#!/usr/bin/bash

# TODO: Support other flavours.
readonly IMAGE_URL='https://cloud.debian.org/images/cloud/sid/daily/latest/debian-sid-generic-amd64-daily.tar.xz'
readonly IMAGE_SHA512SUMS='https://cloud.debian.org/images/cloud/sid/daily/latest/SHA512SUMS'

if [ -x /usr/bin/importctl ]; then
    readonly IMPORTCTL='importctl'
    readonly IMPORTCTL_IMPORT_RAW_ARGS='-m'
else
    readonly IMPORTCTL='machinectl'
fi

CONTAINER_NAME=
NO_INTERNET=

log()
{
    printf "I: ${@}\n"
}

error()
{
    printf "E: ${@}\n" > /dev/stderr
    exit 1
}

import_image()
{
    local name="${1}"
    local tmpdir=$(mktemp -d)
    local filename=$(basename "${IMAGE_URL}")
    local sha512sum_filename=$(basename "${IMAGE_SHA512SUMS}")

    trap 'rm -f $tmpdir' RETURN EXIT SIGINT SIGTERM

    log "Dowloading image '${IMAGE_URL}' into '${tmpdir}'"
    cd "${tmpdir}"
    wget "${IMAGE_URL}"
    tar xf "${tmpdir}/${filename}"

    log "Verifying hash for '${filename}'"
    wget "${IMAGE_SHA512SUMS}"
    if ! sha512sum --ignore-missing -c "${sha512sum_filename}"; then
	error "Aborting; please check the hash!"
    fi

    log "Importing image '${filename}' as '${name}'"
    $IMPORTCTL import-raw ${IMPORTCTL_IMPORT_RAW_ARGS} "${filename}" "${name}"
}

setup_container()
{
    local name="${1}"
    local etcpath='/etc/systemd/nspawn'

    mkdir -p "${etcpath}"
    cat > "${etcpath}/${name}.nspawn" << _EOF_
[Network]
Private=yes
VirtualEthernet=yes
Zone=${name}
_EOF_

    if [ -z "${NO_INTERNET}" ]; then
	iptables -A FORWARD -i "vz-${name}" -o enp5s0 -j ACCEPT
	iptables-save
	log "Don't forget to enable port-forwarding on sysctl"
    fi
}

create_container()
{
    local name="${1}"

    log "Starting container '${name}'"
    machinectl start "${name}"
}

usage()
{
    cat << EOF
${0} -- Create a container using machinectl

Arguments:

  -n|--name NAME: The container name.  Mandatory.
  -x|--no-internet: Whether the container should not have access to
                    the internet
  -h|--help: This help message
EOF
}

parse_args()
{
    while [ -n "${1}" ]; do
	case "${1}" in
	    "-n"|"--name")
		CONTAINER_NAME="${2}"
		shift 2
		;;
	    "-x"|"--no-internet")
		NO_INTERNET=1
		shift
		;;
	    "-h"|"--help")
		usage
		exit 0
		;;
	esac
    done
}

sanitize_args()
{
    if [ -z "${CONTAINER_NAME}" ]; then
	error "You must specify a container name (-n)"
    fi
}

main()
{
    parse_args "$@"
    sanitize_args
    import_image "${CONTAINER_NAME}"
    setup_container "${CONTAINER_NAME}"
    create_container "${CONTAINER_NAME}"

    log "Container '${CONTAINER_NAME}' created"
}

main "$@"