#!/usr/bin/env python3

import json
import subprocess
from os.path import isfile

CONFIGFILE = "/etc/snmp/dhcp.json"

# Configfile is needed /etc/snmp/dhcp.json
#
# {"leasefile": "/var/lib/dhcp/dhcpd.leases"
# }
#

error = 0
error_string = ""
version = 2

with open(CONFIGFILE, "r") as json_file:
    try:
        configfile = json.load(json_file)
    except json.decoder.JSONDecodeError as e:
        error = 1
        error_string = "Configfile Error: '%s'" % e


if not error:
    leases = {
        "total": 0,
        "active": 0,
        "expired": 0,
        "released": 0,
        "abandoned": 0,
        "reset": 0,
        "bootp": 0,
        "backup": 0,
        "free": 0,
    }
    if not isfile(configfile["leasefile"]):
        error = 1
        error_string = "Lease File not found"
    else:
        with open(configfile["leasefile"]) as fp:
            line = fp.readline()
            while line:
                line = fp.readline()

                if "rewind" not in line:
                    if line.startswith("lease"):
                        leases["total"] += 1
                    elif "binding state active" in line:
                        leases["active"] += 1
                    elif "binding state expired" in line:
                        leases["expired"] += 1
                    elif "binding state released" in line:
                        leases["released"] += 1
                    elif "binding state abandoned" in line:
                        leases["abandoned"] += 1
                    elif "binding state reset" in line:
                        leases["reset"] += 1
                    elif "binding state bootp" in line:
                        leases["bootp"] += 1
                    elif "binding state backup" in line:
                        leases["backup"] += 1
                    elif "binding state free" in line:
                        leases["free"] += 1

shell_cmd = "dhcpd-pools -s i -A -l" + configfile["leasefile"]
pool_data = (
    subprocess.Popen(shell_cmd, shell=True, stdout=subprocess.PIPE)
    .stdout.read()
    .split(b"\n")
)

data = {"leases": leases, "pools": [], "networks": [], "all_networks": []}

category = None
jump_line = 0
for p in pool_data:
    line = p.decode("utf-8")

    if jump_line:
        jump_line -= 1
        continue

    if line.startswith("Ranges:"):
        category = "pools"
        jump_line = 1
        continue

    if line.startswith("Shared networks:"):
        category = "networks"
        jump_line = 1
        continue

    if line.startswith("Sum of all ranges:"):
        category = "all_networks"
        jump_line = 1
        continue

    if not len(line):
        continue

    p = line.split()

    if category == "pools":
        data[category].append(
            {
                "first_ip": p[1],
                "last_ip": p[3],
                "max": p[4],
                "cur": p[5],
                "percent": p[6],
            }
        )
        continue

    if category == "networks":
        data[category].append(
            {
                "network": p[0],
                "max": p[1],
                "cur": p[2],
                "percent": p[3],
            }
        )
        continue

    if category == "all_networks":
        data[category] = {
            "max": p[2],
            "cur": p[3],
            "percent": p[4],
        }
        continue


output = {"version": version, "error": error, "errorString": error_string, "data": data}

print(json.dumps(output))