#!/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'

FORCE='n'
RUN=''
NOCOPY='n'

working_dir=''

APPNAME=$(basename "${0}")

# usage: usage <exitvalue>
usage() {
	echo "Usage: ${APPNAME} [options] working-dir [package-list | app]"
	echo ' options:'
	echo '    -r <app>      Run "app" within the context of the chroot'
	echo '    -u            Update the chroot via pacman'
	echo '    -f            Force overwrite of files in the working-dir'
	echo '    -C <file>     Location of a pacman config file'
	echo '    -M <file>     Location of a makepkg config file'
	echo '    -n            Do not copy config files into the chroot'
	echo '    -c <dir>      Set pacman cache'
	echo '    -h            This message'
	exit 1
}

while getopts 'r:ufnhC:M:c:' arg; do
	case "${arg}" in
		r) RUN="$OPTARG" ;;
		u) RUN='pacman -Syu --noconfirm' ;;
		f) FORCE='y' ;;
		C) pac_conf="$OPTARG" ;;
		M) makepkg_conf="$OPTARG" ;;
		n) NOCOPY='y' ;;
		c) cache_dir="$OPTARG" ;;
		h|?) usage ;;
		*) error "invalid argument '${arg}'"; usage ;;
	esac
done

if (( $EUID != 0 )); then
	die 'This script must be run as root.'
fi

shift $(($OPTIND - 1))

if [[ -z $RUN ]] && (( $# < 2 )); then
	die 'You must specify a directory and one or more packages.'
elif (( $# < 1 )); then
	die 'You must specify a directory.'
fi

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=$(pacman -Sddp extra/devtools 2>/dev/null | sed -E 's#(.*/)extra/os/.*#\1$repo/os/$arch#')
if echo "${host_mirror}" | grep -q 'file://'; then
	host_mirror_path=$(echo "${host_mirror}" | sed -E 's#file://(/.*)/\$repo/os/\$arch#\1#g')
fi

# {{{ 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

	if [[ -n $pac_conf && $NOCOPY = 'n' ]]; then
		cp ${pac_conf} ${working_dir}/etc/pacman.conf
	fi

	if [[ -n $makepkg_conf && $NOCOPY = 'n' ]]; then
		cp ${makepkg_conf} ${working_dir}/etc/makepkg.conf
	fi

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

chroot_lock () {
	# Only reopen the FD if it wasn't handed to us
	if [[ $(readlink -f /dev/fd/9) != "${working_dir}.lock" ]]; then
	  exec 9>"${working_dir}.lock"
	fi

	# Lock the chroot. Take note of the FD number.
	if ! flock -n 9; then
		stat_busy "Locking chroot"
		flock 9
		stat_done
	fi
}

chroot_run() {
	local dir=$1
	shift
	systemd-nspawn -D "${dir}" "${mount_args[@]}" -- ${@} 2>/dev/null
}

# }}}

umask 0022
if [[ -n $RUN ]]; then
	# run chroot {{{
	#Sanity check
	if [[ ! -f "${working_dir}/.arch-chroot" ]]; then
		die "'${working_dir}' does not appear to be a Arch chroot."
	elif [[ $(cat "${working_dir}/.arch-chroot") != ${CHROOT_VERSION} ]]; then
		die "'${working_dir}' is not compatible with ${APPNAME} version ${CHROOT_VERSION}. Please rebuild."
	fi

	chroot_lock
	build_mount_args
	copy_hostconf

	chroot_run "${working_dir}" ${RUN}

	# }}}
else
	# {{{ build chroot
	if [[ -e $working_dir && $FORCE = 'n' ]]; then
		die "Working directory '${working_dir}' already exists - try using -f"
	fi

	if [[ ! -d "${working_dir}" ]]; then
		mkdir -p "${working_dir}"
	fi

	if [[ "$(stat -f -c %T "${working_dir}")" == btrfs ]]; then
		if { type -P btrfs && btrfs subvolume create "${working_dir}"; } &>/dev/null; then
			chmod 0755 "${working_dir}"
		fi
	fi

	chroot_lock

	pacargs=("${cache_dirs[@]/#/--cachedir=}")
	if [[ -n $pac_conf ]]; then
		pacargs+=("--config=${pac_conf}")
	fi

	if [[ $FORCE = 'y' ]]; then
		pacargs+=("--force")
	fi
	if ! pacstrap -GMcd "${working_dir}" "${pacargs[@]}" "$@"; then
		die 'Failed to install all packages'
	fi

	printf '%s.UTF-8 UTF-8\n' en_US de_DE > "${working_dir}/etc/locale.gen"
	chroot_run "${working_dir}" locale-gen
	echo 'LANG=C' > "${working_dir}/etc/locale.conf"

	copy_hostconf

	echo "${CHROOT_VERSION}" > "${working_dir}/.arch-chroot"
	# }}}
fi