package cron

import (
	"time"

	"github.com/andeya/goutil/calendar"
)

// ConstantDelaySchedule represents a simple recurring duty cycle, e.g. "Every 5 minutes".
// It does not support jobs more frequent than once a second.
type ConstantDelaySchedule struct {
	Delay time.Duration
}

// Every returns a crontab Schedule that activates once every duration.
// Delays of less than a second are not supported (will round up to 1 second).
// Any fields less than a Second are truncated.
func Every(duration time.Duration) ConstantDelaySchedule {
	if duration < time.Second {
		duration = time.Second
	}
	return ConstantDelaySchedule{
		Delay: duration - time.Duration(duration.Nanoseconds())%time.Second,
	}
}

// Next returns the next time this should be run.
// This rounds so that the next activation time will be on the second.
func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time {
	return t.Add(schedule.Delay - time.Duration(t.Nanosecond())*time.Nanosecond)
}

// Next returns the next time this should be run.
// This rounds so that the next activation time will be on the second.
func (schedule ConstantDelaySchedule) LunarNext(t *calendar.Lunar) *calendar.Lunar {
	days, hours, minutes, seconds, nanosecond := calendar.SplitDuration(int(schedule.Delay/time.Second), 0)
	return t.Add(0, 0, days, hours, minutes, seconds, nanosecond)
}
