decode method

@override BigInt? decode(String? base64)

Decodes a value of storage type TStore back to type T.

Returns null if the stored value is null or cannot be decoded.

Implementation

@override
BigInt? decode(String? base64) {
  if (base64 == null) return null;
  try {
    final bytes = base64Decode(base64);
    if (bytes.isEmpty) return BigInt.zero;

    // First byte indicates sign (0 for positive, 1 for negative)
    final isNegative = bytes[0] == 1;

    // Remaining bytes are the magnitude
    var result = BigInt.zero;
    for (var i = 1; i < bytes.length; i++) {
      result = (result << 8) | BigInt.from(bytes[i]);
    }

    return isNegative ? -result : result;
  } catch (_) {
    return null; // Invalid format
  }
}