[Client] Show live connection latency in the status bar

Add a permanent status-bar label fed by ConnectionController's
pingStatsUpdated: shows the latest round-trip time, hides while
disconnected or without samples, and carries a tooltip with
Last/Median/95th percentile/Maximum over the rolling sample window
(mirrored into the accessible description). The server tab gets the
same stats as its tooltip. Placement on the classic status bar is a
deliberate stopgap until ping re-homes to lobby furniture per the
design plans.

Took 2 minutes

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Took 48 seconds

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Took 4 minutes

cockatrice/src/interface/widgets/tabs/tab_supervisor.cpp

@@ -141,6 +141,7 @@ TabSupervisor::TabSupervisor(AbstractClient *_client, QMenu *tabsMenu, QWidget *
     connect(client, &AbstractClient::gameJoinedEventReceived, this, &TabSupervisor::gameJoined);
     connect(client, &AbstractClient::userMessageEventReceived, this, &TabSupervisor::processUserMessageEvent);
     connect(client, &AbstractClient::maxPingTime, this, &TabSupervisor::updatePingTime);
+    connect(client, &AbstractClient::pingStatsUpdated, this, &TabSupervisor::updateLatencyTooltip);
     connect(client, &AbstractClient::notifyUserEventReceived, this, &TabSupervisor::processNotifyUserEvent);
 
     // create tabs menu actions
@@ -883,6 +884,23 @@ void TabSupervisor::updatePingTime(int value, int max)
     setTabIcon(indexOf(tabServer), QIcon(PingPixmapGenerator::generatePixmap(15, value, max)));
 }
 
+void TabSupervisor::updateLatencyTooltip(int lastMs, int medianMs, int p95Ms, int maxMs, int sampleCount)
+{
+    if (!tabServer) {
+        return;
+    }
+
+    if (sampleCount == 0) {
+        setTabToolTip(indexOf(tabServer), QString());
+        return;
+    }
+
+    setTabToolTip(indexOf(tabServer), tr("Connection quality over the last %n sample(s):", "", sampleCount) + "\n" +
+                                          tr("Last: %1 ms").arg(lastMs) + "\n" + tr("Median: %1 ms").arg(medianMs) +
+                                          "\n" + tr("95th percentile: %1 ms").arg(p95Ms) + "\n" +
+                                          tr("Maximum: %1 ms").arg(maxMs));
+}
+
 void TabSupervisor::gameJoined(const Event_GameJoined &event)
 {
     QMap<int, QString> roomGameTypes;

cockatrice/src/interface/widgets/tabs/tab_supervisor.h

@@ -220,6 +220,7 @@ private slots:
 
     void updateCurrent(int index);
     void updatePingTime(int value, int max);
+    void updateLatencyTooltip(int lastMs, int medianMs, int p95Ms, int maxMs, int sampleCount);
     void gameJoined(const Event_GameJoined &event);
     void localGameJoined(const Event_GameJoined &event);
     void gameLeft(TabGame *tab);

cockatrice/src/interface/window_main.cpp

@@ -56,6 +56,7 @@
 #include <QDesktopServices>
 #include <QFile>
 #include <QFileDialog>
+#include <QLabel>
 #include <QMenu>
 #include <QMenuBar>
 #include <QMessageBox>
@@ -144,6 +145,23 @@ void MainWindow::statusChanged(ClientStatus _status)
     }
 }
 
+void MainWindow::updatePingDisplay(int lastMs, int medianMs, int p95Ms, int maxMs, int sampleCount)
+{
+    if (!pingLabel || sampleCount == 0) {
+        if (pingLabel) {
+            pingLabel->hide();
+        }
+        return;
+    }
+
+    pingLabel->setText(tr("Ping: %1 ms").arg(lastMs));
+    pingLabel->setToolTip(tr("Connection quality over the last %n sample(s):", "", sampleCount) + "\n" +
+                          tr("Last: %1 ms").arg(lastMs) + "\n" + tr("Median: %1 ms").arg(medianMs) + "\n" +
+                          tr("95th percentile: %1 ms").arg(p95Ms) + "\n" + tr("Maximum: %1 ms").arg(maxMs));
+    pingLabel->setAccessibleDescription(pingLabel->toolTip());
+    pingLabel->show();
+}
+
 // Actions
 
 void MainWindow::actConnect()
@@ -535,6 +553,12 @@ MainWindow::MainWindow(QWidget *parent)
             [this](bool show) { statusBar()->setVisible(show); });
     statusBar()->setVisible(SettingsCache::instance().userInterface().getShowStatusBar());
 
+    pingLabel = new QLabel(this);
+    pingLabel->setAccessibleName(tr("Ping"));
+    pingLabel->hide();
+    statusBar()->addPermanentWidget(pingLabel);
+    connect(connectionController, &ConnectionController::pingStatsUpdated, this, &MainWindow::updatePingDisplay);
+
     connect(&SettingsCache::instance().shortcuts(), &ShortcutsSettings::shortCutChanged, this,
             &MainWindow::refreshShortcuts);
     refreshShortcuts();

cockatrice/src/interface/window_main.h

@@ -50,6 +50,7 @@ class GameReplay;
 class HandlePublicServers;
 class LocalClient;
 class LocalServer;
+class QLabel;
 class QThread;
 class RemoteClient;
 class ServerInfo_User;
@@ -72,6 +73,7 @@ public slots:
 private slots:
     void updateTabMenu(const QList<QMenu *> &newMenuList);
     void statusChanged(ClientStatus _status);
+    void updatePingDisplay(int lastMs, int medianMs, int p95Ms, int maxMs, int sampleCount);
     void localGameEnded();
     void pixmapCacheSizeChanged(int newSizeInMBs);
     void actDisconnect();
@@ -146,6 +148,7 @@ private:
     WndSets *wndSets;
     ConnectionController *connectionController;
     LocalServer *localServer;
+    QLabel *pingLabel = nullptr; ///< status bar label with live round-trip stats
     LagMonitor lagMonitor; ///< watches the main thread for event loop stalls
     bool bHasActivated, askedForDbUpdater;
     QProcess *cardUpdateProcess;