Initial support for backwards pagination

CMakeLists.txt

@@ -91,6 +91,7 @@ set(SRC_FILES
     src/MatrixClient.cc
     src/Profile.cc
     src/RoomInfoListItem.cc
+    src/RoomMessages.cc
     src/RoomList.cc
     src/RoomState.cc
     src/Register.cc

include/MatrixClient.h

@@ -21,6 +21,7 @@
 #include <QtNetwork/QNetworkAccessManager>
 
 #include "Profile.h"
+#include "RoomMessages.h"
 #include "Sync.h"
 
 /*
@@ -43,6 +44,7 @@ public:
 	void fetchRoomAvatar(const QString &roomid, const QUrl &avatar_url);
 	void fetchOwnAvatar(const QUrl &avatar_url);
 	void downloadImage(const QString &event_id, const QUrl &url);
+	void messages(const QString &room_id, const QString &from_token) noexcept;
 
 	inline QUrl getHomeServer();
 	inline int transactionId();
@@ -77,19 +79,21 @@ signals:
 	void syncCompleted(const SyncResponse &response);
 	void syncFailed(const QString &msg);
 	void messageSent(const QString &event_id, const QString &roomid, const int txn_id);
+	void messagesRetrieved(const QString &room_id, const RoomMessages &msgs);
 
 private slots:
 	void onResponse(QNetworkReply *reply);
 
 private:
 	enum class Endpoint {
-		GetOwnProfile,
 		GetOwnAvatar,
+		GetOwnProfile,
 		GetProfile,
 		Image,
 		InitialSync,
 		Login,
 		Logout,
+		Messages,
 		Register,
 		RoomAvatar,
 		SendTextMessage,
@@ -109,6 +113,7 @@ private:
 	void onSyncResponse(QNetworkReply *reply);
 	void onRoomAvatarResponse(QNetworkReply *reply);
 	void onImageResponse(QNetworkReply *reply);
+	void onMessagesResponse(QNetworkReply *reply);
 
 	// Client API prefix.
 	QString api_url_;

include/RoomMessages.h

@@ -0,0 +1,56 @@
+/*
+ * nheko Copyright (C) 2017  Konstantinos Sideris <siderisk@auth.gr>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef ROOM_MESSAGES_H
+#define ROOM_MESSAGES_H
+
+#include <QJsonArray>
+#include <QJsonDocument>
+
+#include "Deserializable.h"
+
+class RoomMessages : public Deserializable
+{
+public:
+	void deserialize(const QJsonDocument &data) override;
+
+	inline QString start() const;
+	inline QString end() const;
+	inline QJsonArray chunk() const;
+
+private:
+	QString start_;
+	QString end_;
+	QJsonArray chunk_;
+};
+
+inline QString RoomMessages::start() const
+{
+	return start_;
+}
+
+inline QString RoomMessages::end() const
+{
+	return end_;
+}
+
+inline QJsonArray RoomMessages::chunk() const
+{
+	return chunk_;
+}
+
+#endif  // ROOM_MESSAGES_H

include/TimelineView.h

@@ -51,32 +51,50 @@ struct PendingMessage {
 	}
 };
 
+// In which place new TimelineItems should be inserted.
+enum class TimelineDirection {
+	Top,
+	Bottom,
+};
+
 class TimelineView : public QWidget
 {
 	Q_OBJECT
 
 public:
-	TimelineView(QSharedPointer<MatrixClient> client, QWidget *parent = 0);
-	TimelineView(const QJsonArray &events, QSharedPointer<MatrixClient> client, QWidget *parent = 0);
-	~TimelineView();
+	TimelineView(const Timeline &timeline, QSharedPointer<MatrixClient> client, const QString &room_id, QWidget *parent = 0);
 
-	void addHistoryItem(const events::MessageEvent<msgs::Image> &e, const QString &color, bool with_sender);
-	void addHistoryItem(const events::MessageEvent<msgs::Notice> &e, const QString &color, bool with_sender);
-	void addHistoryItem(const events::MessageEvent<msgs::Text> &e, const QString &color, bool with_sender);
+	TimelineItem *createTimelineItem(const events::MessageEvent<msgs::Image> &e, const QString &color, bool with_sender);
+	TimelineItem *createTimelineItem(const events::MessageEvent<msgs::Notice> &e, const QString &color, bool with_sender);
+	TimelineItem *createTimelineItem(const events::MessageEvent<msgs::Text> &e, const QString &color, bool with_sender);
 
-	int addEvents(const QJsonArray &events);
+	// Add new events at the end of the timeline.
+	int addEvents(const Timeline &timeline);
 	void addUserTextMessage(const QString &msg, int txn_id);
 	void updatePendingMessage(int txn_id, QString event_id);
+	void scrollDown();
 	void clear();
 
 public slots:
 	void sliderRangeChanged(int min, int max);
+	void sliderMoved(int position);
+
+	// Add old events at the top of the timeline.
+	void addBackwardsEvents(const QString &room_id, const RoomMessages &msgs);
 
 private:
 	void init();
 	void removePendingMessage(const events::MessageEvent<msgs::Text> &e);
+	void addTimelineItem(TimelineItem *item, TimelineDirection direction);
+	void updateLastSender(const QString &user_id, TimelineDirection direction);
+
+	// Used to determine whether or not we should prefix a message with the sender's name.
+	bool isSenderRendered(const QString &user_id, TimelineDirection direction);
 	bool isPendingMessage(const events::MessageEvent<msgs::Text> &e, const QString &userid);
 
+	// Return nullptr if the event couldn't be parsed.
+	TimelineItem *parseMessageEvent(const QJsonObject &event, TimelineDirection direction);
+
 	QVBoxLayout *top_layout_;
 	QVBoxLayout *scroll_layout_;
 
@@ -84,6 +102,19 @@ private:
 	QWidget *scroll_widget_;
 
 	QString last_sender_;
+	QString last_sender_backwards_;
+	QString room_id_;
+	QString prev_batch_token_;
+	QString local_user_;
+
+	bool isPaginationInProgress_ = false;
+	bool isInitialized = false;
+	bool isTimelineFinished = false;
+
+	const int SCROLL_BAR_GAP = 300;
+
+	int scroll_height_ = 0;
+	int previous_max_height_ = 0;
 
 	QList<PendingMessage> pending_msgs_;
 	QSharedPointer<MatrixClient> client_;

src/MainWindow.cc

@@ -108,6 +108,7 @@ void MainWindow::showChatPage(QString userid, QString homeserver, QString token)
 	if (progress_modal_ == nullptr) {
 		progress_modal_ = new OverlayModal(this, spinner_);
 		progress_modal_->fadeIn();
+		progress_modal_->setDuration(300);
 	}
 
 	login_page_->reset();

src/MatrixClient.cc

@@ -333,6 +333,32 @@ void MatrixClient::onImageResponse(QNetworkReply *reply)
 	emit imageDownloaded(event_id, pixmap);
 }
 
+void MatrixClient::onMessagesResponse(QNetworkReply *reply)
+{
+	reply->deleteLater();
+
+	int status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+
+	if (status == 0 || status >= 400) {
+		qWarning() << reply->errorString();
+		return;
+	}
+
+	auto data = reply->readAll();
+	auto room_id = reply->property("room_id").toString();
+
+	RoomMessages msgs;
+
+	try {
+		msgs.deserialize(QJsonDocument::fromJson(data));
+	} catch (const DeserializationException &e) {
+		qWarning() << "Room messages from" << room_id << e.what();
+		return;
+	}
+
+	emit messagesRetrieved(room_id, msgs);
+}
+
 void MatrixClient::onResponse(QNetworkReply *reply)
 {
 	switch (static_cast<Endpoint>(reply->property("endpoint").toInt())) {
@@ -369,6 +395,9 @@ void MatrixClient::onResponse(QNetworkReply *reply)
 	case Endpoint::GetOwnAvatar:
 		onGetOwnAvatarResponse(reply);
 		break;
+	case Endpoint::Messages:
+		onMessagesResponse(reply);
+		break;
 	default:
 		break;
 	}
@@ -581,3 +610,21 @@ void MatrixClient::fetchOwnAvatar(const QUrl &avatar_url)
 	QNetworkReply *reply = get(avatar_request);
 	reply->setProperty("endpoint", static_cast<int>(Endpoint::GetOwnAvatar));
 }
+
+void MatrixClient::messages(const QString &room_id, const QString &from_token) noexcept
+{
+	QUrlQuery query;
+	query.addQueryItem("access_token", token_);
+	query.addQueryItem("from", from_token);
+	query.addQueryItem("dir", "b");
+
+	QUrl endpoint(server_);
+	endpoint.setPath(api_url_ + QString("/rooms/%1/messages").arg(room_id));
+	endpoint.setQuery(query);
+
+	QNetworkRequest request(QString(endpoint.toEncoded()));
+
+	QNetworkReply *reply = get(request);
+	reply->setProperty("endpoint", static_cast<int>(Endpoint::Messages));
+	reply->setProperty("room_id", room_id);
+}

src/RoomMessages.cc

@@ -0,0 +1,42 @@
+/*
+ * nheko Copyright (C) 2017  Konstantinos Sideris <siderisk@auth.gr>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "RoomMessages.h"
+
+void RoomMessages::deserialize(const QJsonDocument &data)
+{
+	if (!data.isObject())
+		throw DeserializationException("response is not a JSON object");
+
+	QJsonObject object = data.object();
+
+	if (!object.contains("start"))
+		throw DeserializationException("start key is missing");
+
+	if (!object.contains("end"))
+		throw DeserializationException("end key is missing");
+
+	if (!object.contains("chunk"))
+		throw DeserializationException("chunk key is missing");
+
+	if (!object.value("chunk").isArray())
+		throw DeserializationException("chunk isn't a JSON array");
+
+	start_ = object.value("start").toString();
+	end_ = object.value("end").toString();
+	chunk_ = object.value("chunk").toArray();
+}

src/TimelineView.cc

@@ -34,19 +34,19 @@
 namespace events = matrix::events;
 namespace msgs = matrix::events::messages;
 
-TimelineView::TimelineView(const QJsonArray &events, QSharedPointer<MatrixClient> client, QWidget *parent)
+TimelineView::TimelineView(const Timeline &timeline,
+			   QSharedPointer<MatrixClient> client,
+			   const QString &room_id,
+			   QWidget *parent)
     : QWidget(parent)
+    , room_id_{room_id}
     , client_{client}
 {
-	init();
-	addEvents(events);
-}
+	QSettings settings;
+	local_user_ = settings.value("auth/user_id").toString();
 
-TimelineView::TimelineView(QSharedPointer<MatrixClient> client, QWidget *parent)
-    : QWidget(parent)
-    , client_{client}
-{
 	init();
+	addEvents(timeline);
 }
 
 void TimelineView::clear()
@@ -58,84 +58,176 @@ void TimelineView::clear()
 void TimelineView::sliderRangeChanged(int min, int max)
 {
 	Q_UNUSED(min);
+
+	if (!scroll_area_->verticalScrollBar()->isVisible())
+		return;
+
+	if (max - scroll_area_->verticalScrollBar()->value() < SCROLL_BAR_GAP)
 		scroll_area_->verticalScrollBar()->setValue(max);
 }
 
-int TimelineView::addEvents(const QJsonArray &events)
+void TimelineView::scrollDown()
 {
-	QSettings settings;
-	auto local_user = settings.value("auth/user_id").toString();
+	int current = scroll_area_->verticalScrollBar()->value();
+	int max = scroll_area_->verticalScrollBar()->maximum();
 
-	int message_count = 0;
-	events::EventType ty;
+	// The first time we enter the room move the scroll bar to the bottom.
+	if (!isInitialized) {
+		scroll_area_->ensureVisible(0, scroll_widget_->size().height(), 0, 0);
+		isInitialized = true;
+		return;
+	}
 
-	for (const auto &event : events) {
-		ty = events::extractEventType(event.toObject());
+	// If the gap is small enough move the scroll bar down. e.g when a new message appears.
+	if (max - current < SCROLL_BAR_GAP)
+		scroll_area_->verticalScrollBar()->setValue(max);
+}
+
+void TimelineView::sliderMoved(int position)
+{
+	if (!scroll_area_->verticalScrollBar()->isVisible())
+		return;
+
+	// The scrollbar is high enough so we can start retrieving old events.
+	if (position < SCROLL_BAR_GAP) {
+		if (isTimelineFinished)
+			return;
+
+		// Prevent user from moving up when there is pagination in progress.
+		if (isPaginationInProgress_) {
+			scroll_area_->verticalScrollBar()->setValue(SCROLL_BAR_GAP);
+			return;
+		}
+
+		isPaginationInProgress_ = true;
+		scroll_height_ = scroll_area_->verticalScrollBar()->value();
+		previous_max_height_ = scroll_area_->verticalScrollBar()->maximum();
+
+		// FIXME: Maybe move this to TimelineViewManager to remove the extra calls?
+		client_.data()->messages(room_id_, prev_batch_token_);
+	}
+}
+
+void TimelineView::addBackwardsEvents(const QString &room_id, const RoomMessages &msgs)
+{
+	if (room_id_ != room_id)
+		return;
+
+	if (msgs.chunk().count() == 0) {
+		isTimelineFinished = true;
+		return;
+	}
+
+	isTimelineFinished = false;
+	last_sender_backwards_.clear();
+	QList<TimelineItem *> items;
+
+	// Parse in reverse order to determine where we should not show sender's name.
+	auto it = msgs.chunk().constEnd();
+	while (it != msgs.chunk().constBegin()) {
+		--it;
+
+		TimelineItem *item = parseMessageEvent((*it).toObject(), TimelineDirection::Top);
+
+		if (item != nullptr)
+			items.push_back(item);
+	}
+
+	// Reverse again to render them.
+	std::reverse(items.begin(), items.end());
+
+	for (const auto &item : items)
+		addTimelineItem(item, TimelineDirection::Top);
+
+	prev_batch_token_ = msgs.end();
+	isPaginationInProgress_ = false;
+}
+
+TimelineItem *TimelineView::parseMessageEvent(const QJsonObject &event, TimelineDirection direction)
+{
+	events::EventType ty = events::extractEventType(event);
 
 	if (ty == events::EventType::RoomMessage) {
-			events::MessageEventType msg_type = events::extractMessageEventType(event.toObject());
+		events::MessageEventType msg_type = events::extractMessageEventType(event);
 
 		if (msg_type == events::MessageEventType::Text) {
 			events::MessageEvent<msgs::Text> text;
 
 			try {
-					text.deserialize(event.toObject());
+				text.deserialize(event);
 			} catch (const DeserializationException &e) {
 				qWarning() << e.what() << event;
-					continue;
+				return nullptr;
 			}
 
-				if (isPendingMessage(text, local_user)) {
+			if (isPendingMessage(text, local_user_)) {
 				removePendingMessage(text);
-					continue;
+				return nullptr;
 			}
 
-				auto with_sender = last_sender_ != text.sender();
-				auto color = TimelineViewManager::getUserColor(text.sender());
+			auto with_sender = isSenderRendered(text.sender(), direction);
+			updateLastSender(text.sender(), direction);
 
-				addHistoryItem(text, color, with_sender);
+			auto color = TimelineViewManager::getUserColor(text.sender());
 			last_sender_ = text.sender();
 
-				message_count += 1;
+			return createTimelineItem(text, color, with_sender);
 		} else if (msg_type == events::MessageEventType::Notice) {
 			events::MessageEvent<msgs::Notice> notice;
 
 			try {
-					notice.deserialize(event.toObject());
+				notice.deserialize(event);
 			} catch (const DeserializationException &e) {
 				qWarning() << e.what() << event;
-					continue;
+				return nullptr;
 			}
 
-				auto with_sender = last_sender_ != notice.sender();
-				auto color = TimelineViewManager::getUserColor(notice.sender());
+			auto with_sender = isSenderRendered(notice.sender(), direction);
+			updateLastSender(notice.sender(), direction);
 
-				addHistoryItem(notice, color, with_sender);
+			auto color = TimelineViewManager::getUserColor(notice.sender());
 			last_sender_ = notice.sender();
 
-				message_count += 1;
+			return createTimelineItem(notice, color, with_sender);
 		} else if (msg_type == events::MessageEventType::Image) {
 			events::MessageEvent<msgs::Image> img;
 
 			try {
-					img.deserialize(event.toObject());
+				img.deserialize(event);
 			} catch (const DeserializationException &e) {
 				qWarning() << e.what() << event;
-					continue;
+				return nullptr;
 			}
 
-				auto with_sender = last_sender_ != img.sender();
+			auto with_sender = isSenderRendered(img.sender(), direction);
+			updateLastSender(img.sender(), direction);
+
 			auto color = TimelineViewManager::getUserColor(img.sender());
-
-				addHistoryItem(img, color, with_sender);
-
 			last_sender_ = img.sender();
-				message_count += 1;
+
+			return createTimelineItem(img, color, with_sender);
 		} else if (msg_type == events::MessageEventType::Unknown) {
-				qWarning() << "Unknown message type" << event.toObject();
-				continue;
+			qWarning() << "Unknown message type" << event;
+			return nullptr;
 		}
 	}
+
+	return nullptr;
+}
+
+int TimelineView::addEvents(const Timeline &timeline)
+{
+	int message_count = 0;
+
+	prev_batch_token_ = timeline.previousBatch();
+
+	for (const auto &event : timeline.events()) {
+		TimelineItem *item = parseMessageEvent(event.toObject(), TimelineDirection::Bottom);
+
+		if (item != nullptr) {
+			message_count += 1;
+			addTimelineItem(item, TimelineDirection::Bottom);
+		}
 	}
 
 	return message_count;
@@ -165,35 +257,59 @@ void TimelineView::init()
 
 	setLayout(top_layout_);
 
-	connect(scroll_area_->verticalScrollBar(),
-		SIGNAL(rangeChanged(int, int)),
-		this,
-		SLOT(sliderRangeChanged(int, int)));
+	connect(client_.data(), &MatrixClient::messagesRetrieved, this, &TimelineView::addBackwardsEvents);
+
+	connect(scroll_area_->verticalScrollBar(), SIGNAL(valueChanged(int)), this, SLOT(sliderMoved(int)));
+	connect(scroll_area_->verticalScrollBar(), SIGNAL(rangeChanged(int, int)), this, SLOT(sliderRangeChanged(int, int)));
 }
 
-void TimelineView::addHistoryItem(const events::MessageEvent<msgs::Image> &event, const QString &color, bool with_sender)
+void TimelineView::updateLastSender(const QString &user_id, TimelineDirection direction)
+{
+	if (direction == TimelineDirection::Bottom)
+		last_sender_ = user_id;
+	else
+		last_sender_backwards_ = user_id;
+}
+
+bool TimelineView::isSenderRendered(const QString &user_id, TimelineDirection direction)
+{
+	if (direction == TimelineDirection::Bottom)
+		return last_sender_ != user_id;
+	else
+		return last_sender_backwards_ != user_id;
+}
+
+TimelineItem *TimelineView::createTimelineItem(const events::MessageEvent<msgs::Image> &event, const QString &color, bool with_sender)
 {
 	auto image = new ImageItem(client_, event);
 
 	if (with_sender) {
 		auto item = new TimelineItem(image, event, color, scroll_widget_);
-		scroll_layout_->addWidget(item);
-	} else {
-		auto item = new TimelineItem(image, event, scroll_widget_);
-		scroll_layout_->addWidget(item);
+		return item;
 	}
+
+	auto item = new TimelineItem(image, event, scroll_widget_);
+	return item;
 }
 
-void TimelineView::addHistoryItem(const events::MessageEvent<msgs::Notice> &event, const QString &color, bool with_sender)
+TimelineItem *TimelineView::createTimelineItem(const events::MessageEvent<msgs::Notice> &event, const QString &color, bool with_sender)
 {
 	TimelineItem *item = new TimelineItem(event, with_sender, color, scroll_widget_);
-	scroll_layout_->addWidget(item);
+	return item;
 }
 
-void TimelineView::addHistoryItem(const events::MessageEvent<msgs::Text> &event, const QString &color, bool with_sender)
+TimelineItem *TimelineView::createTimelineItem(const events::MessageEvent<msgs::Text> &event, const QString &color, bool with_sender)
 {
 	TimelineItem *item = new TimelineItem(event, with_sender, color, scroll_widget_);
+	return item;
+}
+
+void TimelineView::addTimelineItem(TimelineItem *item, TimelineDirection direction)
+{
+	if (direction == TimelineDirection::Bottom)
 		scroll_layout_->addWidget(item);
+	else
+		scroll_layout_->insertWidget(0, item);
 }
 
 void TimelineView::updatePendingMessage(int txn_id, QString event_id)
@@ -254,7 +370,3 @@ void TimelineView::addUserTextMessage(const QString &body, int txn_id)
 
 	pending_msgs_.push_back(message);
 }
-
-TimelineView::~TimelineView()
-{
-}

src/TimelineViewManager.cc

@@ -78,10 +78,9 @@ void TimelineViewManager::initialize(const Rooms &rooms)
 {
 	for (auto it = rooms.join().constBegin(); it != rooms.join().constEnd(); it++) {
 		auto roomid = it.key();
-		auto events = it.value().timeline().events();
 
 		// Create a history view with the room events.
-		TimelineView *view = new TimelineView(events, client_);
+		TimelineView *view = new TimelineView(it.value().timeline(), client_, it.key());
 		views_.insert(it.key(), view);
 
 		// Add the view in the widget stack.
@@ -100,9 +99,8 @@ void TimelineViewManager::sync(const Rooms &rooms)
 		}
 
 		auto view = views_.value(roomid);
-		auto events = it.value().timeline().events();
 
-		int msgs_added = view->addEvents(events);
+		int msgs_added = view->addEvents(it.value().timeline());
 
 		if (msgs_added > 0) {
 			// TODO: When the app window gets active the current
@@ -124,6 +122,7 @@ void TimelineViewManager::setHistoryView(const QString &room_id)
 
 	active_room_ = room_id;
 	auto widget = views_.value(room_id);
+	widget->scrollDown();
 
 	setCurrentWidget(widget);
 }

src/main.cc

@@ -43,7 +43,7 @@ int main(int argc, char *argv[])
 
 	app.setStyleSheet(
 		"QScrollBar:vertical { background-color: #f8fbfe; width: 8px; border: none; margin: 2px; }"
-		"QScrollBar::handle:vertical { background-color : #d6dde3; }"
+		"QScrollBar::handle:vertical { min-height: 40px; background-color : #d6dde3; }"
 		"QScrollBar::add-line:vertical { border: none; background: none; }"
 		"QScrollBar::sub-line:vertical { border: none; background: none; }");