From d79678aae35a871de22318b8d6a46ed9b2a871a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tim=20Z=C3=B6ller?= <tim.zoeller@lambdaschmiede.com>
Date: Mon, 27 Apr 2026 22:16:27 +0200
Subject: [PATCH] Accept Quote Post Requests

---
 .../fitpub/service/FederationService.java     | 31 +++++++++++
 .../fitpub/service/InboxProcessor.java        | 52 +++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/src/main/java/net/javahippie/fitpub/service/FederationService.java b/src/main/java/net/javahippie/fitpub/service/FederationService.java
index 4da6a52..7479fae 100644
--- a/src/main/java/net/javahippie/fitpub/service/FederationService.java
+++ b/src/main/java/net/javahippie/fitpub/service/FederationService.java
@@ -252,6 +252,37 @@ public class FederationService {
         }
     }
 
+    /**
+     * Send an Accept for a quote interaction (FEP-5e53).
+     * This tells the quoting server that the quote has been approved.
+     *
+     * @param createActivityId the ID of the incoming Create activity that contains the quote
+     * @param remoteActorUri   the actor URI of the user who quoted the post
+     * @param localUser        the local user who owns the quoted post
+     */
+    @Async("taskExecutor")
+    public void sendAcceptQuote(String createActivityId, String remoteActorUri, User localUser) {
+        try {
+            RemoteActor remoteActor = fetchRemoteActor(remoteActorUri);
+
+            String acceptId = baseUrl + "/activities/" + UUID.randomUUID();
+            String actorUri = baseUrl + "/users/" + localUser.getUsername();
+
+            Map<String, Object> acceptActivity = new HashMap<>();
+            acceptActivity.put("@context", "https://www.w3.org/ns/activitystreams");
+            acceptActivity.put("type", "Accept");
+            acceptActivity.put("id", acceptId);
+            acceptActivity.put("actor", actorUri);
+            acceptActivity.put("object", createActivityId);
+
+            sendActivity(remoteActor.getInboxUrl(), acceptActivity, localUser);
+            log.info("Sent Accept (quote approval) to: {} for Create {}", remoteActor.getActorUri(), createActivityId);
+
+        } catch (Exception e) {
+            log.error("Failed to send Accept for quote: {}", createActivityId, e);
+        }
+    }
+
     /**
      * Send an activity to a remote inbox.
      *
diff --git a/src/main/java/net/javahippie/fitpub/service/InboxProcessor.java b/src/main/java/net/javahippie/fitpub/service/InboxProcessor.java
index 95e3262..a5afcfb 100644
--- a/src/main/java/net/javahippie/fitpub/service/InboxProcessor.java
+++ b/src/main/java/net/javahippie/fitpub/service/InboxProcessor.java
@@ -238,6 +238,19 @@ public class InboxProcessor {
                 return;
             }
 
+            // Check if this Note quotes a local activity (FEP-5e53).
+            // Mastodon and other implementations use various field names for the quote reference.
+            String quoteUri = firstNonNull(
+                    (String) noteObject.get("quoteUri"),
+                    (String) noteObject.get("quote"),
+                    (String) noteObject.get("quoteUrl"),
+                    (String) noteObject.get("_misskey_quote")
+            );
+
+            if (quoteUri != null) {
+                handleQuoteApproval(username, activity, actor, quoteUri);
+            }
+
             String inReplyTo = (String) noteObject.get("inReplyTo");
 
             if (inReplyTo == null) {
@@ -252,6 +265,45 @@ public class InboxProcessor {
         }
     }
 
+    /**
+     * If the quoted URI points to a local activity, send an Accept back to
+     * the quoting actor so that Mastodon (and other FEP-5e53 implementations)
+     * marks the quote as approved.
+     */
+    private void handleQuoteApproval(String username, Map<String, Object> createActivity, String actor, String quoteUri) {
+        try {
+            UUID activityId = extractActivityIdFromUri(quoteUri);
+            if (activityId == null) {
+                log.debug("Quote URI {} does not reference a local activity, skipping approval", quoteUri);
+                return;
+            }
+
+            Activity localActivity = activityRepository.findById(activityId).orElse(null);
+            if (localActivity == null) {
+                log.warn("Quoted activity not found: {}", activityId);
+                return;
+            }
+
+            User localUser = userRepository.findByUsername(username)
+                    .orElseThrow(() -> new IllegalArgumentException("User not found: " + username));
+
+            String createActivityId = (String) createActivity.get("id");
+            log.info("Approving quote from {} for activity {} (Create id: {})", actor, activityId, createActivityId);
+
+            federationService.sendAcceptQuote(createActivityId, actor, localUser);
+
+        } catch (Exception e) {
+            log.error("Error handling quote approval for {}", quoteUri, e);
+        }
+    }
+
+    private static String firstNonNull(String... values) {
+        for (String v : values) {
+            if (v != null) return v;
+        }
+        return null;
+    }
+
     /**
      * Process a comment (Note with inReplyTo).
      */