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1 : /*
2 : * Famedly Matrix SDK
3 : * Copyright (C) 2020, 2021, 2023 Famedly GmbH
4 : *
5 : * This program is free software: you can redistribute it and/or modify
6 : * it under the terms of the GNU Affero General Public License as
7 : * published by the Free Software Foundation, either version 3 of the
8 : * License, or (at your option) any later version.
9 : *
10 : * This program is distributed in the hope that it will be useful,
11 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 : * GNU Affero General Public License for more details.
14 : *
15 : * You should have received a copy of the GNU Affero General Public License
16 : * along with this program. If not, see <https://www.gnu.org/licenses/>.
17 : */
18 :
19 : import 'package:matrix/matrix.dart';
20 :
21 : // Receipts are pretty complicated nowadays. We basicaly have 3 different aspects, that we need to multiplex together:
22 : // 1. A receipt can be public or private. Currently clients can send either a public one, a private one or both. This means you have 2 receipts for your own user and no way to know, which one is ahead!
23 : // 2. A receipt can be for the normal timeline, but with threads they can also be for the main timeline (which is messages without thread ids) and for threads. So we have have 3 options there basically, with the last one being a thread for each thread id!
24 : // 3. Edits can make the timeline non-linear, so receipts don't match the visual order.
25 : // Additionally of course timestamps are usually not reliable, but we can probably assume they are correct for the same user unless their server had wrong clocks in between.
26 : //
27 : // So how do we solve that? Users of the SDK usually do one of these operations:
28 : // - Check if the current user has read the last event in a room (usually in the global timeline, but also possibly in the main thread or a specific thread)
29 : // - Check if the current users receipt is before or after the current event
30 : // - List users that have read up to a certain point (possibly in a specific timeline?)
31 : //
32 : // One big simplification we could do, would be to always assume our own user sends a private receipt with their public one. This won't play nicely with other SDKs, but it would simplify our work a lot.
33 : // If we don't do that, we have to compare receipts when updating them. This can be very annoying, because we can only compare event ids, if we have stored both of them, which we often have not.
34 : // If we fall back to the timestamp then it will break if a user ever has a client sending laggy public receipts, i.e. sends public receipts at a later point for previous events, because it will move the read marker back.
35 : // Here is how Element solves it: https://github.com/matrix-org/matrix-js-sdk/blob/da03c3b529576a8fcde6f2c9a171fa6cca012830/src/models/read-receipt.ts#L97
36 : // Luckily that is only an issue for our own events. We can also assume, that if we only have one event in the database, that it is newer.
37 :
38 : /// Represents a receipt.
39 : /// This [user] has read an event at the given [time].
40 : class Receipt {
41 : final User user;
42 : final DateTime time;
43 :
44 2 : const Receipt(this.user, this.time);
45 :
46 1 : @override
47 1 : bool operator ==(Object other) => (other is Receipt &&
48 3 : other.user == user &&
49 5 : other.time.millisecondsSinceEpoch == time.millisecondsSinceEpoch);
50 :
51 0 : @override
52 0 : int get hashCode => Object.hash(user, time);
53 : }
54 :
55 : class ReceiptData {
56 : int originServerTs;
57 : String? threadId;
58 :
59 0 : DateTime get timestamp => DateTime.fromMillisecondsSinceEpoch(originServerTs);
60 :
61 42 : ReceiptData(this.originServerTs, {this.threadId});
62 : }
63 :
64 : class ReceiptEventContent {
65 : Map<String, Map<ReceiptType, Map<String, ReceiptData>>> receipts;
66 42 : ReceiptEventContent(this.receipts);
67 :
68 42 : factory ReceiptEventContent.fromJson(Map<String, dynamic> json) {
69 : // Example data:
70 : // {
71 : // "$I": {
72 : // "m.read": {
73 : // "@user:example.org": {
74 : // "ts": 1661384801651,
75 : // "thread_id": "main" // because `I` is not in a thread, but is a threaded receipt
76 : // }
77 : // }
78 : // },
79 : // "$E": {
80 : // "m.read": {
81 : // "@user:example.org": {
82 : // "ts": 1661384801651,
83 : // "thread_id": "$A" // because `E` is in Thread `A`
84 : // }
85 : // }
86 : // },
87 : // "$D": {
88 : // "m.read": {
89 : // "@user:example.org": {
90 : // "ts": 1661384801651
91 : // // no `thread_id` because the receipt is *unthreaded*
92 : // }
93 : // }
94 : // }
95 : // }
96 :
97 42 : final Map<String, Map<ReceiptType, Map<String, ReceiptData>>> receipts = {};
98 84 : for (final eventIdEntry in json.entries) {
99 42 : final eventId = eventIdEntry.key;
100 42 : final contentForEventId = eventIdEntry.value;
101 :
102 84 : if (!eventId.startsWith('\$') || contentForEventId is! Map) continue;
103 :
104 84 : for (final receiptTypeEntry in contentForEventId.entries) {
105 84 : if (receiptTypeEntry.key is! String) continue;
106 :
107 84 : final receiptType = ReceiptType.values.fromString(receiptTypeEntry.key);
108 42 : final contentForReceiptType = receiptTypeEntry.value;
109 :
110 42 : if (receiptType == null || contentForReceiptType is! Map) continue;
111 :
112 84 : for (final userIdEntry in contentForReceiptType.entries) {
113 42 : final userId = userIdEntry.key;
114 42 : final receiptContent = userIdEntry.value;
115 :
116 42 : if (userId is! String ||
117 42 : !userId.isValidMatrixId ||
118 42 : receiptContent is! Map) {
119 : continue;
120 : }
121 :
122 42 : final ts = receiptContent['ts'];
123 42 : final threadId = receiptContent['thread_id'];
124 :
125 43 : if (ts is int && (threadId == null || threadId is String)) {
126 210 : ((receipts[eventId] ??= {})[receiptType] ??= {})[userId] =
127 42 : ReceiptData(ts, threadId: threadId);
128 : }
129 : }
130 : }
131 : }
132 :
133 42 : return ReceiptEventContent(receipts);
134 : }
135 : }
136 :
137 : class LatestReceiptStateData {
138 : String eventId;
139 : int ts;
140 :
141 3 : DateTime get timestamp => DateTime.fromMillisecondsSinceEpoch(ts);
142 :
143 42 : LatestReceiptStateData(this.eventId, this.ts);
144 :
145 2 : factory LatestReceiptStateData.fromJson(Map<String, dynamic> json) {
146 6 : return LatestReceiptStateData(json['e'], json['ts']);
147 : }
148 :
149 84 : Map<String, dynamic> toJson() => {
150 : // abbreviated names, because we will store a lot of these.
151 42 : 'e': eventId,
152 42 : 'ts': ts,
153 : };
154 : }
155 :
156 : class LatestReceiptStateForTimeline {
157 : LatestReceiptStateData? ownPrivate;
158 : LatestReceiptStateData? ownPublic;
159 : LatestReceiptStateData? latestOwnReceipt;
160 :
161 : Map<String, LatestReceiptStateData> otherUsers;
162 :
163 42 : LatestReceiptStateForTimeline({
164 : required this.ownPrivate,
165 : required this.ownPublic,
166 : required this.latestOwnReceipt,
167 : required this.otherUsers,
168 : });
169 :
170 1 : factory LatestReceiptStateForTimeline.empty() =>
171 1 : LatestReceiptStateForTimeline(
172 : ownPrivate: null,
173 : ownPublic: null,
174 : latestOwnReceipt: null,
175 1 : otherUsers: {},
176 : );
177 :
178 42 : factory LatestReceiptStateForTimeline.fromJson(Map<String, dynamic> json) {
179 42 : final private = json['private'];
180 42 : final public = json['public'];
181 42 : final latest = json['latest'];
182 42 : final Map<String, dynamic>? others = json['others'];
183 :
184 : final Map<String, LatestReceiptStateData> byUser = others
185 8 : ?.map((k, v) => MapEntry(k, LatestReceiptStateData.fromJson(v))) ??
186 42 : {};
187 :
188 42 : return LatestReceiptStateForTimeline(
189 : ownPrivate:
190 1 : private != null ? LatestReceiptStateData.fromJson(private) : null,
191 : ownPublic:
192 1 : public != null ? LatestReceiptStateData.fromJson(public) : null,
193 : latestOwnReceipt:
194 1 : latest != null ? LatestReceiptStateData.fromJson(latest) : null,
195 : otherUsers: byUser,
196 : );
197 : }
198 :
199 84 : Map<String, dynamic> toJson() => {
200 45 : if (ownPrivate != null) 'private': ownPrivate!.toJson(),
201 45 : if (ownPublic != null) 'public': ownPublic!.toJson(),
202 45 : if (latestOwnReceipt != null) 'latest': latestOwnReceipt!.toJson(),
203 252 : 'others': otherUsers.map((k, v) => MapEntry(k, v.toJson())),
204 : };
205 : }
206 :
207 : class LatestReceiptState {
208 : static const eventType = 'com.famedly.receipts_state';
209 :
210 : /// Receipts for no specific thread
211 : LatestReceiptStateForTimeline global;
212 :
213 : /// Receipt for the "main" thread, which is the global timeline without any thread events
214 : LatestReceiptStateForTimeline? mainThread;
215 :
216 : /// Receipts inside threads
217 : Map<String, LatestReceiptStateForTimeline> byThread;
218 :
219 42 : LatestReceiptState({
220 : required this.global,
221 : this.mainThread,
222 : this.byThread = const {},
223 : });
224 :
225 42 : factory LatestReceiptState.fromJson(Map<String, dynamic> json) {
226 84 : final global = json['global'] ?? <String, dynamic>{};
227 84 : final Map<String, dynamic> main = json['main'] ?? <String, dynamic>{};
228 84 : final Map<String, dynamic> byThread = json['thread'] ?? <String, dynamic>{};
229 :
230 42 : return LatestReceiptState(
231 42 : global: LatestReceiptStateForTimeline.fromJson(global),
232 : mainThread:
233 43 : main.isNotEmpty ? LatestReceiptStateForTimeline.fromJson(main) : null,
234 42 : byThread: byThread.map(
235 3 : (k, v) => MapEntry(k, LatestReceiptStateForTimeline.fromJson(v)),
236 : ),
237 : );
238 : }
239 :
240 84 : Map<String, dynamic> toJson() => {
241 126 : 'global': global.toJson(),
242 45 : if (mainThread != null) 'main': mainThread!.toJson(),
243 84 : if (byThread.isNotEmpty)
244 6 : 'thread': byThread.map((k, v) => MapEntry(k, v.toJson())),
245 : };
246 :
247 42 : Future<void> update(
248 : ReceiptEventContent content,
249 : Room room,
250 : ) async {
251 42 : final List<LatestReceiptStateForTimeline> updatedTimelines = [];
252 84 : final ownUserid = room.client.userID!;
253 :
254 126 : content.receipts.forEach((eventId, receiptsByType) {
255 84 : receiptsByType.forEach((receiptType, receiptsByUser) {
256 84 : receiptsByUser.forEach((user, receipt) {
257 : LatestReceiptStateForTimeline? timeline;
258 42 : final threadId = receipt.threadId;
259 42 : if (threadId == 'main') {
260 2 : timeline = (mainThread ??= LatestReceiptStateForTimeline.empty());
261 : } else if (threadId != null) {
262 : timeline =
263 3 : (byThread[threadId] ??= LatestReceiptStateForTimeline.empty());
264 : } else {
265 42 : timeline = global;
266 : }
267 :
268 : final receiptData =
269 84 : LatestReceiptStateData(eventId, receipt.originServerTs);
270 42 : if (user == ownUserid) {
271 1 : if (receiptType == ReceiptType.mReadPrivate) {
272 1 : timeline.ownPrivate = receiptData;
273 1 : } else if (receiptType == ReceiptType.mRead) {
274 1 : timeline.ownPublic = receiptData;
275 : }
276 1 : updatedTimelines.add(timeline);
277 : } else {
278 84 : timeline.otherUsers[user] = receiptData;
279 : }
280 : });
281 : });
282 : });
283 :
284 : // set the latest receipt to the one furthest down in the timeline, or if we don't know that, the newest ts.
285 42 : if (updatedTimelines.isEmpty) return;
286 :
287 3 : final eventOrder = await room.client.database.getEventIdList(room);
288 :
289 2 : for (final timeline in updatedTimelines) {
290 5 : if (timeline.ownPrivate?.eventId == timeline.ownPublic?.eventId) {
291 1 : if (timeline.ownPrivate != null) {
292 2 : timeline.latestOwnReceipt = timeline.ownPrivate;
293 : }
294 : continue;
295 : }
296 :
297 1 : final public = timeline.ownPublic;
298 1 : final private = timeline.ownPrivate;
299 :
300 : if (private == null) {
301 1 : timeline.latestOwnReceipt = public;
302 : } else if (public == null) {
303 0 : timeline.latestOwnReceipt = private;
304 : } else {
305 2 : final privatePos = eventOrder.indexOf(private.eventId);
306 2 : final publicPos = eventOrder.indexOf(public.eventId);
307 :
308 1 : if (publicPos < 0 ||
309 1 : privatePos <= publicPos ||
310 0 : (privatePos < 0 && private.ts > public.ts)) {
311 1 : timeline.latestOwnReceipt = private;
312 : } else {
313 0 : timeline.latestOwnReceipt = public;
314 : }
315 : }
316 : }
317 : }
318 : }
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