Add delegates to show room upgrades into the timeline model.

The delegates are at the beginning for upgraded rooms and end for predecessors.

Closes: network/neochat#620 and network/neochat#619

src/models/timelinemodel.cpp

@@ -3,11 +3,15 @@
 
 #include "timelinemodel.h"
 
+#include <Quotient/qt_connection_util.h>
+
 #include "delegatetype.h"
 
 TimelineModel::TimelineModel(QObject *parent)
     : QConcatenateTablesProxyModel(parent)
 {
+    m_timelineBeginningModel = new TimelineBeginningModel(this);
+    addSourceModel(m_timelineBeginningModel);
     m_messageEventModel = new MessageEventModel(this);
     addSourceModel(m_messageEventModel);
     m_timelineEndModel = new TimelineEndModel(this);
@@ -23,6 +27,7 @@ void TimelineModel::setRoom(NeoChatRoom *room)
 {
     // Both models do their own null checking so just pass along.
     m_messageEventModel->setRoom(room);
+    m_timelineBeginningModel->setRoom(room);
     m_timelineEndModel->setRoom(room);
 }
 
@@ -36,6 +41,69 @@ QHash<int, QByteArray> TimelineModel::roleNames() const
     return m_messageEventModel->roleNames();
 }
 
+TimelineBeginningModel::TimelineBeginningModel(QObject *parent)
+    : QAbstractListModel(parent)
+{
+}
+
+void TimelineBeginningModel::setRoom(NeoChatRoom *room)
+{
+    if (room == m_room) {
+        return;
+    }
+
+    beginResetModel();
+
+    if (m_room != nullptr) {
+        m_room->disconnect(this);
+    }
+
+    m_room = room;
+
+    if (m_room != nullptr) {
+        Quotient::connectUntil(m_room.get(), &Quotient::Room::eventsHistoryJobChanged, this, [this]() {
+            if (m_room->allHistoryLoaded()) {
+                // HACK: We have to do it this way because DelegateChooser doesn't update dynamically.
+                beginRemoveRows({}, 0, 0);
+                endRemoveRows();
+                beginInsertRows({}, 0, 0);
+                endInsertRows();
+                return true;
+            }
+            return false;
+        });
+    }
+
+    endResetModel();
+}
+
+QVariant TimelineBeginningModel::data(const QModelIndex &idx, int role) const
+{
+    Q_UNUSED(idx)
+    if (m_room == nullptr) {
+        return {};
+    }
+
+    if (role == DelegateTypeRole) {
+        return DelegateType::Successor;
+    }
+    return {};
+}
+
+int TimelineBeginningModel::rowCount(const QModelIndex &parent) const
+{
+    Q_UNUSED(parent)
+    if (m_room == nullptr) {
+        return 0;
+    }
+    return m_room->successorId().isEmpty() ? 0 : 1;
+}
+
+QHash<int, QByteArray> TimelineBeginningModel::roleNames() const
+{
+    return {{DelegateTypeRole, "delegateType"}};
+}
+
 TimelineEndModel::TimelineEndModel(QObject *parent)
     : QAbstractListModel(parent)
 {
@@ -78,7 +146,11 @@ QVariant TimelineEndModel::data(const QModelIndex &idx, int role) const
     }
 
     if (role == DelegateTypeRole) {
-        return m_room->allHistoryLoaded() ? DelegateType::TimelineEnd : DelegateType::Loading;
+        if (idx.row() == 1 || rowCount() == 1) {
+            return m_room->allHistoryLoaded() ? DelegateType::TimelineEnd : DelegateType::Loading;
+        } else {
+            return DelegateType::Predecessor;
+        }
     }
     return {};
 }
@@ -86,7 +158,10 @@ QVariant TimelineEndModel::data(const QModelIndex &idx, int role) const
 int TimelineEndModel::rowCount(const QModelIndex &parent) const
 {
     Q_UNUSED(parent)
-    return 1;
+    if (m_room == nullptr) {
+        return 0;
+    }
+    return m_room->predecessorId().isEmpty() ? 1 : (m_room->allHistoryLoaded() ? 2 : 1);
 }
 
 QHash<int, QByteArray> TimelineEndModel::roleNames() const

src/models/timelinemodel.h

@@ -10,6 +10,57 @@
 #include "messageeventmodel.h"
 #include "neochatroom.h"
 
+/**
+ * @class TimelineBeginningModel
+ *
+ * A model to provide a delegate at the start of the timeline to show upgrades.
+ */
+class TimelineBeginningModel : public QAbstractListModel
+{
+    Q_OBJECT
+    QML_ELEMENT
+
+public:
+    /**
+     * @brief Defines the model roles.
+     */
+    enum Roles {
+        DelegateTypeRole = MessageEventModel::DelegateTypeRole, /**< The delegate type of the message. */
+    };
+    Q_ENUM(Roles)
+
+    explicit TimelineBeginningModel(QObject *parent = nullptr);
+
+    /**
+     * @brief Set the room for the timeline.
+     */
+    void setRoom(NeoChatRoom *room);
+
+    /**
+     * @brief Get the given role value at the given index.
+     *
+     * @sa QAbstractItemModel::data
+     */
+    [[nodiscard]] QVariant data(const QModelIndex &idx, int role = Qt::DisplayRole) const override;
+
+    /**
+     * @brief 1, the answer is always 1.
+     *
+     * @sa QAbstractItemModel::rowCount
+     */
+    [[nodiscard]] int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+
+    /**
+     * @brief Returns a map with DelegateTypeRole it's the only one.
+     *
+     * @sa Roles, QAbstractItemModel::roleNames()
+     */
+    [[nodiscard]] QHash<int, QByteArray> roleNames() const override;
+
+private:
+    QPointer<NeoChatRoom> m_room = nullptr;
+};
+
 /**
  * @class TimelineEndModel
  *
@@ -108,5 +159,6 @@ Q_SIGNALS:
 
 private:
     MessageEventModel *m_messageEventModel = nullptr;
+    TimelineBeginningModel *m_timelineBeginningModel = nullptr;
     TimelineEndModel *m_timelineEndModel = nullptr;
 };