#!/bin/sh
# Mini/Temporary ProteanOS Development Kit
# miniprokit.sh
# Main program file
#
# Copyright (C) 2013, 2014  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/>.

set -u

SHA256SUMS='
ff4c0b1d3e8e7dfb00442b6cae1ad076b13329aa92edf516ae9c65563edb209f all_all_base
10e53d3d80f37153a8d428c47d37b770386b1252a9c76e562927a273e43d549e amd64-linux-glibc_all_base
a189b7ef5b35364aad0b72e2419dcc791eb28f8b725346fc727a99ddf099624e amd64-linux-glibc_dev_base
733f5b298450c5f2c2cdbb35030100c6c4c44661c0af52307ff2f8c49d16b1e7 i686-linux-glibc_all_base
0122eaaf5afe74d406e608c0b1aa6c9ec2d9d017f5d6a241beaa03d712bbdd6f i686-linux-glibc_ao751h_base
361015543e3326c85a89a0a735cd506f7a52ad9423b82de745fd333963ac8fdf i686-linux-glibc_dev_base
c93dc8608cf9a435b920c9cc9590c9d274c8193b709845cc5409692f00d8b05d src_all_base
'

PKGS=' base-files busybox '\
'libc-bin libc.6 libopkg.1 opkg  '

main()
{
	local cmd=

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

	cmd="${1}"
	shift 1

	case "${cmd}" in
		'install')
			cmd_install "${@}"
			;;
		'shell')
			cmd_shell "${@}"
			;;
	esac

	return 0
}

print_usage()
{
	printf 'Usage: %s <command> [<args>]\n\n' "${0}"

	printf 'Available commands are:\n'
	printf '  install  install a ProteanOS system\n'
	printf '  shell    enter a ProteanOS shell\n'
}

error()
{
	local status=${1}
	local fmt="${2}"
	shift 2

	printf "Error: ${fmt}\n" "${@}" >&2

	exit ${status}
}

info()
{
	local fmt="${1}"
	shift 1

	printf "${fmt}\n" "${@}"
}

cmd_install()
{
	local usage=
	local opt=
	local arch=
	local plat=
	local mirror=
	local root=
	local uname_m=
	local uname_s=
	local aps=
	local url_aps=
	local feed=
	local sha256sum=
	local line=
	local package=
	local filename=

	usage='[-a <arch>] [-P <plat>] [-m <mirror>] <root>'

	while getopts 'a:P:m:' opt; do
		case ${opt} in
			a) arch="${OPTARG}";;
			P) plat="${OPTARG}";;
			m) mirror="${OPTARG}";;
			?)
				printf 'Usage: %s install %s\n' \
					"${0}" "${usage}" >&2
				exit 1
				;;
		esac
	done
	shift $(($OPTIND - 1))

	if [ ${#} -ne 1 ]; then
		printf 'Usage: %s install %s\n' "${0}" "${usage}" >&2
		exit 1
	fi
	root="${1}"

	if [ "x${arch}" = 'x' ]; then
		uname_m="$( (uname -m) 2>/dev/null)" || uname_m='?'
		uname_s="$( (uname -s) 2>/dev/null)" || uname_s='?'
		case "${uname_m}:${uname_s}" in
			'i686:Linux') arch='i686-linux-glibc';;
			'x86_64:Linux') arch='amd64-linux-glibc';;
			'?:?') error 2 'Error: Architecture unknown';;
			*) error 2 'Error: Architecture unsupported';;
		esac
	fi
	info 'Using architecture %s' "${arch}"

	if [ "x${plat}" = 'x' ]; then
		plat='dev'
	fi
	info 'Using platform %s' "${plat}"

	if [ "x${mirror}" = 'x' ]; then
		rand=$(date '+%S')
		rand=$(($rand % 2))
		case ${rand} in
			0)
				mirror='http://mirror.gnu.dk/pub/proteanos'
				;;
			1)
				mirror='http://mirror.oss.maxcdn.com/proteanos'
				;;
		esac
	fi
	info 'Using mirror %s' "${mirror}"

	info 'Setting up root...'
	mkdir -p "${root}/etc/opkg" \
		"${root}/var/lib/opkg/lists" "${root}/var/lib/opkg/info" \
		"${root}/var/cache/opkg/archives" "${root}/tmp/opkg" || \
		error 2 'Failed to set up root'

	info 'Configuring opkg and retrieving Packages...'
	exec 3>"${root}/etc/opkg/opkg.conf" || \
		error 2 'Failed to open opkg.conf'
	for aps in "${arch}_${plat}_base" "${arch}_all_base" 'all_all_base' \
			'src_all_base'; do
		url_aps="$(printf '%s\n' "${aps}" | sed 's|_|/|g')"
		feed="${mirror}/feeds/dev/trunk/${url_aps}"
		printf 'src %s %s\n' "trunk_${aps}" "${feed}" >&3
		wget -q -O "${root}/var/lib/opkg/lists/trunk_${aps}" \
			"${feed}/Packages" || \
			error 2 'Failed to download %s' "${feed}/Packages"
		sha256sum="$(sha256sum \
			"${root}/var/lib/opkg/lists/trunk_${aps}" | \
			cut -d ' ' -f 1)"
		printf '%s' "${SHA256SUMS}" | grep -Fq "${sha256sum} ${aps}" \
			|| error 2 'Checksum of Packages index file failed'
	done
	printf '\ndest root /\n' >&3
	printf 'arch %s 1\n' 'all' "${arch}" 'src' >&3
	exec 3>&-

	while IFS='' read -r line; do
		if [ "x${line%: *}" = 'xPackage' ]; then
			package="${line#Package: }"
		elif [ "x${line%: *}" = 'xFilename' ]; then
			filename="${line#Filename: }"
		elif [ "x${line%: *}" = 'xSHA256sum' ]; then
			sha256sum="${line#SHA256sum: }"
		elif [ "x${line}" = 'x' ]; then
			printf '%s\n' "${PKGS}" | grep -Fq " ${package} " || \
				continue
			get_pkg "${root}" "${mirror}" \
				"${package}" "${filename}" "${sha256sum}"
		fi
	done <<-EOF
		$(cat "${root}/var/lib/opkg/lists/trunk_"*)

		EOF

	configure_pkgs "${root}"

	[ -r /etc/resolv.conf ] && cp /etc/resolv.conf "${root}/etc"
	[ -r /etc/hostname ] && cp /etc/hostname "${root}/etc"
}

get_pkg()
{
	local root="${1}"
	local mirror="${2}"
	local package="${3}"
	local filename="${4}"
	local sha256sum="${5}"
	local file=
	local control=
	local field=
	local printed=

	info 'Downloading %s...' "${package}"
	filename="${filename#../../../../../../}"
	wget -q -O "${root}/var/cache/opkg/archives/${filename##*/}" \
		"${mirror}/${filename}" || error 2 'Failed to download package'
	filename="var/cache/opkg/archives/${filename##*/}"
	printf '%s  %s\n' "${sha256sum}" "${root}/${filename}" | \
		sha256sum -c >/dev/null 2>&1 \
		|| error 2 'Checksum of source package file failed'

	info 'Unpacking %s...' "${package}"
	mkdir "${root}/tmp/opkg/${package}"
	(
		cd "${root}"
		tar -xzOf "${filename}" data.tar.gz \
			>"tmp/opkg/${package}/data.tar.gz"
		tar -xzf "tmp/opkg/${package}/data.tar.gz"
		cd "tmp/opkg/${package}"
		tar -xzOf "../../../${filename}" control.tar.gz | \
			tar -xz
	)
	for file in "${root}/tmp/opkg/${package}/"*; do
		mv "${file}" "${root}/var/lib/opkg/info/${package}.${file##*/}"
	done
	tar -tz "${root}/tmp/opkg/${package}/data.tar.gz" | sed 's/^\.//' \
		>"${root}/var/lib/opkg/info/${package}.list"
	rm -f "${root}/tmp/opkg/${package}/data.tar.gz"
	rmdir "${root}/tmp/opkg/${package}"

	# Write status file.
	exec 3>>"${root}/var/lib/opkg/status"
	control="${root}/var/lib/opkg/info/${package}.control"
	for field in Package Version Depends Recommends Suggests \
			Provides Replaces Conflicts; do
		grep "^${field}: " "${control}" >&3
	done
	printf 'Status: install ok unpacked\n' >&3
	for field in Essential Architecture; do
		grep "^${field}: " "${control}" >&3
	done
	if [ -r "${root}/var/lib/opkg/info/${package}.conffiles" ]; then
		printed=false
		while read -r file; do
			${printed} || printf 'Conffiles:\n' >&3
			printf ' %s %s\n' "${file}" "$(md5sum \
				"${root}/${file}" | cut -d ' ' -f 1)" \
				>&3
			printed=true
		done <"${root}/var/lib/opkg/info/${package}.conffiles"
	fi
	printf 'Installed-Time: %s\n\n' "$(date '+%s')" >&3
	exec 3>&-

	rm -f "${root}/${filename}"
}

configure_pkgs()
{
	local root="${1}"

	chroot "${root}" /bin/sh -c \
		'opkg install $(opkg list-installed | cut -d " " -f 1)'
}

cmd_shell()
{
	local root=
	local arch=

	if [ ${#} -ne 1 ]; then
		printf 'Usage: %s shell <root>\n' "${0}" >&2
		exit 1
	fi
	root="${1}"

	if ! [ -d "${root}" ] || ! [ -r "${root}/etc/proteanos_arch" ]; then
		error 2 'Error: ProteanOS root file system not found'
	fi

	arch="$(cat "${root}/etc/proteanos_arch")"

	case "${arch}" in
		*'-linux-'*)
			mount -t proc proc "${root}/proc"
			mount -t sysfs sys "${root}/sys"
			mount -o bind /dev "${root}/dev"
			mount -t devpts -o noexec,nosuid,gid=5,mode=0620 \
				devpts "${root}/dev/pts"
			;;
		*)
			error 2 'ProteanOS architecture %s not supported' \
				"${arch}"
	esac

	chroot "${root}" /bin/sh
	printf '\nExiting...\n'

	case "$(cat "${root}/etc/proteanos_arch")" in
		*'-linux-'*)
			umount "${root}/dev/pts"
			umount "${root}/proc"
			umount "${root}/sys"
			while ! umount "${root}/dev"; do
				# umount sometimes complains that ${root}/dev is
				# busy.  Here's a kludge to try to handle that.
				# This is a bind mount, so we better make sure
				# it gets unmounted; otherwise, `rm -Rf ${root}`
				# can be painful.
				sleep 1
			done
			;;
	esac
}

main "${@}"