# -*- coding: utf-8 -*-

import csv

FILENAME = "users.csv"

all_data = []
users = []
systems = []

try:
    etc_pass = open("/etc/passwd", "r").read()[:-1]
except IOError:
    exit()


for line in etc_pass.split('\n'):
    uid = int(line.split(':')[2])
    username = line.split(':')[0]
    if uid > 999 and uid < 65534 :
        users.append(username)
    else:
        systems.append(username)

try:
    group_all = open("/etc/group", "r").read()[:-1]
except IOError:
    exit()

for user in users:
    collect_groups = []
    for i in group_all.split('\n'):
        group_name = i.split(':')[0]
        group_user = i.split(':')[3]
        if user in group_user:
            collect_groups.append(group_name)
    collect_list = []
    collect_list.append(user)
    collect_list.append(collect_groups)
    all_data.append(collect_list)

with open(FILENAME, "w") as file:
    for i in all_data:
        writer = csv.writer(file)
        writer.writerow(i)