gistfile1.rb

class MigrateTimeZones
  attr_reader :old_zone, :new_zone
  def initialize(old_zone = "Pacific Time (US & Canada)", new_zone = Company.current.time_zone)
    @old_zone = ActiveSupport::TimeZone.new old_zone
    @new_zone = ActiveSupport::TimeZone.new new_zone
  end

  def call
    update_appointments
    update_shifts
    update_requested_appointments
  end

  def update_appointments
    Appointment.find_each do |a|
      a.start_at = in_zone(a.start_at)
      a.end_at = in_zone(a.end_at)
      a.save
    end

  end

  def update_shifts

  end

  def update_requested_appointments

  end

  def in_zone(old_time)
    old_time + difference_for_date(old_time)
  end

  def difference_for_date(datetime)
    date = datetime.to_date

    old = old_zone.parse "#{date} 00:00:00"
    new = new_zone.parse "#{date} 00:00:00"

    new - old
  end
end