#!/bin/bash

# Semestralni prace z predmetu 36UNX = Operacni system UNIX
# Michal Trs
# Zadani c.8  
# useradd

#c comment for password
#d home dir
#e expire date format YYYY-MM-DD
#f inactive time
#g group (default 1)
#G group seznam dalsich skupin oddelenych carkou
 
# CHYBOVE KODY
# 0 - OK
# 1 - login name wasn't insert
# 2 - unknown parametr
# 3 - run without any arguments
# 4 - not existing directory
# 5 - bad format
# 6 - user/uid already exist
# 7 - group not exist
# 8 - invalid interpret

# zadano bez parametru => vypsani helpu 
if  [[ $# == 0 ]]; then
  echo \
'use: useradd [-u uid [-o]] [-g group [-G group members,...] 
             [-d home_dir] [-s shell] [-c comment] [-m [-k skel]]
             [-f inactive] [-e expire] [-p password] login
  useradd -D [-g group] [-b home_dir] [-s shell]
             [-f inactive] [-e expire]'
  exit 3;
fi;

# nastaveni promenych
#ROOT="/cygdrive/c/skola/6.semestr/36unx/semestralka";
#ROOT="/home/misak/tmp";

#default skel
group=100;
home='/home/temp';
inactive=-1;
expire='';
shell='';
skel='/etc/skel';

# pokud soubor jiz existuje => nactu z nej hodnoty
if [ -e $ROOT/etc/default/useradd ]; then
  S=$SHELL # promenna prostredi
  source $ROOT/etc/default/useradd;
  home=$HOME;
  expire=$EXPIRE;
  inactive=$INACTIVE;
  group=$GROUP;
  shell=$SHELL;
  [[ $SHELL == '' ]] && SHELL=$S;
fi;


if [[ $1 = "-D" ]]; then
  # UPDATE DEFAULT
 
  if [[ $# == 1 ]]; then 
    # PRINT DEFAULT

      echo "GROUP=$group";
      echo "HOME=$home";
      echo "INACTIVE=$inactive";
      echo "EXPIRE=$expire"
      echo "SHELL=$shell"
      echo "SKEL=$skel"

    exit 0;
  
  else  
    # UPDATE DEFAULT
    shift;
    
    while getopts b:e:f:g:s: volba 
    do
      case $volba in
	      b)  home=$OPTARG;;
	      e)  expire=$OPTARG;
	          if ! echo $expire | grep -e "^$" \
		   -e "[0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}" >/dev/null; then 
		    echo "Bad format of expire date. expected YYYY-MM-DD";
                    exit 5;
 		  fi;;
	      f)  inactive=$OPTARG;;
	      g)  group=$OPTARG;;
	      s)  shell=$OPTARG;
	          [ -r $shell ] || { echo "Invalid inerpret"; exit 8; };;
	      \?) exit 2 ;;
      esac
    done
    
    # existuje skupina?
      grep -e ":$group:" -e "^$group:" "$ROOT/etc/group"  >/dev/null \
        || { echo "group doesn't exist"; exit 7; };

    # zapsani do souboru
    { echo '# useradd defaults file';
      echo "GROUP=$group";
      echo "HOME=$home";
      echo "INACTIVE=$inactive";
      echo "EXPIRE=$expire";
      echo "SHELL=$shell";
      echo "SKEL=$skel"
    } > $ROOT/etc/default/useradd;      
  fi;
  
else
  # NEW USER
  
  allowcreate=0;
  copymode=0;
  
  while getopts c:d:e:f:g:G:mk:op:s:u: volba
  do
    case $volba in
	    c)  coment=$OPTARG;;
      	    d)  homedir=$OPTARG;;
	    e)  expire=$OPTARG;;
	    f)	inactive=$OPTARG;;
	    g)  group=$OPTARG;;
	    G)  groupadd=$OPTARG;;
	    m)  ((copymode++));;
	    k)  skel=$OPTARG; 
          [ -d $ROOT$skel ] || { echo "Not valid skeleton directory"; exit 4; } ;
          ((copymode+=2));;
	    o)  allowcreate=1;;
	    p)  password=$OPTARG;;
	    s)  shell=$OPTARG;
	        [ -r $shell ] || { echo "Invalid inerpret"; exit 8; };;
	    u)  uid=$OPTARG;;
	    \?) exit 2;;
    esac
  done
  
  # nahrani login name
  shift `expr $OPTIND - 1`
  if [[ $# == 0 ]]; then 
    echo "error: login name expected";
    exit 1;
  else
    login=$1;
  fi;
  
  # OSETRENI VSTUPU pridani uzivatele
  
  # pouziti parametru -k bez -m
  if [[ $copymode == 2 ]]; then
    echo "Error: Using parametr -k without parametr -m";
    exit 2;
  fi;
  
  # spravne zadane datum vyprseni platnosti
  if [[ $expire != '' ]]; then
    if echo $expire | grep "[0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}" >/dev/null; then
      y=${expire:0:4} 
      m=${expire:5:2} 
      d=${expire:7:2}
     (( expire = (y-1970) * 365 + m * 30 + d ));
    else
      echo "Bad format of expire date. expected YYYY-MM-DD";
      exit 5;
    fi;
  fi;

  # existuje skupina? + if slovne => prevod na GID  
  if grep "^$group:" "$ROOT/etc/group" >/dev/null; then
    group=`grep "^$group:" "$ROOT/etc/group" | cut -d: -f3`;
  elif ! grep ":$group:" "$ROOT/etc/group" >/dev/null; then
    echo "group doesn't exist"; 
    exit 7;
  fi;
  
  # existuje uzivatel?
  if grep "^$login:" "$ROOT/etc/passwd" 1>/dev/null; then
    echo "username already exist";
    exit 6;
  fi;
   
  [ -z $shell ] && shell=$SHELL;
  
  # nastaveni UID
  if [[ $uid != '' ]]; then
    if [[ $allowcreate == 0 ]]; then
      # pokud UID existuje => konec
      cut -d: -f3 $ROOT/etc/passwd | grep "^$uid$" >/dev/null && { echo "UID already exist"; exit 6; };
    fi;
  else
    # najdu 1.volne uid nad 1000
    uid=1000;
    while cat $ROOT/etc/passwd | cut -d: -f3 | grep "^$uid$" >/dev/null; 
    do
      ((uid++));
    done;
  fi;

 # MODIFIKACE SOUBORU v etc


  # priprava a zapis do passwd
  
  if [[ -z $homedir ]]; then
    home="$home/$login";
  else
    home=$homedir;
  fi;
  
  pswline="$login:x:$uid:$group:$coment:$home:$shell"; 
  #echo $pswline
  cp "$ROOT/etc/passwd" "$ROOT/etc/passwd-" 2>/dev/null
  { cat "$ROOT/etc/passwd-" 2>/dev/null; echo $pswline; } > "$ROOT/etc/passwd";

  # kopiruj skeleton
  if [[ $copymode > 0 ]]; then
    [ -d "$home" ] || mkdir "$home";
    cp -f -R "$ROOT$skel/"* "$ROOT$skel/".[!.]* "$home" 2>/dev/null;
    echo "prikazy vyuzivajici /etc/passwd a /etc/group"
    echo 'chown -R "$login" "$home"';
    echo 'chgrp -R "$group" "$home"';
  fi;

  # priprava a zapis shadow
  
  days=`date +"%s"`
  days=`expr $days / 86400`;
    
  shdline="$login:$password:$days:0:99999::$inactive:$expire:"
  #echo $shdline 
  
  cp "$ROOT/etc/shadow" "$ROOT/etc/shadow-" 2>/dev/null
  { cat "$ROOT/etc/shadow-" 2>/dev/null; 
    echo $shdline; } > "$ROOT/etc/shadow";
  
  # priprava a zapis do group
  
  if [ -n $groupadd ]; then
    cp "$ROOT/etc/group" "$ROOT/etc/group-";
    cp "$ROOT/etc/group" /tmp/$$_src;
    cp "$ROOT/etc/group" /tmp/$$_dst;
  fi;

  IFS=','; 
  for grp in $groupadd; do
    cat /tmp/$$_src | sed -e 's/^\(.*:'${grp}':.*[^:]\)$/\1,/' \
                          -e 's/^\(.*:'${grp}':.*\)$/\1'${login}'/' \
                          -e 's/^\('${grp}':.*[^:]\)$/\1,/' \
                          -e 's/^\('${grp}':.*\)$/\1'${login}'/' > /tmp/$$_dst;
    cp -f /tmp/$$_dst /tmp/$$_src;
  done;
    
    cat /tmp/$$_dst > "$ROOT/etc/group";
    rm -f /tmp/$$* 
fi;

  exit 0;