Room::predecessor() and Room::successor()

2 files changed, 35 insertions, 0 deletions

diff --git a/lib/room.cpp b/lib/room.cpp
index fe50aa9a..41a8888c 100644
--- a/lib/room.cpp
+++ b/lib/room.cpp
@@ -387,11 +387,31 @@ QString Room::predecessorId() const
     return d->getCurrentState<RoomCreateEvent>()->predecessor().roomId;
 }
 
+Room* Room::predecessor(JoinStates statesFilter) const
+{
+    if (const auto& predId = predecessorId(); !predId.isEmpty())
+        if (auto* r = connection()->room(predId, statesFilter);
+                r && r->successorId() == id())
+            return r;
+
+    return nullptr;
+}
+
 QString Room::successorId() const
 {
     return d->getCurrentState<RoomTombstoneEvent>()->successorRoomId();
 }
 
+Room* Room::successor(JoinStates statesFilter) const
+{
+    if (const auto& succId = successorId(); !succId.isEmpty())
+        if (auto* r = connection()->room(succId, statesFilter);
+                r && r->predecessorId() == id())
+            return r;
+
+    return nullptr;
+}
+
 const Room::Timeline& Room::messageEvents() const { return d->timeline; }
 
 const Room::PendingEvents& Room::pendingEvents() const
diff --git a/lib/room.h b/lib/room.h
index 2c958033..fa3c6ff3 100644
--- a/lib/room.h
+++ b/lib/room.h
@@ -167,7 +167,22 @@ public:
     QString version() const;
     bool isUnstable() const;
     QString predecessorId() const;
+    /// Room predecessor
+    /** This function validates that the predecessor has a tombstone and
+     * the tombstone refers to the current room. If that's not the case,
+     * or if the predecessor is in a join state not matching \p stateFilter,
+     * the function returns nullptr.
+     */
+    Room* predecessor(JoinStates statesFilter = JoinState::Invite
+                                                | JoinState::Join) const;
     QString successorId() const;
+    /// Room successor
+    /** This function validates that the successor room's creation event
+     * refers to the current room. If that's not the case, or if the successor
+     * is in a join state not matching \p stateFilter, it returns nullptr.
+     */
+    Room* successor(JoinStates statesFilter = JoinState::Invite
+                                              | JoinState::Join) const;
     QString name() const;
     /// Room aliases defined on the current user's server
     /// \sa remoteAliases, setLocalAliases