Initial support for backwards pagination

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_;