1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
// Copyright 2024 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Facilities to edit existing events.

use std::future::Future;

use matrix_sdk_base::{deserialized_responses::SyncTimelineEvent, SendOutsideWasm};
use ruma::{
    events::{
        poll::unstable_start::{
            ReplacementUnstablePollStartEventContent, UnstablePollStartContentBlock,
            UnstablePollStartEventContent,
        },
        room::message::{Relation, ReplacementMetadata, RoomMessageEventContentWithoutRelation},
        AnyMessageLikeEvent, AnyMessageLikeEventContent, AnySyncMessageLikeEvent,
        AnySyncTimelineEvent, AnyTimelineEvent, MessageLikeEvent, SyncMessageLikeEvent,
    },
    EventId, RoomId, UserId,
};
use thiserror::Error;
use tracing::{debug, instrument, trace, warn};

use crate::Room;

/// The new content that will replace the previous event's content.
pub enum EditedContent {
    /// The content is a `m.room.message`.
    RoomMessage(RoomMessageEventContentWithoutRelation),

    /// The content is a new poll start.
    PollStart {
        /// New fallback text for the poll.
        fallback_text: String,
        /// New start block for the poll.
        new_content: UnstablePollStartContentBlock,
    },
}

#[cfg(not(tarpaulin_include))]
impl std::fmt::Debug for EditedContent {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::RoomMessage(_) => f.debug_tuple("RoomMessage").finish(),
            Self::PollStart { .. } => f.debug_tuple("PollStart").finish(),
        }
    }
}

/// An error occurring while editing an event.
#[derive(Debug, Error)]
pub enum EditError {
    /// We tried to edit a state event, which is not allowed, per spec.
    #[error("State events can't be edited")]
    StateEvent,

    /// We tried to edit an event which sender isn't the current user, which is
    /// forbidden, per spec.
    #[error("You're not the author of the event you'd like to edit.")]
    NotAuthor,

    /// We couldn't fetch the remote event with /room/event.
    #[error("Couldn't fetch the remote event: {0}")]
    Fetch(Box<crate::Error>),

    /// We couldn't properly deserialize the target event.
    #[error(transparent)]
    Deserialize(#[from] serde_json::Error),

    /// We tried to edit an event of type A with content of type B.
    #[error("The original event type ({target}) isn't the same as the parameter's new content type ({new_content})")]
    IncompatibleEditType {
        /// The type of the target event.
        target: String,
        /// The type of the new content.
        new_content: &'static str,
    },
}

impl Room {
    /// Create a new edit event for the target event id with the new content.
    ///
    /// The event can then be sent with [`Room::send`] or a
    /// [`crate::send_queue::RoomSendQueue`].
    #[instrument(skip(self, new_content), fields(room = %self.room_id()))]
    pub async fn make_edit_event(
        &self,
        event_id: &EventId,
        new_content: EditedContent,
    ) -> Result<AnyMessageLikeEventContent, EditError> {
        make_edit_event(self, self.room_id(), self.own_user_id(), event_id, new_content).await
    }
}

trait EventSource {
    fn get_event(
        &self,
        event_id: &EventId,
    ) -> impl Future<Output = Result<SyncTimelineEvent, EditError>> + SendOutsideWasm;
}

impl<'a> EventSource for &'a Room {
    async fn get_event(&self, event_id: &EventId) -> Result<SyncTimelineEvent, EditError> {
        match self.event_cache().await {
            Ok((event_cache, _drop_handles)) => {
                if let Some(event) = event_cache.event(event_id).await {
                    return Ok(event);
                }
                // Fallthrough: try with /event.
            }

            Err(err) => {
                debug!("error when getting the event cache: {err}");
            }
        }

        trace!("trying with /event now");
        self.event(event_id, None)
            .await
            .map(Into::into)
            .map_err(|err| EditError::Fetch(Box::new(err)))
    }
}

async fn make_edit_event<S: EventSource>(
    source: S,
    room_id: &RoomId,
    own_user_id: &UserId,
    event_id: &EventId,
    new_content: EditedContent,
) -> Result<AnyMessageLikeEventContent, EditError> {
    let target = source.get_event(event_id).await?;

    let event = target.raw().deserialize().map_err(EditError::Deserialize)?;

    // The event must be message-like.
    let AnySyncTimelineEvent::MessageLike(message_like_event) = event else {
        return Err(EditError::StateEvent);
    };

    // The event must have been sent by the current user.
    if message_like_event.sender() != own_user_id {
        return Err(EditError::NotAuthor);
    }

    match new_content {
        EditedContent::RoomMessage(new_content) => {
            // Handle edits of m.room.message.
            let AnySyncMessageLikeEvent::RoomMessage(SyncMessageLikeEvent::Original(original)) =
                message_like_event
            else {
                return Err(EditError::IncompatibleEditType {
                    target: message_like_event.event_type().to_string(),
                    new_content: "room message",
                });
            };

            let mentions = original.content.mentions.clone();

            // Do a best effort at finding the replied-to original event.
            let replied_to_sync_timeline_event =
                if let Some(Relation::Reply { in_reply_to }) = original.content.relates_to {
                    source
                        .get_event(&in_reply_to.event_id)
                        .await
                        .map_err(|err| {
                            warn!("couldn't fetch the replied-to event, when editing: {err}");
                            err
                        })
                        .ok()
                } else {
                    None
                };

            let replied_to_original_room_msg = replied_to_sync_timeline_event
                .and_then(|sync_timeline_event| {
                    sync_timeline_event
                        .raw()
                        .deserialize()
                        .map_err(|err| warn!("unable to deserialize replied-to event: {err}"))
                        .ok()
                })
                .and_then(|event| {
                    if let AnyTimelineEvent::MessageLike(AnyMessageLikeEvent::RoomMessage(
                        MessageLikeEvent::Original(original),
                    )) = event.into_full_event(room_id.to_owned())
                    {
                        Some(original)
                    } else {
                        None
                    }
                });

            Ok(new_content
                .make_replacement(
                    ReplacementMetadata::new(event_id.to_owned(), mentions),
                    replied_to_original_room_msg.as_ref(),
                )
                .into())
        }

        EditedContent::PollStart { fallback_text, new_content } => {
            if !matches!(
                message_like_event,
                AnySyncMessageLikeEvent::UnstablePollStart(SyncMessageLikeEvent::Original(_))
            ) {
                return Err(EditError::IncompatibleEditType {
                    target: message_like_event.event_type().to_string(),
                    new_content: "poll start",
                });
            }

            let replacement = UnstablePollStartEventContent::Replacement(
                ReplacementUnstablePollStartEventContent::plain_text(
                    fallback_text,
                    new_content,
                    event_id.to_owned(),
                ),
            );

            Ok(replacement.into())
        }
    }
}

#[cfg(test)]
mod tests {
    use std::collections::BTreeMap;

    use assert_matches2::{assert_let, assert_matches};
    use matrix_sdk_base::deserialized_responses::SyncTimelineEvent;
    use matrix_sdk_test::async_test;
    use ruma::{
        event_id,
        events::{
            room::message::{Relation, RoomMessageEventContentWithoutRelation},
            AnyMessageLikeEventContent, AnySyncTimelineEvent,
        },
        room_id,
        serde::Raw,
        user_id, EventId, OwnedEventId,
    };
    use serde_json::json;

    use super::{make_edit_event, EditError, EventSource};
    use crate::{room::edit::EditedContent, test_utils::events::EventFactory};

    #[derive(Default)]
    struct TestEventCache {
        events: BTreeMap<OwnedEventId, SyncTimelineEvent>,
    }

    impl EventSource for TestEventCache {
        async fn get_event(&self, event_id: &EventId) -> Result<SyncTimelineEvent, EditError> {
            Ok(self.events.get(event_id).unwrap().clone())
        }
    }

    #[async_test]
    async fn test_edit_state_event() {
        let event_id = event_id!("$1");
        let own_user_id = user_id!("@me:saucisse.bzh");

        let mut cache = TestEventCache::default();

        cache.events.insert(
            event_id.to_owned(),
            // TODO: use the EventFactory for state events too.
            SyncTimelineEvent::new(
                Raw::<AnySyncTimelineEvent>::from_json_string(
                    json!({
                        "content": {
                            "name": "The room name"
                        },
                        "event_id": event_id,
                        "sender": own_user_id,
                        "state_key": "",
                        "origin_server_ts": 1,
                        "type": "m.room.name",
                    })
                    .to_string(),
                )
                .unwrap(),
            ),
        );

        let room_id = room_id!("!galette:saucisse.bzh");
        let new_content = RoomMessageEventContentWithoutRelation::text_plain("the edit");

        assert_matches!(
            make_edit_event(
                cache,
                room_id,
                own_user_id,
                event_id,
                EditedContent::RoomMessage(new_content),
            )
            .await,
            Err(EditError::StateEvent)
        );
    }

    #[async_test]
    async fn test_edit_event_other_user() {
        let event_id = event_id!("$1");
        let f = EventFactory::new();

        let mut cache = TestEventCache::default();

        cache.events.insert(
            event_id.to_owned(),
            f.text_msg("hi").event_id(event_id).sender(user_id!("@other:saucisse.bzh")).into(),
        );

        let room_id = room_id!("!galette:saucisse.bzh");
        let own_user_id = user_id!("@me:saucisse.bzh");
        let new_content = RoomMessageEventContentWithoutRelation::text_plain("the edit");

        assert_matches!(
            make_edit_event(
                cache,
                room_id,
                own_user_id,
                event_id,
                EditedContent::RoomMessage(new_content),
            )
            .await,
            Err(EditError::NotAuthor)
        );
    }

    #[async_test]
    async fn test_make_edit_event_success() {
        let event_id = event_id!("$1");
        let own_user_id = user_id!("@me:saucisse.bzh");

        let mut cache = TestEventCache::default();
        let f = EventFactory::new();
        cache.events.insert(
            event_id.to_owned(),
            f.text_msg("hi").event_id(event_id).sender(own_user_id).into(),
        );

        let room_id = room_id!("!galette:saucisse.bzh");
        let new_content = RoomMessageEventContentWithoutRelation::text_plain("the edit");

        let edit_event = make_edit_event(
            cache,
            room_id,
            own_user_id,
            event_id,
            EditedContent::RoomMessage(new_content),
        )
        .await
        .unwrap();

        assert_let!(AnyMessageLikeEventContent::RoomMessage(msg) = &edit_event);
        // This is the fallback text, for clients not supporting edits.
        assert_eq!(msg.body(), "* the edit");
        assert_let!(Some(Relation::Replacement(repl)) = &msg.relates_to);

        assert_eq!(repl.event_id, event_id);
        assert_eq!(repl.new_content.msgtype.body(), "the edit");
    }

    #[async_test]
    async fn test_make_edit_event_success_with_response() {
        let event_id = event_id!("$1");
        let resp_event_id = event_id!("$resp");
        let own_user_id = user_id!("@me:saucisse.bzh");

        let mut cache = TestEventCache::default();
        let f = EventFactory::new();

        cache.events.insert(
            event_id.to_owned(),
            f.text_msg("hi").event_id(event_id).sender(user_id!("@steb:saucisse.bzh")).into(),
        );

        cache.events.insert(
            resp_event_id.to_owned(),
            f.text_msg("you're the hi")
                .event_id(resp_event_id)
                .sender(own_user_id)
                .reply_to(event_id)
                .into(),
        );

        let room_id = room_id!("!galette:saucisse.bzh");
        let new_content = RoomMessageEventContentWithoutRelation::text_plain("uh i mean hi too");

        let edit_event = make_edit_event(
            cache,
            room_id,
            own_user_id,
            resp_event_id,
            EditedContent::RoomMessage(new_content),
        )
        .await
        .unwrap();

        assert_let!(AnyMessageLikeEventContent::RoomMessage(msg) = &edit_event);
        // This is the fallback text, for clients not supporting edits.
        assert_eq!(
            msg.body(),
            r#"> <@steb:saucisse.bzh> hi

* uh i mean hi too"#
        );
        assert_let!(Some(Relation::Replacement(repl)) = &msg.relates_to);

        assert_eq!(repl.event_id, resp_event_id);
        assert_eq!(repl.new_content.msgtype.body(), "uh i mean hi too");
    }
}