Swag and unswag your IP address

swag.py

def swag(ip: str) -> int:
    parts = ip.strip().split('.')

    if len(parts) != 4:
        raise ValueError("Invalid IPv4 address: must have 4 octets")

    total = 0

    for i, p in enumerate(parts):
        if not p.isdigit():
            raise ValueError(f"Octet {i + 1} is not a number")
        n = int(p)

        if not (0 <= n <= 255):
            raise ValueError(f"Octet {i + 1} out of range (0-255)")

        total = (total << 8) | n

    if (total >> 24) == 0:
        raise ValueError("First octet cannot be 0")

    return total

def unswag(num: int) -> str:
    if not (0x01000000 <= num <= 0xFFFFFFFF):
        raise ValueError("Number out of IPv4 range (16777216–4294967295)")

    octets = []

    for shift in (24, 16, 8, 0):
        octets.append(str((num >> shift) & 0xFF))

    return ".".join(octets)


def main():
    print("1. IP to Decimal")
    print("2. Decimal to IP")

    try:
        mode = int(input("Enter mode (1 or 2): ").strip())

        if mode == 1:
            ip = input("Enter IPv4 address: ").strip()
            print(swag(ip))
            
        elif mode == 2:
            num = int(input("Enter decimal number: ").strip())
            print(unswag(num))
            
        else:
            print("Invalid mode. Please enter 1 or 2.")
            
    except Exception as e:
        print(f"Error: {e}")

if __name__ == "__main__":
    main()