its for when you want to get like notifications for your reposts
ptr.pet
1package main
2
3import (
4 "context"
5 "encoding/json"
6 "log"
7 "log/slog"
8 "net/http"
9 "sync/atomic"
10 "time"
11
12 "github.com/bluesky-social/indigo/api/bsky"
13 "github.com/bluesky-social/indigo/atproto/syntax"
14 "github.com/bluesky-social/indigo/xrpc"
15 "github.com/bluesky-social/jetstream/pkg/models"
16 "github.com/cornelk/hashmap"
17 "github.com/google/uuid"
18 "github.com/gorilla/mux"
19 "github.com/gorilla/websocket"
20)
21
22type Set[T comparable] map[T]struct{}
23
24const ListenTypeNone = "none"
25const ListenTypeFollows = "follows"
26
27type SubscriberData struct {
28 forActor syntax.DID
29 conn *websocket.Conn
30 listenType string
31 listenTo Set[syntax.DID]
32}
33
34type ActorData struct {
35 targets *hashmap.Map[string, *SubscriberData]
36 likes *hashmap.Map[syntax.RecordKey, bsky.FeedLike]
37 follows *hashmap.Map[syntax.RecordKey, bsky.GraphFollow]
38 followsCursor atomic.Pointer[string]
39 profile *bsky.ActorDefs_ProfileViewDetailed
40 profileFetchedAt time.Time
41}
42
43type NotificationActor struct {
44 DID syntax.DID `json:"did"` // the DID of the actor that (un)liked the post
45 Profile *bsky.ActorDefs_ProfileViewDetailed `json:"profile"` // the detailed profile of the actor that (un)liked the post
46}
47
48type NotificationMessage struct {
49 Liked bool `json:"liked"` // whether the message was liked or unliked
50 Actor NotificationActor `json:"actor"` // information about the actor that (un)liked
51 Record bsky.FeedLike `json:"record"` // the raw like record
52 Time int64 `json:"time"` // when the like event came in
53}
54
55type SubscriberMessage struct {
56 Type string `json:"type"`
57 Content json.RawMessage `json:"content"`
58}
59
60type SubscriberUpdateListenTo struct {
61 ListenTo []syntax.DID `json:"listen_to"`
62}
63
64var (
65 // storing the subscriber data in both Should Be Fine
66 // we dont modify subscriber data at the same time in two places
67 subscribers = hashmap.New[string, *SubscriberData]()
68 actorData = hashmap.New[syntax.DID, *ActorData]()
69
70 likeStreams *StreamManager
71 followStreams *StreamManager
72
73 upgrader = websocket.Upgrader{
74 CheckOrigin: func(r *http.Request) bool {
75 return true
76 },
77 }
78
79 logger *slog.Logger
80)
81
82func getSubscriberDids() []string {
83 _dids := make(Set[string], subscribers.Len())
84 subscribers.Range(func(s string, sd *SubscriberData) bool {
85 _dids[string(sd.forActor)] = struct{}{}
86 return true
87 })
88 dids := make([]string, 0, len(_dids))
89 for k := range _dids {
90 dids = append(dids, k)
91 }
92 return dids
93}
94
95func getLikeDids() []string {
96 _dids := make(Set[string], subscribers.Len()*5000)
97 subscribers.Range(func(s string, sd *SubscriberData) bool {
98 for did := range sd.listenTo {
99 _dids[string(did)] = struct{}{}
100 }
101 return true
102 })
103 dids := make([]string, 0, len(_dids))
104 for k := range _dids {
105 dids = append(dids, k)
106 }
107 return dids
108}
109
110func getActorData(did syntax.DID) *ActorData {
111 ud, _ := actorData.GetOrInsert(did, &ActorData{
112 targets: hashmap.New[string, *SubscriberData](),
113 likes: hashmap.New[syntax.RecordKey, bsky.FeedLike](),
114 follows: hashmap.New[syntax.RecordKey, bsky.GraphFollow](),
115 })
116 return ud
117}
118
119func markActorForLikes(sid string, sd *SubscriberData, did syntax.DID) {
120 ud := getActorData(did)
121 ud.targets.Insert(sid, sd)
122}
123
124func unmarkActorForLikes(sid string, did syntax.DID) {
125 if ud, exists := actorData.Get(did); exists {
126 ud.targets.Del(sid)
127 }
128}
129
130func main() {
131 logger = slog.Default()
132
133 likeStreams = NewStreamManager(logger, "like-tracker", HandleLikeEvent, getLikeStreamOpts)
134 followStreams = NewStreamManager(logger, "subscriber", HandleFollowEvent, getFollowStreamOpts)
135
136 r := mux.NewRouter()
137 r.HandleFunc("/subscribe/{did}", handleSubscribe).Methods("GET")
138
139 log.Println("server starting on :8080")
140 if err := http.ListenAndServe(":8080", r); err != nil {
141 log.Fatalf("error while serving: %s", err)
142 }
143}
144
145func handleSubscribe(w http.ResponseWriter, r *http.Request) {
146 vars := mux.Vars(r)
147 did, err := syntax.ParseDID(vars["did"])
148 if err != nil {
149 http.Error(w, "not a valid did", http.StatusBadRequest)
150 return
151 }
152 sid := uuid.New().String()
153
154 query := r.URL.Query()
155 listenType := query.Get("listenTo")
156 if len(listenType) == 0 {
157 listenType = ListenTypeFollows
158 }
159
160 logger := logger.With("did", did, "subscriberId", sid)
161
162 conn, err := upgrader.Upgrade(w, r, nil)
163 if err != nil {
164 logger.Error("WebSocket upgrade failed", "error", err)
165 return
166 }
167 defer conn.Close()
168
169 logger.Info("new subscriber")
170
171 pdsURI, err := findUserPDS(r.Context(), did)
172 if err != nil {
173 logger.Error("cant resolve user pds", "error", err)
174 return
175 }
176 logger = logger.With("pds", pdsURI)
177
178 xrpcClient := &xrpc.Client{
179 Host: pdsURI,
180 }
181
182 ud := getActorData(did)
183 sd := &SubscriberData{
184 forActor: did,
185 conn: conn,
186 listenType: listenType,
187 }
188
189 switch listenType {
190 case ListenTypeFollows:
191 follows, err := fetchFollows(r.Context(), xrpcClient, ud.followsCursor.Load(), did)
192 if err != nil {
193 logger.Error("error fetching follows", "error", err)
194 return
195 }
196 sd.listenTo = make(Set[syntax.DID])
197 // use we have stored
198 ud.follows.Range(func(rk syntax.RecordKey, f bsky.GraphFollow) bool {
199 sd.listenTo[syntax.DID(f.Subject)] = struct{}{}
200 return true
201 })
202 if len(follows) > 0 {
203 // store cursor for later requests so we dont have to fetch the whole thing again
204 ud.followsCursor.Store((*string)(&follows[len(follows)-1].rkey))
205 for _, f := range follows {
206 ud.follows.Insert(f.rkey, f.follow)
207 sd.listenTo[syntax.DID(f.follow.Subject)] = struct{}{}
208 }
209 }
210 logger.Info("fetched follows")
211 case ListenTypeNone:
212 sd.listenTo = make(Set[syntax.DID])
213 default:
214 http.Error(w, "invalid listen type", http.StatusBadRequest)
215 return
216 }
217
218 subscribers.Set(sid, sd)
219 for listenDid := range sd.listenTo {
220 markActorForLikes(sid, sd, listenDid)
221 }
222 updateStreamOpts()
223 // delete subscriber after we are done
224 defer func() {
225 for listenDid := range sd.listenTo {
226 unmarkActorForLikes(sid, listenDid)
227 }
228 subscribers.Del(sid)
229 updateStreamOpts()
230 }()
231
232 logger.Info("serving subscriber")
233
234 for {
235 var msg SubscriberMessage
236 err := conn.ReadJSON(&msg)
237 if err != nil {
238 logger.Info("WebSocket connection closed", "error", err)
239 break
240 }
241 switch msg.Type {
242 case "update_listen_to":
243 // only allow this if we arent managing listen to
244 if sd.listenType != ListenTypeNone {
245 continue
246 }
247
248 var innerMsg SubscriberUpdateListenTo
249 if err := json.Unmarshal(msg.Content, &innerMsg); err != nil {
250 logger.Info("invalid message", "error", err)
251 break
252 }
253
254 // remove all current listens and add the ones the user requested
255 for listenDid := range sd.listenTo {
256 unmarkActorForLikes(sid, listenDid)
257 delete(sd.listenTo, listenDid)
258 }
259 for _, listenDid := range innerMsg.ListenTo {
260 sd.listenTo[listenDid] = struct{}{}
261 markActorForLikes(sid, sd, listenDid)
262 }
263
264 updateStreamOpts()
265 }
266 }
267}
268
269func getLikeStreamOpts() models.SubscriberOptionsUpdatePayload {
270 return models.SubscriberOptionsUpdatePayload{
271 WantedCollections: []string{"app.bsky.feed.like"},
272 WantedDIDs: getLikeDids(),
273 }
274}
275
276func getFollowStreamOpts() models.SubscriberOptionsUpdatePayload {
277 return models.SubscriberOptionsUpdatePayload{
278 WantedCollections: []string{"app.bsky.graph.follow"},
279 WantedDIDs: getSubscriberDids(),
280 }
281}
282
283func updateStreamOpts() {
284 likeStreams.updateOpts()
285 followStreams.updateOpts()
286}
287
288func HandleLikeEvent(ctx context.Context, event *models.Event) error {
289 if event == nil || event.Commit == nil {
290 return nil
291 }
292
293 byDid := syntax.DID(event.Did)
294 // skip handling event if its not from a source we are listening to
295 ud, exists := actorData.Get(byDid)
296 if !exists || ud.targets.Len() == 0 {
297 return nil
298 }
299
300 logger := logger.With("actor", byDid, "type", "like")
301
302 deleted := event.Commit.Operation == models.CommitOperationDelete
303 rkey := syntax.RecordKey(event.Commit.RKey)
304
305 var like bsky.FeedLike
306 if deleted {
307 if l, exists := ud.likes.Get(rkey); exists {
308 like = l
309 defer ud.likes.Del(rkey)
310 } else {
311 logger.Error("like record not found", "rkey", rkey)
312 return nil
313 }
314 } else if err := unmarshalEvent(event, &like); err != nil {
315 return nil
316 }
317
318 // if there is no via it means its not a repost anyway
319 if like.Via == nil {
320 return nil
321 }
322
323 // store for later when it gets deleted so we can fetch the record
324 if !deleted {
325 ud.likes.Insert(rkey, like)
326 }
327
328 repostURI := syntax.ATURI(like.Via.Uri)
329 // if not a repost we dont care
330 if repostURI.Collection() != "app.bsky.feed.repost" {
331 return nil
332 }
333 reposterDID, err := repostURI.Authority().AsDID()
334 if err != nil {
335 return err
336 }
337 ud.targets.Range(func(sid string, sd *SubscriberData) bool {
338 if sd.forActor != reposterDID {
339 return true
340 }
341
342 if ud.profile == nil || time.Since(ud.profileFetchedAt) > time.Hour*24 {
343 profile, err := fetchProfile(ctx, byDid)
344 if err != nil {
345 logger.Error("cant fetch profile", "error", err)
346 } else {
347 ud.profile = profile
348 ud.profileFetchedAt = time.Now()
349 }
350 }
351
352 notification := NotificationMessage{
353 Liked: !deleted,
354 Actor: NotificationActor{
355 DID: byDid,
356 Profile: ud.profile,
357 },
358 Record: like,
359 Time: event.TimeUS,
360 }
361
362 if err := sd.conn.WriteJSON(notification); err != nil {
363 logger.Error("failed to send notification", "error", err)
364 }
365 return true
366 })
367
368 return nil
369}
370
371func HandleFollowEvent(ctx context.Context, event *models.Event) error {
372 if event == nil || event.Commit == nil {
373 return nil
374 }
375
376 byDid := syntax.DID(event.Did)
377 ud, exists := actorData.Get(byDid)
378 if !exists || ud.targets.Len() == 0 {
379 return nil
380 }
381
382 deleted := event.Commit.Operation == models.CommitOperationDelete
383 rkey := syntax.RecordKey(event.Commit.RKey)
384
385 switch event.Commit.Collection {
386 case "app.bsky.graph.follow":
387 var r bsky.GraphFollow
388 if deleted {
389 if f, exists := ud.follows.Get(rkey); exists {
390 r = f
391 } else {
392 // most likely no ListenTypeFollows subscriber attached on actor
393 logger.Warn("follow record not found", "rkey", rkey, "actor", byDid)
394 return nil
395 }
396 ud.follows.Del(rkey)
397 } else {
398 if err := unmarshalEvent(event, &r); err != nil {
399 return nil
400 }
401 ud.follows.Insert(rkey, r)
402 }
403
404 ud.targets.Range(func(sid string, sd *SubscriberData) bool {
405 // if we arent managing then we dont need to update anything
406 if sd.listenType != ListenTypeFollows {
407 return true
408 }
409 subjectDid := syntax.DID(r.Subject)
410 if deleted {
411 unmarkActorForLikes(sid, subjectDid)
412 delete(sd.listenTo, subjectDid)
413 } else {
414 sd.listenTo[subjectDid] = struct{}{}
415 markActorForLikes(sid, sd, subjectDid)
416 }
417 return true
418 })
419 }
420
421 return nil
422}
423
424func unmarshalEvent[v any](event *models.Event, val *v) error {
425 if err := json.Unmarshal(event.Commit.Record, val); err != nil {
426 logger.Error("cant unmarshal record", "error", err, "raw", event.Commit.Record)
427 return err
428 }
429 return nil
430}