prelude: add Editable trait

youmubot-prelude/src/editable.rs

@@ -0,0 +1,50 @@
+use poise::{CreateReply, ReplyHandle};
+use serenity::all::Message;
+
+use crate::CmdContext;
+use core::future::Future;
+
+/// Represents an editable message context.
+pub trait Editable {
+    /// Edits the underlying message.
+    fn edit_msg(&mut self, reply: CreateReply) -> impl Future<Output = anyhow::Result<()>> + Send;
+}
+
+struct ReplyHandleEdit<'a, 'env, Env>(ReplyHandle<'a>, CmdContext<'env, Env>);
+
+impl<'a, 'b, Env: Send + Sync> Editable for ReplyHandleEdit<'a, 'b, Env> {
+    async fn edit_msg(&mut self, reply: CreateReply) -> anyhow::Result<()> {
+        Ok(self.0.edit(self.1.clone(), reply).await?)
+    }
+}
+
+/// Returns an [`Editable`] from a [`ReplyHandle`].
+pub fn editable_reply_handle<'a, 'b, Env: Send + Sync>(
+    reply: ReplyHandle<'a>,
+    ctx: CmdContext<'b, Env>,
+) -> impl Editable + use<'a, 'b, Env> {
+    ReplyHandleEdit(reply, ctx)
+}
+
+struct MsgEdit(Message, serenity::all::Context);
+
+/// Returns an [`Editable`] from a [`Message`].
+pub fn editable_message(msg: Message, ctx: serenity::all::Context) -> impl Editable {
+    MsgEdit(msg, ctx)
+}
+
+impl Editable for MsgEdit {
+    async fn edit_msg(&mut self, reply: CreateReply) -> anyhow::Result<()> {
+        self.0
+            .edit(&self.1, {
+                // Clear builder so that adding embeds or attachments won't add on top of
+                // the pre-edit items but replace them (which is apparently the more
+                // intuitive behavior). Notably, setting the builder to default doesn't
+                // mean the entire message is reset to empty: Discord only updates parts
+                // of the message that have had a modification specified
+                reply.to_prefix_edit(serenity::all::EditMessage::new())
+            })
+            .await?;
+        Ok(())
+    }
+}

youmubot-prelude/src/lib.rs

@@ -15,6 +15,7 @@ pub use tokio::spawn as spawn_future;
 pub use announcer::{Announcer, AnnouncerRunner};
 pub use args::{ChannelId, Duration, RoleId, UserId, UsernameArg};
 pub use debugging_ok::OkPrint;
+pub use editable::{editable_message, editable_reply_handle, Editable};
 pub use flags::Flags;
 pub use hook::Hook;
 pub use member_cache::MemberCache;
@@ -22,6 +23,7 @@ pub use pagination::{paginate, paginate_from_fn, paginate_reply, Paginate};
 
 pub mod announcer;
 pub mod args;
+pub mod editable;
 pub mod flags;
 pub mod hook;
 pub mod member_cache;