#!/bin/sh
#
# debeagle - Install Debian on a Beagle SBC
#
# Copyright (C) 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

main()
{
	local opt=
	local mirror=
	local suite=
	local target=

	while getopts 'm:' opt; do
		case ${opt} in
			m) mirror="${OPTARG}";;
			?)
				print_usage >&2
				exit 1
				;;
		esac
	done
	shift $(($OPTIND - 1))

	case ${#} in
		1)
			suite="${1}"
			target=''
			;;
		2)
			suite="${1}"
			target="${2}"
			;;
		*)
			print_usage >&2
			exit 1
			;;
	esac

	make_parts_and_fs "${target}"
	install_debian "${mirror}" "${suite}" "${target}"
}

print_usage()
{
	printf 'Usage: %s [-m <mirror>] <suite> [<target>]\n' "${0}"
}

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

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

	exit ${status}
}

_select()
{
	# Field width of the prompt numbers.
	select_width=$(expr ${#} : '.*')

	select_i=

	while :; do
		case "${select_i}" in
			'')
				select_i=0
				for select_word in "${@}"; do
					select_i=$(expr ${select_i} + 1)
					printf "%${select_width}d) %s\\n" \
						${select_i} "${select_word}" \
						>&2
				done
				;;
			*[!0-9]*)
				printf 'Please enter a number in range.\n' >&2
				;;
			*)
				if [ ${select_i} -gt 0 ] && \
						[ ${select_i} -le ${#} ]; then
					shift $(expr $select_i - 1)
					select_result="${1}"
					break
				fi
				printf 'Please enter a number in range.\n' >&2
				;;
		esac

		# Prompt and read input.
		printf '%s' "${PS3-#? }" >&2
		read -r select_i || exit
	done
}

pretty_print_size_dec()
{
	local size="${1}"

	awk -v size=${size} 'BEGIN {
		split("B KB MB GB TB", units, " ");
		i=1;
		while (size >= 1000) {
			size /= 1000;
			++i;
		};
		printf("%.2f %s\n", size, units[i]); }'
}

pretty_print_size_bin()
{
	local size="${1}"

	awk -v size=${size} 'BEGIN {
		split("B KiB MiB GiB TiB", units, " ");
		i=1;
		while (size >= 1024) {
			size /= 1024;
			++i;
		};
		printf("%.2f %s\n", size, units[i]); }'
}

get_block_dev_name()
{
	local dev="${1}"
	local vendor=
	local model=

	if [ -e "/sys/block/${dev}/device/vendor" ]; then
		vendor="$(cat "/sys/block/${dev}/device/vendor")"
		model="$(cat "/sys/block/${dev}/device/model")"
		name="${vendor} ${model}"
	else
		name="$(cat "/sys/block/${dev}/device/name")"
	fi

	printf '%s' "${name}"
}

prompt_block_dev()
{
	local dev=
	local name=
	local size=
	local size_s=
	local desc=
	local devs=

	set --
	for dev in /sys/block/*; do
		dev="${dev#/sys/block/}"
		case "${dev}" in
			loop*|sr*) continue;;
		esac
		name="$(get_block_dev_name "${dev}")"
		size="$(cat "/sys/block/${dev}/size")"
		size="$(expr ${size} \* 512)"
		size_s="$(pretty_print_size_dec "${size}")"
		size_s="${size_s} ($(pretty_print_size_bin "${size}"))"
		desc="$(printf '%s (%s) - %s\n' "${name}" "${dev}" "${size_s}")"
		set -- "${@}" "${desc}"
		devs="$(printf '%s\n%s\t%s\n' "${devs}" "${desc}" "${dev}")"
	done

	printf 'Select a block device:\n' >&2
	_select "${@}"

	while IFS='	' read -r desc dev; do
		if [ "x${desc}" = "x${select_result}" ]; then
			printf '%s\n' "${dev}"
		fi
	done <<-EOF
		${devs}
		EOF
}

make_parts_and_fs()
{
	local target="${1}"
	local part_prefix=''

	if [ "x${target}" = 'x' ]; then
		target="/dev/$(prompt_block_dev)"
	elif [ -e "/sys/block/${target#/dev/}" ]; then
		printf 'Installing to %s\n' \
			"$(get_block_dev_name "${target#/dev/}")"
	else
		error 1 'Device %s not found\n' "${target}"
	fi
	if grep "^${target}" /proc/mounts >/dev/null 2>&1; then
		error 1 'File system(s) on device %s mounted\n' "${target}"
	fi

	dd if=/dev/zero of="${target}" bs=512 count=1
	sfdisk -u S "${target}" <<-EOF
		,102400,0x0E,*
		,,0x83,-
		EOF

	case "${target}" in
		/dev/mmcblk*) part_prefix='p';;
	esac
	mkdosfs -F 16 "${target}${part_prefix}1"
	mke2fs -t ext4 "${target}${part_prefix}2"
}

install_debian()
{
	local mirror="${1}"
	local suite="${2}"
	local target="${3}"
	local part_prefix=''
	local boot_mp=''
	local root_mp=''
	local archives=''
	local linux_version=''

	case "${target}" in
		/dev/mmcblk*) part_prefix='p';;
	esac
	boot_mp="$(mktemp -d)"
	root_mp="$(mktemp -d)"
	mount -o 'iocharset=iso8859-1' "${target}${part_prefix}1" "${boot_mp}"
	mount "${target}${part_prefix}2" "${root_mp}"

	debootstrap --arch=armhf --include=linux-image-armmp,u-boot-omap \
		--foreign "${suite}" "${root_mp}" ${mirror}

	archives="${root_mp}/var/cache/apt/archives"
	ar p "${archives}/"u-boot-omap_*_armhf.deb data.tar.xz | \
		tar -xJO ./usr/lib/u-boot/omap3_beagle/MLO \
		>"${boot_mp}/MLO"
	ar p "${archives}/"u-boot-omap_*_armhf.deb data.tar.xz | \
		tar -xJO ./usr/lib/u-boot/omap3_beagle/u-boot.bin \
		>"${boot_mp}/u-boot.img"
	cat >"${boot_mp}/uEnv.txt" <<-EOF
		mpurate=1000

		dvimode="hd720 omapfb.vram=0:8M,1:4M,2:4M"
		vram=16M
		optargs="consoleblank=0"
		console="tty0 console=ttyO2,115200n8"
		EOF
	linux_version="$(printf '%s\n' \
		"${archives}/"linux-image-*-armmp_*_armhf.deb | sed \
		"s|^${archives}/linux-image-\\(.*-armmp\\)_.*\$|\1|")"
	(
		cd "${root_mp}"
		ar p var/cache/apt/archives/linux-image-*-armmp_*.deb \
			data.tar.xz | tar -xJ
	)
	mkimage -A arm -O linux -T kernel -C none \
		-a 0x80008000 -e 0x80008000 -n "Linux ${linux_version}" \
		-d "${root_mp}/boot/vmlinuz-${linux_version}" \
		"${root_mp}/boot/uImage"
	cp "${root_mp}/boot/uImage" "${boot_mp}/uImage"

	umount "${boot_mp}"
	umount "${root_mp}"
	rmdir "${boot_mp}"
	rmdir "${root_mp}"
}

main "${@}"