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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 31 : ReceiptData(this.originServerTs, {this.threadId});
62 : }
63 :
64 : class ReceiptEventContent {
65 : Map<String, Map<ReceiptType, Map<String, ReceiptData>>> receipts;
66 31 : ReceiptEventContent(this.receipts);
67 :
68 31 : 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 31 : final Map<String, Map<ReceiptType, Map<String, ReceiptData>>> receipts = {};
98 62 : for (final eventIdEntry in json.entries) {
99 31 : final eventId = eventIdEntry.key;
100 31 : final contentForEventId = eventIdEntry.value;
101 :
102 62 : if (!eventId.startsWith('\$') || contentForEventId is! Map) continue;
103 :
104 62 : for (final receiptTypeEntry in contentForEventId.entries) {
105 62 : if (receiptTypeEntry.key is! String) continue;
106 :
107 62 : final receiptType = ReceiptType.values.fromString(receiptTypeEntry.key);
108 31 : final contentForReceiptType = receiptTypeEntry.value;
109 :
110 31 : if (receiptType == null || contentForReceiptType is! Map) continue;
111 :
112 62 : for (final userIdEntry in contentForReceiptType.entries) {
113 31 : final userId = userIdEntry.key;
114 31 : final receiptContent = userIdEntry.value;
115 :
116 31 : if (userId is! String ||
117 31 : !userId.isValidMatrixId ||
118 31 : receiptContent is! Map) continue;
119 :
120 31 : final ts = receiptContent['ts'];
121 31 : final threadId = receiptContent['thread_id'];
122 :
123 32 : if (ts is int && (threadId == null || threadId is String)) {
124 155 : ((receipts[eventId] ??= {})[receiptType] ??= {})[userId] =
125 31 : ReceiptData(ts, threadId: threadId);
126 : }
127 : }
128 : }
129 : }
130 :
131 31 : return ReceiptEventContent(receipts);
132 : }
133 : }
134 :
135 : class LatestReceiptStateData {
136 : String eventId;
137 : int ts;
138 :
139 3 : DateTime get timestamp => DateTime.fromMillisecondsSinceEpoch(ts);
140 :
141 31 : LatestReceiptStateData(this.eventId, this.ts);
142 :
143 2 : factory LatestReceiptStateData.fromJson(Map<String, dynamic> json) {
144 6 : return LatestReceiptStateData(json['e'], json['ts']);
145 : }
146 :
147 62 : Map<String, dynamic> toJson() => {
148 : // abbreviated names, because we will store a lot of these.
149 31 : 'e': eventId,
150 31 : 'ts': ts,
151 : };
152 : }
153 :
154 : class LatestReceiptStateForTimeline {
155 : LatestReceiptStateData? ownPrivate;
156 : LatestReceiptStateData? ownPublic;
157 : LatestReceiptStateData? latestOwnReceipt;
158 :
159 : Map<String, LatestReceiptStateData> otherUsers;
160 :
161 31 : LatestReceiptStateForTimeline({
162 : required this.ownPrivate,
163 : required this.ownPublic,
164 : required this.latestOwnReceipt,
165 : required this.otherUsers,
166 : });
167 :
168 1 : factory LatestReceiptStateForTimeline.empty() =>
169 1 : LatestReceiptStateForTimeline(
170 : ownPrivate: null,
171 : ownPublic: null,
172 : latestOwnReceipt: null,
173 1 : otherUsers: {});
174 :
175 31 : factory LatestReceiptStateForTimeline.fromJson(Map<String, dynamic> json) {
176 31 : final private = json['private'];
177 31 : final public = json['public'];
178 31 : final latest = json['latest'];
179 31 : final Map<String, dynamic>? others = json['others'];
180 :
181 : final Map<String, LatestReceiptStateData> byUser = others
182 8 : ?.map((k, v) => MapEntry(k, LatestReceiptStateData.fromJson(v))) ??
183 31 : {};
184 :
185 31 : return LatestReceiptStateForTimeline(
186 : ownPrivate:
187 1 : private != null ? LatestReceiptStateData.fromJson(private) : null,
188 : ownPublic:
189 1 : public != null ? LatestReceiptStateData.fromJson(public) : null,
190 : latestOwnReceipt:
191 1 : latest != null ? LatestReceiptStateData.fromJson(latest) : null,
192 : otherUsers: byUser,
193 : );
194 : }
195 :
196 62 : Map<String, dynamic> toJson() => {
197 34 : if (ownPrivate != null) 'private': ownPrivate!.toJson(),
198 34 : if (ownPublic != null) 'public': ownPublic!.toJson(),
199 34 : if (latestOwnReceipt != null) 'latest': latestOwnReceipt!.toJson(),
200 186 : 'others': otherUsers.map((k, v) => MapEntry(k, v.toJson())),
201 : };
202 : }
203 :
204 : class LatestReceiptState {
205 : static const eventType = 'com.famedly.receipts_state';
206 :
207 : /// Receipts for no specific thread
208 : LatestReceiptStateForTimeline global;
209 :
210 : /// Receipt for the "main" thread, which is the global timeline without any thread events
211 : LatestReceiptStateForTimeline? mainThread;
212 :
213 : /// Receipts inside threads
214 : Map<String, LatestReceiptStateForTimeline> byThread;
215 :
216 31 : LatestReceiptState({
217 : required this.global,
218 : this.mainThread,
219 : this.byThread = const {},
220 : });
221 :
222 31 : factory LatestReceiptState.fromJson(Map<String, dynamic> json) {
223 62 : final global = json['global'] ?? <String, dynamic>{};
224 62 : final Map<String, dynamic> main = json['main'] ?? <String, dynamic>{};
225 62 : final Map<String, dynamic> byThread = json['thread'] ?? <String, dynamic>{};
226 :
227 31 : return LatestReceiptState(
228 31 : global: LatestReceiptStateForTimeline.fromJson(global),
229 : mainThread:
230 31 : main.isNotEmpty ? LatestReceiptStateForTimeline.fromJson(main) : null,
231 31 : byThread: byThread.map(
232 3 : (k, v) => MapEntry(k, LatestReceiptStateForTimeline.fromJson(v))),
233 : );
234 : }
235 :
236 62 : Map<String, dynamic> toJson() => {
237 93 : 'global': global.toJson(),
238 31 : if (mainThread != null) 'main': mainThread!.toJson(),
239 62 : if (byThread.isNotEmpty)
240 6 : 'thread': byThread.map((k, v) => MapEntry(k, v.toJson())),
241 : };
242 :
243 31 : Future<void> update(
244 : ReceiptEventContent content,
245 : Room room,
246 : ) async {
247 31 : final List<LatestReceiptStateForTimeline> updatedTimelines = [];
248 62 : final ownUserid = room.client.userID!;
249 :
250 93 : content.receipts.forEach((eventId, receiptsByType) {
251 62 : receiptsByType.forEach((receiptType, receiptsByUser) {
252 62 : receiptsByUser.forEach((user, receipt) {
253 : LatestReceiptStateForTimeline? timeline;
254 31 : final threadId = receipt.threadId;
255 31 : if (threadId == 'main') {
256 0 : timeline = (mainThread ??= LatestReceiptStateForTimeline.empty());
257 : } else if (threadId != null) {
258 : timeline =
259 3 : (byThread[threadId] ??= LatestReceiptStateForTimeline.empty());
260 : } else {
261 31 : timeline = global;
262 : }
263 :
264 : final receiptData =
265 62 : LatestReceiptStateData(eventId, receipt.originServerTs);
266 31 : if (user == ownUserid) {
267 1 : if (receiptType == ReceiptType.mReadPrivate) {
268 1 : timeline.ownPrivate = receiptData;
269 1 : } else if (receiptType == ReceiptType.mRead) {
270 1 : timeline.ownPublic = receiptData;
271 : }
272 1 : updatedTimelines.add(timeline);
273 : } else {
274 62 : timeline.otherUsers[user] = receiptData;
275 : }
276 : });
277 : });
278 : });
279 :
280 : // set the latest receipt to the one furthest down in the timeline, or if we don't know that, the newest ts.
281 31 : if (updatedTimelines.isEmpty) return;
282 :
283 3 : final eventOrder = await room.client.database?.getEventIdList(room) ?? [];
284 :
285 2 : for (final timeline in updatedTimelines) {
286 5 : if (timeline.ownPrivate?.eventId == timeline.ownPublic?.eventId) {
287 1 : if (timeline.ownPrivate != null) {
288 2 : timeline.latestOwnReceipt = timeline.ownPrivate;
289 : }
290 : continue;
291 : }
292 :
293 1 : final public = timeline.ownPublic;
294 1 : final private = timeline.ownPrivate;
295 :
296 : if (private == null) {
297 1 : timeline.latestOwnReceipt = public;
298 : } else if (public == null) {
299 0 : timeline.latestOwnReceipt = private;
300 : } else {
301 2 : final privatePos = eventOrder.indexOf(private.eventId);
302 2 : final publicPos = eventOrder.indexOf(public.eventId);
303 :
304 1 : if (publicPos < 0 ||
305 1 : privatePos <= publicPos ||
306 0 : (privatePos < 0 && private.ts > public.ts)) {
307 1 : timeline.latestOwnReceipt = private;
308 : } else {
309 0 : timeline.latestOwnReceipt = public;
310 : }
311 : }
312 : }
313 : }
314 : }
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