package coalesce

import "context"

// Signal keeps at most one pending notification and never blocks producers.
type Signal struct {
	ready chan struct{}
}

func NewSignal() *Signal {
	return &Signal{ready: make(chan struct{}, 1)}
}

func (s *Signal) Notify() {
	select {
	case s.ready <- struct{}{}:
	default:
	}
}

func (s *Signal) Wait(ctx context.Context) error {
	select {
	case <-s.ready:
		return nil
	case <-ctx.Done():
		return ctx.Err()
	}
}