Avoid changing active AC input serviceUid after Device is created

Although Global.acInputs.activeInput is not added to a DeviceModel,
avoid modifying the serviceUid of the activeInput after creation, for
consistency with the behavior of other Device objects.

The main work is to create the new activeInput object imperatively
in onActiveInputInfoChanged instead of using Loader to create an
instance of ActiveAcInput that dynamically changes its serviceUid
depending on the active serviceName and serviceType.

Contributes to #1035

data/AcInputs.qml

@@ -9,7 +9,7 @@ import Victron.VenusOS
 QtObject {
 	id: root
 
-	readonly property ActiveAcInput activeInput: _activeInputLoader.item
+	property ActiveAcInput activeInput
 	readonly property ActiveAcInput generatorInput: activeInput && activeInput.source === VenusOS.AcInputs_InputSource_Generator ? activeInput : null
 
 	readonly property AcInputSystemInfo activeInputInfo: input1Info.isActiveInput ? input1Info
@@ -30,23 +30,36 @@ QtObject {
 	// AC input metadata from com.victronenergy.system/Ac/In/<1|2>. There are always two inputs.
 	property AcInputSystemInfo input1Info: AcInputSystemInfo {
 		inputIndex: 0
-		isActiveInput: source === _activeInputSource.sourceAsInt
+		isActiveInput: valid && source === _activeInputSource.sourceAsInt
 	}
 	property AcInputSystemInfo input2Info: AcInputSystemInfo {
 		inputIndex: 1
-		isActiveInput: source === _activeInputSource.sourceAsInt
+		isActiveInput: valid && source === _activeInputSource.sourceAsInt
 	}
 
-	// Set activeInput to a valid object when /Ac/ActiveIn/Source is set to a valid source.
 	readonly property VeQuickItem _activeInputSource: VeQuickItem {
-		readonly property int sourceAsInt: value === undefined ? VenusOS.AcInputs_InputSource_NotAvailable : parseInt(value)
-
+		readonly property int sourceAsInt: !isValid ? VenusOS.AcInputs_InputSource_NotAvailable : parseInt(value)
 		uid: Global.system.serviceUid + "/Ac/ActiveIn/Source"
 	}
-	readonly property Loader _activeInputLoader: Loader {
-		active: root.sourceValid(root._activeInputSource.sourceAsInt)
-		sourceComponent: ActiveAcInput {
-			inputInfo: root.activeInputInfo
+
+	readonly property Component _activeAcInputComponent: Component {
+		ActiveAcInput {}
+	}
+
+	// Set activeInput to a valid object when /Ac/ActiveIn/Source is set to a valid source and
+	// triggers input1Info or input2Info to become the active input.
+	onActiveInputInfoChanged: {
+		if (activeInput) {
+			activeInput.destroy()
+			activeInput = null
+		}
+		if (activeInputInfo) {
+			const serviceUid = BackendConnection.type === BackendConnection.MqttSource
+				  // this looks like: 'mqtt/vebus/289/'
+				? "mqtt/" + activeInputInfo.serviceType + "/" + activeInputInfo.deviceInstance
+				  // this looks like: "dbus/com.victronenergy.vebus.ttyO1"
+				: BackendConnection.uidPrefix() + "/" + activeInputInfo.serviceName
+			activeInput = _activeAcInputComponent.createObject(root, { serviceUid: serviceUid, inputInfo: activeInputInfo })
 		}
 	}
 

data/common/AcInputSystemInfo.qml

@@ -15,6 +15,8 @@ QtObject {
 	required property int inputIndex
 	readonly property string bindPrefix: Global.system.serviceUid + "/Ac/In/" + inputIndex
 	property bool isActiveInput
+	readonly property bool valid: deviceInstance >= 0 && serviceType.length && serviceName.length
+
 	readonly property bool connected: _connected.value === 1
 	readonly property int deviceInstance: _deviceInstance.isValid ? _deviceInstance.value : -1
 	readonly property string serviceType: _serviceType.value || "" // e.g. "vebus"

data/common/ActiveAcInput.qml

@@ -26,7 +26,6 @@ Device {
 	// Phase measurements from com.victronenergy.system/Ac/ActiveIn/L<1|2|3>
 	readonly property AcInputPhaseModel _phases: AcInputPhaseModel {
 		id: _phases
-
 	}
 
 	// Data from the input-specific service, e.g. com.victronenergy.vebus for a VE.Bus input,
@@ -38,12 +37,4 @@ Device {
 		serviceUid: root.serviceUid
 		serviceType: root.serviceType
 	}
-
-	serviceUid: BackendConnection.type === BackendConnection.MqttSource
-			  // this looks like: 'mqtt/vebus/289/'
-			? inputInfo && serviceType.length && inputInfo.deviceInstance >= 0
-					? "mqtt/" + serviceType + "/" + inputInfo.deviceInstance
-					: ""
-			  // this looks like: "dbus/com.victronenergy.vebus.ttyO1"
-			: serviceName.length ? BackendConnection.uidPrefix() + "/" + serviceName : ""
 }