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