urlhandler: Fix devicePicker selection with --device

When using 'Send a file/URL' in the indicator with multiple devices, the
device the user selects for file sharing is not automatically selected in
the URL handler dialog that follows.

This happens because `model.rowForDevice(deviceId)` is called without
waiting for the model to be populated, always returning -1.

Resolving this exposed another bug, where the selected device was still
not the one picked. This happens because `proxyModel` is used to fill the
`QComboBox` but `model` is used to find the correct index. Since
`DevicesPluginFilterProxyModel` sorts and filters the data from `model`
the indices do not match.

This commit addresses these issues by deferring the device selection until
data is available and implementing `rowForDevice` for filtered/sorted data
in `DevicesPluginFilterProxyModel`.

interfaces/devicespluginfilterproxymodel.cpp

@@ -23,4 +23,14 @@ QString DevicesPluginFilterProxyModel::pluginFilter() const
     return m_pluginFilter;
 }
 
+int DevicesPluginFilterProxyModel::rowForDevice(const QString &id) const
+{
+    for (int i = 0, c = rowCount(); i < c; ++i) {
+        if (data(index(i, 0), DevicesModel::IdModelRole).value<QString>() == id) {
+            return i;
+        }
+    }
+    return -1;
+}
+
 #include "moc_devicespluginfilterproxymodel.cpp"

interfaces/devicespluginfilterproxymodel.h

@@ -19,6 +19,7 @@ public:
     bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const override;
     void setPluginFilter(const QString plugin);
     QString pluginFilter() const;
+    int rowForDevice(const QString &id) const;
 
 private:
     QString m_pluginFilter;

urlhandler/kdeconnect-handler.cpp

@@ -86,7 +86,18 @@ int main(int argc, char **argv)
     uidialog.devicePicker->setModel(&proxyModel);
 
     if (!deviceId.isEmpty()) {
-        uidialog.devicePicker->setCurrentIndex(model.rowForDevice(deviceId));
+        // This is done on rowsInserted because the model isn't populated yet
+        QObject::connect(&model, &QAbstractItemModel::rowsInserted, &app, [&uidialog, &deviceId, &proxyModel](const QModelIndex &parent, int first) {
+            Q_UNUSED(parent);
+            /**
+             * We want to run this only once, but on startup the data is populated, removed then repopulated (rowsInserted() -> rowsRemoved() ->
+             * rowsInserted()). Thus by running only when there were no devices previously, it ensures that the user's selection doesn't change without them
+             * realising.
+             */
+            if (first == 0) {
+                uidialog.devicePicker->setCurrentIndex(proxyModel.rowForDevice(deviceId));
+            }
+        });
     }
 
     uidialog.openOnPeerCheckBox->setChecked(open);