#!/bin/bash

# Copyright 2016 Matthew Thode
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

if [ "${DIB_DEBUG_TRACE:-0}" -gt 0 ]; then
    set -x
fi
set -eu
set -o pipefail

[ -n "${ARCH}" ]
[ -n "${TARGET_ROOT}" ]

if [[ 'amd64' != "${ARCH}" ]] && [[ 'arm64' != "${ARCH}" ]]; then
    echo "Only amd64 or arm64 images are currently available but ARCH is set to ${ARCH}."
    exit 1
fi

# valid gentoo profiles are as follows
# default/linux/amd64/13.0
# default/linux/amd64/13.0/no-multilib
# hardened/linux/amd64
# hardened/linux/amd64/no-multilib
# default/linux/arm64/17.0
# default/linux/arm64/17.0/systemd
GENTOO_PROFILE=${GENTOO_PROFILE:-'default/linux/amd64/17.1'}
if [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.1" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3'
    SIGNED_SOURCE_SUFFIX=''
elif [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.1/no-multilib" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3-nomultilib'
    SIGNED_SOURCE_SUFFIX='-nomultilib'
elif [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.1/hardened" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3-hardened'
    SIGNED_SOURCE_SUFFIX='-hardened'
elif [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.1/no-multilib/hardened" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3-hardened-nomultilib'
    SIGNED_SOURCE_SUFFIX='-hardened+nomultilib'
elif [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.0/musl/hardened" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3-hardened-musl'
    SIGNED_SOURCE_SUFFIX='-musl-hardened'
elif [[ "${GENTOO_PROFILE}" == "default/linux/amd64/17.1/systemd" ]]; then
    FILENAME_BASE='amd64_gentoo-stage3-systemd'
    SIGNED_SOURCE_SUFFIX='-systemd'
elif [[ "${GENTOO_PROFILE}" == "default/linux/arm64/17.0" ]]; then
    FILENAME_BASE='arm64_gentoo-stage3'
    SIGNED_SOURCE_SUFFIX=''
elif [[ "${GENTOO_PROFILE}" == "default/linux/arm64/17.0/systemd" ]]; then
    FILENAME_BASE='arm64_gentoo-stage3-systemd'
    SIGNED_SOURCE_SUFFIX='-systemd'
else
    echo 'invalid profile, please select from the following profiles'
    echo 'default/linux/amd64/17.1'
    echo 'default/linux/amd64/17.1/no-multilib'
    echo 'default/linux/amd64/17.1/hardened'
    echo 'default/linux/amd64/17.1/no-multilib/hardened'
    echo 'default/linux/amd64/17.1/systemd'
    echo 'default/linux/arm64/17.0'
    echo 'default/linux/arm64/17.0/systemd'
    exit 1
fi

if [[ "${GENTOO_PROFILE}" == *'amd64'* ]]; then
    ARCH_PATH='amd64'
elif [[ "${GENTOO_PROFILE}" == *'arm64'* ]]; then
    ARCH_PATH='arm64'
fi
DIB_CLOUD_SOURCE=${DIB_CLOUD_SOURCE:-"http://distfiles.gentoo.org/releases/${ARCH_PATH}/autobuilds/latest-stage3-${ARCH_PATH}${SIGNED_SOURCE_SUFFIX}.txt"}
BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-"http://distfiles.gentoo.org/releases/${ARCH_PATH}/autobuilds/$(curl "${DIB_CLOUD_SOURCE}" -s -f | tail -n 1 | cut -d\  -f 1)"}
BASE_IMAGE_FILE_SUFFIX=${BASE_IMAGE_FILE_SUFFIX:-"$(basename "${BASE_IMAGE_FILE}" | cut -d. -f 2,3)"}
SIGNATURE_FILE="${SIGNATURE_FILE:-${BASE_IMAGE_FILE}.DIGESTS.asc}"
CACHED_FILE="${DIB_IMAGE_CACHE}/${FILENAME_BASE}.${BASE_IMAGE_FILE_SUFFIX}"
CACHED_SIGNATURE_FILE="${DIB_IMAGE_CACHE}/${FILENAME_BASE}.asc"

if [[ -n "${DIB_OFFLINE}" ]] && [[ -f "${CACHED_FILE}" ]] ; then
    echo "Not checking freshness of cached ${CACHED_FILE}"
else
    echo 'Fetching Base Image'
    "${TMP_HOOKS_PATH}"/bin/cache-url "${SIGNATURE_FILE}" "${CACHED_SIGNATURE_FILE}"
    "${TMP_HOOKS_PATH}"/bin/cache-url "${BASE_IMAGE_FILE}" "${CACHED_FILE}"
    pushd "${DIB_IMAGE_CACHE}"
    # import the key
    # this key can be verified at one of the following places
    # https://wiki.gentoo.org/wiki/Project:RelEng#Keys
    # https://dev.gentoo.org/~dolsen/releases/keyrings/gentoo-keys-*.tar.xz
    # http://distfiles.gentoo.org/distfiles/gentoo-keys-*.tar.xz
    # check the sig file
    if ! gpgv --keyring "${TMP_HOOKS_PATH}"/extra-data.d/gentoo-releng.gpg "${CACHED_SIGNATURE_FILE}"; then
        echo 'invalid signature file'
        exit 1
    fi
    echo 'valid key used'
    CACHED_SHA512SUM=$(grep -A1 -e 'SHA512' "${CACHED_SIGNATURE_FILE}" | grep -e "${BASE_IMAGE_FILE_SUFFIX}$" | cut -d\  -f 1)
    ACTUAL_SHA512SUM=$(sha512sum "${CACHED_FILE}" | cut -d\  -f 1)
    if [[ "${ACTUAL_SHA512SUM}" != "${CACHED_SHA512SUM}" ]]; then
        echo "invalid checksum on downloaded tarball: ${CACHED_FILE}"
        exit 1
    fi
    echo 'valid checksum'
    popd
fi

# Extract the base image (use --numeric-owner to avoid UID/GID mismatch between
# image tarball and host OS)
sudo tar -C "${TARGET_ROOT}" --numeric-owner --xattrs -xf "${CACHED_FILE}"

# Put in a dummy /etc/resolv.conf over the temporary one we used
# to bootstrap.  systemd has a bug/feature [1] that it will assume
# you want systemd-networkd as the network manager and create a
# broken symlink to /run/... if the base image doesn't have one.
# This broken link confuses things like dhclient.
# [1] https://bugzilla.redhat.com/show_bug.cgi?id=1197204
echo -e "# This file intentionally left blank\n" | sudo tee "${TARGET_ROOT}"/etc/resolv.conf