catbus

type Client interface {
	Connect() error
	Subscribe(topic string, f MessageHandler) error
	Publish(topic string, retention Retention, payload string) error
}

type ClientOptions struct {
	DisconnectHandler func(Client, error)
	ConnectHandler    func(Client)

	// SubscribeEveryMessage determines if the Subscribe callback will be called for all incoming messages.
	// When SubscribeEveryMessage is false, the Subscribe callback will only trigger when the value changes.
	SubscribeEveryMessage bool

	// Publish previously seen or default values on connecting after OnconnectDelay ± [0,OnconnectJitter).
	OnconnectDelay  time.Duration
	OnconnectJitter time.Duration

	// DefaultPayloadByTopic are optional values to publish on connect if no prior values are seen.
	// E.g. unless we've been told otherwise, assume a device is off.
	DefaultPayloadByTopic map[string]string
}

type Message struct {
	Payload   string
	Retention Retention
	Topic     string
}

type MessageHandler func(Client, Message)

type Retention bool