mobile: add status text for cloud sync state

This allows the mobile UI to reflect the three states that the dive list can be
in:
- changes that haven't been written to local storage
- there potentially are changes in local storage that were not synced with the cloud
- dive list is in sync with cloud storage

The last state could be misleading if the user access the cloud from a
different device and makes changes to the cloud storage from there, but from
the point of view of this device, the states are consistent.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

mobile-widgets/qmlmanager.cpp

@@ -733,6 +733,7 @@ void QMLManager::loadDivesWithValidCredentials()
 		appendTextToLog(QStringLiteral("%1 dives loaded after importing nocloud local storage").arg(dive_table.nr));
 		noCloudToCloud = false;
 		mark_divelist_changed(true);
+		emit syncStateChanged();
 		saveChangesLocal();
 		if (git_local_only == false) {
 			appendTextToLog(QStringLiteral("taking things back offline now that storage is synced"));
@@ -1292,6 +1293,7 @@ void QMLManager::changesNeedSaving()
 	// on iOS
 	// on all other platforms we just save the changes and be done with it
 	mark_divelist_changed(true);
+	emit syncStateChanged();
 #if defined(Q_OS_IOS)
 	saveChangesLocal();
 #else
@@ -2251,4 +2253,15 @@ QStringList QMLManager::cloudCacheList() const
 void QMLManager::updateHaveLocalChanges(bool status)
 {
 	localChanges = status;
+	emit syncStateChanged();
+}
+
+// show the state of the dive list
+QString QMLManager::getSyncState() const
+{
+	if (unsavedChanges())
+		return tr("(unsaved changes in memory)");
+	if (localChanges)
+		return tr("(changes synced locally)");
+	return tr("(synced with cloud)");
 }