#!/bin/bash
# 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; version 2 of the License.
#
# 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.

m4_include(lib/common.sh)

CHROOT_VERSION='v3'

working_dir=''

usage() {
	echo "Usage: ${0##*/} [options] working-dir [systemd-nspawn arguments]"
	echo "A wrapper around systemd-nspawn. Provides support for pacman."
	echo
	echo ' options:'
	echo '    -C <file>     Location of a pacman config file'
	echo '    -M <file>     Location of a makepkg config file'
	echo '    -c <dir>      Set pacman cache'
	echo '    -h            This message'
	exit 1
}

while getopts 'hC:M:c:' arg; do
	case "$arg" in
		C) pac_conf="$OPTARG" ;;
		M) makepkg_conf="$OPTARG" ;;
		c) cache_dir="$OPTARG" ;;
		h|?) usage ;;
		*) error "invalid argument '$arg'"; usage ;;
	esac
done
shift $(($OPTIND - 1))

(( $EUID != 0 )) && die 'This script must be run as root.'
(( $# < 1 )) && die 'You must specify a directory.'

working_dir="$(readlink -f $1)"
shift 1

[[ -z $working_dir ]] && die 'Please specify a working directory.'

if [[ -z $cache_dir ]]; then
	cache_dirs=($(pacman -v $cache_conf 2>&1 | grep '^Cache Dirs:' | sed 's/Cache Dirs:\s*//g'))
else
	cache_dirs=(${cache_dir})
fi

host_mirror=$(pacman -Sddp extra/devtools 2>/dev/null | sed -r 's#(.*/)extra/os/.*#\1$repo/os/$arch#')
[[ $host_mirror == *file://* ]] && host_mirror_path=$(echo "$host_mirror" | sed -r 's#file://(/.*)/\$repo/os/\$arch#\1#g')

# {{{ functions
build_mount_args() {
	local p
	declare -g mount_args=()

	if [[ -n $host_mirror_path ]]; then
		printf -v p '%q' "$host_mirror_path"
		mount_args+=(--bind-ro="$p")
	fi

	printf -v p '%q' "${cache_dirs[0]}"
	mount_args+=(--bind="$p")

	for cache_dir in ${cache_dirs[@]:1}; do
		printf -v p '%q' "$cache_dir"
		mount_args+=(--bind-ro="$p")
	done
}

copy_hostconf () {
	cp -a /etc/pacman.d/gnupg "$working_dir/etc/pacman.d"
	echo "Server = $host_mirror" > $working_dir/etc/pacman.d/mirrorlist

	[[ -n $pac_conf ]] && cp $pac_conf $working_dir/etc/pacman.conf
	[[ -n $makepkg_conf ]] && cp $makepkg_conf $working_dir/etc/makepkg.conf

	sed -r "s|^#?\\s*CacheDir.+|CacheDir = $(echo -n ${cache_dirs[@]})|g" -i $working_dir/etc/pacman.conf
}
# }}}

umask 0022

# Sanity check
if [[ ! -f "$working_dir/.arch-chroot" ]]; then
	die "'$working_dir' does not appear to be a Arch chroot."
elif [[ $(cat "$working_dir/.arch-chroot") != $CHROOT_VERSION ]]; then
	die "chroot '$working_dir' is not at version $CHROOT_VERSION. Please rebuild."
fi

build_mount_args
copy_hostconf

eval $(grep '^CARCH=' "$working_dir/etc/makepkg.conf")

machine_name="${working_dir//\//-}"
machine_name="${machine_name#-}"

exec ${CARCH:+setarch "$CARCH"} systemd-nspawn 2>/dev/null \
	-D "$working_dir" \
	--machine "$machine_name" \
	"${mount_args[@]}" \
	"$@"