#! /usr/bin/env python3
from pprint import pprint
import sys
import utilities
from argv import argv_value


def read_file(path: str) -> "List of lines":
    #f = open(path, 'r')
    with open(path, 'r') as f: 
    # f.read(buflen) - binary read
    # f.readline() - 1 Textzeile lesen -> str
    # f.readlines - alle Textzeilen lesen ->str
    # f ist gleichzeitig Iterator
    # 1 möglichkeit
    #lines = list(map(lambda s : s.rstrip(), f))
    # 2 möflichkeit
        lines = list(map(str.rstrip, f))
    # 3 möglichkeit
    #lines = []
    #for line in f.readlines():
    #    lines.append(line.rstrip())
    #f.close()
    return lines

def parse_passwd_lines(line: str) -> "Dict of passwd details":
    parts = line.split(':')
    userdict = {
        "username" : parts[0],
        "uid" : int(parts[2]),
        "gid" : int(parts[3]),
        "realname" : parts[4].split(',')[0],
        "gecos" : parts[4],
        "home" : parts[5],
        "shell": parts[6]
    }
    return userdict

def build_userlist(lines) -> "List of user dicts":
    result = []
    for line in lines:
        result.append(parse_passwd_lines(line))
    return result


def print_userlist_sorted_by_username(userlist):
    #ruft für jedes Element key(elem) also e im Lambda-Ausdruck ist ein Element der Liste user dict
    for user in sorted(userlist, key=lambda e: e['username'].lower()):
        #print("{username:{width}} {realname}".format(width=32 **user))
        print("{:5} {:32} {}".format(
            user['uid'],
            user['username'],
            user['realname'], 
            user['home'], 
            user['shell']
        ))
def print_to_file(userlist):
    userlen = max(map(lambda u: len(u['username']), userlist))
    try:
        with open('/etc/userlist.txt', 'w') as outfile:
            for user in userlist:
                print("{uid:5} {username:{width}} {realname}".format(
                width=userlen, **user), 
                file=outfile)
    except ImportError:
        pass
#  Wird vom Mdule utilities gesteuert
#    except OSError as e:
#        print("Kann Datei nicht schreiben", e, file=sys.stderr)
    else:
        print("Wird ausgefuehrt wenn keine Execption ausgeloest wird.")
    finally:
        print("Wird immer durchlaufen, unabhaengig von ausgeloesten Exceptions")

    
    #with open('/tmp/userlist.txt', 'w') as outfile:
    #    for user in userlist:
    #        print("{uid:5} {username:{width}} {realname}".format(
    #            width=userlen, **user), 
    #            file=outfile)

def print_userlist_sorted_by_uid(userlist):
    userlen = max(map(lambda u: len(u['username']), userlist))
    for user in sorted(userlist, key=lambda e: e['uid']):
        print("{uid:5} {username:{width}} {realname}".format(width=userlen, **user))

def main():
    output_functions = {
        'pprint': pprint,
        'logger': print_to_file,
        'username': print_userlist_sorted_by_username,
        'uid': print_userlist_sorted_by_uid,
        
    }
    #outfunc = output_functions['username']
    outfunc = output_functions[argv_value('-o', default='uid')]
    lines = read_file("/etc/passwd")
    userlist = build_userlist(lines)

    outfunc(userlist)


utilities.hide_exception(main)