#!/bin/sh

usage() {
cat 1>&2 <<EOL
usage: $0 [ -w ] [ -a ] <vm>
   stops the given VM, restores the current snapshot and restarts it again

OPTIONS
   -w         attach host's webcam to VM
   -a         if no <vm> is given, try to automatically guess it
              (using the currently running one, if this is unambiguous)
EOL

if [ "x${1}" != "x" ]; then
    cat 1>&2 <<EOL

 here's a list of running VMs:
EOL
    vboxmanage list runningvms
    echo "" 1>&2
fi
}


webcam=no
auto_vm=no

while getopts "h?wa" opt; do
    case $opt in
        w)
            webcam=yes
            ;;
        a)
            auto_vm=yes
            ;;
        h|\?)
            usage
            exit 0
            ;;
        :)
            usage
            exit 0
            ;;
    esac
done
shift $((OPTIND-1))

vm=$1

if test "x${auto_vm}" = "xyes" && test "x${vm}" = "x"; then
    vm=$(vboxmanage list runningvms | grep -c .)
    if [ "${vm}" -eq 1 ]; then
        vboxmanage list runningvms
        vm=$(vboxmanage list runningvms | awk '{print $2}' | tail -1)
    else
        cat 1>&2 <<EOL
unable to unambiguously determine VM

EOL
        usage vms
        exit 1
    fi
fi


if [ "x${vm}" = "x" ]; then
    usage 1
    exit 1
fi

restore() {
    vboxmanage controlvm "${vm}" poweroff \
        && vboxmanage snapshot "${vm}" restorecurrent
}
restart() {
    # don't know why, but if we start the VM immediately after restoring the
    # current snapshot, it fails...
    sleep 2
    vboxmanage startvm "${vm}"
}
configure() {
    if [ "x${webcam}" = "xyes" ]; then
       vboxmanage controlvm "${vm}" webcam attach /dev/video0
    fi
}
restore && restart && configure