From 9fde835673d3a227fd3f9740edf17076a5e01a28 Mon Sep 17 00:00:00 2001
From: morguldir <morguldir@protonmail.com>
Date: Fri, 30 Aug 2024 18:23:42 +0200
Subject: [PATCH] syncv3: read receipts extension (MSC3960)

---
 src/api/client/sync.rs                 | 25 +++++++++++++---
 src/service/rooms/read_receipt/data.rs | 10 ++-----
 src/service/rooms/read_receipt/mod.rs  | 41 +++++++++++++++++++++++---
 3 files changed, 60 insertions(+), 16 deletions(-)

diff --git a/src/api/client/sync.rs b/src/api/client/sync.rs
index d95a88ffb..236b85dda 100644
--- a/src/api/client/sync.rs
+++ b/src/api/client/sync.rs
@@ -36,6 +36,7 @@ use ruma::{
 	state_res::Event,
 	uint, DeviceId, EventId, MilliSecondsSinceUnixEpoch, OwnedRoomId, OwnedUserId, RoomId, UInt, UserId,
 };
+use service::rooms::read_receipt::pack_receipts;
 use tracing::{Instrument as _, Span};
 
 use crate::{
@@ -1168,6 +1169,10 @@ pub(crate) async fn sync_events_v4_route(
 	let mut device_list_changes = HashSet::new();
 	let mut device_list_left = HashSet::new();
 
+	let mut receipts = sync_events::v4::Receipts {
+		rooms: BTreeMap::new(),
+	};
+
 	let mut account_data = sync_events::v4::AccountData {
 		global: Vec::new(),
 		rooms: BTreeMap::new(),
@@ -1509,7 +1514,21 @@ pub(crate) async fn sync_events_v4_route(
 				.collect(),
 		);
 
-		if roomsince != &0 && timeline_pdus.is_empty() && account_data.rooms.get(room_id).is_some_and(Vec::is_empty) {
+		let room_receipts = services
+			.rooms
+			.read_receipt
+			.readreceipts_since(room_id, *roomsince);
+		let vector: Vec<_> = room_receipts.into_iter().collect();
+		let receipt_size = vector.len();
+		receipts
+			.rooms
+			.insert(room_id.clone(), pack_receipts(Box::new(vector.into_iter())));
+
+		if roomsince != &0
+			&& timeline_pdus.is_empty()
+			&& account_data.rooms.get(room_id).is_some_and(Vec::is_empty)
+			&& receipt_size == 0
+		{
 			continue;
 		}
 
@@ -1723,9 +1742,7 @@ pub(crate) async fn sync_events_v4_route(
 				device_unused_fallback_key_types: None,
 			},
 			account_data,
-			receipts: sync_events::v4::Receipts {
-				rooms: BTreeMap::new(),
-			},
+			receipts,
 			typing: sync_events::v4::Typing {
 				rooms: BTreeMap::new(),
 			},
diff --git a/src/service/rooms/read_receipt/data.rs b/src/service/rooms/read_receipt/data.rs
index 0f400ff3a..0c156df38 100644
--- a/src/service/rooms/read_receipt/data.rs
+++ b/src/service/rooms/read_receipt/data.rs
@@ -2,17 +2,11 @@ use std::{mem::size_of, sync::Arc};
 
 use conduit::{utils, Error, Result};
 use database::Map;
-use ruma::{
-	events::{receipt::ReceiptEvent, AnySyncEphemeralRoomEvent},
-	serde::Raw,
-	CanonicalJsonObject, OwnedUserId, RoomId, UserId,
-};
+use ruma::{events::receipt::ReceiptEvent, serde::Raw, CanonicalJsonObject, RoomId, UserId};
 
+use super::AnySyncEphemeralRoomEventIter;
 use crate::{globals, Dep};
 
-type AnySyncEphemeralRoomEventIter<'a> =
-	Box<dyn Iterator<Item = Result<(OwnedUserId, u64, Raw<AnySyncEphemeralRoomEvent>)>> + 'a>;
-
 pub(super) struct Data {
 	roomuserid_privateread: Arc<Map>,
 	roomuserid_lastprivatereadupdate: Arc<Map>,
diff --git a/src/service/rooms/read_receipt/mod.rs b/src/service/rooms/read_receipt/mod.rs
index d202d8935..da11e2a0f 100644
--- a/src/service/rooms/read_receipt/mod.rs
+++ b/src/service/rooms/read_receipt/mod.rs
@@ -1,10 +1,17 @@
 mod data;
 
-use std::sync::Arc;
+use std::{collections::BTreeMap, sync::Arc};
 
-use conduit::Result;
+use conduit::{debug, Result};
 use data::Data;
-use ruma::{events::receipt::ReceiptEvent, serde::Raw, OwnedUserId, RoomId, UserId};
+use ruma::{
+	events::{
+		receipt::{ReceiptEvent, ReceiptEventContent},
+		AnySyncEphemeralRoomEvent, SyncEphemeralRoomEvent,
+	},
+	serde::Raw,
+	OwnedUserId, RoomId, UserId,
+};
 
 use crate::{sending, Dep};
 
@@ -17,6 +24,9 @@ struct Services {
 	sending: Dep<sending::Service>,
 }
 
+type AnySyncEphemeralRoomEventIter<'a> =
+	Box<dyn Iterator<Item = Result<(OwnedUserId, u64, Raw<AnySyncEphemeralRoomEvent>)>> + 'a>;
+
 impl crate::Service for Service {
 	fn build(args: crate::Args<'_>) -> Result<Arc<Self>> {
 		Ok(Arc::new(Self {
@@ -44,7 +54,7 @@ impl Service {
 	#[tracing::instrument(skip(self), level = "debug")]
 	pub fn readreceipts_since<'a>(
 		&'a self, room_id: &RoomId, since: u64,
-	) -> impl Iterator<Item = Result<(OwnedUserId, u64, Raw<ruma::events::AnySyncEphemeralRoomEvent>)>> + 'a {
+	) -> impl Iterator<Item = Result<(OwnedUserId, u64, Raw<AnySyncEphemeralRoomEvent>)>> + 'a {
 		self.db.readreceipts_since(room_id, since)
 	}
 
@@ -65,3 +75,26 @@ impl Service {
 		self.db.last_privateread_update(user_id, room_id)
 	}
 }
+
+#[must_use]
+pub fn pack_receipts(receipts: AnySyncEphemeralRoomEventIter<'_>) -> Raw<SyncEphemeralRoomEvent<ReceiptEventContent>> {
+	let mut json = BTreeMap::new();
+	for (_user, _count, value) in receipts.flatten() {
+		let receipt = serde_json::from_str::<SyncEphemeralRoomEvent<ReceiptEventContent>>(value.json().get());
+		if let Ok(value) = receipt {
+			for (event, receipt) in value.content {
+				json.insert(event, receipt);
+			}
+		} else {
+			debug!("failed to parse receipt: {:?}", receipt);
+		}
+	}
+	let content = ReceiptEventContent::from_iter(json);
+
+	Raw::from_json(
+		serde_json::value::to_raw_value(&SyncEphemeralRoomEvent {
+			content,
+		})
+		.expect("received valid json"),
+	)
+}