pubsub

type Message interface {
	ID() string
	Data() []byte
}

type Queue interface {
	io.Closer
	Topic(ctx context.Context, name string) (Topic, error)
}

type RetryPolicy struct {
	MaxAttempts            int
	MinBackoff, MaxBackoff time.Duration
}

type SubscribeConfig struct {
	RetryPolicy RetryPolicy
}

type SubscribeHandler = func(ctx context.Context, msg SubscriberMessage)

type SubscribeOption = func(config *SubscribeConfig)

type SubscriberMessage interface {
	Message
	// Ack signals completion of a message which will then be removed from the pub/sub topic.
	Ack()
	// Nack signals failure of message processing. The message will be retried according to
	// the retry policy of the subscription.
	Nack()
}

type Subscription interface {
	// Receive receives messages sent to the subscription. The given handler
	// will be invoked for each message in a goroutine. To stop `Receive`
	// cancel the context.
	Receive(ctx context.Context, handler SubscribeHandler) error
}

type Topic interface {
	// Publish publishes a message to the topic.
	Publish(ctx context.Context, msg Message) error
	// Subscribe creates (or resumes) a subscription to a topic. All messages
	// published to the topic will be sent to all subscribers.
	Subscribe(ctx context.Context, name string, opts ...SubscribeOption) (Subscription, error)
}