#!/usr/bin/env bash

SUDO=''
if [ "$(id -u)" != "0" ]; then
  SUDO='sudo'
  echo "This script requires superuser access."
  echo "You will be prompted for your password by sudo."
  # clear any previous sudo permission
  sudo -k
fi

function usage() {
    echo "Usage: $0 -u <host_user> -h <host_ip> [-p <port>] [-i <identity_file>]";
    exit 1;
}

while getopts :u:h:p:i: flag; do
    case "${flag}" in
    u) username=${OPTARG} ;;
    h) hostname=${OPTARG} ;;
    p) port=${OPTARG} ;;
    i) filename=${OPTARG} ;;
    ?) usage ;;
    esac
done

if [[ -z $username ]] || [[ -z $hostname ]]; then
    usage;
fi

if [[ -z $port ]]; then
    port=3128;
fi

if [[ ! -z $filename ]]; then
    if [[ $filename =~ ^[^\/~] ]]; then
        filename="~/.ssh/$filename";
    fi
    filename="-i $filename";
fi

list=($(networksetup -listnetworkserviceorder \
            | grep -B1 'Hardware Port: Wi-Fi' \
            | sed -n -e 's/([0-9]\{1,\}) \(.*\)/\1/p' \
));

disable_proxy()
{
    if [[ -z $disabled ]]; then
        for i in "${list[@]}"; do
            networksetup -setsocksfirewallproxystate "${i}" off;
        done
        echo "\n\nSOCKS proxy disabled.";
        disabled=true;
    fi;

    exit;
}
trap disable_proxy INT QUIT EXIT KILL;

for i in "${list[@]}"; do
    networksetup -setsocksfirewallproxy "${i}" localhost ${port};
    ${SUDO} networksetup -setsocksfirewallproxystate "${i}" on;
done

echo "SOCKS proxy enabled.";
echo "Tunneling...";

ssh -ND $port "$username@$hostname" $filename;