import time

import dns.resolver

from .base import BaseChecker, CheckResult
from .ping import PingChecker


class DnsChecker(BaseChecker):
    def check(self) -> CheckResult:
        host = self.config["host"]
        query_name = self.config["query"]
        query_type = self.config.get("record_type", "A")
        timeout = self.config.get("timeout", 5)

        # First check if host is reachable via ping
        ping_checker = PingChecker(self.name, {"host": host, "timeout": timeout})
        ping_result = ping_checker.check()

        if not ping_result.success:
            return CheckResult(
                success=False,
                message=f"DNS server unreachable: {ping_result.message}",
                response_time=None
            )

        # Now perform DNS query
        resolver = dns.resolver.Resolver()
        resolver.nameservers = [host]
        resolver.timeout = timeout
        resolver.lifetime = timeout

        start = time.time()
        try:
            answers = resolver.resolve(query_name, query_type)
            response_time = (time.time() - start) * 1000  # ms

            records = [str(rdata) for rdata in answers]
            return CheckResult(
                success=True,
                message=f"DNS {query_type} query OK ({len(records)} record(s))",
                response_time=response_time,
                details={"records": records, "query": query_name, "type": query_type}
            )
        except dns.resolver.NXDOMAIN:
            return CheckResult(
                success=False,
                message=f"DNS query failed: {query_name} does not exist",
                response_time=None
            )
        except dns.resolver.NoAnswer:
            return CheckResult(
                success=False,
                message=f"DNS query failed: no {query_type} record for {query_name}",
                response_time=None
            )
        except dns.resolver.Timeout:
            return CheckResult(
                success=False,
                message="DNS query timeout",
                response_time=None
            )
        except Exception as e:
            return CheckResult(
                success=False,
                message=f"DNS error: {e}",
                response_time=None
            )