#!@@SHELL@@
#
# opkbootstrap
# src/opkbootstrap.sh
# Main program script.
#
# Copyright (C) 2012 Patrick "P. J." McDermott
#
# 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 3 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 <http://www.gnu.org/licenses/>.

TARGET=                                 # set in main
LISTS_DIR=/var/lib/opkg/lists
PKGS_DIR=/var/cache/opkg/archives

ARCH_MACHINE=                           # set in main
ARCH_SYSTEM=                            # set in main
PLAT_SYSTEM=                            # set in main

PKGS_ESSENTIAL=                         # set in find_essential
PKGS_ALL=                               # set in find_essential and find_depends
PKGS_INCLUDE=                           # set in main
PKGS_EXCLUDE=                           # set in main

# main <target> <arch> <src> [<src>]...
main()
{
	SCRIPT_NAME="${0}"

	while getopts 'hVi:x:' opt; do
		case "${opt}" in
			h)
				print_help
				exit
				;;
			V)
				print_version
				exit
				;;
			i)
				PKGS_INCLUDE="${PKGS_INCLUDE},${OPTARG}"
				;;
			x)
				PKGS_EXCLUDE="${PKGS_EXCLUDE},${OPTARG}"
				;;
			?)
				print_usage >&2
				exit 1
				;;
		esac
	done
	shift $(($OPTIND - 1))

	if [ ${#} -lt 4 ]; then
		print_usage >&2
		exit 1
	fi

	TARGET="${1}"
	ARCH_MACHINE="${2%:*}"
	ARCH_SYSTEM="${2#*:}"
	PLAT_SYSTEM="${3}"
	shift 3

	set_paths

	# Find packages.
	for src; do
		get_src_list ${src}
	done
	find_essential
	find_depends

	# Download packages.
	get_pkgs

	# Unpack packages ("first stage" installation in debootstrap terms).
	unpack_pkgs

	# Configure packages ("second stage" installation in debootstrap terms).
	if [ "${ARCH_MACHINE}" = "${ARCH_SYSTEM}" ]; then
		setup_chroot
		configure_pkgs
	else
		printf 'Cross installation currently not supported.  Exiting...\n'
		exit
	fi
}

# print_usage
print_usage()
{
	cat <<EOF
Usage: ${SCRIPT_NAME} [OPTION]... <target> <arch> <plat> <src> [<src>]...
EOF
}

# print_help
print_help()
{
	print_usage

	cat <<EOF
Bootstrap the installation of a base system into a target directory.

    -h              display this help and exit
    -V              display version information and exit
    -i A,B,C        includes specified packages in the base system
    -x A,B,C        excludes specified packages from the base system
EOF
}

# print_version
print_version()
{
	cat <<EOF
@@PACKAGE@@ @@VERSION@@
Copyright (C) 2012 Patrick "P. J." McDermott
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by P. J. McDermott.
EOF
}

# error <fmt> [<args>]...
error()
{
	_msg="${1}"
	shift
	printf "Error: ${_msg}\n" ${@}
	exit 2
}

# set_paths
set_paths()
{
	TARGET=$(cd "${TARGET}" && pwd)
	LISTS_DIR="${TARGET}/${LISTS_DIR}"
	PKGS_DIR="${TARGET}/${PKGS_DIR}"
}

# get_src_list src|src/gz <name> <value> [<comp>]
# get_src_list dist|dist/gz <name> <value> [<comp>]...
get_src_list()
{
	case "${1}" in
		src)
			shift
			get_pkg_src_list false ${@}
			;;
		src/gz)
			shift
			get_pkg_src_list true ${@}
			;;
		dist)
			shift
			get_dist_src_list false ${@}
			;;
		dist/gz)
			shift
			get_dist_src_list true ${@}
			;;
		*)
			error 'Invalid source type "%s"' "${1}"
			;;
	esac
}

# get_pkg_src_list <gzip> <name> <value> [<comp>]
get_pkg_src_list()
{
	if [ ${#} -ne 3 -a ${#} -ne 4 ]; then
		error 'Malformed src configuration'
	fi

	_gzip=${1}
	_name="${2}"
	_value="${3}"
	_comp="${4}"

	_url="${_value}/${_comp}/Packages"

	if ${_gzip}; then
		wget -q -O - "${_url}.gz" | gzcat > "${LISTS_DIR}/${_name}"
	else
		wget -q -O "${LISTS_DIR}/${_name}" "${_url}"
	fi
}

# get_dist_src_list <gzip> <name> <value> [<comp>]...
get_dist_src_list()
{
	:
}

# find_essential
find_essential()
{
	for _list in "${LISTS_DIR}/"*; do
		_pkg=
		_essential=false
		while read _line; do
			if [ -z "${line}" ]; then
				if ${_essential}; then
					PKGS_ESSENTIAL="${PKGS_ESSENTIAL} ${_pkg}"
					PKGS_ALL="${PKGS_ALL} ${_pkg}"
				fi
				_pkg=
				_essential=false
				continue
			fi
			if [ "${_line#Package: }" != "${_line}" ]; then
				_pkg="${_line#Package: }"
				continue
			fi
			if [ "${_line}" = 'Essential: yes' ]; then
				_essential=true
				continue
			fi
			# TODO: Make sure Architecture is one of:
			# all, ${ARCH_SYSTEM}, or ${PLAT_SYSTEM}
		done < "${_list}"
	done
}

# find_depends
find_depends()
{
	:
}

# get_pkgs
get_pkgs()
{
	:
}

# unpack_pkgs
unpack_pkgs()
{
	cd "${TARGET}"

	for _opk in "${PKGS_DIR}"/*; do
		_pkg="${opk##*/}"
		_pkg="${pkg%%_*}"

		tar -xzOf "${_opk}" data.tar.gz | tar -xz

		mkdir -p tmp/control
		(cd tmp/control; tar -xzf "${_opk}" control.tar.gz)
		for _script in conffiles md5sums preinst postinst prerm postrm; do
			if [ -e tmp/control/${_file} ]; then
				mv tmp/control/${_script} "${INFO_DIR}/${_pkg}.${_file}"
			fi
		done
		# TODO: Generate pkg.list
		rm -Rf tmp/control
	done
}

# setup_chroot
setup_chroot()
{
	:
}

# configure_pkgs
configure_pkgs()
{
	:
}

main ${@}