diceware

#!/usr/bin/env bash

err () {
	echo "[$(date +'%Y-%m-%dT%H:%M:%S%z')]: Diceware: $*" >&2;
}

usage () {
	cat <<EOF
Usage: ${0##*/} [-d delimiting_character][-l|-s][-w word_number]
OPTIONS:
    [ -d | --delim ] Sets delimiter between words. (Default: ' ')
    [ -h | --help  ] Usage information.
    [ -l | --large ] Generate with large wordlist. (Default)
    [ -s | --short ] Generate with short wordlist.
    [ -w | --words ] Number of words to generate.  (Default: 6)
                     (WARNING: Anything less than 5 is considered insecure.)
EOF
}

check-deps () {
	getopt -T &>/dev/null && rc=$? || rc=$?;
	if ! [ "$rc" -eq 4 ]; then
		err "This script requires GNU getopt";
		exit 1;
	fi
	local lists=0;
	local nowget=0;
	if [ -s "${XDG_DATA_HOME}/diceware/eff_large_wordlist.txt" ] && [ -s "${XDG_DATA_HOME}/diceware/eff_short_wordlist_2_0.txt" ]; then
		lists=1;
	else
		echo "Wordlists not found. Attempting to download them.";
		mkdir -p "${XDG_DATA_HOME}/diceware";
		if ! wget -h &>/dev/null; then
			((nowget++));
			if ! curl -h &>/dev/null; then
				err "Neither wget or curl are available. Please install one or download the wordlists yourself.";
				exit 1;
			fi
		fi
		if [ "${nowget}" -eq 0 ]; then
			echo "Using wget to download wordlists...";
			wget -q -P "${XDG_DATA_HOME}/diceware" https://www.eff.org/files/2016/07/18/eff_large_wordlist.txt;
			wget -q -P "${XDG_DATA_HOME}/diceware" https://eff.org/files/2016/09/08/eff_short_wordlist_2_0.txt;
			echo "Done!"
			((lists++));
		else
			echo "Using curl to download wordlists...";
			curl -s --output-dir "${XDG_DATA_HOME}/diceware" https://www.eff.org/files/2016/07/18/eff_large_wordlist.txt;
			curl -s --output-dir "${XDG_DATA_HOME}/diceware" https://eff.org/files/2016/09/08/eff_short_wordlist_2_0.txt;
			echo "Done!"
			((lists++));
		fi
	fi
	if [ ${lists} -eq 0 ]; then
		err "Wordlists could not be found or downloaded."
		exit 1
	fi
}

parse-opts () {
	if ! args=$(getopt -n "${0##*/}" -o d:hlsw: --long delim:,help,large,short,words: -- "$@"); then
		usage;
		exit 1
	fi
	eval set -- "${args}";
	while true; do
		case "$1" in
			-s|--short)
				if [ $action = 'def' ]; then
					action='short'; shift;
				else
					err "Short and Large options are mutually exclusive!";
					usage;
					exit 1;
				fi;;
			-l|--large)
				if [ $action = 'def' ]; then
					action='large'; shift;
				else
					err "Short and Large options are mutually exclusive!";
					usage;
					exit 1;
				fi;;
			-d|--delim)
				delim=$2; shift 2;;
			-w|--words)
				wordnum=$2; shift 2;;
			-h|--help)
				usage; exit 0;;
			--) 
				shift; break;;
			*) err "Failed to parse options."; exit 1 ;;
		esac
	done
}

words='Empty';
delim=' ';
action='def';
wordnum=6;

check-deps
parse-opts "$@"

case $action in
	'def') words=$(shuf -n"${wordnum}" ~/.local/share/diceware/eff_large_wordlist.txt | cut -f2 | tr '\n' "${delim}");;
	'short') words=$(shuf -n"${wordnum}" ~/.local/share/diceware/eff_short_wordlist_2_0.txt | cut -f2 | tr '\n' "${delim}");;
	'large') words=$(shuf -n"${wordnum}" ~/.local/share/diceware/eff_large_wordlist.txt | cut -f2 | tr '\n' "${delim}");;
	*) err "Action is set to unexpected value"; exit 1;;
esac;
echo "${words::-1}";
exit 0;