collector.rb

require 'pry'

class Collector
  def initialize(db)
    @db = db
  end

  def payments_collected_in(date)
    case date
    when Date.new(2016, 1, 1)
      @db[:collectors].get(:payment_day) - 1
    when Date.new(2016, 2, 1)
      @db[:collectors].get(:payment_day) - 7
    when Date.new(2016, 3, 1)
      @db[:collectors].get(:payment_day) - 6
    when Date.new(2016, 4, 1)
      @db[:collectors].get(:payment_day) - 6
    when Date.new(2016, 6, 1)
      @db[:collectors].get(:payment_day) - 5
    when Date.new(2016, 10, 1)
      @db[:collectors].get(:payment_day) - 6
    when Date.new(2016, 11, 1)
      @db[:collectors].get(:payment_day) - 4
    when Date.new(2016, 3, 20)
      @db[:collectors].get(:payment_day) - 8
    when Date.new(2016, 11, 15)
      @db[:collectors].get(:payment_day) - 6
    end
  end
end