#!/usr/bin/env bash
# 2018 Luke Shumaker
declare -r NAME=osi-mk
declare -r VERSION=20180812

# Why is this different than mkosi[1]?
#
# - mkosi claims to be "legacy-free"--but they call everything that's
#   not systemd "legacy"; that clearly won't do for creating OpenRC
#   images.
#
# - mkosi claims to be "legacy-free", only supporting GPT
#   disk-labels--but btrfs can be booted directly, without a separate
#   disk-label, or a separate ESP partition.  To a btrfs disk, GPT/ESP
#   is legacy.
#
# - Using a raw btrfs disk means that it can easily be mounted without
#   first disecting the disk-label.
#
# [1]: https://github.com/systemd/mkosi

set -euE -o pipefail
source "${BASH_SOURCE[0]%/*}/lib/osi.sh"

loaded_modules=()
load_module() {
	local module
	if ! [[ -f $1 ]]; then
		error 2 'Module does not exist: %s' "$1"
	fi
	module="$(realpath -- "$1")"
	if in_array "$module" "${loaded_modules[@]}"; then
		return 0
	fi
	loaded_modules+=("$module")
	source "$1"
}

osi-mk:genfstab() {
	local arg_mountpoint=$1
	genfstab -t uuid "$arg_mountpoint" > "${arg_mountpoint}/etc/fstab"
}

osi-mk:directories() {
	local arg_mountpoint=$1
	local spec outside inside
	for spec in "${arg_directories[@]}"; do
		outside="${spec%:*}"
		inside="${spec#"${outside}:"}"
		# TODO: maybe rsync would be better?
		if [[ -d "${arg_mountpoint}/${inside}" ]]; then
			print 'Removing existing %q:%q' "$arg_file" "$inside"
			rm -rf -- "${arg_mountpoint}/${inside}"
		fi
		mkdir -p -- "$(dirname -- "${arg_mountpoint}/${inside}")"
		print 'Copying %q to %q:%q' "$outside" "$arg_file" "$inside"
		cp -aT -- "$outside" "${arg_mountpoint}/${inside}"
	done
}

osi-mk:grub-install() {
	local arg_mountpoint=$1
	cat <<-'EOT' >> "$arg_mountpoint/etc/default/grub"
			GRUB_TIMEOUT=0
			GRUB_DEFAULT=1 # Use the fallback initramfs, to get all drivers
			EOT
	arch-chroot -- "$arg_mountpoint" sh -c \
		    'grub-install "$(awk '\''$2 == "/" { print $1 }'\'' </proc/mounts)"'
}

osi-mk:grub-mkconfig() {
	local arg_mountpoint=$1
	arch-chroot -- "$arg_mountpoint" grub-mkconfig -o /boot/grub/grub.cfg
}

main() {
	local arg_orig=("$@")
	local arg_mode=outside
	local arg_mountpoint=
	local arg_size=1G
	local arg_edit=false
	local arg_edit_base=

	local arg_directories=()
	local arg_modules=()
	local arg_packages=()

	local args
	if ! args="$(getopt -n "${0##*/}" -o "s:e::d:m:p:hV" -l "inside:,size:,edit::,directory:,module:,package:,help,version" -- "$@")"; then
		arg_mode=error
	else
		eval "set -- $args"
		while true; do
			case "$1" in
				--inside) shift; arg_mode=inside; arg_mountpoint=$1; shift;;
				-s|--size) shift; arg_size=$1; shift;;
				-e|--edit) shift; arg_edit=true; arg_edit_base=$1; shift;;

				-d|--directory) shift; arg_directories+=("$1"); shift;;
				-m|--module) shift; arg_modules+=("$1"); shift;;
				-p|--package) shift; arg_packages+=("$1"); shift;;

				-V|--version) shift; arg_mode=version;;
				-h|--help) shift; arg_mode=usage;;
				--) shift; break;;
				*) error 1 'Internal error.  The programmer writing this tool screwed up.';;
			esac
		done
		case "$arg_mode" in
			outside|inside)
				if (( $# != 1 )); then
					if (( $# == 0 )); then
						error 0 "Expected 1 positional argument, got none"
					else
						error 0 "Expected 1 positional argument, got %d: %s" "$#" "${*@Q}"
					fi
					arg_mode=error
				else
					arg_file=$1
				fi
				for module in "${arg_modules[@]}"; do
					if ! [[ -f $module ]]; then
						error 0 'Module does not exist: %s' "$module"
						arg_mode=error
					fi
				done
				for dirspec in "${arg_directories[@]}"; do
					if ! [[ -d "${dirspec%:*}" ]]; then
						error 0 'Directory does not exist: %s' "${dirspec%:*}"
						arg_mode=error
					fi
				done
				;;
		esac
	fi
	case "$arg_mode" in
		error) print "Try '%q --help' for more information" "${0##*/}" >&2; return 2;;
		version)
			print "%s (notsystemd) %s" "$NAME" "$VERSION"
			return 0
			;;
		usage)
			print 'Usage: %s [OPTIONS] FILENAME.img' "${0##*/}"
			print 'Operating System Image: Make'
			echo
			print 'Create a mountable, bootable OS image.'
			echo
			print 'OPTIONS:'
			# --inside is internal-only; undocumented
			print '  -s SIZE, --size=SIZE             set the size of the image (default: 1G)'
			print '  -e[BASE.img], --edit[=BASE.img]  edit an existing image'
			echo
			print '  -d OUTSIDE:INSIDE, --directory=OUTSIDE:INSIDE  include the given directory'
			print '  -m MOD.sh, --module=MOD.sh                     include the given module'
			print '  -p PACKAGE, --package=package                  include the given package (or group)'
			echo
			print '  -h, --help     display this help'
			print '  -V, --version  output version information'
			return 0
			;;

		# main code starts here
		outside)
			if [[ ( $arg_edit = false || -n $arg_edit_base ) && -e $arg_file ]]; then
				error 1 'Image file already exists, refusing to overwrite: %s' "$arg_file"
			fi
			if $arg_edit; then
				if ! [[ -f "${arg_edit_base:-$arg_file}" ]]; then
					error 1 'Image must already exist to --edit: %s' "${arg_edit_base:-$arg_file}"
				fi
				if [[ -n $arg_edit_base ]]; then
					printf -v prefix "$(gettext -- '%s [format]')" "$NAME"
					{
						cp -T -- "$arg_edit_base" "$arg_file"
						btrfstune -fu "$arg_file"
					} |& sed "s|^|${prefix} |"
				fi
				# TODO: resize according to $arg_size
			else
				printf -v prefix "$(gettext -- '%s [format]')" "$NAME"
				{
					truncate --size="$arg_size" -- "$arg_file"
					mkfs.btrfs -- "$arg_file"
				} |& sed "s|^|${prefix} |"
			fi
			arg_mountpoint=$(mktemp -dt -- "${0##*/}.XXXXXXXXXX")
			# shellcheck disable=SC2064
			trap "rmdir -- ${arg_mountpoint@Q}" EXIT
			sudo -- ./osi-mount --root -- "$arg_file" "$arg_mountpoint" "${BASH_SOURCE[0]}" --inside="$arg_mountpoint" "${arg_orig[@]}"
			;;
		inside) # just keep reading...
			needs_sudo

			### Load modules ###
			packages=("${arg_packages[@]}")
			cache_packages=()
			post_install=(
				00:osi-mk:genfstab
				50:osi-mk:directories
				99:osi-mk:grub-mkconfig
			)
			if ! $arg_edit; then
				packages+=(grub btrfs-progs)
				post_install+=(
					98:osi-mk:grub-install
				)
			fi
			for module in "${arg_modules[@]}"; do
				load_module "$module"
			done
			cache_packages+=("${packages[@]}")

			#### install ###
			printf -v prefix "$(gettext -- '%s [install]')" "$NAME"
			{
				# Pre-fill the package cache
				if (( ${#cache_packages[@]} > 0 )); then
					mkdir -p -- "$arg_mountpoint"/var/{cache/pacman/pkg,lib/pacman,log}
					# Download anything the host doesn't already have cached
					pacman -r "$arg_mountpoint" --config=/usr/share/pacman/defaults/pacman.conf.x86_64 \
					       -Syw --noconfirm -- "${cache_packages[@]}"
					# Copy needed packages from host cache to image cache
					pacman -r "$arg_mountpoint" --config=/usr/share/pacman/defaults/pacman.conf.x86_64 \
					       -Sp --print-format='%l' -- "${cache_packages[@]}" \
					    | sed -n 's,^file://,,p' \
					    | xargs -d $'\n' -r cp -t "$arg_mountpoint/var/cache/pacman/pkg" --
				fi
				if (( ${#packages[@]} > 0 )); then
					# The --hookdir bit is to hack around https://bugs.archlinux.org/task/49347
					pacstrap -M -C /usr/share/pacman/defaults/pacman.conf.x86_64 -- "$arg_mountpoint" \
						 --hookdir="$arg_mountpoint/etc/pacman.d/hooks" \
						 --needed \
						 "${packages[@]}"
				fi
			} |& sed "s|^|${prefix} |"

			### post_install ###
			while IFS=: read -r n fn; do
				printf -v prefix "$(gettext -- '%s [post_install:%s:%s]')" "$NAME" "$n" "$fn"
				{
					print Begin
					"$fn" "$arg_mountpoint"
					print End
				} |& sed "s|^|${prefix} |"
			done < <(printf '%s\n' "${post_install[@]}" | sort)

			### End ###
			print '%s Done' "$NAME"
			;;

		*) error 1 'Internal error.  The programmer writing this tool screwed up.';;
	esac
}

main "$@"