Implement loading of history, when timeline is displayed

resources/qml/TimelineView.qml

@@ -9,12 +9,6 @@ Rectangle {
 		text: qsTr("No room open")
 		font.pointSize: 24
 	}
-	Text {
-		visible: timelineManager.timeline != null
-		anchors.centerIn: parent
-		text: qsTr("room open")
-		font.pointSize: 24
-	}
 
 	ListView {
 		visible: timelineManager.timeline != null

src/timeline2/TimelineModel.cpp

@@ -24,6 +24,14 @@ senderId(const T &event)
 }
 }
 
+TimelineModel::TimelineModel(QString room_id, QObject *parent)
+  : QAbstractListModel(parent)
+  , room_id_(room_id)
+{
+        connect(
+          this, &TimelineModel::oldMessagesRetrieved, this, &TimelineModel::addBackwardsEvents);
+}
+
 QHash<int, QByteArray>
 TimelineModel::roleNames() const
 {
@@ -65,6 +73,11 @@ TimelineModel::data(const QModelIndex &index, int role) const
 void
 TimelineModel::addEvents(const mtx::responses::Timeline &events)
 {
+        if (isInitialSync) {
+                prev_batch_token_ = QString::fromStdString(events.prev_batch);
+                isInitialSync     = false;
+        }
+
         nhlog::ui()->info("add {} events", events.events.size());
         std::vector<QString> ids;
         for (const auto &e : events.events) {
@@ -83,6 +96,58 @@ TimelineModel::addEvents(const mtx::responses::Timeline &events)
         endInsertRows();
 }
 
+void
+TimelineModel::fetchHistory()
+{
+        if (paginationInProgress) {
+                nhlog::ui()->warn("Already loading older messages");
+                return;
+        }
+
+        paginationInProgress = true;
+        mtx::http::MessagesOpts opts;
+        opts.room_id = room_id_.toStdString();
+        opts.from    = prev_batch_token_.toStdString();
+
+        nhlog::ui()->info("Paginationg room {}", opts.room_id);
+
+        http::client()->messages(
+          opts, [this, opts](const mtx::responses::Messages &res, mtx::http::RequestErr err) {
+                  if (err) {
+                          nhlog::net()->error("failed to call /messages ({}): {} - {}",
+                                              opts.room_id,
+                                              mtx::errors::to_string(err->matrix_error.errcode),
+                                              err->matrix_error.error);
+                          return;
+                  }
+
+                  emit oldMessagesRetrieved(std::move(res));
+          });
+}
+
+void
+TimelineModel::addBackwardsEvents(const mtx::responses::Messages &msgs)
+{
+        nhlog::ui()->info("add {} backwards events", msgs.chunk.size());
+        std::vector<QString> ids;
+        for (const auto &e : msgs.chunk) {
+                QString id =
+                  boost::apply_visitor([](const auto &e) -> QString { return eventId(e); }, e);
+
+                this->events.insert(id, e);
+                ids.push_back(id);
+                nhlog::ui()->info("add event {}", id.toStdString());
+        }
+
+        beginInsertRows(QModelIndex(), 0, static_cast<int>(ids.size() - 1));
+        this->eventOrder.insert(this->eventOrder.begin(), ids.rbegin(), ids.rend());
+        endInsertRows();
+
+        prev_batch_token_ = QString::fromStdString(msgs.end);
+
+        paginationInProgress = false;
+}
+
 QColor
 TimelineModel::userColor(QString id, QColor background)
 {

src/timeline2/TimelineModel.h

@@ -11,9 +11,7 @@ class TimelineModel : public QAbstractListModel
         Q_OBJECT
 
 public:
-        explicit TimelineModel(QObject *parent = 0)
-          : QAbstractListModel(parent)
-        {}
+        explicit TimelineModel(QString room_id, QObject *parent = 0);
 
         enum Roles
         {
@@ -31,12 +29,29 @@ public:
 
         Q_INVOKABLE QColor userColor(QString id, QColor background);
 
+
         void addEvents(const mtx::responses::Timeline &events);
 
+public slots:
+        void fetchHistory();
+
+private slots:
+        // Add old events at the top of the timeline.
+        void addBackwardsEvents(const mtx::responses::Messages &msgs);
+
+signals:
+        void oldMessagesRetrieved(const mtx::responses::Messages &res);
+
 private:
         QHash<QString, mtx::events::collections::TimelineEvents> events;
         std::vector<QString> eventOrder;
 
+        QString room_id_;
+        QString prev_batch_token_;
+
+        bool isInitialSync = true;
+        bool paginationInProgress = false;
+
         QHash<QString, QColor> userColors;
 };
   

src/timeline2/TimelineViewManager.cpp

@@ -27,7 +27,7 @@ void
 TimelineViewManager::addRoom(const QString &room_id)
 {
         if (!models.contains(room_id))
-                models.insert(room_id, QSharedPointer<TimelineModel>(new TimelineModel()));
+                models.insert(room_id, QSharedPointer<TimelineModel>(new TimelineModel(room_id)));
 }
 
 void
@@ -38,6 +38,7 @@ TimelineViewManager::setHistoryView(const QString &room_id)
         auto room = models.find(room_id);
         if (room != models.end()) {
                 timeline_ = room.value().get();
+                timeline_->fetchHistory();
                 emit activeTimelineChanged(timeline_);
                 nhlog::ui()->info("Activated room {}", room_id.toStdString());
         }