Modify message_update behaviour when cache is enabled

2 files changed, 21 insertions, 7 deletions

diff --git a/src/client/dispatch.rs b/src/client/dispatch.rs
index 57160d4..fa0f801 100644
--- a/src/client/dispatch.rs
+++ b/src/client/dispatch.rs
@@ -490,11 +490,16 @@ fn handle_event<H: EventHandler + Send + Sync + 'static>(
             });
         },
         DispatchEvent::Model(Event::MessageUpdate(mut event)) => {
-            update!(cache_and_http, event);
+            let _before = update!(cache_and_http, event);
             let event_handler = Arc::clone(event_handler);
 
             threadpool.execute(move || {
-                event_handler.message_update(context, event);
+                feature_cache! {{
+                    let _after = cache_and_http.cache.read().message(event.channel_id, event.id);
+                    event_handler.message_update(context, _before, _after, event);
+                } else {
+                    event_handler.message_update(context, event);
+                }}
             });
         },
         DispatchEvent::Model(Event::PresencesReplace(mut event)) => {
diff --git a/src/client/event_handler.rs b/src/client/event_handler.rs
index 4b39fef..9fc7c69 100644
--- a/src/client/event_handler.rs
+++ b/src/client/event_handler.rs
@@ -212,6 +212,20 @@ pub trait EventHandler {
     /// Provides the channel's id and the deleted messages' ids.
     fn message_delete_bulk(&self, _ctx: Context, _channel_id: ChannelId, _multiple_deleted_messages_ids: Vec<MessageId>) {}
 
+    /// Dispatched when a message is updated.
+    ///
+    /// Provides the old message if available,
+    /// the new message as an option in case of cache inconsistencies,
+    /// and the raw MessageUpdateEvent as a fallback.
+    #[cfg(feature = "cache")]
+    fn message_update(&self, _ctx: Context, _old_if_available: Option<Message>, _new: Option<Message>, _event: MessageUpdateEvent) {}
+
+    /// Dispatched when a message is updated.
+    ///
+    /// Provides the new data of the message.
+    #[cfg(not(feature = "cache"))]
+    fn message_update(&self, _ctx: Context, _new_data: MessageUpdateEvent) {}
+
     /// Dispatched when a new reaction is attached to a message.
     ///
     /// Provides the reaction's data.
@@ -227,11 +241,6 @@ pub trait EventHandler {
     /// Provides the channel's id and the message's id.
     fn reaction_remove_all(&self, _ctx: Context, _channel_id: ChannelId, _removed_from_message_id: MessageId) {}
 
-    /// Dispatched when a message is updated.
-    ///
-    /// Provides the new data of the message.
-    fn message_update(&self, _ctx: Context, _new_data: MessageUpdateEvent) {}
-
     fn presence_replace(&self, _ctx: Context, _: Vec<Presence>) {}
 
     /// Dispatched when a user's presence is updated (e.g off -> on).