#!/bin/bash

if ! [ -e "/.writable_devices" ]; then
	echo "/.writable_devices not found"
	exit 1
fi
mapfile -t writable_devices < /.writable_devices

declare -rg ntfs_list="/run/openslx/.thin-ntfs-candidates"

. slx-tools

if [ -s "$ntfs_list" ] || [[ "${#writable_devices[@]}" -gt 1 ]]; then
	# More than one device, and/or NTFS space, need linear
	echo "Have more than one writable device, creating linear target"
	tbl="/run/openslx/dmsetup-linear-id44"
	pos=0
	grow_max_sz=9999999999
	for dev in "${writable_devices[@]}"; do
		max="$(( grow_max_sz - pos ))"
		(( max <= 0 )) && break
		sz="$( blockdev --getsz "$dev" )"
		(( sz > 0 )) || continue
		(( sz > max )) && sz="$max"
		echo "$pos $sz linear $dev 0"
		(( pos += sz ))
	done > "$tbl"
	if [ -s "$ntfs_list" ]; then
		sum=
		while read -r sum dev _ || [ -n "$sum" ]; do # each dev
			echo "Appending NTFS partition $dev..."
			word=
			while read -r word range_start_b _ range_sz _ || [ -n "$word" ]; do # each slice of dev
				[ "$word" = "Range" ] || continue
				(( range_sz > 0 )) || continue
				slice_sz="$(( grow_max_sz - pos ))"
				(( slice_sz <= 0 )) && break
				(( slice_sz > range_sz )) && slice_sz="$range_sz"
				# Append line
				if echo "$pos $slice_sz linear $dev $range_start_b" >> "$tbl"; then
					# Update counter
					(( pos += slice_sz ))
				else
					echo "Could not write new table row into $tbl"
				fi
			done < <( ntfsfree --block-size 512 --min-size "$(( 256 * 1024 * 1024 ))" "$dev" )
		done < "$ntfs_list"
		# Don't try to add NTFS space again later
		sed -i "s/^SLX_NTFSFREE.*$/# & # disabled in stage3\nSLX_NTFSFREE='never'/" "/etc/openslx"
		rm -f -- "$ntfs_list"
	fi
	# See if we need a linear target at all
	if ! [ -s "$tbl" ]; then
		echo "Empty tmp/id44 table, fallback to RAM"
	elif [ "$( wc -l < "$tbl" )" -eq 1 ] && [[ "${#writable_devices[@]}" -ge 1 ]]; then
		# Only one line, have writable device -> use directly
		echo "Table somehow ended up with one entry, discarding"
		writable_device="${writable_devices[0]}"
	else
		# set up linear device
		echo "Setting up linear id44 device with $( wc -l < "$tbl" ) slices"
		if ! dmsetup_create_noudevsync "id44-group" < "$tbl"; then
			echo "Error creating group of writable devices. Fallback to RAM :-("
		else
			writable_device="/dev/mapper/id44-group"
		fi
	fi
else
	# Single device
	echo "Have a single writable device, using it directly"
	writable_device="${writable_devices[0]}"
fi

if [ -z "$writable_device" ]; then
	echo "Could not find any suitable writable devices."
fi

echo "$writable_device" > "/.writable_device"

exit 0