rpcconsole: display signet challenge

src/qt/forms/debugwindow.ui

@@ -210,7 +210,7 @@
         </widget>
        </item>
        <item row="7" column="1" colspan="2">
-        <widget class="QLabel" name="networkName">
+        <widget class="NetworkName" name="networkName">
          <property name="cursor">
           <cursorShape>IBeamCursor</cursorShape>
          </property>
@@ -1872,6 +1872,11 @@
    <class>PlainCopyTextEdit</class>
    <extends>QTextEdit</extends>
   </customwidget>
+  <customwidget>
+   <class>NetworkName</class>
+   <extends>QLabel</extends>
+   <header>qt/rpcconsole.h</header>
+  </customwidget>
  </customwidgets>
  <resources>
   <include location="../bitcoin.qrc"/>

src/qt/rpcconsole.cpp

@@ -57,6 +57,9 @@ const int INITIAL_TRAFFIC_GRAPH_MINS = 30;
 const QSize FONT_RANGE(4, 40);
 const char fontSizeSettingsKey[] = "consoleFontSize";
 
+const std::string DEFAULT_CHALLENGE_STRING =
+    "512103ad5e0edad18cb1f0fc0d28a3d4f1f3e445640337489abb10404f2d1e086be430210359ef5021964fe22d6f8e05b2463c9540ce96883fe3b278760f048f5189f2e6c452ae";
+
 const struct {
     const char *url;
     const char *source;
@@ -717,6 +720,39 @@ void RPCConsole::setClientModel(ClientModel *model, int bestblock_height, int64_
         ui->blocksDir->setText(model->blocksDir());
         ui->startupTime->setText(model->formatClientStartupTime());
         ui->networkName->setText(QString::fromStdString(Params().GetChainTypeString()));
+        ui->networkName->setWordWrap(true);
+
+        if (Params().GetChainTypeString() == "signet") {
+            std::vector<uint8_t> vChallenge = Params().GetConsensus().signet_challenge;
+            std::string challengeString = HexStr(vChallenge);
+            if (challengeString != DEFAULT_CHALLENGE_STRING) {
+                LogDebug(BCLog::QT, "rpcconsole:challengeString=%s\n", challengeString);
+                if (challengeString.length() > 16) { // a sane minimum
+                    std::string challenge_fingerprint = challengeString.substr(0, 8);
+                    const QString title = tr("Node window - [signet] (%1)").arg(QString::fromStdString(challenge_fingerprint));
+                    // display fingerprint in Node window title
+                    this->setWindowTitle(title);
+                } else {
+                    // A trivial challenge is supported. Example: signetchallenge=51
+                    std::string challenge_fingerprint = challengeString.substr(0, challengeString.length());
+                    const QString title = tr("Node window - [signet] (%1)").arg(QString::fromStdString(challenge_fingerprint));
+                    // display fingerprint in Node window title
+                    this->setWindowTitle(title);
+                }
+                if (challengeString.length() > (size_t)ui->networkName->width()) {
+                    challengeString.insert(0, "\n");  // break after Signet:
+                    challengeString.insert(65, "\n"); // then split at (130/2)
+                }
+                ui->networkName->setToolTip(
+                    tr("%1").arg(QString::fromStdString(challengeString)));
+                ui->networkName->setText(
+                    tr("%1\nChallenge: %2").arg("Signet").arg(QString::fromStdString(challengeString)));
+            } else {
+                ui->networkName->setText(tr("Signet: Default"));
+                ui->networkName->setToolTip(QString());
+                this->setWindowTitle(tr("[signet] Default"));
+            }
+        }
 
         //Setup autocomplete and attach it
         QStringList wordList;

src/qt/rpcconsole.h

@@ -15,6 +15,8 @@
 
 #include <QByteArray>
 #include <QCompleter>
+#include <QFontMetrics>
+#include <QLabel>
 #include <QMimeData>
 #include <QTextDocumentFragment>
 #include <QTextEdit>
@@ -210,4 +212,56 @@ class PlainCopyTextEdit : public QTextEdit {
     }
 };
 
+class NetworkName : public QLabel
+{
+    Q_OBJECT
+
+public:
+    explicit NetworkName(QWidget *parent = nullptr) : QLabel(parent) {}
+
+    void setText(const QString& text) {
+        m_fullText = text;
+        recalculateElidedText();
+    }
+
+    const QString& fullText() const { return m_fullText; }
+    QString selectedText() const {
+        return m_fullText;
+    }
+
+protected:
+    void resizeEvent(QResizeEvent *event) override {
+        QLabel::resizeEvent(event);
+        recalculateElidedText();
+    }
+
+    // Provide the full challenge when Copy&Paste
+    QMimeData* createMimeDataFromSelection() const {
+        auto md = new QMimeData();
+        md->setText(m_fullText);
+        return md;
+    }
+
+private:
+    QString m_fullText;
+
+    void recalculateElidedText() {
+        if (m_fullText.isEmpty()) {
+            QLabel::setText(QString());
+            return;
+        }
+
+        QFontMetrics fm(font());
+        int availableWidth = width()-1;
+        //int availableWidth = contentsRect().width()-1;
+
+        QString elidedText = fm.elidedText(m_fullText, Qt::ElideMiddle, availableWidth);
+
+        if (QLabel::text() != elidedText) {
+            QLabel::setText(elidedText);
+            //QLabel::setText(m_fullText);
+        }
+    }
+};
+
 #endif // BITCOIN_QT_RPCCONSOLE_H