correcto promediar promedios?
    Stat::INTERVALS.reduce do |previous, current|
      rollup(name: 'builds', interval_previous: previous, interval: current)
      rollup(name: 'space_used', interval_previous: previous, interval: current, operation: :average)
      rollup(name: 'build_time', interval_previous: previous, interval: current, operation: :average)

      current
    end

    # Registrar que se hicieron todas las recolecciones
    site.stats.create! name: STAT_NAME

    run_again! unless once
  end

  private

  # Genera un rollup recursivo en base al período anterior y aplica una
  # operación.
  #
  # @return [NilClass]
  def rollup(name:, interval_previous:, interval:, operation: :sum)
    Rollup.where(name: name, interval: interval_previous)
          .where('time >= ?', beginning_of_interval.try(:"beginning_of_#{interval}"))
          .where_dimensions(site_id: site.id)
          .group("dimensions->'site_id'")
          .rollup(name, interval: interval, update: true) do |rollup|
            rollup.try(operation, :value)
          end
  end

  # Los registros a procesar
  #
  # @return [ActiveRecord::Relation]
  def scope
    @scope ||= site.build_stats
                   .jekyll
                   .where('created_at => ?', beginning_of_interval)
                   .group(:site_id)
  end

  # Las opciones por defecto
  #
  # @return [Hash]
  def options
    @options ||= { interval: starting_interval, update: true }
  end
end