poro-controller-statistics.rb

class StatisticsController < ApplicationController

  WeeklyReport = Struct.new(
    :week_number,
    :date_from,
    :date_to,
    :count_entries,
    :avg_distance,
    :avg_speed
  )

  def index
    @weekly_reports = []

    current_user.entries.group_by(&:week).each do |week, entries|
      @weekly_reports << WeeklyReport.new.tap do |r|
         r.week_number   = week
         r.date_from     = weeks_to_date_from(week)
         r.date_to       = weeks_to_date_to(week)
         r.count_entries = entries.count
         r.avg_distance  = avg_distance(entries)
         r.avg_speed     = avg_speed(entries)
       end
    end
  end

  private

  def weeks_to_date_from(week)
    (Date.new + week.to_i.weeks).to_s.split(',')[0]
  end

  def weeks_to_date_to(week)
    (Date.new + week.to_i.weeks + 7.days).to_s.split(',')[0]
  end

  def avg_distance(entries)
    distances = entries.sum(&:distance)
    (distances / entries.count).round(2)
  end

  def avg_speed(entries)
    speeds = entries.sum(&:speed)
    (speeds / entries.count).round(2)
  end
end