From 65be779bb0725ef0809a602cb8ab9f2225393b90 Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <benjamin@bouvier.cc>
Date: Thu, 27 Mar 2025 15:47:14 +0100
Subject: [PATCH] refactor(event cache): move relation extraction into common
 store helpers

---
 .../src/event_cache/store/mod.rs              | 31 ++++++++++++++++++
 .../src/event_cache_store.rs                  | 32 ++++---------------
 2 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/crates/matrix-sdk-base/src/event_cache/store/mod.rs b/crates/matrix-sdk-base/src/event_cache/store/mod.rs
index 08679cb11..d6ffaf2c6 100644
--- a/crates/matrix-sdk-base/src/event_cache/store/mod.rs
+++ b/crates/matrix-sdk-base/src/event_cache/store/mod.rs
@@ -32,6 +32,8 @@ use matrix_sdk_common::store_locks::{
     BackingStore, CrossProcessStoreLock, CrossProcessStoreLockGuard, LockStoreError,
 };
 pub use matrix_sdk_store_encryption::Error as StoreEncryptionError;
+use ruma::{events::AnySyncTimelineEvent, serde::Raw, OwnedEventId};
+use tracing::trace;
 
 #[cfg(any(test, feature = "testing"))]
 pub use self::integration_tests::EventCacheStoreIntegrationTests;
@@ -193,3 +195,32 @@ impl BackingStore for LockableEventCacheStore {
         self.0.try_take_leased_lock(lease_duration_ms, key, holder).await
     }
 }
+
+/// Helper to extract the relation information from an event.
+///
+/// If the event isn't in relation to another event, then this will return
+/// `None`. Otherwise, returns both the event id this event relates to, and the
+/// kind of relation as a string (e.g. `m.replace`).
+pub fn extract_event_relation(event: &Raw<AnySyncTimelineEvent>) -> Option<(OwnedEventId, String)> {
+    #[derive(serde::Deserialize)]
+    struct RelatesTo {
+        event_id: OwnedEventId,
+        rel_type: String,
+    }
+
+    #[derive(serde::Deserialize)]
+    struct EventContent {
+        #[serde(rename = "m.relates_to")]
+        rel: Option<RelatesTo>,
+    }
+
+    match event.get_field::<EventContent>("content") {
+        Ok(event_content) => {
+            event_content.and_then(|c| c.rel).map(|rel| (rel.event_id, rel.rel_type))
+        }
+        Err(err) => {
+            trace!("when extracting relation data from an event: {err}");
+            None
+        }
+    }
+}
diff --git a/crates/matrix-sdk-sqlite/src/event_cache_store.rs b/crates/matrix-sdk-sqlite/src/event_cache_store.rs
index 288c1c7ed..dda5d5441 100644
--- a/crates/matrix-sdk-sqlite/src/event_cache_store.rs
+++ b/crates/matrix-sdk-sqlite/src/event_cache_store.rs
@@ -22,6 +22,7 @@ use matrix_sdk_base::{
     deserialized_responses::TimelineEvent,
     event_cache::{
         store::{
+            extract_event_relation,
             media::{
                 EventCacheStoreMedia, IgnoreMediaRetentionPolicy, MediaRetentionPolicy,
                 MediaService,
@@ -199,35 +200,16 @@ impl SqliteEventCacheStore {
 
         // Extract the relationship info here.
         let raw_event = event.raw();
-
-        #[derive(serde::Deserialize)]
-        struct RelatesTo {
-            // For the purpose of storing the related event id in the database, a string is
-            // sufficient; we'll lose the static typing of `OwnedEventId` immediately anyways.
-            event_id: String,
-            rel_type: String,
-        }
-
-        #[derive(serde::Deserialize)]
-        struct EventContent {
-            #[serde(rename = "m.relates_to")]
-            rel: Option<RelatesTo>,
-        }
-
-        let (relates_to, rel_type) = match raw_event.get_field::<EventContent>("content") {
-            Ok(event_content) => {
-                event_content.and_then(|c| c.rel).map(|rel| (rel.event_id, rel.rel_type)).unzip()
-            }
-            Err(err) => {
-                error!("when extracting relation data before inserting in database: {err}");
-                (None, None)
-            }
-        };
+        let (relates_to, rel_type) = extract_event_relation(raw_event).unzip();
 
         // The content may be encrypted.
         let content = self.encode_value(serialized)?;
 
-        Ok(EncodedEvent { content, rel_type, relates_to })
+        Ok(EncodedEvent {
+            content,
+            rel_type,
+            relates_to: relates_to.map(|relates_to| relates_to.to_string()),
+        })
     }
 }