#!/bin/bash
#
#   offload-build - build a PKGBUILD on a remote server using makechrootpkg.
#
#   Copyright (c) 2019 by Eli Schwartz <eschwartz@archlinux.org>
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <https://www.gnu.org/licenses/>.
#

source /usr/share/makepkg/util/config.sh


# global defaults suitable for use by Arch staff
repo=extra
arch=x86_64
server=build.archlinux.org

die() { printf "error: $1\n" "${@:2}"; exit 1; }

usage() {
    cat <<- _EOF_
		Usage: ${BASH_SOURCE[0]##*/} [--repo REPO] [--arch ARCHITECTURE] [--server SERVER] -- [ARCHBUILD_ARGS]

		Build a PKGBUILD on a remote server using makechrootpkg. Requires a remote user
		that can run archbuild without password auth. Options passed after a -- are
		passed on to archbuild, and eventually to makechrootpkg.

		OPTIONS
		    -r, --repo      Build against a specific repository (current: $repo)
		    -a, --arch      Build against a specific architecture (current: $arch)
		    -s, --server    Offload to a specific build server (current: $server)
		    -h, --help      Show this help text
_EOF_
}

# option checking
while (( $# )); do
    case $1 in
        -h|--help)
            usage
            exit 0
            ;;
        -r|--repo)
            repo=$2
            shift 2
            ;;
        -a|--arch)
            arch=$2
            shift 2
            ;;
        -s|--server)
            server=$2
            shift 2
            ;;
        --)
            shift
            break
            ;;
        *)
            die "invalid argument: %s" "$1"
            ;;
    esac
done

# multilib must be handled specially
archbuild_arch="${arch}"
if [[ $repo = multilib* ]]; then
    archbuild_arch=
fi

archbuild_cmd=("${repo}${archbuild_arch:+-$archbuild_arch}-build" "$@")

trap 'rm -rf $TEMPDIR' EXIT INT TERM QUIT

# Load makepkg.conf variables to be available
load_makepkg_config

# Use a source-only tarball as an intermediate to transfer files. This
# guarantees the checksums are okay, and guarantees that all needed files are
# transferred, including local sources, install scripts, and changelogs.
export TEMPDIR=$(mktemp -d --tmpdir offload-build.XXXXXXXXXX)
export SRCPKGDEST=${TEMPDIR}
makepkg --source || die "unable to make source package"

# Temporary cosmetic workaround makepkg if SRCDEST is set somewhere else
# but an empty src dir is created in PWD. Remove once fixed in makepkg.
rmdir --ignore-fail-on-non-empty src 2>/dev/null || true

mapfile -t files < <(
    # This is sort of bash golfing but it allows running a mildly complex
    # command over ssh with a single connection.
    # shellcheck disable=SC2145
    cat "$SRCPKGDEST"/*"$SRCEXT" |
        ssh $server '
            temp="${XDG_CACHE_HOME:-$HOME/.cache}/offload-build" &&
            mkdir -p "$temp" &&
            temp=$(mktemp -d -p "$temp") &&
            cd "$temp" &&
            {
                bsdtar --strip-components 1 -xvf - &&
                script -qefc "'"${archbuild_cmd[@]@Q}"'" /dev/null &&
                printf "%s\n" "" "-> build complete" &&
                printf "\t%s\n" "$temp"/*
            } >&2 &&
            makepkg_user_config="${XDG_CONFIG_HOME:-$HOME/.config}/pacman/makepkg.conf" &&
            makepkg_config="/usr/share/devtools/makepkg-'"${arch}"'.conf" &&
            if [[ -f /usr/share/devtools/makepkg-'"${repo}"'-'"${arch}"'.conf ]]; then
                makepkg_config="/usr/share/devtools/makepkg-'"${repo}"'-'"${arch}"'.conf"
            fi &&
            makepkg --config <(cat "${makepkg_user_config}" "${makepkg_config}" 2>/dev/null) --packagelist &&
            printf "%s\n" "${temp}/PKGBUILD"
')


if (( ${#files[@]} )); then
    printf '%s\n' '' '-> copying files...'
    scp "${files[@]/#/$server:}" "${TEMPDIR}/"
    mv "${TEMPDIR}"/*.pkg.tar* "${PKGDEST:-${PWD}}/"
    mv "${TEMPDIR}/PKGBUILD" "${PWD}/"
else
    exit 1
fi