generateUuid function
Generate a v4 UUID string.
Implementation
String generateUuid() {
final rng = Random.secure();
final bytes = List<int>.generate(16, (_) => rng.nextInt(256));
// Set version 4
bytes[6] = (bytes[6] & 0x0f) | 0x40;
// Set variant 1
bytes[8] = (bytes[8] & 0x3f) | 0x80;
final hex = bytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
return '${hex.substring(0, 8)}-${hex.substring(8, 12)}-'
'${hex.substring(12, 16)}-${hex.substring(16, 20)}-'
'${hex.substring(20)}';
}