/**
 * @file   OpcUaMonitoredNode.h
 * @brief  QML component for monitoring a single OPC UA node.
 *
 * Inherits QObject + QQmlParserStatus so that initialisation is
 * deferred until all QML bindings are applied (componentComplete).
 */
#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 (QString 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;
  QString accessLevel;
  QString status;
  QDateTime sourceTimestamp;
  QDateTime serverTimestamp;
};
Q_DECLARE_METATYPE (OpcUaNodeInfo)

class OpcUaMonitoredNode : public QObject, public QQmlParserStatus
{
  Q_OBJECT
  Q_INTERFACES (QQmlParserStatus)
  QML_ELEMENT

  Q_PROPERTY (QString nodeId READ nodeId WRITE setNodeId NOTIFY nodeIdChanged)
  Q_PROPERTY (
      bool monitored READ monitored WRITE setMonitored NOTIFY monitoredChanged)
  Q_PROPERTY (double publishingInterval READ publishingInterval WRITE
                  setPublishingInterval NOTIFY publishingIntervalChanged)
  Q_PROPERTY (QVariant value READ value NOTIFY valueChanged)
  Q_PROPERTY (bool writable READ writable NOTIFY writableChanged)
  Q_PROPERTY (OpcUaNodeInfo info READ info NOTIFY infoChanged)

public:
  explicit OpcUaMonitoredNode (QObject *parent = nullptr);

  QString nodeId () const;
  void setNodeId (const QString &id);

  bool monitored () const;
  void setMonitored (bool monitored);

  double publishingInterval () const;
  void setPublishingInterval (double interval);

  QVariant value () const;
  bool writable () const;
  OpcUaNodeInfo info () const;

  /**
   * @brief Write a value to the OPC UA node.
   *
   * Coerces @a value to the node's data type (auto-detected from the
   * server's DataType attribute).  For array nodes, a comma-separated
   * string is split and each element coerced individually.
   * Result is reported asynchronously via writeCompleted().
   */
  Q_INVOKABLE void writeValue (const QVariant &value);

  void classBegin () override;
  void componentComplete () override;

signals:
  void nodeIdChanged ();
  void monitoredChanged ();
  void publishingIntervalChanged ();
  void valueChanged ();
  void writableChanged ();
  void infoChanged ();
  void writeCompleted (bool success, const QString &message);

private slots:
  void handleAttributeUpdated (QOpcUa::NodeAttribute attr,
                               const QVariant &value);
  void handleValueUpdated (const QVariant &value);
  void handleClientConnectedChanged ();
  void handleAttributeWritten (QOpcUa::NodeAttribute attr,
                               QOpcUa::UaStatusCode statusCode);
  void handleEnableMonitoringFinished (QOpcUa::NodeAttribute attr,
                                       QOpcUa::UaStatusCode statusCode);
  void handleDisableMonitoringFinished (QOpcUa::NodeAttribute attr,
                                        QOpcUa::UaStatusCode statusCode);

private:
  void setupNode ();
  void teardownNode ();
  void startMonitoring ();
  void stopMonitoring ();
  QVariant coerceValue (const QVariant &input) const;

  QString m_nodeId;
  bool m_monitored = true;
  double m_publishingInterval = 250.0;
  bool m_componentComplete = false;

  QOpcUaNode *m_node = nullptr;
  QOpcUa::Types m_valueType = QOpcUa::Types::Undefined;
  bool m_writable = false;
  QVariant m_value;
  OpcUaNodeInfo m_info;
};

#endif // OPCUAMONITOREDNODE_H