#!/usr/bin/env bash
# ------------------------------------------------------------------------------
# Copyright (c) 2013-2022 Geoffray Levasseur <fatalerrors@geoffray-levasseur.org>
# Protected by the BSD3 license. Please read bellow for details.
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# ------------------------------------------------------------------------------

# ------------------------------------------------------------------------------
# genpwd : generate a password with different criteria
# Usage: genpwd [options] [--extracars=<cars>] [--length=<n>] [nb_passwd]
# Options:
# 	-h, --help	Display that help screen
# 	-s, --nosymbols	Exclude symbols
# 	-n, --nonumbers	Exclude numbers
# 	-u, --noup	Exclude uppercase letters
# 	-l, --nolow	Exclude lowercase letters
# 	-e=<c>, --extracars=<c>
# 			Add the given caracters to the possible caracter list
# 	-L=<n>, --length=<n>
# 			Set length of the password (default is 16)
# 	-o=<n>, --occurences=<n>
# 			Set the maximum occurences of a same caracter (default is 2)
# The function is very slow on Windows
genpwd()
{
    local length=16
    local occurs=2 # Bug, if set to 1, seems to be ignored
    local symb=1 maj=1 min=1 numb=1
    local nbpwd=1
    local extcar

local PARSED
    PARSED=$(getopt -o hsnu l e:L:o: --long \
        help,nosymbols,nonumbers,noup,nolow,extracars:,length:,occurences: -n 'genpwd' -- "$@")
    if [[ $? -ne 0 ]]; then return 1; fi
    eval set -- "$PARSED"

    while true; do
        case "$1" in
            -h|--help)
                printf "genpwd: Generate secure random password(s).\n\n"
                printf "Usage: genpwd [options] [nb_passwd]\n\n"
                printf "Options:\n"
                printf "\t-h, --help\t\tDisplay this help screen\n"
                printf "\t-s, --nosymbols\t\tExclude symbols\n"
                printf "\t-n, --nonumbers\t\tExclude numbers\n"
                printf "\t-u, --noup\t\tExclude uppercase letters\n"
                printf "\t-l, --nolow\t\tExclude lowercase letters\n"
                printf "\t-e, --extracars <c>\tAdd characters to list\n"
                printf "\t-L, --length <n>\tSet password length (default: 16)\n"
                printf "\t-o, --occurences <n>\tMax occurences per character (default: 2)\n"
                return 0
                ;;
            -s|--nosymbols)
                symb=0
                shift
                ;;
            -n|--nonumbers)
                numb=0
                shift
                ;;
            -u|--noup)
                maj=0
                shift
                ;;
            -l|--nolow)
                min=0
                shift
                ;;
            -e|--extracars)
                extcar="$2"
                shift 2
                ;;
            -L|--length)
                length="$2"
                if ! [[ $length =~ ^[0-9]+$ ]]; then
                    disp E "The --length parameter requires a number."
                    return 1
                fi
                shift 2
                ;;
            -o|--occurences)
                occurs="$2"
                if ! [[ $occurs =~ ^[1-9]+$ ]]; then
                    disp E "The --occurs parameter requires a number from 1 to 9."
                    return 1
                fi
                shift 2
                ;;
            --)
                shift; break
                ;;
            *)
                break
                ;;
        esac
    done

    if [[ -n "$1" ]]; then
        nbpwd="$1"
        if ! [[ $nbpwd =~ ^[0-9]+$ ]]; then
            disp E "The number of password to generate must be a number."
            return 1
        fi
    fi

    # Function selecting a random caracter from the list in parameter
    pickcar() {
        # When a character is picked we check if it's not appearing already twice
        # elsewhere, we choose an other char, to compensate weak bash randomizer
        while [[ -z $char ]]; do
            local char="${1:RANDOM%${#1}:1} $RANDOM"
            if [[ $(awk -F"$char" '{print NF-1}' <<<"$picked") -gt $occurs ]]; then
                unset char
            fi
        done
        picked+="$char"
        echo "$char"
    }

    disp I "Generating $nbpwd passwords, please wait..."
    for (( n=1; n<=nbpwd; n++ )); do
        {
            local carset='' # store final caracter set to use
            local picked='' # store already used caracter
            local rlength=0 # store already assigned length of caracters

            # ?, *, $ and \ impossible to use to my knowledge as it would be interpreted
            if [[ $symb == 1 ]]; then
                pickcar '!.@#&%/^-_'
                carset+='!.@#&%/^-_'
                ((rlength++))
            fi
            if [[ $numb == 1 ]]; then
                pickcar '0123456789'
                carset+='0123456789'
                ((rlength++))
            fi
            if [[ $maj == 1 ]]; then
                pickcar 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                carset+='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                ((rlength++))
            fi
            if [[ $min == 1 ]]; then
                pickcar 'abcdefghijklmnopqrstuvwxyz'
                carset+='abcdefghijklmnopqrstuvwxyz'
                ((rlength++))
            fi
            if [[ -n $extcar ]]; then
                pickcar "$extcar"
                carset+=$extcar
                ((rlength++))
            fi

            # Check if we have enough car to have something viable
            if [[ ${#carset} -lt $length ]]; then
                disp E 'Not enought caracters are authorised for the password length.'
                disp E 'Please allow more caracter (preferably) or reduce password lentgh.'
                return 1
            fi

            for i in $(seq 1 $(($length - $rlength))); do
                pickcar "$carset"
            done
        } | sort -R | awk '{printf "%s", $1}'
        unset picked carset rlength
        echo
    done
}
export -f genpwd
# ------------------------------------------------------------------------------


# EOF