module Mailings
  class SendClock
    def initialize(mailing, time: Time.zone.now)
      @mailing = mailing
      @time = time.in_time_zone
    end

    def open?(at = @time)
      t = at.in_time_zone
      return true unless @mailing.send_window_enabled?

      working_day?(t.to_date) && minutes_in_window?(t)
    end

    def next_send_at(earliest: @time)
      t = earliest.in_time_zone
      return t unless @mailing.send_window_enabled?

      next_open_at(from: t)
    end

    def next_open_at(from: @time)
      t = from.in_time_zone
      return t unless @mailing.send_window_enabled?

      0.upto(21) do |offset|
        day = t.to_date + offset
        next unless working_day?(day)

        start_at = time_on(day, start_minutes)
        end_at = time_on(day, end_minutes)
        if offset.zero?
          return t if t >= start_at && t < end_at
          return start_at if t < start_at

          next
        end
        return start_at
      end

      t + 21.days
    end

    def window_label
      "#{format_minutes(start_minutes)}–#{format_minutes(end_minutes)}"
    end

    private

    def working_day?(date)
      date.on_weekday? && !Italy::Holidays.holiday?(date)
    end

    def minutes_in_window?(time)
      minutes = (time.hour * 60) + time.min
      minutes >= start_minutes && minutes < end_minutes
    end

    def start_minutes
      @mailing.send_window_start_minutes.presence || (10 * 60)
    end

    def end_minutes
      @mailing.send_window_end_minutes.presence || (18 * 60)
    end

    def time_on(date, minutes)
      if minutes >= (24 * 60)
        Time.zone.local(date.year, date.month, date.day).beginning_of_day + 1.day
      else
        Time.zone.local(date.year, date.month, date.day, minutes / 60, minutes % 60, 0)
      end
    end

    def format_minutes(minutes)
      format("%02d:%02d", minutes / 60, minutes % 60)
    end
  end
end