#!/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.

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. Default: /var/cache/pacman/pkg'
	echo '    -h            This message'
	exit $1
}

while getopts 'r:ufnhC:M:c:' arg; do
	case "${arg}" in
		r) RUN="$OPTARG" ;;
		u) RUN='/bin/sh -c "pacman -Syu --noconfirm && (pacman -Qqu >/dev/null && pacman -Su --noconfirm || exit 0)"' ;;
		f) FORCE='y' ;;
		C) pac_conf="$OPTARG" ;;
		M) makepkg_conf="$OPTARG" ;;
		n) NOCOPY='y' ;;
		c) cache_dir="$OPTARG" ;;
		h|?) usage 0 ;;
		*) echo "invalid argument '${arg}'"; usage 1 ;;
	esac
done

if [ "$EUID" != '0' ]; then
	echo 'error: this script must be run as root.'
	exit 1
fi

shift $(($OPTIND - 1))

if [ "$RUN" = '' -a $# -lt 2 ]; then
	echo 'you must specify a directory and one or more packages'
	usage 1
elif [ $# -lt 1 ]; then
	echo 'you must specify a directory'
	usage 1
fi

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

[ "${working_dir}" = '' ] && echo 'error: please specify a working directory' && usage 1

if [ -z "$cache_dir" ]; then
	cache_conf=${working_dir}/etc/pacman.conf
	[ ! -f $cache_conf ] && cache_conf=${pac_conf:-/etc/pacman.conf}
	cache_dir=$( (grep -m 1 '^CacheDir' $cache_conf || echo 'CacheDir = /var/cache/pacman/pkg') | sed 's/CacheDir\s*=\s*//')
	unset cache_conf
fi

if [ -f /etc/pacman.d/mirrorlist ]; then
	host_mirror=$(pacman -Sddp extra/devtools 2>/dev/null | sed -E 's#(.*/)extra/os/.*#\1$repo/os/$arch#')
fi
if [ -z "${host_mirror}" ]; then
	host_mirror='http://mirrors.kernel.org/archlinux/$repo/os/$arch'
fi
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
chroot_mount() {
	[ -e "${working_dir}/sys" ] || mkdir "${working_dir}/sys"
	mount -t sysfs sysfs "${working_dir}/sys"

	[ -e "${working_dir}/proc" ] || mkdir "${working_dir}/proc"
	mount -t proc proc "${working_dir}/proc"

	[ -e "${working_dir}/dev" ] || mkdir "${working_dir}/dev"
	mount -t tmpfs dev "${working_dir}/dev" -o mode=0755,size=10M,nosuid
	mknod -m 666 "${working_dir}/dev/null" c 1 3
	mknod -m 666 "${working_dir}/dev/zero" c 1 5
	mknod -m 600 "${working_dir}/dev/console" c 5 1
	mknod -m 644 "${working_dir}/dev/random" c 1 8
	mknod -m 644 "${working_dir}/dev/urandom" c 1 9
	mknod -m 666 "${working_dir}/dev/tty" c 5 0
	mknod -m 666 "${working_dir}/dev/tty0" c 4 0
	mknod -m 666 "${working_dir}/dev/full" c 1 7
	ln -s /proc/kcore "${working_dir}/dev/core"
	ln -s /proc/self/fd "${working_dir}/dev/fd"
	ln -s /proc/self/fd/0 "${working_dir}/dev/stdin"
	ln -s /proc/self/fd/1 "${working_dir}/dev/stdout"
	ln -s /proc/self/fd/2 "${working_dir}/dev/stderr"

	[ -e "${working_dir}/dev/shm" ] || mkdir "${working_dir}/dev/shm"
	mount -t tmpfs shm "${working_dir}/dev/shm" -o nodev,nosuid,size=128M

	[ -e "${working_dir}/dev/pts" ] || mkdir "${working_dir}/dev/pts"
	mount -t devpts devpts "${working_dir}/dev/pts" -o newinstance,ptmxmode=666
	ln -s pts/ptmx "${working_dir}/dev/ptmx"

	[ -e "${cache_dir}" ] || mkdir -p "${cache_dir}"
	[ -e "${working_dir}/${cache_dir}" ] || mkdir -p "${working_dir}/${cache_dir}"
	mount -o bind "${cache_dir}" "${working_dir}/${cache_dir}"

	if [ -n "${host_mirror_path}" ]; then
		[ -e "${working_dir}/${host_mirror_path}" ] || mkdir -p "${working_dir}/${host_mirror_path}"
		mount -o bind "${host_mirror_path}" "${working_dir}/${host_mirror_path}"
		mount -o remount,ro,bind "${host_mirror_path}" "${working_dir}/${host_mirror_path}"
	fi

	trap 'chroot_umount' EXIT INT QUIT TERM HUP
}

copy_hostconf () {
	chroot "${working_dir}" /bin/findmnt -rnu -o SOURCE,TARGET,FSTYPE,OPTIONS > "${working_dir}/etc/mtab"
	cp /etc/resolv.conf "${working_dir}/etc/resolv.conf"
	echo "Server = ${host_mirror}" > ${working_dir}/etc/pacman.d/mirrorlist
}

chroot_umount () {
	umount "${working_dir}/proc"
	umount "${working_dir}/sys"
	umount "${working_dir}/dev/pts"
	umount "${working_dir}/dev/shm"
	umount "${working_dir}/dev"
	umount "${working_dir}/${cache_dir}"
	[ -n "${host_mirror_path}" ] && umount "${working_dir}/${host_mirror_path}"
}

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
		echo -n "locking chroot..."
		flock 9
		echo "done"
	fi
}
# }}}

umask 0022
if [ "$RUN" != "" ]; then
	# run chroot {{{
	#Sanity check
	if [ ! -f "${working_dir}/.arch-chroot" ]; then
		echo "error: '${working_dir}' does not appear to be a Arch chroot"
		echo '       please build the image using mkarchroot'
		exit 1
	fi

	chroot_lock
	chroot_mount
	copy_hostconf

	eval chroot "${working_dir}" ${RUN}

	# }}}
else
	# {{{ build chroot
	if [ -e "${working_dir}" -a "${FORCE}" = "n" ]; then
		echo "error: working dir '${working_dir}' already exists - try using -f"
		exit 1
	fi

	if { type -P btrfs && btrfs subvolume create "${working_dir}"; } &>/dev/null; then
		chmod 0755 "${working_dir}"
	fi

	mkdir -p "${working_dir}/var/lib/pacman/sync"
	mkdir -p "${working_dir}/etc/"

	chroot_lock
	chroot_mount

	pacargs="--noconfirm --root=${working_dir} --cachedir=${cache_dir}"
	if [ "$pac_conf" != "" ]; then
		pacargs="$pacargs --config=${pac_conf}"
	fi

	if [ $# -ne 0 ]; then
		op='-Sy'
		if [ "$FORCE" = "y" ]; then
			op="${op}f"
		fi
		if ! pacman ${op} ${pacargs} $@; then
			echo 'error: failed to install all packages'
			exit 1
		fi
	fi

	if [ -d "${working_dir}/lib/modules" ]; then
		ldconfig -r "${working_dir}"
	fi

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

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

	if [ -e "${working_dir}/etc/locale.gen" ]; then
		sed -i 's@^#\(en_US\|de_DE\)\(\.UTF-8\)@\1\2@' "${working_dir}/etc/locale.gen"
		chroot "${working_dir}" locale-gen
	fi

	if [ ! -e "${working_dir}/.arch-chroot" ]; then
		date +%s > "${working_dir}/.arch-chroot"
	fi
	# }}}
fi