#!/usr/bin/env bash
# Copyright (C) 2018  Luke Shumaker
# SPDX-License-Identifier: AGPL-3.0-or-later
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 ./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")
	# shellcheck disable=SC1090
	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
	# shellcheck disable=SC2016
	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=
	local arg_edit=false
	local arg_edit_base=

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

	local args
	if ! args="$(getopt -n "${0##*/}" -o "s:e::d:m:p:P:hV" -l "inside:,size:,edit::,directory:,module:,package:,package-file:,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;;
				-P|--package-file) shift; arg_package_files+=("$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' "${dirspec%:*}"
						arg_mode=error
					fi
				done
				for package_file in "${arg_package_files[@]}"; do
					if ! [[ -f "$package_file" ]]; then
						error 0 'Package file does not exist: %s' "$package_file"
						arg_mode=error
					fi
				done
				if [[ $arg_mode = outside ]]; then
					if [[ ( $arg_edit = false || -n $arg_edit_base ) && -e $arg_file ]]; then
						error 2 'Image file already exists, refusing to overwrite: %s' "$arg_file"
					fi
					if $arg_edit; then
						if ! [[ -f ${arg_edit_base:-$arg_file} ]]; then
							error 2 'Image must already exist to --edit: %s' "${arg_edit_base:-$arg_file}"
						fi
					else
						if [[ -z $arg_size ]]; then
							error 2 'Must specify --size when creating a new image'
						fi
					fi
				fi
				;;
		esac
	fi
	case "$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:'
			#     000000000011111111112222222222333333333344444444445555555555666666666677777777778
			#     012345678901234567890123456789012345678901234567890123456789012345678901234567890
			print '  -s SIZE,           --size=SIZE                    set the size of the image'
			print '  -e[BASE.img],      --edit[=BASE.img]              edit an existing image'
			# --inside is internal-only; undocumented
			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 PKGNAME,        --package=PKGNAME              include the given package (or group)'
			print '  -P PKG.pkg.tar.xz, --package-file=PKG.pkg.tar.xz  include the given package file'
			echo
			print '  -h,                --help                         display this help'
			print '  -V,                --version                      output version information'
			return 0
			;;

		# main code starts here
		outside)
			# shellcheck disable=SC2059
			printf -v prefix "$(gettext -- '%s [format]')" "$NAME"
			{
				if $arg_edit; then
					if [[ -n $arg_edit_base ]]; then
						cp -T -- "$arg_edit_base" "$arg_file"
						btrfstune -fu "$arg_file"
					fi
					if [[ -n $arg_size ]]; then
						# Calculate sizes in exact bytes now, to avoid any discrepancies
						# between truncate(1) and btrfs-filesystem(8).
						# Use truncate(1) to do this.  It's a little gross,
						# but because TMPDIR is likely on tmpfs, it's time-cheap,
						# and because of sparse files, it's space-cheap.
						tmpfile=$(mktemp -t -- "${0##*/}.XXXXXXXXXX")
						trap "rm -- ${tmpfile@Q}" EXIT
						case "$arg_size" in
							'+'*|'-'*|'<'*|'>'*|'/'*|'%'*)
								truncate --reference="$arg_file" --size="$arg_size" -- "$tmpfile";;
							*)
								truncate --size="$arg_size" -- "$tmpfile";;
						esac
						old_size=$(stat --format='%s' -- "$arg_file")
						new_size=$(stat --format='%s' -- "$tmpfile")
						rm -- "$tmpfile"
						trap - EXIT

						# Do the resize
						arg_mountpoint=$(mktemp -dt -- "${0##*/}.XXXXXXXXXX")
						trap "rmdir -- ${arg_mountpoint@Q}" EXIT
						if (( new_size > old_size )); then
							truncate --size="$new_size" -- "$arg_file"
							sudo -- ./osi-mount --root -- "$arg_file" "$arg_mountpoint" btrfs filesystem resize max "$arg_mountpoint"
						elif (( new_size < old_size )); then
							sudo -- ./osi-mount --root -- "$arg_file" "$arg_mountpoint" btrfs filesystem resize "$new_size" "$arg_mountpoint"
							truncate --size="$new_size" -- "$arg_file"
						fi
						rmdir -- "$arg_mountpoint"
						trap - EXIT
					fi
				else
					truncate --size="$arg_size" -- "$arg_file"
					mkfs.btrfs -- "$arg_file"
				fi
			} |& sed "s|^|${prefix} |"
			arg_mountpoint=$(mktemp -dt -- "${0##*/}.XXXXXXXXXX")
			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=(
				50:osi-mk:directories
				99:osi-mk:grub-mkconfig
			)
			if [[ -n $arg_edit_base ]]; then
				post_install+=(
					00:osi-mk:genfstab
				)
			fi
			if ! $arg_edit; then
				packages+=(grub btrfs-progs)
				post_install+=(
					00:osi-mk:genfstab
					98:osi-mk:grub-install
				)
			fi
			for module in "${arg_modules[@]}"; do
				load_module "$module"
			done
			cache_packages+=("${packages[@]}")

			#### install ###
			# shellcheck disable=SC2059
			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
				if (( ${#arg_package_files[@]} > 0 )); then
					dir="$(mktemp -d -- "$arg_mountpoint/tmp/package-files.XXXXXXXXXX")"
					trap "rm -rf -- ${dir@Q}" EXIT
					cp -t "$dir" -- "${arg_package_files[@]}"
					arch-chroot -- "$arg_mountpoint" pacman -U --noconfirm -- "${arg_package_files[@]/#*\//"/tmp/${dir##*/tmp/}"}"
					rm -rf -- "$dir"
					trap - EXIT
				fi
			} |& sed "s|^|${prefix} |"

			### post_install ###
			while IFS=: read -r n fn; do
				# shellcheck disable=SC2059
				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 "$@"