ctx, cancel := context.WithCancel(context.Background())
defer cancel()

db, err := sql.Open("postgres", os.Getenv("DS_DSN"))
if err != nil {
    fmt.Printf("could not connect to amqp: %s", err)
    return
}

// we need to create a data store instance first
ds, err := postgres.WithInstance(ctx, db)
if err != nil {
    fmt.Printf("could not setup the data store: %s", err)
    return
}
defer ds.Close()

// we create an event stream passing the pusub connection
client, err := pubsub.NewClient(ctx, os.Getenv("GCP_PROJECT_ID"))
if err != nil {
    fmt.Printf("failed to connect to gcp: %s", err)
    return
}

es := pubsubOut.New(client)

// now we create an outboxer instance passing the data store and event stream
o, err := outboxer.New(
    outboxer.WithDataStore(ds),
    outboxer.WithEventStream(es),
    outboxer.WithCheckInterval(1*time.Second),
    outboxer.WithCleanupInterval(5*time.Second),
    outboxer.WithCleanUpBefore(time.Now().AddDate(0, 0, -5)),
)
if err != nil {
    fmt.Printf("could not create an outboxer instance: %s", err)
    return
}

// here we initialize the outboxer checks and cleanup go rotines
o.Start(ctx)
defer o.Stop()

// finally we are ready to send messages
if err = o.Send(ctx, &outboxer.OutboxMessage{
    Payload: []byte("test payload"),
    Options: map[string]interface{}{
        amqpOut.ExchangeNameOption: "test",
        amqpOut.ExchangeTypeOption: "topic",
        amqpOut.RoutingKeyOption:   "test.send",
    },
}); err != nil {
    fmt.Printf("could not send message: %s", err)
    return
}

// we can also listen for errors and ok messages that were send
for {
    select {
    case err := <-o.ErrChan():
        fmt.Printf("could not send message: %s", err)
    case <-o.OkChan():
        fmt.Printf("message received")
        return
    }
}