import time

from pysnmp.hlapi import (
    SnmpEngine,
    CommunityData,
    UdpTransportTarget,
    ContextData,
    ObjectType,
    ObjectIdentity,
    getCmd,
)

from .base import BaseChecker, CheckResult


class SnmpChecker(BaseChecker):
    def check(self) -> CheckResult:
        host = self.config["host"]
        port = self.config.get("port", 161)
        community = self.config.get("community", "public")
        oid = self.config.get("oid", "1.3.6.1.2.1.1.1.0")  # sysDescr
        timeout_val = self.config.get("timeout", 5)

        start = time.time()
        try:
            iterator = getCmd(
                SnmpEngine(),
                CommunityData(community),
                UdpTransportTarget((host, port), timeout=timeout_val, retries=1),
                ContextData(),
                ObjectType(ObjectIdentity(oid))
            )

            error_indication, error_status, error_index, var_binds = next(iterator)
            response_time = (time.time() - start) * 1000  # ms

            if error_indication:
                return CheckResult(
                    success=False,
                    message=f"SNMP error: {error_indication}",
                    response_time=None
                )
            elif error_status:
                return CheckResult(
                    success=False,
                    message=f"SNMP error: {error_status.prettyPrint()}",
                    response_time=None
                )
            else:
                values = {str(oid): str(val) for oid, val in var_binds}
                return CheckResult(
                    success=True,
                    message="SNMP response OK",
                    response_time=response_time,
                    details=values
                )
        except Exception as e:
            return CheckResult(
                success=False,
                message=f"SNMP error: {e}",
                response_time=None
            )