indexIncrement method
Implementation
void indexIncrement(String? key, int maxIndex) {
failCounter = 0;
if (key != null) {
routeIndex[key] = (routeIndex[key] == null)
? (maxIndex == 0 ? 0 : 1)
: (routeIndex[key] < maxIndex ? routeIndex[key] + 1 : 0);
} else {
currentAdIndex = currentAdIndex < maxIndex ? currentAdIndex + 1 : 0;
}
}