Implement OpcUaMonitoredNode attribute reading with OpcUaNodeInfo gadget

3 files changed, 337 insertions, 13 deletions

diff --git a/demo/NodePage.qml b/demo/NodePage.qml
index e00f468..2de0a15 100644
--- a/demo/NodePage.qml
+++ b/demo/NodePage.qml
@@ -1,4 +1,4 @@
-// NodePage.qml — Demo page with OpcUaMonitoredNode lifecycle logging.
+// NodePage.qml — Demo page displaying a single OPC UA node.
 
 import QtQuick
 import QtQuick.Controls
@@ -14,17 +14,16 @@ Page {
 
     OpcUaMonitoredNode {
         id: demoNode
-        nodeId: "ns=2;s=DemoVariable.Page" + nodePage.pageNumber
+        nodeId: nodePage.pageNumber === 1 ? "ns=1;s=double_rw_scalar" : "ns=1;s=string_rw_scalar"
         monitored: nodePage.StackView.status === StackView.Active
-        onMonitoredChanged: nodePage.logFunction(
-            "Page " + nodePage.pageNumber + " node [" + nodeId + "] "
-            + (monitored ? "MONITORED" : "UNMONITORED"))
+        onMonitoredChanged: nodePage.logFunction("Page " + nodePage.pageNumber + " node [" + nodeId + "] " + (monitored ? "MONITORED" : "UNMONITORED"))
+        onValueChanged: nodePage.logFunction("Page " + nodePage.pageNumber + " value = " + value)
     }
 
     ColumnLayout {
         anchors.fill: parent
         anchors.margins: 20
-        spacing: 12
+        spacing: 8
 
         RowLayout {
             Label {
@@ -32,22 +31,135 @@ Page {
                 font.bold: true
                 font.pointSize: 14
             }
-            Item { Layout.fillWidth: true }
+            Item {
+                Layout.fillWidth: true
+            }
             Button {
                 text: "Disconnect"
                 onClicked: Bobink.disconnectFromServer()
             }
         }
 
-        Label {
-            text: "Node: " + demoNode.nodeId
+        // Value (prominent)
+        Rectangle {
+            Layout.fillWidth: true
+            height: 60
+            color: "#f0f0f0"
+            radius: 4
+
+            ColumnLayout {
+                anchors.fill: parent
+                anchors.margins: 8
+                spacing: 2
+
+                Label {
+                    text: "Value"
+                    font.pointSize: 10
+                    color: "gray"
+                }
+                Label {
+                    text: demoNode.value !== undefined ? String(demoNode.value) : "—"
+                    font.pointSize: 16
+                    font.bold: true
+                    elide: Text.ElideRight
+                    Layout.fillWidth: true
+                }
+            }
         }
-        Label {
-            text: "Monitored: " + demoNode.monitored
-            color: demoNode.monitored ? "green" : "gray"
+
+        // Node info
+        GridLayout {
+            Layout.fillWidth: true
+            columns: 2
+            columnSpacing: 12
+            rowSpacing: 4
+
+            Label {
+                text: "Node ID:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.nodeId
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Display Name:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.displayName || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Data Type:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.dataType || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Node Class:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.nodeClass || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Access Level:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.accessLevel
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Status:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.status || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Source Time:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.sourceTimestamp.toLocaleString() || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Server Time:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.info.serverTimestamp.toLocaleString() || "—"
+                Layout.fillWidth: true
+            }
+
+            Label {
+                text: "Monitored:"
+                color: "gray"
+            }
+            Label {
+                text: demoNode.monitored ? "Yes" : "No"
+                color: demoNode.monitored ? "green" : "gray"
+                Layout.fillWidth: true
+            }
         }
 
-        Item { Layout.fillHeight: true }
+        Item {
+            Layout.fillHeight: true
+        }
 
         Button {
             Layout.fillWidth: true
diff --git a/src/OpcUaMonitoredNode.cpp b/src/OpcUaMonitoredNode.cpp
index f7a5c9f..0ffe300 100644
--- a/src/OpcUaMonitoredNode.cpp
+++ b/src/OpcUaMonitoredNode.cpp
@@ -3,9 +3,17 @@
  * @brief  OpcUaMonitoredNode implementation.
  */
 #include "OpcUaMonitoredNode.h"
+#include "OpcUaClient.h"
+
+#include <QMetaEnum>
+#include <QOpcUaLocalizedText>
 
 OpcUaMonitoredNode::OpcUaMonitoredNode (QObject *parent) : QObject (parent) {}
 
+/* ======================================
+ *  Properties
+ * ====================================== */
+
 QString
 OpcUaMonitoredNode::nodeId () const
 {
@@ -19,6 +27,13 @@ OpcUaMonitoredNode::setNodeId (const QString &id)
     return;
   m_nodeId = id;
   emit nodeIdChanged ();
+
+  if (!m_componentComplete)
+    return;
+
+  teardownNode ();
+  if (OpcUaClient::instance () && OpcUaClient::instance ()->connected ())
+    setupNode ();
 }
 
 bool
@@ -36,6 +51,22 @@ OpcUaMonitoredNode::setMonitored (bool monitored)
   emit monitoredChanged ();
 }
 
+QVariant
+OpcUaMonitoredNode::value () const
+{
+  return m_value;
+}
+
+OpcUaNodeInfo
+OpcUaMonitoredNode::info () const
+{
+  return m_info;
+}
+
+/* ======================================
+ *  QQmlParserStatus
+ * ====================================== */
+
 void
 OpcUaMonitoredNode::classBegin ()
 {
@@ -45,4 +76,130 @@ void
 OpcUaMonitoredNode::componentComplete ()
 {
   m_componentComplete = true;
+
+  auto *client = OpcUaClient::instance ();
+  if (!client)
+    return;
+
+  connect (client, &OpcUaClient::connectedChanged, this,
+           &OpcUaMonitoredNode::handleClientConnectedChanged);
+
+  if (client->connected () && !m_nodeId.isEmpty ())
+    setupNode ();
+}
+
+/* ======================================
+ *  Node lifecycle
+ * ====================================== */
+
+void
+OpcUaMonitoredNode::setupNode ()
+{
+  if (m_node || m_nodeId.isEmpty ())
+    return;
+
+  auto *client = OpcUaClient::instance ();
+  if (!client || !client->connected ())
+    return;
+
+  m_node = client->opcuaClient ()->node (m_nodeId);
+  if (!m_node)
+    return;
+
+  m_node->setParent (this);
+
+  connect (m_node, &QOpcUaNode::attributeUpdated, this,
+           &OpcUaMonitoredNode::handleAttributeUpdated);
+  connect (m_node, &QOpcUaNode::valueAttributeUpdated, this,
+           &OpcUaMonitoredNode::handleValueUpdated);
+
+  m_node->readAttributes (
+      QOpcUa::NodeAttribute::Value | QOpcUa::NodeAttribute::DisplayName
+      | QOpcUa::NodeAttribute::Description | QOpcUa::NodeAttribute::NodeClass
+      | QOpcUa::NodeAttribute::DataType | QOpcUa::NodeAttribute::AccessLevel);
+}
+
+void
+OpcUaMonitoredNode::teardownNode ()
+{
+  if (!m_node)
+    return;
+
+  delete m_node;
+  m_node = nullptr;
+
+  m_value.clear ();
+  emit valueChanged ();
+
+  m_info = OpcUaNodeInfo{};
+  emit infoChanged ();
+}
+
+/* ======================================
+ *  Signal handlers
+ * ====================================== */
+
+void
+OpcUaMonitoredNode::handleAttributeUpdated (QOpcUa::NodeAttribute attr,
+                                            const QVariant &value)
+{
+  switch (attr)
+    {
+    case QOpcUa::NodeAttribute::DisplayName:
+      m_info.displayName = value.value<QOpcUaLocalizedText> ().text ();
+      break;
+    case QOpcUa::NodeAttribute::Description:
+      m_info.description = value.value<QOpcUaLocalizedText> ().text ();
+      break;
+    case QOpcUa::NodeAttribute::NodeClass:
+      {
+        auto me = QMetaEnum::fromType<QOpcUa::NodeClass> ();
+        auto nc = static_cast<QOpcUa::NodeClass> (value.toInt ());
+        const char *key = me.valueToKey (static_cast<int> (nc));
+        m_info.nodeClass
+            = key ? QLatin1StringView (key) : QStringLiteral ("Unknown");
+      }
+      break;
+    case QOpcUa::NodeAttribute::DataType:
+      m_info.dataType = value.toString ();
+      break;
+    case QOpcUa::NodeAttribute::AccessLevel:
+      m_info.accessLevel = value.toUInt ();
+      break;
+    default:
+      return;
+    }
+  emit infoChanged ();
+}
+
+void
+OpcUaMonitoredNode::handleValueUpdated (const QVariant &value)
+{
+  m_value = value;
+  emit valueChanged ();
+
+  m_info.status = QOpcUa::statusToString (m_node->valueAttributeError ());
+  m_info.sourceTimestamp
+      = m_node->sourceTimestamp (QOpcUa::NodeAttribute::Value);
+  m_info.serverTimestamp
+      = m_node->serverTimestamp (QOpcUa::NodeAttribute::Value);
+  emit infoChanged ();
+}
+
+void
+OpcUaMonitoredNode::handleClientConnectedChanged ()
+{
+  auto *client = OpcUaClient::instance ();
+  if (!client)
+    return;
+
+  if (client->connected ())
+    {
+      if (!m_nodeId.isEmpty ())
+        setupNode ();
+    }
+  else
+    {
+      teardownNode ();
+    }
 }
diff --git a/src/OpcUaMonitoredNode.h b/src/OpcUaMonitoredNode.h
index 9d093b5..53e9537 100644
--- a/src/OpcUaMonitoredNode.h
+++ b/src/OpcUaMonitoredNode.h
@@ -8,9 +8,44 @@
 #ifndef OPCUAMONITOREDNODE_H
 #define OPCUAMONITOREDNODE_H
 
+#include <QDateTime>
 #include <QObject>
+#include <QOpcUaNode>
 #include <QQmlEngine>
 #include <QQmlParserStatus>
+#include <QVariant>
+
+/**
+ * @brief Metadata bundle for a monitored OPC UA node.
+ *
+ * Exposed as a single Q_PROPERTY on OpcUaMonitoredNode so that
+ * the QML API stays simple (only `value` is top-level).
+ * Advanced users can access fields via dot notation:
+ *   node.info.displayName, node.info.status, etc.
+ */
+struct OpcUaNodeInfo
+{
+  Q_GADGET
+  Q_PROPERTY (QString displayName MEMBER displayName)
+  Q_PROPERTY (QString description MEMBER description)
+  Q_PROPERTY (QString nodeClass MEMBER nodeClass)
+  Q_PROPERTY (QString dataType MEMBER dataType)
+  Q_PROPERTY (quint32 accessLevel MEMBER accessLevel)
+  Q_PROPERTY (QString status MEMBER status)
+  Q_PROPERTY (QDateTime sourceTimestamp MEMBER sourceTimestamp)
+  Q_PROPERTY (QDateTime serverTimestamp MEMBER serverTimestamp)
+
+public:
+  QString displayName;
+  QString description;
+  QString nodeClass;
+  QString dataType;
+  quint32 accessLevel = 0;
+  QString status;
+  QDateTime sourceTimestamp;
+  QDateTime serverTimestamp;
+};
+Q_DECLARE_METATYPE (OpcUaNodeInfo)
 
 class OpcUaMonitoredNode : public QObject, public QQmlParserStatus
 {
@@ -21,6 +56,8 @@ class OpcUaMonitoredNode : public QObject, public QQmlParserStatus
   Q_PROPERTY (QString nodeId READ nodeId WRITE setNodeId NOTIFY nodeIdChanged)
   Q_PROPERTY (
       bool monitored READ monitored WRITE setMonitored NOTIFY monitoredChanged)
+  Q_PROPERTY (QVariant value READ value NOTIFY valueChanged)
+  Q_PROPERTY (OpcUaNodeInfo info READ info NOTIFY infoChanged)
 
 public:
   explicit OpcUaMonitoredNode (QObject *parent = nullptr);
@@ -31,17 +68,35 @@ public:
   bool monitored () const;
   void setMonitored (bool monitored);
 
+  QVariant value () const;
+  OpcUaNodeInfo info () const;
+
   void classBegin () override;
   void componentComplete () override;
 
 signals:
   void nodeIdChanged ();
   void monitoredChanged ();
+  void valueChanged ();
+  void infoChanged ();
+
+private slots:
+  void handleAttributeUpdated (QOpcUa::NodeAttribute attr,
+                               const QVariant &value);
+  void handleValueUpdated (const QVariant &value);
+  void handleClientConnectedChanged ();
 
 private:
+  void setupNode ();
+  void teardownNode ();
+
   QString m_nodeId;
   bool m_monitored = true;
   bool m_componentComplete = false;
+
+  QOpcUaNode *m_node = nullptr;
+  QVariant m_value;
+  OpcUaNodeInfo m_info;
 };
 
 #endif // OPCUAMONITOREDNODE_H