#!/bin/bash

usage()
{
cat <<HELP
Usage: $0 -uaifrpd

options:
    -u - User for forward server connection (*optional)
    -a - User for remote server connection (default: equal to -u option)
    -i - Path to identity file (*optional)
    -f - host of a forward server (example: nat.server.com)
    -r - host of a remote server (example: 10.0.1.0)
    -p - port of a remote server (default: 22)
    -d - rsync destination on a server (*optional, example: "~/some_dir_in_home")

Examples:
    $0 -f 54.77.123.123 -r 10.0.1.20 -u ec2-user -a ubuntu -i some_key.pem
    $0 -f 54.77.123.123 -r 10.0.1.20 -d "~/provision"
HELP
    exit 1
}

error_log()
{
    echo ***ERROR*** $1
    usage
}

load_local_port()
{
    for port in $(seq 10000 20000); do
        echo -ne "\035" | telnet 127.0.0.1 $port > /dev/null 2>&1; [ $? -eq 1 ] && LOCAL_PORT=$port && break
    done
}

while getopts ":u:a:i:f:r:p:d:" optname
    do
        case "$optname" in
            "u")
                USER=$OPTARG
                ;;
            "a")
                REMOTE_USER=$OPTARG
                ;;
            "i")
                PRIVATE_KEY=$OPTARG
                ;;
            "f")
                FORWARD_SERVER=$OPTARG
                ;;
            "r")
                REMOTE_SERVER=$OPTARG
                ;;
            "p")
                REMOTE_PORT=$OPTARG
                ;;
            "d")
                RSYNC_TARGET=$OPTARG
                ;;
            "?")
                error_log "Unknown option $OPTARG"
                ;;
            ":")
                error_log "No argument value for option $OPTARG"
                ;;
            *)
                error_log "Unknown error while processing options"
                ;;
        esac
    done

if [ -z $FORWARD_SERVER ]; then
    error_log "Please, specify a forward server"
fi

if [ -z $REMOTE_SERVER ]; then
    error_log "Please, specify a remote server"
fi

if [ -z $REMOTE_PORT ]; then
    REMOTE_PORT=22
fi

SSH_OPTS="-oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null"

if [ ! -z $PRIVATE_KEY ]; then
    SSH_OPTS="$SSH_OPTS -i $PRIVATE_KEY"
fi

if [ -z $REMOTE_USER ]; then
    REMOTE_USER=$USER
fi

load_local_port

echo Creating a tunnel with local port $LOCAL_PORT...

ssh $SSH_OPTS -l $REMOTE_USER -N -L $LOCAL_PORT:$REMOTE_SERVER:$REMOTE_PORT $USER@$FORWARD_SERVER &

TUNNEL_PID=$!
IS_OPEN=$?

if [ $IS_OPEN -ne 0 ]; then
    error_log "The tunnel is cannot be established"
fi

echo Connecting...
sleep 1

if [ -z "$RSYNC_TARGET" ]; then
    ssh $SSH_OPTS -p $LOCAL_PORT $REMOTE_USER@localhost
else
    rsync -rlvztp --delete \
        -e "ssh $SSH_OPTS -p $LOCAL_PORT" \
        --exclude=".git" \
        --exclude="nbproject" \
        --exclude="/cache" \
        * $REMOTE_USER@localhost:$RSYNC_TARGET
fi

read -p "Press ENTER to exit..."

echo Terminating $TUNNEL_PID...
kill $TUNNEL_PID