#!/bin/bash

VERSION_ID=alpha
SSH_KEYS=""
CORE_UID=500
CORE_GID=500

USAGE="Usage: $0 [-V version] [-d /target/path] [-a authorized_keys]
Options:
    -d DEST     Create CoreOS VDI image to the given path.
    -V VERSION  Version to install (e.g. alpha) [default: ${VERSION_ID}]
    -a FILE     SSH public keys for login access. [~/.ssh/id_{dsa,rsa}.pub]
    -h          This help

This tool creates a CoreOS VDI image to be used with VirtualBox.
"

# Image signing key: buildbot@coreos.com
GPG_LONG_ID="50E0885593D2DCB4"
GPG_KEY="-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v2.0.20 (GNU/Linux)

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=4Qn0
-----END PGP PUBLIC KEY BLOCK-----
"

while getopts "V:d:a:h" OPTION
do
    case $OPTION in
        V) VERSION_ID="$OPTARG" ;;
        d) DEST="$OPTARG" ;;
        a) SSH_KEYS="$OPTARG" ;;
        h) echo "$USAGE"; exit;;
        *) exit 1;;
    esac
done

# root user required
if [ $(id -u) -ne 0 ]; then
    echo "$0: You must be root to run this script." >&2
    exit 1
fi

# VirtualBox tools required
which VBoxManage &>/dev/null
if [ $? -ne 0 ]; then
    echo "$0: VBoxManage tool is required to convert image." >&2
    exit 1
fi

# Verify provided keys file
if [[ -n "${SSH_KEYS}" ]]; then
    if [[ ! -f "${SSH_KEYS}" ]]; then
        echo "$0: SSH keys file not found: ${SSH_KEYS}." >&2
        exit 1
    fi
else
    # SSH keys file was not provided, setting to default
    SSH_KEYS=~/.ssh/id_*.pub
fi



if [[ ! -d "${DEST}" ]]; then
    echo "$0: Target path (${DEST}) do not exists." >&2
    exit 1
fi

WORKDIR="${DEST}/tmp.${RANDOM}"
mkdir "$WORKDIR"
trap "rm -rf '${WORKDIR}'" EXIT

RAW_IMAGE_NAME="coreos_production_image.bin"
VDI_IMAGE_NAME="coreos_production_${VERSION_ID}.vdi"
IMAGE_NAME="${RAW_IMAGE_NAME}.bz2"
DIGESTS_NAME="${IMAGE_NAME}.DIGESTS.asc"

BASE_URL="http://storage.core-os.net/coreos/amd64-usr/${VERSION_ID}"
IMAGE_URL="${BASE_URL}/${IMAGE_NAME}"
DIGESTS_URL="${BASE_URL}/${DIGESTS_NAME}"
DOWN_IMAGE="${WORKDIR}/${RAW_IMAGE_NAME}"
VDI_IMAGE="${DEST}/${VDI_IMAGE_NAME}"

if ! wget --spider --quiet "${IMAGE_URL}"; then
    echo "$0: Image URL unavailable: $IMAGE_URL" >&2
    exit 1
fi

if ! wget --spider --quiet "${DIGESTS_URL}"; then
    echo "$0: Image signature unavailable: $DIGESTS_URL" >&2
    exit 1
fi

# Setup GnuPG for verifying the image signature
export GNUPGHOME="${WORKDIR}/gnupg"
mkdir "${GNUPGHOME}"
gpg --batch --quiet --import <<<"$GPG_KEY"

echo "Downloading and verifying ${IMAGE_NAME}..."
wget --no-verbose -O "${WORKDIR}/${DIGESTS_NAME}" "${DIGESTS_URL}"
if ! gpg --batch --trusted-key "${GPG_LONG_ID}" \
    --verify "${WORKDIR}/${DIGESTS_NAME}"
then
    echo "$0: GPG signature verification failed for ${DIGESTS_NAME}" >&2
    exit 1
fi

wget -O "${WORKDIR}/${IMAGE_NAME}" "${IMAGE_URL}"

# DIGESTS may include README and other extra files we don't need, filter them.
# Also filter one hash at a time, not required but avoids warnings from *sum.
for sum in sha1 sha512; do
    (cd "${WORKDIR}"
    grep -i -A1 "^# ${sum} HASH$" "${WORKDIR}/${DIGESTS_NAME}" \
        | grep "${IMAGE_NAME}$" | ${sum}sum -c /dev/stdin)
done

echo "Writing ${IMAGE_NAME} to ${DOWN_IMAGE}..."
bzcat -v --stdout "${WORKDIR}/${IMAGE_NAME}" >"${DOWN_IMAGE}"

# The ROOT partition should be #9 but make no assumptions here!
# Also don't mount by label directly in case other devices conflict.
PART_OFFSET=$(parted ${DOWN_IMAGE} unit b print | grep "ROOT" | awk '{print $2}')
PART_OFFSET=${PART_OFFSET//B/}
if [[ -z "${PART_OFFSET}" ]]; then
    echo "Unable to find new ROOT partition on ${DOWN_IMAGE}" >&2
    exit 1
fi

MOUNT_DEST="${WORKDIR}/rootfs"
CORE_SSH_DIR="${MOUNT_DEST}/home/core/.ssh"
AUTHORIZED_KEYS="${CORE_SSH_DIR}/authorized_keys"

echo "Adding SSH key to authorized keys file..."
mkdir -p "${MOUNT_DEST}"
mount -t btrfs -o loop,offset=${PART_OFFSET},subvol=root "${DOWN_IMAGE}" "${MOUNT_DEST}"
trap "umount '${MOUNT_DEST}' && rm -rf '${WORKDIR}'" EXIT

if [ ! -d "${CORE_SSH_DIR}" ]; then
    mkdir -p ${CORE_SSH_DIR}
    chmod 0600 ${CORE_SSH_DIR}
fi

cat ${SSH_KEYS} > ${AUTHORIZED_KEYS}
chmod 0600 ${AUTHORIZED_KEYS}
chown -R $CORE_UID:$CORE_GID "${CORE_SSH_DIR}"

umount "${MOUNT_DEST}"

echo "Converting ${RAW_IMAGE_NAME} to VirtualBox format..."
VBoxManage convertdd ${DOWN_IMAGE} ${VDI_IMAGE} --format VDI

rm -rf "${WORKDIR}"
trap - EXIT

echo "Success! CoreOS ${VERSION_ID} VDI image was created on ${VDI_IMAGE_NAME}"