#
# This file is part of pysnmp software.
#
# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
# License: http://snmplabs.com/pysnmp/license.html
#
from pysnmp import debug
from pysnmp import nextid
from pysnmp.entity.rfc3413 import config
from pysnmp.proto import errind
from pysnmp.proto import error
from pysnmp.proto import rfc3411
from pysnmp.proto.api import v2c
from pysnmp.proto.proxy import rfc2576

getNextHandle = nextid.Integer(0x7fffffff)


class NotificationOriginator(object):
    ACM_ID = 3  # default MIB access control method to use

    def __init__(self, **options):
        self.__pendingReqs = {}
        self.__pendingNotifications = {}
        self.snmpContext = options.pop('snmpContext', None)  # this is deprecated
        self.__options = options

    def processResponsePdu(self, snmpEngine, messageProcessingModel,
                           securityModel, securityName, securityLevel,
                           contextEngineId, contextName, pduVersion,
                           PDU, statusInformation, sendPduHandle, cbInfo):
        sendRequestHandle, cbFun, cbCtx = cbInfo

        # 3.3.6d
        if sendPduHandle not in self.__pendingReqs:
            raise error.ProtocolError('Missing sendPduHandle %s' % sendPduHandle)

        (origTransportDomain, origTransportAddress,
         origMessageProcessingModel, origSecurityModel,
         origSecurityName, origSecurityLevel, origContextEngineId,
         origContextName, origPdu, origTimeout,
         origRetryCount, origRetries, origDiscoveryRetries) = self.__pendingReqs.pop(sendPduHandle)

        snmpEngine.transportDispatcher.jobFinished(id(self))

        if statusInformation:
            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponsePdu: sendRequestHandle %s, sendPduHandle %s statusInformation %s' % (
                    sendRequestHandle, sendPduHandle, statusInformation))

            errorIndication = statusInformation['errorIndication']

            if errorIndication in (errind.notInTimeWindow, errind.unknownEngineID):
                origDiscoveryRetries += 1
                origRetries = 0
            else:
                origDiscoveryRetries = 0
                origRetries += 1

            if origRetries > origRetryCount or origDiscoveryRetries > self.__options.get('discoveryRetries', 4):
                debug.logger & debug.FLAG_APP and debug.logger(
                    'processResponsePdu: sendRequestHandle %s, sendPduHandle %s retry count %d exceeded' % (
                        sendRequestHandle, sendPduHandle, origRetries))
                cbFun(snmpEngine, sendRequestHandle, errorIndication, None, cbCtx)
                return

            # Convert timeout in seconds into timeout in timer ticks
            timeoutInTicks = float(origTimeout) / 100 / snmpEngine.transportDispatcher.getTimerResolution()

            # User-side API assumes SMIv2
            if messageProcessingModel == 0:
                reqPDU = rfc2576.v2ToV1(origPdu)
                pduVersion = 0
            else:
                reqPDU = origPdu
                pduVersion = 1

            # 3.3.6a
            try:
                sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
                    snmpEngine, origTransportDomain, origTransportAddress,
                    origMessageProcessingModel, origSecurityModel,
                    origSecurityName, origSecurityLevel,
                    origContextEngineId, origContextName, pduVersion,
                    reqPDU, True, timeoutInTicks, self.processResponsePdu,
                    (sendRequestHandle, cbFun, cbCtx)
                )
            except error.StatusInformation as exc:
                statusInformation = exc
                debug.logger & debug.FLAG_APP and debug.logger(
                    'processResponsePdu: sendRequestHandle %s: sendPdu() failed with %r ' % (
                        sendRequestHandle, statusInformation))
                cbFun(snmpEngine, sendRequestHandle,
                      statusInformation['errorIndication'], None, cbCtx)
                return

            snmpEngine.transportDispatcher.jobStarted(id(self))

            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponsePdu: sendRequestHandle %s, sendPduHandle %s, timeout %d, retry %d of %d' % (
                    sendRequestHandle, sendPduHandle, origTimeout, origRetries, origRetryCount))

            # 3.3.6b
            self.__pendingReqs[sendPduHandle] = (
                origTransportDomain, origTransportAddress,
                origMessageProcessingModel, origSecurityModel,
                origSecurityName, origSecurityLevel,
                origContextEngineId, origContextName, origPdu,
                origTimeout, origRetryCount, origRetries, origDiscoveryRetries
            )
            return

        # 3.3.6c
        # User-side API assumes SMIv2
        if messageProcessingModel == 0:
            PDU = rfc2576.v1ToV2(PDU, origPdu)

        cbFun(snmpEngine, sendRequestHandle, None, PDU, cbCtx)

    def sendPdu(self, snmpEngine, targetName, contextEngineId,
                contextName, pdu, cbFun=None, cbCtx=None):
        (transportDomain, transportAddress, timeout,
         retryCount, params) = config.getTargetAddr(snmpEngine, targetName)

        (messageProcessingModel, securityModel, securityName,
         securityLevel) = config.getTargetParams(snmpEngine, params)

        # User-side API assumes SMIv2
        if messageProcessingModel == 0:
            reqPDU = rfc2576.v2ToV1(pdu)
            pduVersion = 0
        else:
            reqPDU = pdu
            pduVersion = 1

        # 3.3.5
        if reqPDU.tagSet in rfc3411.CONFIRMED_CLASS_PDUS:
            # Convert timeout in seconds into timeout in timer ticks
            timeoutInTicks = float(timeout) / 100 / snmpEngine.transportDispatcher.getTimerResolution()

            sendRequestHandle = getNextHandle()

            # 3.3.6a
            sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
                snmpEngine, transportDomain, transportAddress,
                messageProcessingModel, securityModel, securityName,
                securityLevel, contextEngineId, contextName,
                pduVersion, reqPDU, True, timeoutInTicks,
                self.processResponsePdu, (sendRequestHandle, cbFun, cbCtx)
            )

            debug.logger & debug.FLAG_APP and debug.logger(
                'sendPdu: sendPduHandle %s, timeout %d' % (sendPduHandle, timeout))

            # 3.3.6b
            self.__pendingReqs[sendPduHandle] = (
                transportDomain, transportAddress, messageProcessingModel,
                securityModel, securityName, securityLevel, contextEngineId,
                contextName, pdu, timeout, retryCount, 0, 0
            )
            snmpEngine.transportDispatcher.jobStarted(id(self))
        else:
            snmpEngine.msgAndPduDsp.sendPdu(
                snmpEngine, transportDomain, transportAddress,
                messageProcessingModel, securityModel,
                securityName, securityLevel, contextEngineId,
                contextName, pduVersion, reqPDU, False
            )

            sendRequestHandle = None

            debug.logger & debug.FLAG_APP and debug.logger('sendPdu: message sent')

        return sendRequestHandle

    def processResponseVarBinds(self, snmpEngine, sendRequestHandle,
                                errorIndication, pdu, cbCtx):
        notificationHandle, cbFun, cbCtx = cbCtx

        self.__pendingNotifications[notificationHandle].remove(sendRequestHandle)

        debug.logger & debug.FLAG_APP and debug.logger(
            'processResponseVarBinds: notificationHandle %s, sendRequestHandle %s, errorIndication %s, pending requests %s' % (
                notificationHandle, sendRequestHandle, errorIndication, self.__pendingNotifications[notificationHandle]))

        if not self.__pendingNotifications[notificationHandle]:
            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponseVarBinds: notificationHandle %s, sendRequestHandle %s -- completed' % (
                    notificationHandle, sendRequestHandle))
            del self.__pendingNotifications[notificationHandle]
            cbFun(snmpEngine, sendRequestHandle, errorIndication,
                  pdu and v2c.apiPDU.getErrorStatus(pdu) or 0,
                  pdu and v2c.apiPDU.getErrorIndex(pdu, muteErrors=True) or 0,
                  pdu and v2c.apiPDU.getVarBinds(pdu) or (),
                  cbCtx)

    #
    # Higher-level API to Notification Originator. Supports multiple
    # targets, automatic var-binding formation and is fully LCD-driven.
    #
    def sendVarBinds(self, snmpEngine, notificationTarget, contextEngineId,
                     contextName, varBinds=(), cbFun=None, cbCtx=None):
        debug.logger & debug.FLAG_APP and debug.logger(
            'sendVarBinds: notificationTarget %s, contextEngineId %s, contextName "%s", varBinds %s' % (
                notificationTarget, contextEngineId or '<default>', contextName, varBinds))

        mibBuilder = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder

        if contextName:
            __SnmpAdminString, = mibBuilder.importSymbols(
                'SNMP-FRAMEWORK-MIB', 'SnmpAdminString')
            contextName = __SnmpAdminString(contextName)

        # 3.3
        notifyTag, notifyType = config.getNotificationInfo(
            snmpEngine, notificationTarget)

        notificationHandle = getNextHandle()

        debug.logger & debug.FLAG_APP and debug.logger(
            'sendVarBinds: notificationHandle %s, notifyTag %s, '
            'notifyType %s' % (notificationHandle, notifyTag, notifyType))

        varBinds = [(v2c.ObjectIdentifier(x), y) for x, y in varBinds]

        # 3.3.2 & 3.3.3
        snmpTrapOID, sysUpTime = mibBuilder.importSymbols(
            '__SNMPv2-MIB', 'snmpTrapOID', 'sysUpTime')

        snmpTrapOID = snmpTrapOID.getName()
        sysUpTime, uptime = sysUpTime.getName(), sysUpTime.getSyntax()

        # Add sysUpTime if not present already
        if not varBinds or varBinds[0][0] != sysUpTime:
            varBinds.insert(0, (v2c.ObjectIdentifier(sysUpTime), uptime.clone()))

        # Search for and reposition sysUpTime if it's elsewhere
        for idx, varBind in enumerate(varBinds[1:]):
            if varBind[0] == sysUpTime:
                varBinds[0] = varBind
                del varBinds[idx]
                break

        if len(varBinds) < 2:
            raise error.PySnmpError('SNMP notification PDU requires '
                                    'SNMPv2-MIB::snmpTrapOID.0 to be present')

        # Search for and reposition snmpTrapOID if it's elsewhere
        for idx, varBind in enumerate(varBinds[2:]):
            if varBind[0] == snmpTrapOID:
                del varBinds[idx]
                if varBinds[1][0] == snmpTrapOID:
                    varBinds[1] = varBind
                else:
                    varBinds.insert(1, varBind)
                break

        if varBinds[1][0] != snmpTrapOID:
            raise error.PySnmpError('SNMP notification PDU requires '
                                    'SNMPv2-MIB::snmpTrapOID.0 to be present')

        sendRequestHandle = -1

        debug.logger & debug.FLAG_APP and debug.logger('sendVarBinds: final varBinds %s' % (varBinds,))

        for targetAddrName in config.getTargetNames(snmpEngine, notifyTag):
            (transportDomain, transportAddress, timeout,
             retryCount, params) = config.getTargetAddr(snmpEngine,
                                                        targetAddrName)
            (messageProcessingModel, securityModel, securityName,
             securityLevel) = config.getTargetParams(snmpEngine, params)

            # 3.3.1 XXX
            # XXX filtering's yet to be implemented
            #             filterProfileName = config.getNotifyFilterProfile(params)

            #             (filterSubtree, filterMask,
            #              filterType) = config.getNotifyFilter(filterProfileName)

            debug.logger & debug.FLAG_APP and debug.logger(
                'sendVarBinds: notificationHandle %s, notifyTag %s yields: transportDomain %s, transportAddress %r, securityModel %s, securityName %s, securityLevel %s' % (
                    notificationHandle, notifyTag, transportDomain, transportAddress, securityModel,
                    securityName, securityLevel))

            for varName, varVal in varBinds:
                if varName in (sysUpTime, snmpTrapOID):
                    continue
                try:
                    snmpEngine.accessControlModel[self.ACM_ID].isAccessAllowed(
                        snmpEngine, securityModel, securityName,
                        securityLevel, 'notify', contextName, varName
                    )

                    debug.logger & debug.FLAG_APP and debug.logger(
                        'sendVarBinds: ACL succeeded for OID %s securityName %s' % (varName, securityName))

                except error.StatusInformation:
                    debug.logger & debug.FLAG_APP and debug.logger(
                        'sendVarBinds: ACL denied access for OID %s securityName %s, droppping notification' % (
                            varName, securityName))
                    return

            # 3.3.4
            if notifyType == 1:
                pdu = v2c.SNMPv2TrapPDU()
            elif notifyType == 2:
                pdu = v2c.InformRequestPDU()
            else:
                raise error.ProtocolError('Unknown notify-type %r', notifyType)

            v2c.apiPDU.setDefaults(pdu)
            v2c.apiPDU.setVarBinds(pdu, varBinds)

            # 3.3.5
            try:
                sendRequestHandle = self.sendPdu(
                    snmpEngine, targetAddrName, contextEngineId,
                    contextName, pdu, self.processResponseVarBinds,
                    (notificationHandle, cbFun, cbCtx)
                )

            except error.StatusInformation as exc:
                statusInformation = exc
                debug.logger & debug.FLAG_APP and debug.logger(
                    'sendVarBinds: sendRequestHandle %s: sendPdu() failed with %r' % (
                        sendRequestHandle, statusInformation))
                if notificationHandle not in self.__pendingNotifications or \
                        not self.__pendingNotifications[notificationHandle]:
                    if notificationHandle in self.__pendingNotifications:
                        del self.__pendingNotifications[notificationHandle]
                    if cbFun:
                        cbFun(snmpEngine, notificationHandle,
                              statusInformation['errorIndication'], 0, 0, (),
                              cbCtx)
                return notificationHandle

            debug.logger & debug.FLAG_APP and debug.logger(
                'sendVarBinds: notificationHandle %s, sendRequestHandle %s, timeout %d' % (
                    notificationHandle, sendRequestHandle, timeout))

            if notifyType == 2:
                if notificationHandle not in self.__pendingNotifications:
                    self.__pendingNotifications[notificationHandle] = set()
                self.__pendingNotifications[notificationHandle].add(sendRequestHandle)

        debug.logger & debug.FLAG_APP and debug.logger(
            'sendVarBinds: notificationHandle %s, sendRequestHandle %s, notification(s) sent' % (
                notificationHandle, sendRequestHandle))

        return notificationHandle

# XXX
# move/group/implement config setting/retrieval at a stand-alone module