#!/bin/sh
# Arguments: old name, new name

if [ $# -lt 3 ]; then
    printf '%s\n' "Wrong number of arguments\!" >&2
    printf '%s\n' "Usage: user-rename [old name] [new name] [new home]" >&2
    exit 1
fi

OLD=$1
NEW=$2
HOME=$3

# Get old home dir (no longer used, keeping around for a bit in case it is needed)
#OLD_HOME=$(grep $OLD /etc/passwd | awk -F: '{print $6}')

# Begin sanity check
if ! id "$OLD" 2>&1 >/dev/null; then
    printf '%s\n' "ERROR 11: OLD user name not found: $OLD" >&2
    exit 11
fi

if id "$NEW" 2>&1 >/dev/null; then
    printf '%s\n' "ERROR 12: NEW user name already exists: $NEW" >&2
    exit 12
fi

if [ -d "$HOME" ]; then
    printf '%s\n' "ERROR 13: New HOME directory already exists: $HOME" >&2
    exit 13
fi
# End sanity check

# Rename user
usermod -l $NEW $OLD || { printf '%s\n' "Error renaming user\!" >&2 && exit 1 }

# Change home dir location
usermod -d $HOME -m $NEW || { printf '%s\n' "Error moving home directory\!" >&2 && exit 1 }


# Check if primary group matches old user name; modify if so
if [ ! "$(id -gn $NEW)" == "$OLD" ]; then
    groupmod -n $NEW $OLD || { printf '%s\n' "Error renaming primary group\!" >&2 && exit 1 }
fi

# Done! Print some info and exit
grep $NEW /etc/passwd
id $NEW

exit 0