import argparse
from typing import List

import dns.message
import dns.query

from dns.resolver import resolve, NXDOMAIN
from dns.rcode import Rcode

def get_resolvers(tld: str) -> List[str] | None:
    try:
        answers = resolve(tld, 'NS')
    except NXDOMAIN:
        return

    return [resolve(i.target, 'A')[0].address for i in answers]

def name_exists(name: str, resolver: str) -> bool:
    msg = dns.message.make_query(name, 'NS')
    answer_msg = dns.query.udp(msg, resolver)

    return answer_msg.rcode() == Rcode.NOERROR

def main(tld: str, min_num: int, max_num: int) -> int:
    resolvers = get_resolvers(tld)

    if resolvers is None:
        print(f"Unknown TLD: {tld}")
        return 0
    
    print(f"Scanning TLD '{tld}' with {len(resolvers)} rootservers")
    run_loop(tld, min_num, max_num, resolvers)

def run_loop(tld: str, min_num: int, max_num: int, resolvers: List[str]):
    global name
    
    for i in range(min_num, max_num):
        name = f'{i}.{tld}'
        resolver = resolvers[i % len(resolvers)]

        if not name_exists(name, resolver):
            print(name)
            try:
                input('Press Enter to continue, or Ctrl+C to skip TLD')
            except KeyboardInterrupt:
                print('')
                return

    print(f"No free domains found in range {min_num} - {max_num} for TLD: {tld}")

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('-m', '--min', help='Min number', type=int, default=10)
    parser.add_argument('--max', help='Max number', type=int, default=10000)
    parser.add_argument('tld', help='TLD', nargs='+')

    args = parser.parse_args()

    try:
        for tld in args.tld:
            if main(tld, args.min, args.max) == 1:
                break
    except KeyboardInterrupt:
        print(f"You interrupted at {name}")