#!/bin/sh

set -e

get_mac_address() {
	echo $(ifconfig en0 ether | grep ether | rev | cut -d' ' -f2 | rev)
}

get_ip_address() {
	echo $(ifconfig en0 inet | grep inet | cut -d' ' -f2)
}

set_mac_address() {
	sudo ifconfig en0 ether $1
}

set_branch() {
	echo "Updating mac address: $(get_mac_address) -> $1"
	set_mac_address $1
	echo "Done. New MAC: $(get_mac_address)"

}

randomise_branch() {
	echo "Current MAC: $(get_mac_address)"
	NEW_MAC=$(openssl rand -hex 6 | sed 's/\(..\)/\1:/g; s/.$//')
	set_mac_address ${NEW_MAC}
	echo "Done. New MAC: $(get_mac_address)"
}

select_branch() {
	IP_ADDRESS=$(get_ip_address)
	DEVICES=$(sudo nmap -sn ${IP_ADDRESS}/24 | awk '/Nmap/{ip=$NF;next} /MAC/{printf "%s|%s|", ip,$3} /MAC/{for(i=4;i<=NF;i++) printf "%s_", $i; printf ";"} ')

	# This part is needlessly clunky as, for whatever reason, the version of bash/sh on MAC misbehaves with arrays -- counts and index iteration didn't work properly
	i=0
	IFS=";" read -ra DEVICE_ARRAY <<< ${DEVICES}
	for DEV in ${DEVICE_ARRAY[@]}; do
		i=$((i+1)) && printf "\t%s) %s\n" "${i}" "${DEV}"
	done

	read -p "Select a device to spoof: " selected

	NEW_MAC=$(echo ${DEVICE_ARRAY} | cut -d' ' -f${selected} | cut -d \| -f2)
	echo "Spoofing MAC address: $(get_mac_address) -> ${NEW_MAC}"
	set_mac_address $NEW_MAC
	echo "Done. New MAC: $(get_mac_address)"
}

case $1 in
	--set)
		set_branch $2
		;;

	--randomise)
		randomise_branch
		;;

	--select)
		select_branch
		;;
	*)
		echo "Unknown or no option given"
		exit 64  # User error code
esac