Classes for pulling statistics data from Rails models

daily_iterator.rb

# encoding: utf-8

class Statistics::DailyIterator
  def initialize(period_start = nil, period_end = nil)
    @period_start = (period_start || 30.days.ago).to_date
    @period_end = (period_end || 1.day.ago).to_date
  end

  def each(&block)
    period = @period_start..@period_end
    period.map do |date|
      period_start = date.midnight
      period_end = (date + 1.day).midnight
      yield period_start, period_end
    end
  end
end

invoices.rb

# encoding: utf-8

class Statistics::Invoices < Statistics::PeriodMetric
  def get_count(period_start, period_end)
    # scope on Invoice: 
    #   scope :created_between, ->(from, to){ where(:created_at.gte => from, :created_at.lte => to) }
    Invoice.created_between(period_start, period_end).count
  end
end

monthly_iterator.rb

# encoding: utf-8

class Statistics::MonthlyIterator
  def initialize(period_start = nil, period_end = nil)
    @period_start = period_start || 1.year.ago
    @period_end = period_end || (Time.now.beginning_of_month - 1.day)
  end

  def each(&block)
    period = @period_end - @period_start
    number_of_months = period / 1.month
    number_of_months.round.times.map do |i|
      period_start = (@period_start + i.months).beginning_of_month
      period_end = (@period_start + i.months).end_of_month
      yield period_start, period_end
    end
  end
end

period_metric.rb

# encoding: utf-8

class Statistics::PeriodMetric
  def self.daily_data
    metric = self.new
    periods = Statistics::DailyIterator.new
    periods.each do |period_start, period_end|
      count = metric.get_count period_start, period_end
      [period_start, count]
    end
  end

  def self.monthly_data
    metric = self.new
    periods = Statistics::MonthlyIterator.new
    periods.each do |period_start, period_end|
      count = metric.get_count period_start, period_end
      [period_start, count]
    end
  end


  def get_count(period_start, period_end)
  end
end