events: Improve usability and docs of m.room.message reply constructors

crates/ruma-events/src/room/message.rs

@@ -20,6 +20,8 @@ pub mod feedback;
 mod relation_serde;
 mod reply;
 
+pub use reply::ReplyBaseEvent;
+
 /// The content of an `m.room.message` event.
 ///
 /// This event is used when sending messages in a room.
@@ -81,20 +83,28 @@ impl RoomMessageEventContent {
     }
 
     /// Creates a plain text reply to a message.
-    pub fn text_reply_plain(reply: impl fmt::Display, original_message: &RoomMessageEvent) -> Self {
+    pub fn text_reply_plain(
+        reply: impl fmt::Display,
+        original_message: &impl ReplyBaseEvent,
+    ) -> Self {
         let quoted = reply::get_plain_quote_fallback(original_message);
 
         let body = format!("{}\n\n{}", quoted, reply);
 
         Self {
             relates_to: Some(Relation::Reply {
-                in_reply_to: InReplyTo { event_id: original_message.event_id.clone() },
+                in_reply_to: InReplyTo { event_id: original_message.event_id().clone() },
             }),
             ..Self::text_plain(body)
         }
     }
 
     /// Creates a html text reply to a message.
+    ///
+    /// Different from `text_reply_plain`, this constructor requires specifically a
+    /// [`RoomMessageEvent`] since it creates a permalink to the previous message, for which the
+    /// room ID is required. If you want to reply to a [`SyncRoomMessageEvent`], you have to convert
+    /// it first by calling [`.into_full_event()`][crate::SyncMessageEvent::into_full_event].
     pub fn text_reply_html(
         reply: impl fmt::Display,
         html_reply: impl fmt::Display,
@@ -115,16 +125,21 @@ impl RoomMessageEventContent {
     }
 
     /// Creates a plain text notice reply to a message.
+    ///
+    /// Different from `notice_reply_plain`, this constructor requires specifically a
+    /// [`RoomMessageEvent`] since it creates a permalink to the previous message, for which the
+    /// room ID is required. If you want to reply to a [`SyncRoomMessageEvent`], you have to convert
+    /// it first by calling [`.into_full_event()`][crate::SyncMessageEvent::into_full_event].
     pub fn notice_reply_plain(
         reply: impl fmt::Display,
-        original_message: &RoomMessageEvent,
+        original_message: &impl ReplyBaseEvent,
     ) -> Self {
         let quoted = reply::get_plain_quote_fallback(original_message);
 
         let body = format!("{}\n\n{}", quoted, reply);
         Self {
             relates_to: Some(Relation::Reply {
-                in_reply_to: InReplyTo { event_id: original_message.event_id.clone() },
+                in_reply_to: InReplyTo { event_id: original_message.event_id().clone() },
             }),
             ..Self::notice_plain(body)
         }

crates/ruma-events/src/room/message/reply.rs

@@ -1,42 +1,90 @@
 use indoc::formatdoc;
+use ruma_identifiers::{EventId, UserId};
 
-use super::{FormattedBody, MessageType, RoomMessageEvent};
+use super::{
+    FormattedBody, MessageType, RoomMessageEvent, RoomMessageEventContent, SyncRoomMessageEvent,
+};
 
-pub fn get_plain_quote_fallback(original_message: &RoomMessageEvent) -> String {
-    match &original_message.content.msgtype {
+/// An event that can be replied to.
+///
+/// This trait only exists to allow the plain-text `reply` constructors on `MessageEventContent` to
+/// use either a [`RoomMessageEvent`] or a [`SyncRoomMessageEvent`] as the event being replied to.
+pub trait ReplyBaseEvent {
+    #[doc(hidden)]
+    fn event_id(&self) -> &EventId;
+
+    #[doc(hidden)]
+    fn sender(&self) -> &UserId;
+
+    #[doc(hidden)]
+    fn content(&self) -> &RoomMessageEventContent;
+}
+
+impl ReplyBaseEvent for RoomMessageEvent {
+    fn event_id(&self) -> &EventId {
+        &self.event_id
+    }
+
+    fn sender(&self) -> &UserId {
+        &self.sender
+    }
+
+    fn content(&self) -> &RoomMessageEventContent {
+        &self.content
+    }
+}
+
+impl ReplyBaseEvent for SyncRoomMessageEvent {
+    fn event_id(&self) -> &EventId {
+        &self.event_id
+    }
+
+    fn sender(&self) -> &UserId {
+        &self.sender
+    }
+
+    fn content(&self) -> &RoomMessageEventContent {
+        &self.content
+    }
+}
+
+pub fn get_plain_quote_fallback(original_message: &impl ReplyBaseEvent) -> String {
+    let sender = original_message.sender();
+
+    match &original_message.content().msgtype {
         MessageType::Audio(_) => {
-            format!("> <{}> sent an audio file.", original_message.sender)
+            format!("> <{}> sent an audio file.", sender)
         }
         MessageType::Emote(content) => {
-            format!("> * <{}> {}", original_message.sender, content.body)
+            format!("> * <{}> {}", sender, content.body)
         }
         MessageType::File(_) => {
-            format!("> <{}> sent a file.", original_message.sender)
+            format!("> <{}> sent a file.", sender)
         }
         MessageType::Image(_) => {
-            format!("> <{}> sent an image.", original_message.sender)
+            format!("> <{}> sent an image.", sender)
         }
         MessageType::Location(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
         MessageType::Notice(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
         MessageType::ServerNotice(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
         MessageType::Text(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
         MessageType::Video(_) => {
-            format!("> <{}> sent a video.", original_message.sender)
+            format!("> <{}> sent a video.", sender)
         }
         MessageType::_Custom(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
         #[cfg(feature = "unstable-pre-spec")]
         MessageType::VerificationRequest(content) => {
-            format!("> <{}> {}", original_message.sender, content.body)
+            format!("> <{}> {}", sender, content.body)
         }
     }
     .replace('\n', "\n> ")