package common

import "time"

// A Backoff waits on errors with exponential backoff (limited by maximum
// backoff). Resetting Backoff will reset the next sleep timer to the initial
// backoff duration.
type Backoff struct {
	duration time.Duration
	done     <-chan struct{}

	init time.Duration
	max  time.Duration

	last time.Time
}

func NewBackoff(done <-chan struct{}, init, max time.Duration) *Backoff {
	return &Backoff{
		duration: init,
		done:     done,
		init:     init,
		max:      max,
	}
}

func (b *Backoff) Reset() {
	b.duration = b.init
}

func (b *Backoff) Wait() bool {
	backoff := b.duration
	b.duration *= 2
	if b.duration > b.max {
		b.duration = b.max
	}

	select {
	case <-b.done:
		return false
	case <-time.After(backoff):
		b.last = time.Now()
		return true
	}
}

func (b *Backoff) WaitOnError(err error) bool {
	if err == nil {
		b.Reset()
		return true
	}
	return b.Wait()
}

func (b *Backoff) TryWaitOnError(failTS time.Time, err error) bool {
	if err == nil {
		b.Reset()
		return true
	}

	if failTS.Before(b.last) {
		return true
	}

	return b.Wait()
}