#!/usr/bin/env python3
""" Template python check for SNMP checks developed by teccle"""
"""dependencys:
- pip3 install nagiosplugin
- pip3 install argparse
- pip3 install easysnmp
    - https://easysnmp.readthedocs.io/en/latest/index.html
    - https://easysnmp.readthedocs.io/en/latest/session_api.html
"""

__version__     = '0.4.0'
__author__      = 'anima'

# imports
import logging
import argparse
import nagiosplugin
from easysnmp import Session

# log settings
logging.basicConfig(format='[%(asctime)s] %(levelname)s %(message)s', level=logging.INFO)

def init_snmp_session(hostname: str = 'localhost', snmp_version: str | int = '2', snmp_community: str = 'public',
    snmp_security_level: str = 'auth_with_privacy', snmp_security_username: str = 'monitoring',
    snmp_auth_protocol: str = 'SHA256', snmp_auth_password: str | None = None,
    snmp_privacy_protocol: str = 'AES', snmp_privacy_password: str | None = None
    ) -> Session:
    """init a easysnmp session

    Args:
        hostname (str, optional): hostname or ip of host. Defaults to 'localhost'.
        snmp_version (str, optional): version of snmp (1, 2, 3). Defaults to 2.
        snmp_community (str, only need for v1 & v2): snmp community if snmp v1 or v2 used (any). Defaults to 'public'.
        snmp_security_level (str, only need for v3): security level (no_auth_or_privacy, auth_without_privacy or auth_with_privacy). Defaults to 'auth_with_privacy'.
        snmp_security_username (str, only need for v3): security name (any). Defaults to 'monitoring'.
        snmp_auth_protocol (str, only need for v3): authentication protocol (MD5, SHA256, SHA512). Defaults to 'SHA256'.
        snmp_auth_password (str, only need for v3): authentication passphrase (any). Defaults to None.
        snmp_privacy_protocol (str, only need for v3): privacy protocol (AES, DES). Defaults to 'AES'.
        snmp_privacy_password (str, only need for v3): privacy passphrase (any). Defaults to None.
    
    Return:
        easysnmp.Session: session for get or walk actions
    """
    # check if snmp version an valid str or int and saves as int
    valid_versions: list[str, int] = ['1','2','3', 1, 2, 3]
    if snmp_version not in valid_versions:
        raise ValueError(f'{snmp_version=} non of {valid_versions=}')
    else:
        snmp_version = int(snmp_version)

    if snmp_version == '3':
        # check if snmp security level valid
        valid_security_levels: list[str] = ['no_auth_or_privacy', 'auth_without_privacy', 'auth_with_privacy']
        if snmp_security_level not in valid_security_levels:
            raise ValueError(f'{snmp_security_level=} is non of {valid_security_levels=}')

        # check if auth protocol valid
        if snmp_security_level.startswith('auth'):
            valid_auth_protocols: list[str] = ['MD5', 'SHA', 'SHA256', 'SHA512']
            if snmp_auth_protocol not in valid_auth_protocols:
                raise ValueError(f'{snmp_auth_protocol=} is non of {valid_auth_protocols=}')

            if snmp_auth_password is None:
                raise ValueError(f'{snmp_auth_password=} is not set')

        # check if privacy protocol valid
        if not snmp_security_level.startswith('no'):
            valid_privacy_protocols: list[str] = ['AES', 'DES']
            if snmp_privacy_protocol not in valid_privacy_protocols:
                raise ValueError(f'{snmp_privacy_protocol=} is non of {valid_privacy_protocols=}')

            if snmp_privacy_password is None:
                raise ValueError(f'{snmp_privacy_password=} is not set')


    if snmp_version == 3: # 2025-01-02: only 'auth_with_privacy' is tested
        session = Session(hostname=hostname, version=snmp_version, 
            security_level=snmp_security_level, security_username=snmp_security_username,
            privacy_protocol=snmp_privacy_protocol, privacy_password=snmp_privacy_password,
            auth_protocol=snmp_auth_protocol, auth_password=snmp_auth_password)
    else:
        session = Session(hostname=hostname, version=snmp_version, community=snmp_community)
    return session

#
# Synology [DSM & DSM UC] System partition status. 
#
class SNMPSynologySystemResource(nagiosplugin.Resource):
    def __init__(self, session) -> None:
        self.session = session

    def probe(self) -> list:
        """check system status (normal or failed)
        
        Returns:
            nagiosplugin.Metric: single metric element (return)
        """
        baseoid = '.1.3.6.1.4.1.6574.1'
        oids = dict()
        oids['status'] = '.1.0'
        oids['model'] = '.5.1.0'
        oids['sn'] = '.5.2.0'
        # oids['hostname'] = '.1.0'

        result = dict()
        for key, oid in oids.items():
            result[key] = self.session.get(baseoid + oid).value
        return nagiosplugin.Metric(name='status', value=result, context='system_context')


class SNMPSynologySystemResult(nagiosplugin.Result):
    def __str__(self):
        if self.metric.value['status'] == '1': status = 'normal'
        else: status = 'failed'
        return f'{self.metric.value["model"]} (SN: {self.metric.value["sn"]}) is in status {status}!'


class SNMPSynologySystemContext(nagiosplugin.Context):
    def __init__(self, name):
        super().__init__(name, fmt_metric='{name} is', result_cls=SNMPSynologySystemResult)

    def evaluate(self, metric, resource):
        if metric.value['status'] == '2':
            return self.result_cls(nagiosplugin.Critical, "critical", metric)
        elif metric.value['status'] == '1':
            return self.result_cls(nagiosplugin.Ok, "ok", metric)
        return self.result_cls(nagiosplugin.Unknown, "unknown", metric)


#
# Synology [DSM & DSM UC] Temperature of NAS
# 
class SNMPSynologySysTempResource(nagiosplugin.Resource):
    def __init__(self, session) -> None:
        self.session = session

    def probe(self) -> list:
        """check system temperature in °C
        
        Returns:
            nagiosplugin.Metric: single metric element (return)
        """
        baseoid = '.1.3.6.1.4.1.6574.1'
        oids = dict()
        result = self.session.get(baseoid + '.2.0').value
        return nagiosplugin.Metric(name='systemp', value=int(result), uom='°C', context='systemp_scalar_context')

    def __init__(self, session) -> None:
        self.session = session


#
# Synology [DSM & DSM UC] Returns error if power supplies fail
#
class SNMPSynologyPowerSupplyResource(nagiosplugin.Resource):
    def __init__(self, session) -> None:
        self.session = session

    def probe(self) -> list:
        """check power supply status (normal or failed)
        
        Returns:
            nagiosplugin.Metric: single metric element (return)
        """
        baseoid = '.1.3.6.1.4.1.6574.1'
        result = self.session.get(baseoid + '.3.0').value
        return nagiosplugin.Metric(name='status', value=result, context='powersupply_context')


class SNMPSynologyPowerSupplyResult(nagiosplugin.Result):
    def __str__(self):
        if self.metric.value == '1': status = 'normal'
        else: status = 'failed'
        return f'Power Supply is in status {status}!'


class SNMPSynologyPowerSupplyContext(nagiosplugin.Context):
    def __init__(self, name):
        super().__init__(name, fmt_metric='{name} is', result_cls=SNMPSynologyPowerSupplyResult)

    def evaluate(self, metric, resource):
        if metric.value == '2':
            return self.result_cls(nagiosplugin.Critical, "critical", metric)
        elif metric.value == '1':
            return self.result_cls(nagiosplugin.Ok, "ok", metric)
        return self.result_cls(nagiosplugin.Unknown, "unknown", metric)


#
# Synology [DSM & DSM UC] Returns error if system fan fails
#
class SNMPSynologyFansResource(nagiosplugin.Resource):
    def __init__(self, session) -> None:
        self.session = session

    def probe(self) -> list:
        """check fans status (normal or failed)
        
        Returns:
            nagiosplugin.Metric: single metric element (return)
        """
        baseoid = '.1.3.6.1.4.1.6574.1'
        fans = dict()
        fans['system'] = '.4.1.0'
        fans['cpu'] = '.4.2.0'

        for fan, oid in fans.items():
            result = self.session.get(baseoid + oid).value
            yield nagiosplugin.Metric(name=fan, value=result, context='fan_context')


class SNMPSynologyFansResult(nagiosplugin.Result):
    def __str__(self):
        if self.metric.value == '1': status = 'normal'
        else: status = 'failed'
        return f'{self.metric.name} fan is in status {status}!'


class SNMPSynologyFansContext(nagiosplugin.Context):
    def __init__(self, name):
        super().__init__(name, fmt_metric='{name} is', result_cls=SNMPSynologyFansResult)

    def evaluate(self, metric, resource):
        if metric.value == '2':
            return self.result_cls(nagiosplugin.Critical, "critical", metric)
        elif metric.value == '1':
            return self.result_cls(nagiosplugin.Ok, "ok", metric)
        return self.result_cls(nagiosplugin.Unknown, "unknown", metric)


class SNMPSynologyFansSummary(nagiosplugin.Summary):
    def verbose(self, results):
        result_str = ''
        for result in results:
            result_str += f'{str(result)}\n'
        return result_str

    def ok(self, results):
        return

    def problem(self, results):
        return


#
# Arguments
#
def parse_args() -> argparse.Namespace:
    """evaluates given arguments

    Returns:
        argsparse.Namespace: Namespace Object with all arguments insert (use: args.long_name_of_argument)
    """
    argp = argparse.ArgumentParser(description=__doc__)
    # Default args
    argp.add_argument('-v', '--verbose', action='count', default=0,
        help='increase output verbosity (use up to 3 times)')
    argp.add_argument('-H', '--hostname', default='localhost',
        help='IP address or hostname of device to query')
    argp.add_argument('-t', '--timeout', default=30,
        help='abort execution after TIMEOUT seconds')
    # TEMPLATE TODO: edit choices
    argp.add_argument('-m', '--check_mode',
        choices=[
            'system',
            'systemp',
            'powersupply',
            'fans',
        ],
        help='check mode to run')

    # Nagios args / see https://nagios-plugins.org/doc/guidelines.html#THRESHOLDFORMAT
    argp.add_argument('-w', '--warning', default=':80',
        help='warning threshold')
    argp.add_argument('-c', '--critical', default=':90',
        help='critical threshold')

    # SNMP args (same -* as snmpwalk / snmpget linux command; exept -C/-c & -V /-v because already used (see above))
    argp.add_argument('-V', '--snmp-version', default='2',
        help='Used SNMP Version. (1, 2, 3)')
    argp.add_argument('-C', '--snmp_community', default='public',
        help='SNMP community if snmp v1 or v2 used (any).')
    argp.add_argument('-l', '--snmp-security-level', default='auth_with_privacy',
        help='Security level (no_auth_or_privacy, auth_without_privacy or auth_with_privacy)')
    argp.add_argument('-u', '--snmp-security-username', default='monitoring',
        help='Security name (any)')
    argp.add_argument('-a', '--snmp-auth-protocol', default='SHA256',
        help='Authentication protocol (MD5, SHA256, SHA512)')
    argp.add_argument('-A', '--snmp-auth-pass', default=None,
        help='Authentication passphrase (any)')
    argp.add_argument('-x', '--snmp-privacy-protocol', default='AES',
        help='Privacy protocol (AES, DES)')
    argp.add_argument('-X', '--snmp-privacy-pass', default=None,
        help='Privacy passphrase (any)')

    args = argp.parse_args()
    return args

#
# init
# 
def main():
    args = parse_args()
    if args.verbose >= 3:
        logging.getLogger().setLevel(logging.DEBUG)

    session = init_snmp_session(hostname=args.hostname, snmp_version=args.snmp_version, snmp_community=args.snmp_community,
        snmp_security_level=args.snmp_security_level, snmp_security_username=args.snmp_security_username,
        snmp_auth_protocol=args.snmp_auth_protocol, snmp_auth_password=args.snmp_auth_pass,
        snmp_privacy_protocol=args.snmp_privacy_protocol, snmp_privacy_password=args.snmp_privacy_pass)

    # dice which check will be run bases on check_mode
    match args.check_mode:
        case 'system':
            check = nagiosplugin.Check(SNMPSynologySystemResource(session=session),
            SNMPSynologySystemContext(name='system_context'),
            nagiosplugin.Summary())
            check.name = "System Status"
        case 'systemp':
            check = nagiosplugin.Check(SNMPSynologySysTempResource(session=session),
            nagiosplugin.ScalarContext(name='systemp_scalar_context', warning=args.warning, critical=args.critical),
            nagiosplugin.Summary())
            check.name = "System Temperatur"
        case 'powersupply':
            check = nagiosplugin.Check(SNMPSynologyPowerSupplyResource(session=session),
            SNMPSynologyPowerSupplyContext(name='powersupply_context'),
            nagiosplugin.Summary())
            check.name = "Power Supply Status"
        case 'fans':
            check = nagiosplugin.Check(SNMPSynologyFansResource(session=session),
            SNMPSynologyFansContext(name='fan_context'),
            SNMPSynologyFansSummary())
            check.name = "Fans Status"
        case _:
            raise nagiosplugin.CheckError(f'Unknown check mode: {args.check_mode}')

    check.main(args.verbose, args.timeout)

if __name__ == '__main__':
    main()