feat: TUI undo op (#5629)

codex-rs/core/src/tasks/undo.rs

@@ -0,0 +1,117 @@
+use std::sync::Arc;
+
+use crate::codex::TurnContext;
+use crate::protocol::EventMsg;
+use crate::protocol::UndoCompletedEvent;
+use crate::protocol::UndoStartedEvent;
+use crate::state::TaskKind;
+use crate::tasks::SessionTask;
+use crate::tasks::SessionTaskContext;
+use async_trait::async_trait;
+use codex_git_tooling::restore_ghost_commit;
+use codex_protocol::models::ResponseItem;
+use codex_protocol::user_input::UserInput;
+use tokio_util::sync::CancellationToken;
+use tracing::error;
+use tracing::info;
+use tracing::warn;
+
+pub(crate) struct UndoTask;
+
+impl UndoTask {
+    pub(crate) fn new() -> Self {
+        Self
+    }
+}
+
+#[async_trait]
+impl SessionTask for UndoTask {
+    fn kind(&self) -> TaskKind {
+        TaskKind::Regular
+    }
+
+    async fn run(
+        self: Arc<Self>,
+        session: Arc<SessionTaskContext>,
+        ctx: Arc<TurnContext>,
+        _input: Vec<UserInput>,
+        cancellation_token: CancellationToken,
+    ) -> Option<String> {
+        let sess = session.clone_session();
+        sess.send_event(
+            ctx.as_ref(),
+            EventMsg::UndoStarted(UndoStartedEvent {
+                message: Some("Undo in progress...".to_string()),
+            }),
+        )
+        .await;
+
+        if cancellation_token.is_cancelled() {
+            sess.send_event(
+                ctx.as_ref(),
+                EventMsg::UndoCompleted(UndoCompletedEvent {
+                    success: false,
+                    message: Some("Undo cancelled.".to_string()),
+                }),
+            )
+            .await;
+            return None;
+        }
+
+        let mut history = sess.clone_history().await;
+        let mut items = history.get_history();
+        let mut completed = UndoCompletedEvent {
+            success: false,
+            message: None,
+        };
+
+        let Some((idx, ghost_commit)) =
+            items
+                .iter()
+                .enumerate()
+                .rev()
+                .find_map(|(idx, item)| match item {
+                    ResponseItem::GhostSnapshot { ghost_commit } => {
+                        Some((idx, ghost_commit.clone()))
+                    }
+                    _ => None,
+                })
+        else {
+            completed.message = Some("No ghost snapshot available to undo.".to_string());
+            sess.send_event(ctx.as_ref(), EventMsg::UndoCompleted(completed))
+                .await;
+            return None;
+        };
+
+        let commit_id = ghost_commit.id().to_string();
+        let repo_path = ctx.cwd.clone();
+        let restore_result =
+            tokio::task::spawn_blocking(move || restore_ghost_commit(&repo_path, &ghost_commit))
+                .await;
+
+        match restore_result {
+            Ok(Ok(())) => {
+                items.remove(idx);
+                sess.replace_history(items).await;
+                let short_id: String = commit_id.chars().take(7).collect();
+                info!(commit_id = commit_id, "Undo restored ghost snapshot");
+                completed.success = true;
+                completed.message = Some(format!("Undo restored snapshot {short_id}."));
+            }
+            Ok(Err(err)) => {
+                let message = format!("Failed to restore snapshot {commit_id}: {err}");
+                warn!("{message}");
+                completed.message = Some(message);
+            }
+            Err(err) => {
+                let message = format!("Failed to restore snapshot {commit_id}: {err}");
+                error!("{message}");
+                completed.message = Some(message);
+            }
+        }
+
+        sess.send_event(ctx.as_ref(), EventMsg::UndoCompleted(completed))
+            .await;
+        None
+    }
+}