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/enums/delegatetype.h

@@ -38,6 +38,8 @@ public:
         ReadMarker, /**< The local user read marker. */
         Loading, /**< A delegate to tell the user more messages are being loaded. */
         TimelineEnd, /**< A delegate to inform that all messages are loaded. */
+        Predecessor, /**< A delegate to show a room predecessor. */
+        Successor, /**< A delegate to show a room successor. */
         Other, /**< Anything that cannot be classified as another type. */
     };
     Q_ENUM(Type);

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;
 };

src/timeline/CMakeLists.txt

@@ -10,8 +10,10 @@ ecm_add_qml_module(timeline GENERATE_PLUGIN_SOURCE
         HiddenDelegate.qml
         MessageDelegate.qml
         LoadingDelegate.qml
+        PredecessorDelegate.qml
         ReadMarkerDelegate.qml
         StateDelegate.qml
+        SuccessorDelegate.qml
         TimelineEndDelegate.qml
         Bubble.qml
         AvatarFlow.qml

src/timeline/EventDelegate.qml

@@ -41,6 +41,20 @@ DelegateChooser {
         delegate: LoadingDelegate {}
     }
 
+    DelegateChoice {
+        roleValue: DelegateType.Predecessor
+        delegate: PredecessorDelegate {
+            room: root.room
+        }
+    }
+
+    DelegateChoice {
+        roleValue: DelegateType.Successor
+        delegate: SuccessorDelegate {
+            room: root.room
+        }
+    }
+
     DelegateChoice {
         roleValue: DelegateType.TimelineEnd
         delegate: TimelineEndDelegate {

src/timeline/PredecessorDelegate.qml

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2024 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+import QtQuick
+import QtQuick.Layouts
+
+import org.kde.kirigami as Kirigami
+
+import org.kde.neochat
+
+TimelineDelegate {
+    id: root
+
+    /**
+     * @brief The current room that user is viewing.
+     */
+    required property NeoChatRoom room
+
+    width: parent?.width
+    rightPadding: NeoChatConfig.compactLayout && root.ListView.view.width >= Kirigami.Units.gridUnit * 20 ? Kirigami.Units.gridUnit * 2 + Kirigami.Units.largeSpacing : Kirigami.Units.largeSpacing
+
+    alwaysFillWidth: NeoChatConfig.compactLayout
+
+    contentItem: Kirigami.InlineMessage {
+        visible: true
+        text: i18n("This room continues another conversation.")
+        type: Kirigami.MessageType.Information
+        actions: Kirigami.Action {
+            text: i18n("See older messages…")
+            onTriggered: RoomManager.resolveResource(root.room.predecessorId)
+        }
+    }
+}

src/timeline/SuccessorDelegate.qml

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2024 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+import QtQuick
+import QtQuick.Layouts
+
+import org.kde.kirigami as Kirigami
+
+import org.kde.neochat
+
+TimelineDelegate {
+    id: root
+
+    /**
+     * @brief The current room that user is viewing.
+     */
+    required property NeoChatRoom room
+
+    width: parent?.width
+    rightPadding: NeoChatConfig.compactLayout && root.ListView.view.width >= Kirigami.Units.gridUnit * 20 ? Kirigami.Units.gridUnit * 2 + Kirigami.Units.largeSpacing : Kirigami.Units.largeSpacing
+
+    alwaysFillWidth: NeoChatConfig.compactLayout
+
+    contentItem: Kirigami.InlineMessage {
+        visible: true
+        text: i18n("This room has been replaced.")
+        type: Kirigami.MessageType.Information
+        actions: Kirigami.Action {
+            text: i18n("See new room…")
+            onTriggered: RoomManager.resolveResource(root.room.successorId)
+        }
+    }
+}