From 26dfbfd08ceb913fd91f123935696d253fca2035 Mon Sep 17 00:00:00 2001
From: Konstantinos Sideris <sideris.konstantin@gmail.com>
Date: Mon, 5 Jun 2017 19:54:45 +0300
Subject: [PATCH] Lazy load initial timeline events

---
 include/MatrixClient.h     |  2 +-
 src/MatrixClient.cc        |  5 +++--
 src/TimelineView.cc        | 14 ++++++++------
 src/TimelineViewManager.cc |  3 ++-
 4 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/include/MatrixClient.h b/include/MatrixClient.h
index 2fde1c1e..7a4ac24b 100644
--- a/include/MatrixClient.h
+++ b/include/MatrixClient.h
@@ -44,7 +44,7 @@ public:
 	void fetchUserAvatar(const QString &userId, const QUrl &avatarUrl);
 	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;
+	void messages(const QString &room_id, const QString &from_token, int limit = 20) noexcept;
 
 	inline QUrl getHomeServer();
 	inline int transactionId();
diff --git a/src/MatrixClient.cc b/src/MatrixClient.cc
index 927db541..ebecb05a 100644
--- a/src/MatrixClient.cc
+++ b/src/MatrixClient.cc
@@ -541,7 +541,7 @@ void MatrixClient::initialSync() noexcept
 	};
 
 	QJsonObject filter{{"room",
-			    QJsonObject{{"timeline", QJsonObject{{"limit", 70}}},
+			    QJsonObject{{"timeline", QJsonObject{{"limit", 20}}},
 					{"ephemeral", QJsonObject{{"limit", 0}}}}},
 			   {"presence", QJsonObject{{"not_types", excluded_presence}}}};
 
@@ -677,12 +677,13 @@ void MatrixClient::fetchOwnAvatar(const QUrl &avatar_url)
 	reply->setProperty("endpoint", static_cast<int>(Endpoint::GetOwnAvatar));
 }
 
-void MatrixClient::messages(const QString &room_id, const QString &from_token) noexcept
+void MatrixClient::messages(const QString &room_id, const QString &from_token, int limit) noexcept
 {
 	QUrlQuery query;
 	query.addQueryItem("access_token", token_);
 	query.addQueryItem("from", from_token);
 	query.addQueryItem("dir", "b");
+	query.addQueryItem("limit", QString::number(limit));
 
 	QUrl endpoint(server_);
 	endpoint.setPath(api_url_ + QString("/rooms/%1/messages").arg(room_id));
diff --git a/src/TimelineView.cc b/src/TimelineView.cc
index 412b9520..418545a6 100644
--- a/src/TimelineView.cc
+++ b/src/TimelineView.cc
@@ -76,7 +76,7 @@ void TimelineView::scrollDown()
 
 	// 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);
+		scroll_area_->verticalScrollBar()->setValue(max);
 		isInitialized = true;
 		return;
 	}
@@ -226,11 +226,6 @@ int TimelineView::addEvents(const Timeline &timeline)
 	QSettings settings;
 	QString localUser = settings.value("auth/user_id").toString();
 
-	if (isInitialSync) {
-		prev_batch_token_ = timeline.previousBatch();
-		isInitialSync = false;
-	}
-
 	for (const auto &event : timeline.events()) {
 		TimelineItem *item = parseMessageEvent(event.toObject(), TimelineDirection::Bottom);
 		auto sender = event.toObject().value("sender").toString();
@@ -243,6 +238,13 @@ int TimelineView::addEvents(const Timeline &timeline)
 		}
 	}
 
+	if (isInitialSync) {
+		prev_batch_token_ = timeline.previousBatch();
+		isInitialSync = false;
+
+		client_->messages(room_id_, prev_batch_token_);
+	}
+
 	return message_count;
 }
 
diff --git a/src/TimelineViewManager.cc b/src/TimelineViewManager.cc
index 008dc5dc..f55d4868 100644
--- a/src/TimelineViewManager.cc
+++ b/src/TimelineViewManager.cc
@@ -119,9 +119,10 @@ void TimelineViewManager::setHistoryView(const QString &room_id)
 
 	active_room_ = room_id;
 	auto widget = views_.value(room_id);
-	widget->scrollDown();
 
 	setCurrentWidget(widget.data());
+
+	widget->scrollDown();
 }
 
 QMap<QString, QString> TimelineViewManager::NICK_COLORS;