"""
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, exval, instrum

(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(
        "{} = {}".format(
            ".".join([str(x) for x in oid]),
            not val.isValue and "N/A" or val.prettyPrint(),
        )
    )
print("done")

print("Read whole MIB (table walk)")
oid, val = (), None
while True:
    oid, val = mibInstrum.readNextVars(((oid, val),))[0]
    if exval.endOfMib.isSameTypeWith(val):
        break
    print(
        "{} = {}".format(
            ".".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")