Add recently pinned message to the top of the window

This makes pinned messages actually quite useful, as rooms can stick
persistent and important information for users to see. (For example, the
KWin has crash triage meeting information pinned in their room.)

For simplicity and space reasons, only one line of the generic message
body is shown.

src/libneochat/neochatroom.cpp

@@ -44,6 +44,7 @@
 
 #include "chatbarcache.h"
 #include "clipboard.h"
+#include "eventhandler.h"
 #include "events/pollevent.h"
 #include "filetransferpseudojob.h"
 #include "neochatconnection.h"
@@ -55,6 +56,7 @@
 #include <KIO/Job>
 #include <KIO/JobTracker>
 #endif
+
 #include <KJobTrackerInterface>
 #include <KLocalizedString>
 
@@ -130,11 +132,13 @@ NeoChatRoom::NeoChatRoom(Connection *connection, QString roomId, JoinState joinS
         this,
         [this]() {
             updatePushNotificationState(u"m.push_rules"_s);
+            loadPinnedMessage();
 
             Q_EMIT canEncryptRoomChanged();
             Q_EMIT inviteTimestampChanged();
         },
         Qt::SingleShotConnection);
+    connect(this, &Room::pinnedEventsChanged, this, &NeoChatRoom::loadPinnedMessage);
     connect(this, &Room::changed, this, [this] {
         Q_EMIT canEncryptRoomChanged();
         Q_EMIT parentIdsChanged();
@@ -1170,6 +1174,19 @@ void NeoChatRoom::setPushNotificationState(PushNotificationState::State state)
     Q_EMIT pushNotificationStateChanged(m_currentPushNotificationState);
 }
 
+void NeoChatRoom::loadPinnedMessage()
+{
+    const auto events = pinnedEventIds();
+    if (!events.isEmpty()) {
+        const QString &mostRecentEventId = events.last();
+        connection()->callApi<GetOneRoomEventJob>(id(), mostRecentEventId).then([this](const auto &job) {
+            auto event = fromJson<event_ptr_tt<RoomEvent>>(job->jsonData());
+            m_pinnedMessage = EventHandler::richBody(this, event.get());
+            Q_EMIT pinnedMessageChanged();
+        });
+    }
+}
+
 void NeoChatRoom::updatePushNotificationState(QString type)
 {
     if (type != "m.push_rules"_L1 || m_pushNotificationStateUpdating) {
@@ -1810,4 +1827,9 @@ bool NeoChatRoom::isCreator(const QString &userId) const
         && (createEvent->senderId() == userId || createEvent->contentPart<QStringList>(u"additional_creators"_s).contains(userId));
 }
 
+QString NeoChatRoom::pinnedMessage() const
+{
+    return m_pinnedMessage;
+}
+
 #include "moc_neochatroom.cpp"