"""
Agent operations on MIB
+++++++++++++++++++++++

This script explains how SNMP Agent application manipulates
its MIB possibly triggered by SNMP Manager's commands.

"""#
# SNMP agent backend e.g. Agent access to Managed Objects
from pysnmp.smi import builder, instrum, exval

print('Loading MIB modules...'),
mibBuilder = builder.MibBuilder().loadModules(
    'SNMPv2-MIB', 'SNMP-FRAMEWORK-MIB', 'SNMP-COMMUNITY-MIB'
)
print('done')

print('Building MIB tree...'),
mibInstrum = instrum.MibInstrumController(mibBuilder)
print('done')

print('Building table entry index from human-friendly representation...'),
snmpCommunityEntry, = mibBuilder.importSymbols(
    'SNMP-COMMUNITY-MIB', 'snmpCommunityEntry'
)
instanceId = snmpCommunityEntry.getInstIdFromIndices('my-router')
print('done')

print('Create/update SNMP-COMMUNITY-MIB::snmpCommunityEntry table row: ')
varBinds = mibInstrum.writeVars(
    (snmpCommunityEntry.name + (2,) + instanceId, 'mycomm'),
    (snmpCommunityEntry.name + (3,) + instanceId, 'mynmsname'),
    (snmpCommunityEntry.name + (7,) + instanceId, 'volatile')
)
for oid, val in varBinds:
    print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
print('done')

print('Read whole MIB (table walk)')
varBinds = [((), None)]
while True:
    varBinds = mibInstrum.readNextVars(*varBinds)
    oid, val = varBinds[0]
    if exval.endOfMib.isSameTypeWith(val):
        break
    print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
print('done')

print('Unloading MIB modules...'),
mibBuilder.unloadModules()
print('done')