#
# This file is part of pysnmp software.
#
# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
# License: http://snmplabs.com/pysnmp/license.html
#
from pyasn1.type import univ

from pysnmp import debug
from pysnmp import error
from pysnmp import nextid
from pysnmp.entity.rfc3413 import config
from pysnmp.proto import errind
from pysnmp.proto.api import v2c
from pysnmp.proto.error import StatusInformation
from pysnmp.proto.proxy import rfc2576

getNextHandle = nextid.Integer(0x7fffffff)

__null = univ.Null('')


class CommandGenerator(object):
    _null = univ.Null('')

    def __init__(self, **options):
        self.__options = options
        self.__pendingReqs = {}

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

        # 3.1.1
        if sendPduHandle not in self.__pendingReqs:
            raise error.PySnmpError('Missing sendPduHandle %s' % sendPduHandle)

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

        snmpEngine.transportDispatcher.jobFinished(id(self))

        # 3.1.3
        if statusInformation:
            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponsePdu: sendPduHandle %s, statusInformation '
                '%s' % (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: sendPduHandle %s, retry count %d '
                    'exceeded' % (sendPduHandle, origRetries))

                cbFun(snmpEngine, origSendRequestHandle,
                      errorIndication, None, cbCtx)
                return

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

            else:
                reqPDU = origPdu
                pduVersion = 1

            try:
                sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
                    snmpEngine, origTransportDomain, origTransportAddress,
                    origMessageProcessingModel, origSecurityModel,
                    origSecurityName, origSecurityLevel, origContextEngineId,
                    origContextName, pduVersion, reqPDU,
                    True, origTimeout, self.processResponsePdu,
                    (origSendRequestHandle, cbFun, cbCtx))

                snmpEngine.transportDispatcher.jobStarted(id(self))

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

                return

            except StatusInformation as exc:
                statusInformation = exc

                debug.logger & debug.FLAG_APP and debug.logger(
                    'processResponsePdu: origSendRequestHandle %s, _sendPdu() '
                    'failed with %r' % (sendPduHandle, statusInformation))

                cbFun(snmpEngine, origSendRequestHandle,
                      statusInformation['errorIndication'],
                      None, cbCtx)

                return

        if (origMessageProcessingModel != messageProcessingModel or
                origSecurityModel != securityModel or
                origSecurityName != origSecurityName or
                origContextEngineId and origContextEngineId != contextEngineId or
                origContextName and origContextName != contextName or
                origPduVersion != pduVersion):

            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponsePdu: sendPduHandle %s, request/response '
                'data mismatch' % sendPduHandle)

            cbFun(snmpEngine, origSendRequestHandle,
                  'badResponse', None, cbCtx)

            return

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

        # 3.1.2
        if v2c.apiPDU.getRequestID(PDU) != v2c.apiPDU.getRequestID(origPdu):
            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponsePdu: sendPduHandle %s, request-id/response-id '
                'mismatch' % sendPduHandle)

            cbFun(snmpEngine, origSendRequestHandle,
                  'badResponse', None, cbCtx)

            return

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

    def sendPdu(self, snmpEngine, targetName, contextEngineId,
                contextName, PDU, cbFun, cbCtx):
        (transportDomain, transportAddress, timeout,
         retryCount, messageProcessingModel, securityModel,
         securityName,
         securityLevel) = config.getTargetInfo(snmpEngine, targetName)

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

        mibBuilder = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder

        SnmpEngineID, SnmpAdminString = mibBuilder.importSymbols(
            'SNMP-FRAMEWORK-MIB', 'SnmpEngineID', 'SnmpAdminString')

        # Cast possible strings into bytes
        if contextEngineId:
            contextEngineId = SnmpEngineID(contextEngineId)

        contextName = SnmpAdminString(contextName)

        origPDU = PDU

        # User-side API assumes SMIv2
        if messageProcessingModel == 0:
            PDU = rfc2576.v2ToV1(PDU)
            pduVersion = 0

        else:
            pduVersion = 1

        sendRequestHandle = getNextHandle()

        # 3.1
        sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
            snmpEngine, transportDomain, transportAddress,
            messageProcessingModel, securityModel, securityName,
            securityLevel, contextEngineId, contextName,
            pduVersion, PDU, True, timeoutInTicks, self.processResponsePdu,
            (sendRequestHandle, cbFun, cbCtx)
        )

        snmpEngine.transportDispatcher.jobStarted(id(self))

        self.__pendingReqs[sendPduHandle] = (
            transportDomain, transportAddress, messageProcessingModel,
            securityModel, securityName, securityLevel, contextEngineId,
            contextName, pduVersion, origPDU, timeoutInTicks,
            retryCount, 0, 0
        )

        debug.logger & debug.FLAG_APP and debug.logger(
            'sendPdu: sendPduHandle %s, timeout %d*10 ms/%d ticks, retry '
            '0 of %d' % (sendPduHandle, timeout, timeoutInTicks, retryCount))

        return sendRequestHandle


class GetCommandGenerator(CommandGenerator):

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

        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)

    def sendVarBinds(self, snmpEngine, targetName, contextEngineId,
                     contextName, varBinds, cbFun, cbCtx=None):
        reqPDU = v2c.GetRequestPDU()
        v2c.apiPDU.setDefaults(reqPDU)

        v2c.apiPDU.setVarBinds(reqPDU, varBinds)

        return self.sendPdu(snmpEngine, targetName, contextEngineId,
                            contextName, reqPDU, self.processResponseVarBinds,
                            (cbFun, cbCtx))


class SetCommandGenerator(CommandGenerator):

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

        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)

    def sendVarBinds(self, snmpEngine, targetName, contextEngineId,
                     contextName, varBinds, cbFun, cbCtx=None):
        reqPDU = v2c.SetRequestPDU()
        v2c.apiPDU.setDefaults(reqPDU)

        v2c.apiPDU.setVarBinds(reqPDU, varBinds)

        return self.sendPdu(snmpEngine, targetName, contextEngineId,
                            contextName, reqPDU, self.processResponseVarBinds,
                            (cbFun, cbCtx))


class NextCommandGeneratorSingleRun(CommandGenerator):

    def processResponseVarBinds(self, snmpEngine, sendRequestHandle,
                                errorIndication, PDU, cbCtx):
        targetName, contextEngineId, contextName, reqPDU, cbFun, cbCtx = cbCtx

        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)

    def sendVarBinds(self, snmpEngine, targetName, contextEngineId,
                     contextName, varBinds, cbFun, cbCtx=None):
        reqPDU = v2c.GetNextRequestPDU()
        v2c.apiPDU.setDefaults(reqPDU)

        v2c.apiPDU.setVarBinds(reqPDU, varBinds)

        return self.sendPdu(snmpEngine, targetName, contextEngineId,
                            contextName, reqPDU, self.processResponseVarBinds,
                            (targetName, contextEngineId, contextName,
                             reqPDU, cbFun, cbCtx))


class NextCommandGenerator(NextCommandGeneratorSingleRun):

    def processResponseVarBinds(self, snmpEngine, sendRequestHandle,
                                errorIndication, PDU, cbCtx):
        targetName, contextEngineId, contextName, reqPDU, cbFun, cbCtx = cbCtx

        if errorIndication:
            cbFun(snmpEngine, sendRequestHandle, errorIndication,
                  0, 0, (), cbCtx)
            return

        varBindTable = v2c.apiPDU.getVarBindTable(reqPDU, PDU)

        if v2c.apiPDU.getErrorStatus(PDU):
            errorIndication, varBinds = None, ()

        elif not varBindTable:
            errorIndication, varBinds = errind.emptyResponse, ()

        else:
            errorIndication, varBinds = v2c.apiPDU.getNextVarBinds(varBindTable[-1])

        if not cbFun(snmpEngine, sendRequestHandle, errorIndication,
                     v2c.apiPDU.getErrorStatus(PDU),
                     v2c.apiPDU.getErrorIndex(PDU, muteErrors=True),
                     varBindTable, cbCtx):

            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponseVarBinds: sendRequestHandle %s, app says to stop walking' % sendRequestHandle)

            return  # app says it's enough

        if not varBinds:
            return  # no more objects available

        v2c.apiPDU.setRequestID(reqPDU, v2c.getNextRequestID())
        v2c.apiPDU.setVarBinds(reqPDU, varBinds)

        try:
            self.sendPdu(snmpEngine, targetName, contextEngineId,
                         contextName, reqPDU,
                         self.processResponseVarBinds,
                         (targetName, contextEngineId, contextName,
                          reqPDU, cbFun, cbCtx))

        except StatusInformation as exc:
            statusInformation = exc

            debug.logger & debug.FLAG_APP and debug.logger(
                'sendVarBinds: sendPduHandle %s: sendPdu() failed with '
                '%r' % (sendRequestHandle, statusInformation))

            cbFun(snmpEngine, sendRequestHandle,
                  statusInformation['errorIndication'],
                  0, 0, (), cbCtx)


class BulkCommandGeneratorSingleRun(CommandGenerator):

    def processResponseVarBinds(self, snmpEngine, sendRequestHandle,
                                errorIndication, PDU, cbCtx):
        (targetName, nonRepeaters, maxRepetitions,
         contextEngineId, contextName, reqPDU, cbFun, cbCtx) = cbCtx

        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)

    def sendVarBinds(self, snmpEngine, targetName, contextEngineId,
                     contextName, nonRepeaters, maxRepetitions,
                     varBinds, cbFun, cbCtx=None):
        reqPDU = v2c.GetBulkRequestPDU()
        v2c.apiBulkPDU.setDefaults(reqPDU)

        v2c.apiBulkPDU.setNonRepeaters(reqPDU, nonRepeaters)
        v2c.apiBulkPDU.setMaxRepetitions(reqPDU, maxRepetitions)

        v2c.apiBulkPDU.setVarBinds(reqPDU, varBinds)

        return self.sendPdu(snmpEngine, targetName, contextEngineId,
                            contextName, reqPDU,
                            self.processResponseVarBinds,
                            (targetName, nonRepeaters, maxRepetitions,
                             contextEngineId, contextName, reqPDU,
                             cbFun, cbCtx))


class BulkCommandGenerator(BulkCommandGeneratorSingleRun):

    def processResponseVarBinds(self, snmpEngine, sendRequestHandle,
                                errorIndication, PDU, cbCtx):
        (targetName, nonRepeaters, maxRepetitions,
         contextEngineId, contextName, reqPDU, cbFun, cbCtx) = cbCtx

        if errorIndication:
            cbFun(snmpEngine, sendRequestHandle, errorIndication,
                  0, 0, (), cbCtx)
            return

        varBindTable = v2c.apiBulkPDU.getVarBindTable(reqPDU, PDU)

        if v2c.apiBulkPDU.getErrorStatus(PDU):
            errorIndication, varBinds = None, ()

        elif not varBindTable:
            errorIndication, varBinds = errind.emptyResponse, ()

        else:
            errorIndication, varBinds = v2c.apiBulkPDU.getNextVarBinds(varBindTable[-1])
            nonRepeaters = v2c.apiBulkPDU.getNonRepeaters(reqPDU)

            if nonRepeaters:
                varBinds = v2c.apiBulkPDU.getVarBinds(reqPDU)[:int(nonRepeaters)] + varBinds[int(nonRepeaters):]

        if not cbFun(
                snmpEngine, sendRequestHandle, errorIndication,
                v2c.apiBulkPDU.getErrorStatus(PDU),
                v2c.apiBulkPDU.getErrorIndex(PDU, muteErrors=True),
                varBindTable, cbCtx):

            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponseVarBinds: sendRequestHandle %s, app says to stop walking' % sendRequestHandle)

            return  # app says it's enough

        if not varBinds:
            return  # no more objects available

        v2c.apiBulkPDU.setRequestID(reqPDU, v2c.getNextRequestID())
        v2c.apiBulkPDU.setVarBinds(reqPDU, varBinds)

        try:
            self.sendPdu(
                snmpEngine, targetName, contextEngineId, contextName, reqPDU,
                self.processResponseVarBinds,
                (targetName, nonRepeaters, maxRepetitions,
                    contextEngineId, contextName, reqPDU, cbFun, cbCtx))

        except StatusInformation as exc:
            statusInformation = exc

            debug.logger & debug.FLAG_APP and debug.logger(
                'processResponseVarBinds: sendPduHandle %s: _sendPdu() failed '
                'with %r' % (sendRequestHandle, statusInformation))

            cbFun(snmpEngine, sendRequestHandle,
                  statusInformation['errorIndication'], 0, 0, (), cbCtx)