From 1a0acca3a0be2305fb4803dd7123a7fe300c15c1 Mon Sep 17 00:00:00 2001
From: Felix Ableitner <me@nutomic.com>
Date: Fri, 8 Nov 2024 15:11:29 +0100
Subject: [PATCH] Add ghost user to be able to fetch articles in case edit
 author cant be fetched

---
 src/backend/database/user.rs           | 27 ++++++++++++++++++++++++++
 src/backend/federation/objects/edit.rs | 11 +++++++++--
 src/backend/mod.rs                     |  3 +++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/backend/database/user.rs b/src/backend/database/user.rs
index c493fd6..13dd02c 100644
--- a/src/backend/database/user.rs
+++ b/src/backend/database/user.rs
@@ -164,4 +164,31 @@ impl DbPerson {
             .select(instance::all_columns)
             .get_results(conn.deref_mut())?)
     }
+
+    /// Ghost user serves as placeholder for deleted accounts
+    pub fn ghost(data: &Data<IbisData>) -> MyResult<DbPerson> {
+        let username = "ghost";
+        let read = DbPerson::read_from_name(username, &None, data);
+        if read.is_ok() {
+            read
+        } else {
+            let domain = &data.config.federation.domain;
+            let ap_id = ObjectId::parse(&format!(
+                "{}://{domain}/user/{username}",
+                http_protocol_str()
+            ))?;
+            let inbox_url = format!("{}://{domain}/inbox", http_protocol_str());
+            let keypair = generate_actor_keypair()?;
+            let person_form = DbPersonForm {
+                username: username.to_string(),
+                ap_id,
+                inbox_url,
+                public_key: keypair.public_key,
+                private_key: Some(keypair.private_key),
+                last_refreshed_at: Utc::now(),
+                local: true,
+            };
+            DbPerson::create(&person_form, data)
+        }
+    }
 }
diff --git a/src/backend/federation/objects/edit.rs b/src/backend/federation/objects/edit.rs
index 1d37cfd..f8353de 100644
--- a/src/backend/federation/objects/edit.rs
+++ b/src/backend/federation/objects/edit.rs
@@ -12,6 +12,7 @@ use activitypub_federation::{
     traits::Object,
 };
 use chrono::{DateTime, Utc};
+use log::warn;
 use serde::{Deserialize, Serialize};
 use url::Url;
 
@@ -77,8 +78,14 @@ impl Object for DbEdit {
 
     async fn from_json(json: Self::Kind, data: &Data<Self::DataType>) -> Result<Self, Self::Error> {
         let article = json.object.dereference(data).await?;
-        let creator = json.attributed_to.dereference(data).await?;
-        // TODO: if creator fails to fetch, make a dummy user
+        let creator = match json.attributed_to.dereference(data).await {
+            Ok(c) => c,
+            Err(e) => {
+                // If actor couldnt be fetched, use ghost as placeholder
+                warn!("Failed to fetch user {}: {e}", json.attributed_to);
+                DbPerson::ghost(data)?
+            }
+        };
         let form = DbEditForm {
             creator_id: creator.id,
             ap_id: json.id,
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 4bec3e3..3670053 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -169,6 +169,9 @@ async fn setup(data: &Data<IbisData>) -> Result<(), Error> {
     )
     .await?;
 
+    // create ghost user
+    DbPerson::ghost(data)?;
+
     Ok(())
 }