From e92c6789d99b6f94258ca669aff272b889788930 Mon Sep 17 00:00:00 2001
From: Gabriel Kaszewski <gabrielkaszewski@gmail.com>
Date: Wed, 13 May 2026 01:32:14 +0200
Subject: [PATCH] feat: add backfill_outbox to ActivityPubService and
 ActivityPubPort

---
 .../adapters/activitypub-base/src/service.rs  | 85 +++++++++++++++++++
 crates/adapters/activitypub/src/port.rs       |  7 ++
 2 files changed, 92 insertions(+)

diff --git a/crates/adapters/activitypub-base/src/service.rs b/crates/adapters/activitypub-base/src/service.rs
index 992ff62..4fbc841 100644
--- a/crates/adapters/activitypub-base/src/service.rs
+++ b/crates/adapters/activitypub-base/src/service.rs
@@ -975,6 +975,91 @@ impl ActivityPubService {
         Ok(())
     }
 
+    pub async fn backfill_outbox(&self, outbox_url: &str, actor_url: &str) -> anyhow::Result<()> {
+        let client = reqwest::Client::builder()
+            .timeout(std::time::Duration::from_secs(30))
+            .build()?;
+        let data = self.federation_config.to_request_data();
+        let actor = url::Url::parse(actor_url)?;
+
+        let root: serde_json::Value = client
+            .get(outbox_url)
+            .header("Accept", "application/activity+json")
+            .send()
+            .await?
+            .json()
+            .await?;
+
+        let first = match root.get("first").and_then(|v| v.as_str()) {
+            Some(url) => url.to_string(),
+            None => {
+                tracing::debug!(outbox = %outbox_url, "outbox has no first page, nothing to backfill");
+                return Ok(());
+            }
+        };
+
+        let mut current_url = first;
+        let mut visited = std::collections::HashSet::new();
+
+        loop {
+            if !visited.insert(current_url.clone()) {
+                tracing::warn!(url = %current_url, "backfill: loop detected, stopping");
+                break;
+            }
+
+            let page: serde_json::Value = match client
+                .get(&current_url)
+                .header("Accept", "application/activity+json")
+                .send()
+                .await
+            {
+                Ok(resp) => match resp.json().await {
+                    Ok(v) => v,
+                    Err(e) => {
+                        tracing::error!(error = %e, url = %current_url, "backfill: failed to parse page JSON");
+                        break;
+                    }
+                },
+                Err(e) => {
+                    tracing::error!(error = %e, url = %current_url, "backfill: HTTP request failed");
+                    break;
+                }
+            };
+
+            if let Some(items) = page.get("orderedItems").and_then(|v| v.as_array()) {
+                for item in items {
+                    let activity_type = item.get("type").and_then(|v| v.as_str()).unwrap_or("");
+                    if activity_type != "Create" && activity_type != "Add" {
+                        continue;
+                    }
+                    let object = match item.get("object") {
+                        Some(o) if o.is_object() => o.clone(),
+                        _ => continue,
+                    };
+                    let ap_id = match object
+                        .get("id")
+                        .and_then(|v| v.as_str())
+                        .and_then(|s| url::Url::parse(s).ok())
+                    {
+                        Some(u) => u,
+                        None => continue,
+                    };
+                    if let Err(e) = data.object_handler.on_create(&ap_id, &actor, object).await {
+                        tracing::warn!(ap_id = %ap_id, error = %e, "backfill: failed to process item, skipping");
+                    }
+                }
+            }
+
+            match page.get("next").and_then(|v| v.as_str()) {
+                Some(next) => current_url = next.to_string(),
+                None => break,
+            }
+        }
+
+        tracing::info!(outbox = %outbox_url, pages = visited.len(), "backfill complete");
+        Ok(())
+    }
+
     fn spawn_backfill(&self, owner_user_id: uuid::Uuid, follower_inbox_url: String) {
         let config = self.federation_config.clone();
         let base_url = self.base_url.clone();
diff --git a/crates/adapters/activitypub/src/port.rs b/crates/adapters/activitypub/src/port.rs
index dea8b31..0fa8296 100644
--- a/crates/adapters/activitypub/src/port.rs
+++ b/crates/adapters/activitypub/src/port.rs
@@ -31,6 +31,7 @@ pub trait ActivityPubPort: Send + Sync {
     async fn add_blocked_domain(&self, domain: &str, reason: Option<&str>) -> anyhow::Result<()>;
     async fn remove_blocked_domain(&self, domain: &str) -> anyhow::Result<()>;
     async fn get_blocked_domains(&self) -> anyhow::Result<Vec<BlockedDomain>>;
+    async fn backfill_outbox(&self, outbox_url: &str, actor_url: &str) -> anyhow::Result<()>;
 }
 
 #[async_trait]
@@ -97,6 +98,9 @@ impl ActivityPubPort for ActivityPubService {
     async fn get_blocked_domains(&self) -> anyhow::Result<Vec<BlockedDomain>> {
         self.get_blocked_domains().await
     }
+    async fn backfill_outbox(&self, outbox_url: &str, actor_url: &str) -> anyhow::Result<()> {
+        self.backfill_outbox(outbox_url, actor_url).await
+    }
 }
 
 pub struct NoopActivityPubService;
@@ -154,4 +158,7 @@ impl ActivityPubPort for NoopActivityPubService {
     async fn get_blocked_domains(&self) -> anyhow::Result<Vec<BlockedDomain>> {
         Ok(vec![])
     }
+    async fn backfill_outbox(&self, _: &str, _: &str) -> anyhow::Result<()> {
+        Ok(())
+    }
 }