#!/bin/bash

# ####################################################################################
# Script for creating high entropy based password strings.
#
# Will iterate and generating high entropy password for char length and total nbr of
# of passwords. If no password length provided Minimum length of characters in
# password string is 8.
#
# Usage: sh entropy_pswd_creator.sh [nbr-passwords] [max-pswd-length]
#
# Exit code of 0 if successful else non zero means failed.
# ####################################################################################

# global Vars
PSWD_LEN=8
NBR_PSWD=1

function usage {
    echo "Usage: $1 [nbr-passwords] [max-pswd-length]"
    echo "-nbr-password     number of passwords to generate"
    echo "-max-pswd-length  maxinum string length of characters in password"
}

function is_nbr {
    # check if positive nbr
    local nbr=$1

    if [ -z "${nbr}" ]; then
       echo 1
    fi
    re='^[0-9]+$'
    if [[ $nbr =~ $re ]] ; then
        echo 0
    else
        echo 1
    fi
}

function generate_pswd {
    local str_len=$1
    if [ -z "$str_len" ]; then
        str_len=${MIN_LEN}
    fi
    pswd=$(LC_ALL=C tr -dc 'A-Za-z0-9!"#$%&'\''()*+,-./:;<=>?@[\]^_`{|}~' </dev/urandom | head -c ${str_len} ; echo)
    echo "${pswd}"
}

# validate input
if [ "$#" -gt 2 ]; then
    echo "Invalid arguments passed: ${@}"
    usage $0
    exit 1
fi

if [ "$#" -ge 1 ]; then
    rc=`is_nbr $1`
    [[ $rc -ne 0 ]] && echo "Invalid input NaN: ${1}" && exit 2
    NBR_PSWD=$1
fi
if [ "$#" -ge 2 ]; then
    rc=`is_nbr $2`
    [[ $rc -ne 0 ]] && echo "Invalid input NaN: ${2}" && exit 3
    PSWD_LEN=$2
fi

#echo "nbr pass ${NBR_PSWD}"
#echo "leng ${PSWD_LEN}"

for i in `seq 1 ${NBR_PSWD}`;
do
    generate_pswd ${PSWD_LEN}
done

exit 0