Feature flagged follow change notification

service/adapters/apns/apns.go

@@ -1,9 +1,14 @@
 package apns
 
 import (
+	"encoding/json"
+	"time"
+
 	"github.com/boreq/errors"
+	"github.com/google/uuid"
 	"github.com/planetary-social/go-notification-service/internal/logging"
 	"github.com/planetary-social/go-notification-service/service/config"
+	"github.com/planetary-social/go-notification-service/service/domain"
 	"github.com/planetary-social/go-notification-service/service/domain/notifications"
 	"github.com/sideshow/apns2"
 	"github.com/sideshow/apns2/certificate"
@@ -73,3 +78,84 @@ func (a *APNS) SendNotification(notification notifications.Notification) error {
 
 	return nil
 }
+
+func (a *APNS) SendFollowChangeNotification(followChange domain.FollowChange, apnsToken domain.APNSToken) error {
+	if apnsToken.Hex() == "" {
+		return errors.New("invalid APNs token")
+	}
+	n, err := a.buildFollowChangeNotification(followChange, apnsToken)
+	if err != nil {
+		return err
+	}
+	resp, err := a.client.Push(n)
+	//a.metrics.ReportCallToAPNS(resp.StatusCode, err)
+	if err != nil {
+		return errors.Wrap(err, "error pushing the follow change notification")
+	}
+
+	if resp.StatusCode == 200 {
+		a.logger.Debug().
+			WithField("uuid", n.ApnsID).
+			WithField("response.reason", resp.Reason).
+			WithField("response.statusCode", resp.StatusCode).
+			WithField("host", a.client.Host).
+			Message("sent a follow change notification")
+	} else {
+		a.logger.Error().
+			WithField("uuid", n.ApnsID).
+			WithField("response.reason", resp.Reason).
+			WithField("response.statusCode", resp.StatusCode).
+			WithField("host", a.client.Host).
+			Message("failed to send a follow change notification")
+	}
+
+	return nil
+}
+
+func (a *APNS) buildFollowChangeNotification(followChange domain.FollowChange, apnsToken domain.APNSToken) (*apns2.Notification, error) {
+	payload, err := followChangePayload(followChange)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating a payload")
+	}
+
+	n := &apns2.Notification{
+		PushType:    apns2.PushTypeAlert,
+		ApnsID:      uuid.New().String(),
+		DeviceToken: apnsToken.Hex(),
+		Topic:       a.cfg.APNSTopic(),
+		Payload:     payload,
+		Priority:    apns2.PriorityLow,
+	}
+
+	return n, nil
+}
+
+func followChangePayload(followChange domain.FollowChange) ([]byte, error) {
+	alertMessage := ""
+	if followChange.ChangeType == "unfollowed" {
+		alertMessage = followChange.FriendlyFollower + " has unfollowed you!"
+	} else {
+		alertMessage = followChange.FriendlyFollower + " is a new follower!"
+	}
+
+	payload := map[string]interface{}{
+		"aps": map[string]interface{}{
+			"alert": alertMessage,
+			"sound": "default",
+			"badge": 1,
+		},
+		"data": map[string]interface{}{
+			"changeType":       followChange.ChangeType,
+			"at":               followChange.At.Format(time.RFC3339),
+			"follower":         followChange.Follower.Hex(),
+			"friendlyFollower": followChange.FriendlyFollower,
+		},
+	}
+
+	payloadBytes, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	return payloadBytes, nil
+}

service/adapters/apns/apns_mock.go

@@ -6,6 +6,7 @@ import (
 	"github.com/planetary-social/go-notification-service/internal"
 	"github.com/planetary-social/go-notification-service/internal/logging"
 	"github.com/planetary-social/go-notification-service/service/config"
+	"github.com/planetary-social/go-notification-service/service/domain"
 	"github.com/planetary-social/go-notification-service/service/domain/notifications"
 )
 
@@ -34,6 +35,12 @@ func (a *APNSMock) SendNotification(notification notifications.Notification) err
 	return nil
 }
 
+func (a *APNSMock) SendFollowChangeNotification(followChange domain.FollowChange, token domain.APNSToken) error {
+	notification := notifications.Notification{}
+
+	return a.SendNotification(notification)
+}
+
 func (a *APNSMock) SentNotifications() []notifications.Notification {
 	a.sentNotificationsLock.Lock()
 	defer a.sentNotificationsLock.Unlock()

service/app/app.go

@@ -80,6 +80,7 @@ type Queries struct {
 
 type APNS interface {
 	SendNotification(notification notifications.Notification) error
+	SendFollowChangeNotification(followChange domain.FollowChange, apnsToken domain.APNSToken) error
 }
 
 type EventOrError struct {

service/app/follow_change_puller.go

@@ -4,53 +4,96 @@ import (
 	"context"
 	"time"
 
+	"github.com/boreq/errors"
 	"github.com/planetary-social/go-notification-service/internal/logging"
 )
 
 type FollowChangePuller struct {
 	externalFollowChangeSubscriber ExternalFollowChangeSubscriber
+	apns                           APNS
+	queries                        Queries
 	logger                         logging.Logger
 	metrics                        Metrics
 	counter                        int
 }
 
 func NewFollowChangePuller(
 	externalFollowChangeSubscriber ExternalFollowChangeSubscriber,
+	apns APNS,
+	queries Queries,
 	logger logging.Logger,
 	metrics Metrics,
 ) *FollowChangePuller {
 	return &FollowChangePuller{
 		externalFollowChangeSubscriber: externalFollowChangeSubscriber,
+		apns:                           apns,
+		queries:                        queries,
 		logger:                         logger.New("followChangePuller"),
 		metrics:                        metrics,
 		counter:                        0,
 	}
 }
 
+// Listens for messages from the follow-change pubsub and for each of them, if
+// they belong to one of our users, we send a notification
 func (f *FollowChangePuller) Run(ctx context.Context) error {
 	go f.storeMetricsLoop(ctx)
 
 	ch, err := f.externalFollowChangeSubscriber.Subscribe(ctx)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "error subscribing to follow changes")
 	}
 
-	for followChange := range ch {
-		f.logger.Debug().Message(followChange.String())
+	for {
+		select {
+		case followChange, ok := <-ch:
+			if !ok {
+				return nil // Channel closed, exit gracefully
+			}
 
-		f.counter += 1
-	}
+			f.logger.Debug().Message(followChange.String())
+
+			// TODO: for the moment, just send notifications to Daniel
+			if followChange.Followee.Hex() != "89ef92b9ebe6dc1e4ea398f6477f227e95429627b0a33dc89b640e137b256be5" {
+				f.logger.Debug().WithField("followee", followChange.Followee.Hex()).Message("ignoring follow change")
+				continue
+			}
+
+			tokens, err := f.queries.GetTokens.Handle(ctx, followChange.Followee)
+			if err != nil {
+				// Not one of our users, ignore
+				continue
+			}
+
+			for _, token := range tokens {
+				if err := f.apns.SendFollowChangeNotification(*followChange, token); err != nil {
+					f.logger.Error().
+						WithField("token", token.Hex()).
+						WithField("followee", followChange.Followee.Hex()).
+						WithError(err).
+						Message("error sending follow change notification")
+					continue
+				}
+			}
 
-	return nil
+			f.counter += 1
+		case <-ctx.Done():
+			f.logger.Debug().Message("context canceled, shutting down FollowChangePuller")
+			return nil
+		}
+	}
 }
 
 func (f *FollowChangePuller) storeMetricsLoop(ctx context.Context) {
-	for {
-		f.storeMetrics()
+	ticker := time.NewTicker(storeMetricsEvery)
+	defer ticker.Stop()
 
+	for {
 		select {
-		case <-time.After(storeMetricsEvery):
+		case <-ticker.C:
+			f.storeMetrics()
 		case <-ctx.Done():
+			f.logger.Debug().Message("context canceled, stopping metrics loop")
 			return
 		}
 	}